WXTLIST APR=AFD WST=PAFC DAY=22357 22358 TIM=00 23 NUM=20 FXAK68 PAFC 241345 2022358 1345 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 445 AM AKST Sat Dec 24 2022 .ANALYSIS AND UPPER LEVELS... At upper levels, a large blocking ridge centered over the Chukchi Sea extends south over the Bering Sea and Aleutian Islands. An Arctic trough is elongated over most of southern Alaska and continues to spread a very cold airmass across the Mainland and eastern Bering and Aleutians. At the surface, a front extends across the southern Bering and is decaying as it tracks towards the North Pacific. Rainfall accompanies the front across the eastern Aleutians. An inverted trough is spreading mixed precipitation across the Alaska Peninsula and snow across the southern Bristol Bay area. The rest of Southwest and Southcentral remain dry and cold this morning. Gusty northeasterly surface winds persist across portions of Southcentral but will gradually diminish through today as the Arctic trough tracks towards the eastern Bering. Blowing snow may continue to reduce visibility through Thompson Pass and across portions of the Matanuska Valley this morning. Strong offshore winds continue along the Kuskokwim Delta and Bristol Bay coasts. Wind Chill Advisories remain in effect through this morning for Thompson Pass, the Copper River Basin, and the Middle Kuskokwim Valley. && .MODEL DISCUSSION... Models are still struggling with the evolution of a surface trough near Kodiak Island and the Alaska Peninsula. There is low confidence in the precipitation forecast for Kodiak Island and across southwest Alaska in the short term. Models are also struggling with the evolution of a surface low that is currently centered over the eastern Gulf and is extending its front along the east Gulf coast. There is general consensus that the low will bring light snow to the Cordova/Valdez area this afternoon and evening and then to the eastern Kenai Mountains during the day on Sunday. There is still some disagreement on whether or not the rest of Prince William Sound will see much, if any, precipitation with this system. && .AVIATION... PANC...VFR conditions will persist through this TAF period. Gusty northerly winds are expected to gradually decrease through this afternoon. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Saturday through Monday night)... Gusty winds will linger across the Matanuska Valley today due to the tight pressure gradient between the arctic high to east and a surface low spinning up near Kodiak Island. These winds, however, are on the decline from yesterday's peak as the upper-level trough moves to the southwest, away from the region, and the cold air advection wanes. Winds will also continue across bays and passes across Prince William Sound, as well as around Valdez and Thompson Pass, as a second surface low lifts northwest from the eastern Gulf. This feature will also begin to spread light snow across the eastern half of Prince William Sound and the Copper River Basin later today. There is still some uncertainty as to the western extent of the snow; however, the latest guidance all have this swath of snow moving over the eastern Kenai Peninsula by Sunday morning as the low weakens and an easterly flow aloft sets up ahead of the next frontal system. The first low near Kodiak Island, will bring snow and occasional wind gusts across the island today. Snow will likely move in from the east later this morning, lingering through late Saturday evening. Expect mesoscale bands of snow with this feature, which will make it difficult to nail down snowfall accumulation for any given location. However, there could be several inches of snow accumulation for locations under the heaviest and most persist bands. Moving into Christmas and beyond, attention shifts to a large deep low tracking into the Gulf from the Northeast Pacific. A strong occluded front out ahead of the low will reach the Gulf coast/Kodiak by late Sunday, bringing widespread gale to storm force winds across the Gulf coastal waters along with moderate to heavy precipitation along much of the coastal zone. Prevailing low level easterly flow will lead to upslope flow and enhanced precipitation amounts across the eastern Kenai Peninsula Mountains. Much warmer air will also accompany the front leading to a fairly quick transition from snow to rain for areas along the coast near sea level. Snow levels for coastal mountains will quickly rise Sunday afternoon/evening, reaching 1000 feet or higher. Precipitation will linger along the coast all the way through Monday. While some moisture will attempt to cross over the coastal mountains, dry and cold air inland will make it difficult to saturate the low levels of the atmosphere. As a result, inland areas of Southcentral look to remain dry. Temperatures will also moderate by Monday with winds increasing once again through the Matanuska Valley and down Cook Inlet in response to the low moving into the western Gulf just east of Kodiak City. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Tuesday)... Colder temperatures and northerly offshore flow continues across the region as a strong shortwave originating from an upper-level trough located across Yukon, Canada continues to advance westward towards Bristol Bay. As a result, wind chills across the region will be in the negative double digits for the next several days. A Wind Chill Advisory is still in effect for the lower Kuskokwim Valley until this afternoon. A surface low will track across the Alaska Peninsula today, but models are having a hard time handling the exact track of the low, and will therefore, impact where the highest winds, precipitation, and blowing snow concerns will be. This forecast package reflects snow continuing for the Alaska Peninsula today before slowly making its way northward towards the Bristol Bay region for tonight, and then reaching the Kuskokwim Delta coast for late tonight into Sunday. As the aforementioned low tracks northeastward along the Chain, northerly winds will increase region wide. With this, the potential for blowing snow coincided with reduced visibilities becomes possible along the Bristol Bay coast and portions of the Alaska Peninsula. As a result, a Winter Weather Advisory has been issued for the Bristol Bay coast. Total snow accumulations of 6 to 10 inches along the southern Bristol Bay coast and 4 to 6 inches along the northern Bristol Bay coast are expected. Expect visibilities reduced to as low as 1/2 mile from Dillingham north and west and from Port Heiden to King Salmon possible as well. A strong North Pacific low and its associated front will approach and impact the region Sunday through Tuesday. This will bring a rain/snow mix to the Alaska Peninsula, while mostly snow is expected for the western interior portions of Bristol Bay. Higher accumulations are forecasted to stay confined to the mountain areas at this time. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today through Tuesday)... Active weather will continue for the Bering and Aleutians for the next several days. A surface low tracking across the Alaska Peninsula will today will eventually make its way into the eastern Bering. Models are having a hard time handling the exact track of the aforementioned low, but colder air and strong winds are likely to occur with snow being the main precipitation type for this system. Depending on where the low tracks and how strong the winds get, the potential for blowing snow coinciding with reducing visibilities is possible for some locations. Snow will make its way to the Pribilofs late tonight into Sunday morning. Strong winds should move out of the area before the snow hits, but some blowing snow may still occur.The system then continues westward through the Bering through Sunday afternoon into the evening before making a southern turn to the North Pacific while crossing the central Chain through Monday. Snow amounts appear to be light for the Aleutians overall, with the highest accumulations confined to the mountain areas. Be sure to check back in with the forecast for updates as the evolution of this system becomes more clear. $$ .LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The latest operational model runs and ensemble means seem to be in a decent agreement with an upper level low over the western Bering Sea near Adak, and high pressure remaining over Siberia. While the upper low sits nearly stationary between Tuesday and Wednesday, a series of North Pacific systems rotates around the low, moving north-northeastward past the Aleutians and into the Gulf of Alaska. This will bring an unsettled pattern for all of the coastal areas of Southcentral heading into late next week. While specific details still need to ironed out, persistent onshore flow will favor moderate to heavy precipitation for the coast, with much of the mainland remaining relatively dry during the period. A general troughing pattern out west will result in a wet pattern for much of the Bering Sea and Aleutians. Cold, northerly flow over the relatively warm waters will also help generate widespread showers over the Pribilof Islands and along the Aleutian Chain. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Blizzard Warning: 111. Wind Chill Advisory: 131, 141, 152. Winter Weather Advisory: 161. MARINE...Storm Warning: 130, 131, 138, 351. Gale Warning: 119, 120, 127, 128, 132, 136, 137, 139, 150, 160, 179-181, 185, 352, 411-414. Heavy Freezing Spray: 127, 160, 139, 179-181, 185, 414. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...AF SOUTHCENTRAL ALASKA...TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS LONG TERM...MF FXAK68 PAFC 240132 2022358 0132 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 432 PM AKST Fri Dec 23 2022 .ANALYSIS AND UPPER LEVELS... A Rex Blocking pattern currently extends across the North Pacific with low pressure south of the Aleutians and high pressure extending from Siberia to across the Alaskan mainland. Closer to the surface, observations show strong northeasterly flow across Southcentral. The strongest winds have been observed in the Matanuska Valley where the strongest gusts have been near 70 mph. Gusts near 60 mph occurred at Ted Stevens International Airport. Radar shows little to no shower activity across the area. && .MODEL DISCUSSION... Forecast confidence remains low overall except for the immediate short term forecast. There is good agreement with the overall trend for strong winds across Southcentral to ease over the next several hours. However, model agreement has diverged since yesterday's runs with respect to a low moving across the Alaska Peninsula on Saturday. This means there is very low confidence with respect to the snowfall forecast for Kodiak and across Southwest Alaska. && .AVIATION... PANC...VFR conditions will persist for this TAF period. Winds will gradually ease during the afternoon and evening hours across the area. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Tonight through Monday)... The upper level trough and associated cold air advection which produced strong winds and blowing snow across portions of Southcentral today has exited to Southwest Alaska. However, low pressure down over the Gulf of Alaska will maintain very tight pressure gradients. Low level flow behind the upper trough will also be slow to slacken. As a result, expect winds to linger tonight into Saturday, especially through mountain passes/valleys. Have extended the Blizzard Warning for the Matanuska Valley all the way through Saturday morning at which point winds should significantly diminish. Gusty winds and blowing snow will also linger along Knik Arm and the Glenn Highway Corridor down into north to west Anchorage. A more aggressive digging of the upper level trough is leading to a change in track of the low currently over the southern Gulf. It will remain over the eastern half of the Gulf as it track northward tonight and Saturday, leading to a much slower arrival of snow for the Copper River Basin and Valdez/Cordova areas. Now expect light snow to arrive in the far southeastern Copper River Basin overnight tonight then spread slowly westward across the Copper River Basin and eastern Prince William Sound on Saturday. The western extent of snow on saturday is very much in question, but it is looking less and less likely that the eastern Kenai Peninsula will see much, if any snow, from this system. Meanwhile, a separate surface trough tracking westward across the Gulf will reach Kodiak Island late tonight through Saturday. Expect mesoscale bands of snow with this trough, which makes it difficult to nail down snowfall accumulation for any given location. Do expect all of Kodiak Island to see some light accumulation. There will also be some stronger gusty winds with this which could briefly reduce visibilities to around one half mile at times. The trough and associated snow will dissipate by late Saturday. As we continue to Christmas Day and beyond, all attention will shift to a large deep low tracking into the Gulf from the Northeast Pacific. A strong occluded front out ahead of the low will reach the Gulf coast/Kodiak by late Sunday, bringing widespread gale to storm force winds across the Gulf coastal waters along with moderate to heavy precipitation along much of the coastal zone. Prevailing low level easterly flow will lead to upslope flow and enhanced precipitation amounts across the eastern Kenai Peninsula Mountains. Much warmer air will also accompany the front leading to a fairly quick transition from snow to rain for areas along the coast near sea level. Snow levels for coastal mountains will quickly rise Sunday afternoon/evening, reaching 1000 feet or higher. Precipitation will linger along the coast all the way through Monday. While some moisture will attempt to cross over the coastal mountains, dry and cold air inland will make it difficult to saturate the low levels of the atmosphere. As a result, inland areas of Southcentral look to remain dry with slowly warming temperatures as we head to the beginning of next week. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: This afternoon through Monday afternoon )... Conditions have largely quieted down for the Alaska Peninsula (AKPEN) although scattered rain showers linger around the southern AKPEN as weak low pressure continues to move westward in the North Pacific. A strong shortwave ejecting from an upper trough across Yukon, Canada continues to advance westward towards Bristol Bay this afternoon and through the evening. This will bring cold temperatures and continued offshore flow to mainland Southwestern Alaska. Windchills are expected to be quite low this evening due to the winds in conjunction with the cold air advection as the closed upper low continues westward towards the eastern Bering Sea. In response, a Windchill Advisory is in effect from this until Saturday afternoon. Meanwhile, a surface low is expected to develop around the northern AKPEN very early Saturday morning. There is uncertainty with the exact track as guidance continues to struggle with how to handle the surface feature. Another level of uncertainty is pinpointing exactly where mesoscale banding will set up along the AKPEN Saturday morning through evening, in addition to how far north into the Southwest mainland the precipitation reaches. The current thinking now is that the AKPEN will see precipitation mostly in the form of snow, while coastal sections of Bristol Bay and the Kuskokwim Delta will see less snow. Precipitation winds down for coastal Southwest overnight Saturday, while easterly to southeasterly upslope flow keeps the North Pacific side of the AKPEN unsettled through Sunday morning. A strong North Pacific low and its front approach Sunday afternoon through Monday afternoon as rain/snow mix is likely for the AKPEN, while mostly snow is expected for the western interior sections of Bristol Bay. Most accumulation is confined to the mountains. Please stay tuned to additional forecast updates as details continue to be fine-tuned in both the near-term and short-term during this complex weather pattern. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: This afternoon through Monday afternoon)... Active weather will continue for the Bering Sea and Aleutians during the short-term period. Scattered snow showers continue to taper off for the Pribilofs tonight as a frontal system continues to push westward across the Bering and the rest of the Aleutian Chain Saturday morning through the afternoon, bringing an additional band of rain/snow showers exiting the western Chain Saturday evening. Back east, a surface low is expected to develop across the Alaska Peninsula early Saturday morning in response to a strong closed upper low moving westward across Southwestern Alaska and into the eastern Bering Sea. There is still lots of uncertainty with this feature as guidance continues to struggle with the evolution of the system. Uncertainty is especially heightened for the Pribilof Islands for Sunday. Snow looks to be the dominant precipitation type as the system will be dragging cold air with it from mainland Alaska. The ultimate track of the surface feature will determine how much snow and how windy the Pribilofs get for Sunday. Some guidance has the system tracking a little more north of the Pribilofs, while some guidance also depicts the system taking a more southern track which would be more favorable for higher winds and more snowfall. The system then continues westward through the Bering during Sunday afternoon into the evening before making a southern turn to the North Pacific while crossing the central Chain through the day on Monday. Snow amounts appear to be light for the Aleutians overall, with most accumulation confined to the mountains. Please check back for the latest forecast updates as finer details on evolution and track continue to be fine-tuned for the surface low pressure system expected to traverse the eastern and central Bering Sea. $$.LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The latest operational model runs and ensemble means seem to be in a decent agreement with an upper level low over the western Bering Sea near Adak, and high pressure remaining over Siberia. While the upper low sits nearly stationary between Tuesday and Wednesday, a series of North Pacific systems rotates around the low, moving north-northeastward past the Aleutians and into the Gulf of Alaska. This will bring an unsettled pattern for all of the coastal areas of Southcentral heading into late next week. While specific details still need to ironed out, persistent onshore flow will favor moderate to heavy precipitation for the coast, with much of the mainland remaining relatively dry during the period. A general troughing pattern out west will result in a wet pattern for much of the Bering Sea and Aleutians. Cold, northerly flow over the relatively warm waters will also help generate widespread showers over the Pribilof Islands and along the Aleutian Chain. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Blizzard Warning: 111, 131. Wind Chill Advisory: 141, 152. MARINE...Storm Warning: 130. Gale Warning: 119, 120, 125, 127-128, 130, 138-140, 160, 179-181, 185, 351, 411-414. Heavy Freezing Spray: 127-128, 139-140, 160, 179-181, 185, 412, 414 FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...ED SOUTHCENTRAL ALASKA...SB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DN LONG TERM...MF FXAK68 PAFC 231422 2022357 1423 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 522 AM AKST Fri Dec 23 2022 .ANALYSIS AND UPPER LEVELS... At upper levels, a large blocking ridge continues to build over the Chukchi Sea while extending over northwest Alaska. A trough from the Arctic is dropping south across southeast Alaska and approaching Southcentral, bringing a very cold airmass with it. A low near the western Aleutians is exiting into the North Pacific. At the surface, cold and clear conditions persist across most of southern Alaska. A front extends from the eastern Gulf of Alaska east to Kodiak Island and the Alaska Peninsula. Another front extends from the eastern Aleutians east across the Bering Sea. Precipitation with the fronts have been quite variable across both the east and west domains. The eastern Aleutians are primarily seeing rain, while Kodiak Island and the Pribilof Islands have been getting rain, snow, and even a rain/snow mix at times. Strong winds are a continued theme across both forecast domains. Widespread easterly gale-force winds blanket the Gulf, Alaska Peninsula, eastern Aleutians, and Bering Sea. Gusty offshore winds persist along the Bristol Bay and Kuskokwim Delta coasts. With the deep Arctic trough approaching Southcentral, gusty northeasterly winds have started developing across portions of the Mat-Su Valleys, northeast Prince William Sound (including Valdez, Thompson Pass, and Cordova), and the Copper River Basin. Various locations within these areas are already seeing reduced visibilities from blowing snow as the strong winds transport existing snow from the ground. Blizzard Warnings remain in effect today for Valdez, Thompson Pass, and the Matanuska Valley. The Anchorage area is seeing an uptick in gusty winds, though they are not expected to get as strong as the winds in the aforementioned areas. Frigid temperatures coupled with strong winds are promoting very low winds chills across much of inland Southcentral, especially for the Copper River Basin and through Thompson Pass where Wind Chill Advisories remain in effect today. && .MODEL DISCUSSION... Guidance remains in decent agreement with larger scale features through approximately Saturday afternoon. Thereafter, models struggle to resolve the exact evolution of a surface low that forms south of the Alaska Peninsula (AKPen) earlier that morning. There is general consensus for the low to eventually push into the Bering, but the timing, track, and strength of the low differs amongst the models. Thus, precipitation and wind forecast confidence decreases beyond Saturday afternoon mainly for Kodiak Island, southwest Alaska, and the eastern Bering/Aleutian region. && .AVIATION... PANC...VFR conditions will persist through this TAF period. Northerly winds are increasing this morning and are expected to peak early this afternoon through this evening. An Airport Weather Warning remains in effect for northerly winds gusting to 35 kt or greater. Gusty winds should be relatively continuous, but there may be brief periods where winds die down. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Friday through Sunday night)... The forecast remains on track for a "bora" windstorm across Southcentral through Friday night, with widespread gusty winds, and with very cold air temperatures and wind chills returning later today. The arctic trough responsible for the impactful weather has moved south over Southcentral this morning. This feature continues to look a bit stronger and has a more southern progression than in previous model runs. As such, wind gusts from Palmer and Wasilla to Valdez have been slightly stronger than initially advertised, and the morning forecast package reflects forecasted wind gusts of up to 75 mph today for the Matanuska Valley and up to 65 mph for Valdez and Thompson Pass. The greatest impacts from this event will come from reduced visibilities due to blowing snow and hazardous travel conditions due to significant drifting of snow. Although the Matanuska Valley and Valdez area will see the strongest winds with this system, gusty winds will also develop across a larger portion of Southcentral gusty winds expected over the northern Copper River Basin (along the Alaska Range), through Thompson Pass/Valdez, the Susitna Valley, north to west Anchorage and the western Kenai Peninsula from Nikiski south to Homer. The gusty winds will begin to slowly diminish Friday night. However, winds will remain elevated through Saturday due to the tight pressure gradient between the arctic high and a surface low spinning up near Kodiak Island, moving northwest across the AKPen on Saturday. This area of low pressure could also bring light snow across the southern half of the Kenai Peninsula later tonight and across Kodiak Island through Saturday. A second area of low pressure will lift north across the eastern Gulf of Alaska, pivoting toward eastern Price William Sound for Saturday. This low is expected to be a compact low, keeping winds strong along the north Gulf coast. This feature will also spread snow from Cordova and the Copper River Basin Saturday west to the eastern Kenai Peninsula late Saturday night or early Sunday morning. Snowfall is expected to be light across all areas due to the antecedent colder and drier airmass. A much larger and stronger storm system is then expected to move toward the southern Gulf for Sunday with its occluded front extending northward across the northern and western Gulf. The front will bring precipitation to Kodiak Island Sunday and along the north Gulf coast by late Sunday. The airmass out ahead of this will start out cold enough for snow, but there likely will be a transition to rain along the immediate coast Sunday night into Monday as warmer air moves in with the front. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Sunday)... A rain/snow mix will continue for the Alaska Peninsula through this morning as easterly to southeasterly upslope flow continues. A robust shortwave will eject westward from an upper-level trough located over Yukon, Canada this afternoon/evening. This will result in producing a strong low pressure system over the Alaska Peninsula. Models are having a hard time handling the exact track of the low, and will therefore, impact where the highest winds, precipitation, and blowing snow concerns will be. This forecast package reflects precipitation impacting the Alaska Peninsula tonight, then working its way north into the Bristol Bay region for Saturday, and finally reaching the Kuskokwim Delta coast for Sunday. As the aforementioned low tracks northeastward along the Chain, northerly winds will increase region wide. With this, the potential for blowing snow coincided with reduced visibilities becomes possible along the Bristol Bay coast and portions of the Alaska Peninsula. Due to elevated frigid northerly winds, wind chill concerns also arise as this system progresses. As a result, a Wind Chill Advisory has been issued for the Middle Kuskokwim Valley starting tonight and expiring Saturday afternoon. Be sure to check back in with the forecast as models get a better handle on this feature and the possible impacts it may have. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today through Sunday)... Active weather will continue for the Bering and Aleutians for the next several days. A Flood Warning is still in effect for Unalaska/ Dutch Harbor until 11:45 AM this morning as scattered showers continue in the area. The low pressure responsible for the rain across the eastern Aleutians the past few days continues to elongate and weaken as it slowly drifts northwestward. The Pribilofs will continue to see scattered rain and snow showers today before tapering off in this afternoon/evening as multiple shortwaves traverse westward over the central Bering. A robust shortwave will eject westward from an upper-level trough located over Yukon, Canada this afternoon/evening. This will result in producing a strong low pressure system over the Alaska Peninsula. Models are having a hard time handling the exact track of the aforementioned low, but colder air and strong winds are likely to occur with snow being the main precipitation type for this system. Depending on where the low tracks and how strong the winds get, the potential for blowing snow coinciding with reducing visibilities is possible for the eastern Aleutians and Pribilof Islands. Be sure to check back in with the forecast for updates as the evolution of this system becomes more clear. $$ .LONG TERM FORECAST (Days 4 through 7: Monday through Thursday)... Looking ahead in the extended forecast, the latest model runs and ensemble guidance are in fairly decent agreement with the evolution and progression of the synoptic features. An upper level wave over northeastern Alaska will retrograde southwestward into a closed upper low. Compared to previous runs where the center of the low was over the eastern Bering, the models now track it to the western Bering instead. The low will remain quasi-stationary early next week, but models significantly diverge from Tuesday onward. Meanwhile, the upper low will push storm systems from the Pacific into the Gulf of Alaska. While specific details still need to ironed out, most of the coastal areas will see some wintry mix and inland areas will stay on the drier side. A general troughing pattern associated with the aforementioned low out west will result in an unsettled pattern for much of the Bering Sea and Aleutians Islands heading into late next week. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Blizzard Warning: 111, 131. Flood Warning: 185. Wind Chill Advisory: 131, 141, 152. MARINE...Storm Warning: 130, 139. Gale Warning: 119, 120, 125, 127, 128, 131, 132, 138, 140, 150, 160, 165, 179-181, 351, 352, 411-414. Heavy Freezing Spray: 127, 128, 130, 139, 140, 180, 181, 185, 160, 414. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...AF SOUTHCENTRAL ALASKA...TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS LONG TERM...MF FXAK68 PAFC 230145 2022357 0145 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 445 PM AKST Thu Dec 22 2022 .ANALYSIS AND UPPER LEVELS... A Rex Blocking pattern currently extends across the North Pacific with high pressure extending from Siberia to across the Alaskan mainland and low pressure to the south of the Aleutian Islands. This pattern is resulting in rain and strong winds for the central and eastern Aleutians. Closer to the surface, radar shows rain slowly moving northward along the Alaska Peninsula. && .MODEL DISCUSSION... Guidance remains in good agreement with respect to the placement and intensity of synoptic scale features at both the surface and in the upper levels. There is some model discrepancy on the exact track of a low in the Gulf Friday into Saturday. Therefore, there is moderate confidence at best with respect to the Friday night through Saturday morning snowfall forecast for Kodiak Island. && .AVIATION... PANC...VFR conditions will persist for this TAF period. Northeasterly winds will increase tonight into Friday. Confidence is high that winds will meet and or exceed 35 kt Friday afternoon and continue into the evening across the air field. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Tonight through Sunday)... The forecast is on track for a "bora" windstorm across Southcentral tonight through Friday night, with widespread gusty winds and very cold air temperatures and wind chill temperatures. The Arctic trough diving southwestward across Southcentral does look a bit stronger than yesterday, which is reflected in the strength of low level cold air advection and strength of the low level jet. As a result, maximum wind gusts on Friday could be a bit higher than the forecast. The greatest impacts from this event will come from reduced visibilities due to blowing snow. Secondarily, areas of drifting snow could deepen and create an additional hazard. The worst hit area will be the Matanuska Valley where some of the strongest winds are expected. However, gusty winds will develop across much of Southcentral tonight and Friday, with some of the stronger winds expected over the northern Copper River Basin (along the Alaska Range), through Thompson Pass/Valdez, the Susitna Valley, north to west Anchorage and the western Kenai Peninsula from Nikiski south to Homer. Winds will begin to diminish friday night, but is will be a slow process as pressure gradient remain tight with a surface low crossing the Gulf. This low will bring snow back into the forecast, arriving in the Copper River Basin and eastern Prince William Sound areas Friday night/Saturday morning before spreading west to the eastern Kenai Peninsula during the day Saturday. This system will be fairly weak in nature, so snowfall will be light. Low level offshore flow out ahead of the low will also tend to maintain drier near surface air, which supports the idea of lighter snowfall. A much larger and stronger storm system will make its way into the Gulf Saturday night through Sunday. With a far south storm track, the strongest winds and heaviest precipitation will initially remain down over the Gulf through Sunday. However, an occluded front will spread out from the low center, bringing precipitation to Kodiak Island Sunday and onshore along the north Gulf coast by late Sunday. The airmass out ahead of this will start out cold enough for snow, but there likely will be a transition to rain along the immediate coast Sunday night into Monday as warmer air moves in with the front. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: This afternoon through Sunday afternoon)... The gusty conditions from this morning have quieted down along the Alaska Peninsula (AKPEN) as pressure gradients have somewhat relaxed. Light precipitation returns are apparent on the King Salmon radar over Bristol Bay land and marine zones this afternoon, but due to dry air near and at the surface, very little is reaching the ground. Any precipitation around Bristol Bay comes to an end tonight as a Bering Sea system continues tracking westward near the central Aleutian Chain. The AKPEN continues with a rain/snow mix through Friday afternoon as easterly to southeasterly upslope flow continues. A robust shortwave ejects westward from an upper trough located over Yukon, Canada Friday afternoon into the evening hours. This will spawn a strong low pressure system over the AKPEN/Extreme southeastern Bering Sea Saturday morning. At this time, it appears that coastal Bristol Bay and southern Kuskokwim Delta locations stand the best chance at seeing some precipitation in the form of snow early Saturday morning. Amounts, if any, appear to be light due to the low being too far off shore at this time. The potential is there for more accumulation if the low forms further eastward and closer to the coast. The bigger story for Saturday will be in the evening and overnight as strong gusty northeast offshore flow strengthens. Wind-chills could be quite low as cold air advects in from the northeast. Conditions for Christmas Day are trending to be quiet and cold for mainland Southwest, with the southern AKPEN remaining somewhat active with scattered rain/snow showers. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: This afternoon through Sunday afternoon)... Active weather will continue for the Bering Sea and Aleutian Chain through the short-term period. The heaviest rain has tapered off from Unalaska/Dutch Harbor with only scattered showers around the area. A flood warning is still out for that area until Friday morning. The low pressure responsible for all the rain over the eastern Aleutians over the past few days continues to elongate and weaken as it slowly drifts northwestward. The Pribilofs continue to see scattered rain and snow showers through day on Saturday before tapering off in the afternoon and evening as multiple shortwaves traverse westward over the central Bering. Some uncertainty then ensues for Saturday afternoon through the rest of the short-term period on Christmas Day. A robust shortwave ejects westward from an upper trough in Yukon, Canada. The general evolution takes the shortwave over Southwest and into Bristol Bay/Eastern Bering where a strong surface low pressure is set to spin up around the Alaska Peninsula. At this time, the exact track of the surface feature is not well resolved, but current indications are that the system will pull down quite a bit of cold air from mainland Alaska and snow would be the dominant precipitation type with this system. Please pay attention to additional forecast updates as details continue to be nailed down and the evolution of this potential winter storm become clearer. $$.LONG TERM FORECAST (Days 4 through 7: Monday through Thursday)... Looking ahead in the extended forecast, the latest model runs and ensemble guidance are in fairly decent agreement with the evolution and progression of the synoptic features. An upper level wave over northeastern Alaska will retrograde southwestward into a closed upper low. Compared to previous runs where the center of the low was over the eastern Bering, the models now track it to the western Bering instead. The low will remain quasi-stationary early next week, but models significantly diverge from Tuesday onward. Meanwhile, the upper low will push storm systems from the Pacific into the Gulf of Alaska. While specific details still need to ironed out, most of the coastal areas will see some wintry mix and inland areas will stay on the drier side. A general troughing pattern associated with the aforementioned low out west will result in an unsettled pattern for much of the Bering Sea and Aleutians Islands heading into late next week. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC - MARINE - FIRE WEATHER: Please visit weather.gov/anchorage for the current list && $$ SYNOPSIS AND MODEL DISCUSSION...ED SOUTHCENTRAL ALASKA...SB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DN LONG TERM...MF WXTLIST APR=AFD WST=PAFC DAY=22358 22359 TIM=00 23 NUM=20 FXAK68 PAFC 251419 2022359 1419 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 519 AM AKST Sun Dec 25 2022 .ANALYSIS AND UPPER LEVELS... Low pressure centered just off the coast of Bristol Bay shifts to track westward across the Bering Sea towards the Western Aleutians into early next week. Longwave troughing extends into southwestern Alaska. Resultant snow across Bristol Bay can be seen on Radar, with the edge of the snow band sitting over Dillingham, and increased winds across the region have been observed throughout the night. Meanwhile, a North Pacific low makes its way towards the western Gulf of Alaska. As it reaches near Kodiak Island, it begins to mesh with the Bering Sea low, becoming an elongated trough in the upper levels. The surface reflection at the base of the upper trough will become relatively stagnant, sitting east of the Barren Islands through Tuesday afternoon. There will be a tightening of the pressure gradient in the Mat Valley Sunday afternoon through Monday morning, leading to another round of windy conditions. Shifting gears back west, the Bering low reaches the Western Aleutians late Monday night, where it will begin to interact with a second North Pacific low. The systems will Fujiwara around each other, with the initial low being pulled into the North Pacific and the second low being shunted off towards the Eastern Aleutians. && .MODEL DISCUSSION... Models remain in good overall synoptic agreement through the short term. There remains some light discrepancies towards as the Bering Sea system begins to interact with another incoming North Pacific low. The main forecast challenge will be winds through the Mat Valley as the pressure gradient tightens Sunday afternoon into Monday morning. && .AVIATION... PANC...VFR conditions will persist. Gusty northerly winds will continue throughout the day. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Christmas Day through Tuesday night)... Area of light snow persists this morning across the eastern Kenai Peninsula, due to the combination of a weakening inverted trough and the easterly flow aloft providing a moisture tap running up against the coastal mountains. Elsewhere, conditions are generally quiet this morning. A surface ridge over the Al-Can continues to keep colder air locked in place over the interior. However, temperatures are moderating slightly as cloud cover increases from south to north. The increase in cloud cover is associated with a mature low over the north Pacific and its associated occluded front lifting north into the Gulf of Alaska. Both feature will move north today, with widespread precipitation and easterly storm-force winds developing out ahead of the front. Expect strong winds and a rain/snow mix changing quickly to rain for Kodiak City later this morning, with precipitation moving to the Southcentral coast by afternoon. Precipitation is expected to begin as all snow, but will transition to rain for Whittier and Portage Valley by tonight as the stout easterly flow and gusty southeasterly surface winds usher in much warmer air, with temperatures pushing above freezing for Whittier, Seward, and Portage. Snow will also quickly changeover to rain for Cordova as gusty east winds drive in warmer air. For Valdez and points north, temperatures should stay cold enough for all snow, as the surface front stalls along the coast. The strong cross-barrier flow will likely limit precipitation changes along the lee of the Chugach and Kenai Mountains. However, there is the change for some moisture to spill over, resulting in flurries or periods of very light snow for Kenai to Anchorage and Talkeetna later today. With warmer air moving in aloft, there is also the potential that some very light freezing rain may mix in with snow around Homer and along the southwestern Kenai Peninsula coast. Any freezing rain/drizzle is expected to be light and not result in any impacts. A fairly active pattern will continue over the next few days across Southcentral Alaska. Low pressure will move into the Gulf on Sunday and will result in widespread gale force winds with areas of storm force winds in the northern Gulf. These winds will gradually ease as the low lifts northward through Monday night. The biggest forecast challenge is snowfall amounts and precipitation type across Kodiak Island and along the southern coast of the Kenai Peninsula. The precipitation is likely to be confined to the windward side of the mountains due to strong downsloping on the leeward side as a result of strong cross barrier flow. The other concern will be an increase in gusty winds across the Matanuska Valley beginning later today. Gusts are expected to peak between 50 and 60 mph Sunday night through Monday morning before slowly diminishing for Tuesday. Precipitation will persist along the coast through Tuesday as the front stays put and the the low slowly moves north toward the southern tip of the Kenai Peninsula. Temperatures will continue to warm through the period, reaching near or slightly above normal by the start of next week. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Tuesday)... The upper low and surface meso will continue to move west and out of the region this morning, bringing an end to snow for most areas today. A strong low currently in the north Pacific will move towards Kodiak Island late tonight, with some overrunning snow expected for Bristol Bay and the Alaska Peninsula (AKPen). The associated upper level feature will quickly break apart at it interacts with ridging over the interior and the dominant upper low over the central Bering. As a result, precipitation will have a hard time making it far inland. Easterly flow off the mountains, in combination with warm air advection, will create a potentially above freezing layer aloft from Egegik to Iliamna through Monday. This layer isn't expected to be particularly deep, so sleet may mix in with any snow that manages to overcome the downsloping. On Tuesday, cold air advection will move back in from the Bering, which will help to negate this problem for any remaining precipitation. Generally speaking precipitation is expected to be very light over the coming days. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today through Tuesday)... A tight upper low between St. Paul and Nunivak Island this morning will expand and become in dominant feature in the Bering for the coming days. Light and intermittent snow will continue for most of the Chain and Pribilof Islands through Monday, with ample cold air continuing to move south through the Strait and off of western Alaska. An additional system will move north towards the Aleutian Chain on Tuesday, returning rain and stronger southeasterly winds to the central and eastern Aleutians. $$.LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)... The overall pattern for the first half of the extended outlook is likely to remain about the same, with a broad Aleutian low drifting slowly along and south of the Aleutian Chain out west through at least Friday. A loosely-defined longwave trough will persist aloft across the Bering, resulting in an unsettled pattern out west with gusty winds likely in gale force range wrapping around the main low at the surface near the southern Bering on Wednesday and Thursday. Light onshore flow over Southcentral should keep any areas of snow and coastal rain confined near the Prince William Sound, eastern Kenai Peninsula and across Kodiak Island, with most inland areas remaining dry and seasonably mild. Very weak steering flow again should result in very slow progression of both the larger scale pattern and smaller waves rotating around the Bering trough/low, with the vast majority of the Pacific jet likely to remain well south of the outlook area until the end of the week. This weak steering also causing models to struggle with the handling of smaller scale features, with the details for individual perturbations really falling apart by Thursday and Friday. There are some early indications for a shift in the pattern to commence by Saturday, as the low meandering near the Aleutians finally begins to shift into the western Gulf and amplifies the upstream ridge over the Gulf and portions of Southcentral. This could result in much heavier precipitation spreading along the coast between Kodiak and the Prince William Sound by this weekend. However, large model spread by this point in time still leaves much of the remaining details left to be determined. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Winter Weather Advisory: 131 195 MARINE...Storm Warning: 119 120 130 131 138 185 351 Gale Warning: 125 127 128 132 136 137 139 140 150 160 181 352 411 414 Heavy Freezing Spray Warning: 139 140 160 180 181 412 414 FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...KM SOUTHCENTRAL ALASKA...TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CJ LONG TERM...AS FXAK68 PAFC 250156 2022359 0156 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 456 PM AKST Sat Dec 24 2022 .ANALYSIS AND UPPER LEVELS... At the upper levels, a large blocking high centered near the Chukchi Sea extends south over the western Bering Sea and Aleutian Islands. An Arctic trough is elongated across the southern Alaska mainland and continues to spread a very cold airmass across the Mainland, eastern Bering, and AKPen. At the surface, a surface low and occluded front sits across the northern AKPen into Bristol Bay while a cold front is south of the AKPen. This frontal system is producing light snow across Kodiak Island, the northern AKPen, and Bristol Bay. Cold temperatures are evident across Southwest Alaska with single digits to below zero temperatures with wind chills ranging from -20 to -35 across the area with the coldest across the Kuskokwim Delta. Gusty winds are also occurring across the southwest with 30 to 40 mph sustained winds and gusts up to 50 mph. Across the Pribilofs and Aleutians temperatures are in the 20s along the Pribilofs and 30s across the Aleutian chain. Temperatures along the AKPen are in the 20s across southern areas with single digits to teens across the northern AKPen. Gusty winds are also seen across the Pribilofs, Bering Sea, and eastern Aleutians with 30 to 40 knot winds with lighter winds across the central and western Aleutians. Over the gulf a compact surface low continues to spin across the northeastern Gulf bringing light snow near eastern Prince William Sound. Cold temperatures continued to be observed across Southcentral with negative teens to single digits inland and teens to 20s near the coast. && .MODEL DISCUSSION... Models are in good agreement through Monday with only minor differences. The low bringing cold air into the Southwest and Bering Sea is handled fairly well as it tracks west across the Bering through Monday with only minor differences in the track and position of the low. A frontal system with strong winds will track into the Gulf Sunday and Monday with good model agreement. Additionally, the parent low to this front will track towards Kodiak Island with only minor differences in track and strength, but overall it is handled well by all the models. The main forecast challenges will be the possibility of blowing snow across the Pribilofs through tonight and Sunday and the strength of the Mat valley winds Sunday afternoon through Monday morning. && .AVIATION... PANC...VFR conditions will persist through this TAF period. Gusty northerly winds are expected to gradually ease through this afternoon and then increase tomorrow morning with gusts of 25 to 30 knots possible. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... A fairly active pattern will continue over the next few days across Southcentral Alaska. Low pressure will move into the Gulf on Sunday and will result in widespread gale force winds with areas of storm force winds in the northern Gulf. These winds will gradually ease as the low lifts northward through Monday night. The biggest forecast challenge is snowfall amounts and precipitation type across Kodiak Island and along the southern coast of the Kenai Peninsula. The precipitation is likely to be confined to the windward side of the mountains due to strong downsloping on the leeward side as a result of strong cross barrier flow. There will be a persistent Matanuska Valley wind during the period. However, this wind will remain in the 12-20 kt range and gusts in the 20-25 kt range. A Wind Chill Advisory remains in effect for Thompson Pass due to wind chill values reaching -40F at times. Temperatures will become warmer over the next few days across Southcentral as the aforementioned low brings warm air advection across the region. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Tuesday)... A developing low pressure system in Bristol Bay will bring significant snowfall accumulations and blowing snow to parts of Bristol Bay tonight into Sunday morning. Some adjustments have been made to the Winter Weather Advisory with the location of heaviest snow accumulations and lowest visibilities from blowing snow. Snow accumulations up to 10 inches can be expected through the morning hours along a line from north and west of Dillingham to the Alaska Peninsula between King Salmon and Pilot Point. Snowfall accumulations approach zero rather abruptly east of Koliganek and King Salmon. Areas that see snow will be at risk for half mile visibilities as strong northerly winds continue to flow offshore. Low visibilities will end with the snow from east to west on Sunday morning as the low pressure system exits into the Bering Sea. Elsewhere, the strong northerly offshore winds will be the main weather influence keeping Southwest Alaska cold through the short term. Wind chills in the -30s continue this evening in parts of the Kuskokwim Delta and Lower Kuskokwim Valley before temperatures begin to warm Sunday morning. The warming will be most pronounced in the lee of the Aleutian Range, as well as the Kilbuck and Ahklun Mountains where easterly flow aloft is causing downslope compressional warming. This will gradually lead to the development of a very thin layer of warm air aloft across Southwest Alaska as a low in the Gulf approaches on Sunday. Some scattered, light precipitation will be possible over Bristol Bay Sunday and Sunday night in the presence of this warm layer, which may lead to some sleet mixing with snow at times. Then, colder air works in on Monday as the low moves in over Southwest Alaska. Light snow will be the result Monday and Monday night, primarily over Bristol Bay, with accumulations of only a few inches expected. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today through Tuesday)... A surface low centered in Bristol Bay this evening will track westward into the eastern Bering Sea tonight. Ahead of the low, widespread light snow will develop and move across the Pribilof Islands. This is now expected to occur while 40 mph northerly winds are still streaming across the Bering. Blowing snow will therefore be likely tonight for the Pribilofs and last through Sunday morning, when the low center tracks near the islands and winds begin to diminish. The system then continues westward through the Bering on Sunday before dipping south toward the Aleutian Islands by Monday. Snow amounts of two inches or less are expected with this system for the central and western Aleutians. Calmer weather returns for Tuesday as winds gradually diminish across the Bering. $$.LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)... The overall pattern for the first half of the extended outlook is likely to remain about the same, with a broad Aleutian low drifting slowly along and south of the Aleutian Chain out west through at least Friday. A loosely-defined longwave trough will persist aloft across the Bering, resulting in an unsettled pattern out west with gusty winds likely in gale force range wrapping around the main low at the surface near the southern Bering on Wednesday and Thursday. Light onshore flow over Southcentral should keep any areas of snow and coastal rain confined near the Prince William Sound, eastern Kenai Peninsula and across Kodiak Island, with most inland areas remaining dry and seasonably mild. Very weak steering flow again should result in very slow progression of both the larger scale pattern and smaller waves rotating around the Bering trough/low, with the vast majority of the Pacific jet likely to remain well south of the outlook area until the end of the week. This weak steering also causing models to struggle with the handling of smaller scale features, with the details for individual perturbations really falling apart by Thursday and Friday. There are some early indications for a shift in the pattern to commence by Saturday, as the low meandering near the Aleutians finally begins to shift into the western Gulf and amplifies the upstream ridge over the Gulf and portions of Southcentral. This could result in much heavier precipitation spreading along the coast between Kodiak and the Prince William Sound by this weekend. However, large model spread by this point in time still leaves much of the remaining details left to be determined. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC... Winter Weather Advisory: 195, 161 Wind Chill Advisory: 131 MARINE... Gale Warning: 127, 136, 137, 139, 150, 160, 179, 180, 181, 185, 411, 412, 414, 352 Storm Warning: 119, 120, 130, 131, 132, 138, 351 Heavy Freezing Spray: 139, 140, 160, 179, 180, 185, 412, 414 FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...RC SOUTHCENTRAL ALASKA...ED SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CQ LONG TERM...AS FXAK68 PAFC 241345 2022358 1345 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 445 AM AKST Sat Dec 24 2022 .ANALYSIS AND UPPER LEVELS... At upper levels, a large blocking ridge centered over the Chukchi Sea extends south over the Bering Sea and Aleutian Islands. An Arctic trough is elongated over most of southern Alaska and continues to spread a very cold airmass across the Mainland and eastern Bering and Aleutians. At the surface, a front extends across the southern Bering and is decaying as it tracks towards the North Pacific. Rainfall accompanies the front across the eastern Aleutians. An inverted trough is spreading mixed precipitation across the Alaska Peninsula and snow across the southern Bristol Bay area. The rest of Southwest and Southcentral remain dry and cold this morning. Gusty northeasterly surface winds persist across portions of Southcentral but will gradually diminish through today as the Arctic trough tracks towards the eastern Bering. Blowing snow may continue to reduce visibility through Thompson Pass and across portions of the Matanuska Valley this morning. Strong offshore winds continue along the Kuskokwim Delta and Bristol Bay coasts. Wind Chill Advisories remain in effect through this morning for Thompson Pass, the Copper River Basin, and the Middle Kuskokwim Valley. && .MODEL DISCUSSION... Models are still struggling with the evolution of a surface trough near Kodiak Island and the Alaska Peninsula. There is low confidence in the precipitation forecast for Kodiak Island and across southwest Alaska in the short term. Models are also struggling with the evolution of a surface low that is currently centered over the eastern Gulf and is extending its front along the east Gulf coast. There is general consensus that the low will bring light snow to the Cordova/Valdez area this afternoon and evening and then to the eastern Kenai Mountains during the day on Sunday. There is still some disagreement on whether or not the rest of Prince William Sound will see much, if any, precipitation with this system. && .AVIATION... PANC...VFR conditions will persist through this TAF period. Gusty northerly winds are expected to gradually decrease through this afternoon. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Saturday through Monday night)... Gusty winds will linger across the Matanuska Valley today due to the tight pressure gradient between the arctic high to east and a surface low spinning up near Kodiak Island. These winds, however, are on the decline from yesterday's peak as the upper-level trough moves to the southwest, away from the region, and the cold air advection wanes. Winds will also continue across bays and passes across Prince William Sound, as well as around Valdez and Thompson Pass, as a second surface low lifts northwest from the eastern Gulf. This feature will also begin to spread light snow across the eastern half of Prince William Sound and the Copper River Basin later today. There is still some uncertainty as to the western extent of the snow; however, the latest guidance all have this swath of snow moving over the eastern Kenai Peninsula by Sunday morning as the low weakens and an easterly flow aloft sets up ahead of the next frontal system. The first low near Kodiak Island, will bring snow and occasional wind gusts across the island today. Snow will likely move in from the east later this morning, lingering through late Saturday evening. Expect mesoscale bands of snow with this feature, which will make it difficult to nail down snowfall accumulation for any given location. However, there could be several inches of snow accumulation for locations under the heaviest and most persist bands. Moving into Christmas and beyond, attention shifts to a large deep low tracking into the Gulf from the Northeast Pacific. A strong occluded front out ahead of the low will reach the Gulf coast/Kodiak by late Sunday, bringing widespread gale to storm force winds across the Gulf coastal waters along with moderate to heavy precipitation along much of the coastal zone. Prevailing low level easterly flow will lead to upslope flow and enhanced precipitation amounts across the eastern Kenai Peninsula Mountains. Much warmer air will also accompany the front leading to a fairly quick transition from snow to rain for areas along the coast near sea level. Snow levels for coastal mountains will quickly rise Sunday afternoon/evening, reaching 1000 feet or higher. Precipitation will linger along the coast all the way through Monday. While some moisture will attempt to cross over the coastal mountains, dry and cold air inland will make it difficult to saturate the low levels of the atmosphere. As a result, inland areas of Southcentral look to remain dry. Temperatures will also moderate by Monday with winds increasing once again through the Matanuska Valley and down Cook Inlet in response to the low moving into the western Gulf just east of Kodiak City. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today through Tuesday)... Colder temperatures and northerly offshore flow continues across the region as a strong shortwave originating from an upper-level trough located across Yukon, Canada continues to advance westward towards Bristol Bay. As a result, wind chills across the region will be in the negative double digits for the next several days. A Wind Chill Advisory is still in effect for the lower Kuskokwim Valley until this afternoon. A surface low will track across the Alaska Peninsula today, but models are having a hard time handling the exact track of the low, and will therefore, impact where the highest winds, precipitation, and blowing snow concerns will be. This forecast package reflects snow continuing for the Alaska Peninsula today before slowly making its way northward towards the Bristol Bay region for tonight, and then reaching the Kuskokwim Delta coast for late tonight into Sunday. As the aforementioned low tracks northeastward along the Chain, northerly winds will increase region wide. With this, the potential for blowing snow coincided with reduced visibilities becomes possible along the Bristol Bay coast and portions of the Alaska Peninsula. As a result, a Winter Weather Advisory has been issued for the Bristol Bay coast. Total snow accumulations of 6 to 10 inches along the southern Bristol Bay coast and 4 to 6 inches along the northern Bristol Bay coast are expected. Expect visibilities reduced to as low as 1/2 mile from Dillingham north and west and from Port Heiden to King Salmon possible as well. A strong North Pacific low and its associated front will approach and impact the region Sunday through Tuesday. This will bring a rain/snow mix to the Alaska Peninsula, while mostly snow is expected for the western interior portions of Bristol Bay. Higher accumulations are forecasted to stay confined to the mountain areas at this time. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Today through Tuesday)... Active weather will continue for the Bering and Aleutians for the next several days. A surface low tracking across the Alaska Peninsula will today will eventually make its way into the eastern Bering. Models are having a hard time handling the exact track of the aforementioned low, but colder air and strong winds are likely to occur with snow being the main precipitation type for this system. Depending on where the low tracks and how strong the winds get, the potential for blowing snow coinciding with reducing visibilities is possible for some locations. Snow will make its way to the Pribilofs late tonight into Sunday morning. Strong winds should move out of the area before the snow hits, but some blowing snow may still occur.The system then continues westward through the Bering through Sunday afternoon into the evening before making a southern turn to the North Pacific while crossing the central Chain through Monday. Snow amounts appear to be light for the Aleutians overall, with the highest accumulations confined to the mountain areas. Be sure to check back in with the forecast for updates as the evolution of this system becomes more clear. $$ .LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The latest operational model runs and ensemble means seem to be in a decent agreement with an upper level low over the western Bering Sea near Adak, and high pressure remaining over Siberia. While the upper low sits nearly stationary between Tuesday and Wednesday, a series of North Pacific systems rotates around the low, moving north-northeastward past the Aleutians and into the Gulf of Alaska. This will bring an unsettled pattern for all of the coastal areas of Southcentral heading into late next week. While specific details still need to ironed out, persistent onshore flow will favor moderate to heavy precipitation for the coast, with much of the mainland remaining relatively dry during the period. A general troughing pattern out west will result in a wet pattern for much of the Bering Sea and Aleutians. Cold, northerly flow over the relatively warm waters will also help generate widespread showers over the Pribilof Islands and along the Aleutian Chain. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Blizzard Warning: 111. Wind Chill Advisory: 131, 141, 152. Winter Weather Advisory: 161. MARINE...Storm Warning: 130, 131, 138, 351. Gale Warning: 119, 120, 127, 128, 132, 136, 137, 139, 150, 160, 179-181, 185, 352, 411-414. Heavy Freezing Spray: 127, 160, 139, 179-181, 185, 414. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...AF SOUTHCENTRAL ALASKA...TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS LONG TERM...MF FXAK68 PAFC 240132 2022358 0132 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 432 PM AKST Fri Dec 23 2022 .ANALYSIS AND UPPER LEVELS... A Rex Blocking pattern currently extends across the North Pacific with low pressure south of the Aleutians and high pressure extending from Siberia to across the Alaskan mainland. Closer to the surface, observations show strong northeasterly flow across Southcentral. The strongest winds have been observed in the Matanuska Valley where the strongest gusts have been near 70 mph. Gusts near 60 mph occurred at Ted Stevens International Airport. Radar shows little to no shower activity across the area. && .MODEL DISCUSSION... Forecast confidence remains low overall except for the immediate short term forecast. There is good agreement with the overall trend for strong winds across Southcentral to ease over the next several hours. However, model agreement has diverged since yesterday's runs with respect to a low moving across the Alaska Peninsula on Saturday. This means there is very low confidence with respect to the snowfall forecast for Kodiak and across Southwest Alaska. && .AVIATION... PANC...VFR conditions will persist for this TAF period. Winds will gradually ease during the afternoon and evening hours across the area. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Tonight through Monday)... The upper level trough and associated cold air advection which produced strong winds and blowing snow across portions of Southcentral today has exited to Southwest Alaska. However, low pressure down over the Gulf of Alaska will maintain very tight pressure gradients. Low level flow behind the upper trough will also be slow to slacken. As a result, expect winds to linger tonight into Saturday, especially through mountain passes/valleys. Have extended the Blizzard Warning for the Matanuska Valley all the way through Saturday morning at which point winds should significantly diminish. Gusty winds and blowing snow will also linger along Knik Arm and the Glenn Highway Corridor down into north to west Anchorage. A more aggressive digging of the upper level trough is leading to a change in track of the low currently over the southern Gulf. It will remain over the eastern half of the Gulf as it track northward tonight and Saturday, leading to a much slower arrival of snow for the Copper River Basin and Valdez/Cordova areas. Now expect light snow to arrive in the far southeastern Copper River Basin overnight tonight then spread slowly westward across the Copper River Basin and eastern Prince William Sound on Saturday. The western extent of snow on saturday is very much in question, but it is looking less and less likely that the eastern Kenai Peninsula will see much, if any snow, from this system. Meanwhile, a separate surface trough tracking westward across the Gulf will reach Kodiak Island late tonight through Saturday. Expect mesoscale bands of snow with this trough, which makes it difficult to nail down snowfall accumulation for any given location. Do expect all of Kodiak Island to see some light accumulation. There will also be some stronger gusty winds with this which could briefly reduce visibilities to around one half mile at times. The trough and associated snow will dissipate by late Saturday. As we continue to Christmas Day and beyond, all attention will shift to a large deep low tracking into the Gulf from the Northeast Pacific. A strong occluded front out ahead of the low will reach the Gulf coast/Kodiak by late Sunday, bringing widespread gale to storm force winds across the Gulf coastal waters along with moderate to heavy precipitation along much of the coastal zone. Prevailing low level easterly flow will lead to upslope flow and enhanced precipitation amounts across the eastern Kenai Peninsula Mountains. Much warmer air will also accompany the front leading to a fairly quick transition from snow to rain for areas along the coast near sea level. Snow levels for coastal mountains will quickly rise Sunday afternoon/evening, reaching 1000 feet or higher. Precipitation will linger along the coast all the way through Monday. While some moisture will attempt to cross over the coastal mountains, dry and cold air inland will make it difficult to saturate the low levels of the atmosphere. As a result, inland areas of Southcentral look to remain dry with slowly warming temperatures as we head to the beginning of next week. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: This afternoon through Monday afternoon )... Conditions have largely quieted down for the Alaska Peninsula (AKPEN) although scattered rain showers linger around the southern AKPEN as weak low pressure continues to move westward in the North Pacific. A strong shortwave ejecting from an upper trough across Yukon, Canada continues to advance westward towards Bristol Bay this afternoon and through the evening. This will bring cold temperatures and continued offshore flow to mainland Southwestern Alaska. Windchills are expected to be quite low this evening due to the winds in conjunction with the cold air advection as the closed upper low continues westward towards the eastern Bering Sea. In response, a Windchill Advisory is in effect from this until Saturday afternoon. Meanwhile, a surface low is expected to develop around the northern AKPEN very early Saturday morning. There is uncertainty with the exact track as guidance continues to struggle with how to handle the surface feature. Another level of uncertainty is pinpointing exactly where mesoscale banding will set up along the AKPEN Saturday morning through evening, in addition to how far north into the Southwest mainland the precipitation reaches. The current thinking now is that the AKPEN will see precipitation mostly in the form of snow, while coastal sections of Bristol Bay and the Kuskokwim Delta will see less snow. Precipitation winds down for coastal Southwest overnight Saturday, while easterly to southeasterly upslope flow keeps the North Pacific side of the AKPEN unsettled through Sunday morning. A strong North Pacific low and its front approach Sunday afternoon through Monday afternoon as rain/snow mix is likely for the AKPEN, while mostly snow is expected for the western interior sections of Bristol Bay. Most accumulation is confined to the mountains. Please stay tuned to additional forecast updates as details continue to be fine-tuned in both the near-term and short-term during this complex weather pattern. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: This afternoon through Monday afternoon)... Active weather will continue for the Bering Sea and Aleutians during the short-term period. Scattered snow showers continue to taper off for the Pribilofs tonight as a frontal system continues to push westward across the Bering and the rest of the Aleutian Chain Saturday morning through the afternoon, bringing an additional band of rain/snow showers exiting the western Chain Saturday evening. Back east, a surface low is expected to develop across the Alaska Peninsula early Saturday morning in response to a strong closed upper low moving westward across Southwestern Alaska and into the eastern Bering Sea. There is still lots of uncertainty with this feature as guidance continues to struggle with the evolution of the system. Uncertainty is especially heightened for the Pribilof Islands for Sunday. Snow looks to be the dominant precipitation type as the system will be dragging cold air with it from mainland Alaska. The ultimate track of the surface feature will determine how much snow and how windy the Pribilofs get for Sunday. Some guidance has the system tracking a little more north of the Pribilofs, while some guidance also depicts the system taking a more southern track which would be more favorable for higher winds and more snowfall. The system then continues westward through the Bering during Sunday afternoon into the evening before making a southern turn to the North Pacific while crossing the central Chain through the day on Monday. Snow amounts appear to be light for the Aleutians overall, with most accumulation confined to the mountains. Please check back for the latest forecast updates as finer details on evolution and track continue to be fine-tuned for the surface low pressure system expected to traverse the eastern and central Bering Sea. $$.LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The latest operational model runs and ensemble means seem to be in a decent agreement with an upper level low over the western Bering Sea near Adak, and high pressure remaining over Siberia. While the upper low sits nearly stationary between Tuesday and Wednesday, a series of North Pacific systems rotates around the low, moving north-northeastward past the Aleutians and into the Gulf of Alaska. This will bring an unsettled pattern for all of the coastal areas of Southcentral heading into late next week. While specific details still need to ironed out, persistent onshore flow will favor moderate to heavy precipitation for the coast, with much of the mainland remaining relatively dry during the period. A general troughing pattern out west will result in a wet pattern for much of the Bering Sea and Aleutians. Cold, northerly flow over the relatively warm waters will also help generate widespread showers over the Pribilof Islands and along the Aleutian Chain. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Blizzard Warning: 111, 131. Wind Chill Advisory: 141, 152. MARINE...Storm Warning: 130. Gale Warning: 119, 120, 125, 127-128, 130, 138-140, 160, 179-181, 185, 351, 411-414. Heavy Freezing Spray: 127-128, 139-140, 160, 179-181, 185, 412, 414 FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...ED SOUTHCENTRAL ALASKA...SB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DN LONG TERM...MF