MODIS AFD Archive Index
Last updated July 22, 2008
| Area Forecast Discussions mentioning MODIS issued by National Weather Service Forecast Office Marquette, Michigan (MQT) |
000 FXUS63 KMQT 250924 AFDMQT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 AM EST MON FEB 25 2008 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SNOW TONIGHT AND TUESDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA AND A STEEP RIDGE OVER THE CANADIAN ROCKIES. A WEAK SHORTWAVE STRETCHES FROM SOUTHERN MANITOBA THROUGH MINNESOTA TO SOUTHERN WISCONSIN. ANOTHER SHORTWAVE IS OVER NORTHERN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A LARGE HIGH BLANKETING MUCH OF THE SOUTHEASTERN STATES...A LOW OVER THE CENTRAL PLAINS CONNECTS VIA A WEAK SURFACE TROUGH TO ANOTHER LOW OVER LAKE SUPERIOR. A COLD FRONT EXTENDS FROM WINNIPEG ACROSS ONTARIO...JUST NORTH OF LAKE SUPERIOR...TO A LOW IN THE CANADIAN MARITIME. PATCHY FOG IS OVER THE UPPER GREAT LAKES. MODELS ARE IN A FAIRLY GOOD AGREEMENT THROUGH DAY 4. A PORTION OF THE LONGWAVE TROUGH WILL DEEPEN OVER CENTRAL CANADA TODAY. A WEAK LOW WILL START TO DEVELOP OVER IOWA IN THIS FLOW. A WEAK SHORTWAVE WILL ADVANCE ACROSS THE FORECAST AREA. THE SURFACE LOW WILL PROCEED INTO CENTRAL MISSOURI. THE COLD FRONT TO THE NORTH OF LAKE SUPERIOR WILL SETTLE OVER THE FORECAST AREA. GUIDANCE SUGGEST THAT THE LOW LEVELS WILL REMAIN FAIRLY DRY. HOWEVER...WITH THE SNOW MELT OVER THE FORECAST AREA ON SUNDAY AND EXPECTED MORE MELTING TODAY...THERE MAY BE ENOUGH TO GENERATE SOME SNOWS WITH THE APPROACH OF THE FRONT. THUS WILL KEEP IN A SLIGHT MENTION OF SNOW TODAY AND AREAS OF FOG EARLY. THE WINDS WILL VEER NORTH FOLLOWING THE FROPA BRINGING COOLER AIR INTO THE AREA. THE TROUGH DEVELOPING OVER CENTRAL CANADA WILL CONTINUE TO DEEPEN OVER THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE THE RIDGE OVER THE ROCKIES BUILDS. THE SURFACE LOW OVER MISSOURI WILL PROCEED TO SOUTHERN OHIO AS THE COLD FRONT OVER THE FORECAST AREA SHIFT INTO LOWER NORTHERN LOWER MICHIGAN. A RIDGE WILL DEVELOP OVER NORTHERN HIGH PLAINS WHILE ANOTHER LOW DEVELOPS OVER NORTHERN ALBERTA. THE LAKE-850MB DELTA-T'S WILL INCREASE TO AROUND 13C. THIS WOULD SUPPORT THE START OF SOME ENHANCE LES OVER THE NORTHERN PART OF THE FORECAST AREA. MODIS SATELLITE VISIBLE IMAGERY SHOWING LARGE AREAS OF ICE ON LAKE SUPERIOR WHICH WILL LIMIT LES DEVELOPMENT. THUS WILL KEEP ONLY A CHANCE OF LES GOING OVER AREAS PRONE TO LES WITH NORTHWEST FLOW. THE LONGWAVE TROUGH WILL DEEPEN OVER THE FORECAST AREA ON TUESDAY. THE DELTA-T'S WILL INCREASE TO AROUND 21C OVER LAKE SUPERIOR. LOW LEVEL MOISTURE ALONG WITH THE INCREASE 850-500MB Q-VECTOR CONVERGENCE OVER THE AREA...AND LOW LEVEL INSTABILITY WILL SUPPORT INCREASED LES OVER THE NORTHERN PART OF THE AREA. ICE OVER THE LAKE WILL CONTINUE TO LIMIT FETCH TIME OVER THE LAKE. SO LES WILL BE MORE WIDESPREAD WITH A ONLY FEW INCHES POSSIBLE. THE LONGWAVE TROUGH WILL TREK INTO EASTERN ONTARIO TUESDAY NIGHT. THE DELTA-T'S WILL REMAIN CONSTANT OVER THE LAKE AROUND 21C. 925MB WINDS SHOWING LOW LEVEL CONVERGENCE OVER THE LAKE WILL CONTINUE...KEEPING LES IN THE GRID THROUGH TUESDAY NIGHT. ICE AND LIMITED LOW LEVEL MOISTURE WILL DECREASE THE CHANCES OF HEAVY LES. THESE SAME CONDITIONS WILL CONTINUE THROUGH WEDNESDAY. ONLY THING IS ON WEDNESDAY THE SURFACE HIGH WILL MOVE OUT OF THE PLAINS INTO THE UPPER GREAT LAKES CASUING THE WINDS TO DIMINISH AND START BACKING WEST. AS THE SURFACE RIDGE MOVES OVER THE FORECAST AREA WEDNESDAY NIGHT. THE LES WILL DIMINISH SIGNIFICANTLY DUE TO LOST OF A NORTHWEST FLOW AND WARM AIR ADVECTION BEHIND WEST OF THE RIDGE WILL DIMINISH THE DELTA-T'S. ON THURSDAY...AS THE RIDGE TRACKS INTO WESTERN QUEBEC... A SOUTHWEST FLOW BEHIND THE RIDGE WILL KILL OFF ANY REMAINING LES. THE NEXT SYSTEM WILL DROP OUT OF ALBERTA AND INTO THE NORTHERN MINNESOTA ON THURSDAY TAKING AIM AT THE GREAT LAKES REGION. THE LOW WILL MOVE INTO THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY. THE ECMWF PLACES THE LOW NORTH OF LAKE SUPERIOR WHEREAS THE GFS PREFERS A SOLUTION THAT BRINGS THE LOW OVER THE U.P. IN EITHER CASE THERE WILL BE CHANCES OF SNOW WITH THIS SYSTEM. HOW MUCH AND THE STRENGTH OF THE WINDS WILL DEPEND ON THE WHICH SOLUTION PANS OUT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... ALTHOUGH NEAR SFC WIND IS SW...FLOW ABV THE SFC APPEARS TO BE MORE WNW...WHICH HAS PREVENTED LO CLD MASS TO THE SW FM ADVANCING TOWARD CMX/SAW. SO ALTHOUGH THERE MAY BE SOME SHALLOW FOG/MVFR VSBY THRU THE NGT...LOOK FOR CLR-PCLDY SKIES WITH LLVL FLOW LIKELY TO VEER SLOWLY THRU THE NGT IN ADVANCE OF COLD FNT TO THE N SINKING SLOWLY SWD. BEST CHC FOR LO CIG TO DVLP WL BE AT CMX...WHERE THIS WNW FLOW WL UPSLOPE. TIMING OF COLD FROPA FM THE N APPEARS TO BE A BIT SLOWER...SO PUSHED BACK ONSET OF PREDOMINANT MVFR CIGS ACCOMPANYING THE LLVL CAD/STEEPENING SFC-H85 LAPSE RATES BEHIND THIS FEATURE. EVENTUAL ARRIVAL OF DRIER AIR WL LIKELY BREAK UP THE CLD AT CMX LATE TDAY... BUT NOT AT SAW WHERE LONGER FETCH/FVRBL UPSLOPE N FLOW WL MAINTAIN SC DECK FOR A LONGER TIME. ANY LES IMMEDIATELY BEHIND THE FROPA WL BE MINIMAL DUE TO MARGINAL CHILL/LO INVRN BASE. ALTHOUGH COLDER AIR WL GRDLY ARRIVE THIS EVNG...SO WL DRIER AIR. SO EXPECT NO VSBY RESTRICTION EVEN AT SAW WHERE FETCH/UPSLOPE MORE FVRBL. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT WINDS OVER SOUTHERN LAKE SUPERIOR TO VEER NORTHERLY TODAY AS A TROUGH SLIDES SOUTH THROUGH THE AREA. NORTH WINDS WILL THEN DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS AND NORTHERN ONTARIO WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG MARINE...JLB AVIATION...KC ---------------------------------------------------------------------- 000 FXUS63 KMQT 260955 AFDMQT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 455 AM EST TUE FEB 26 2008 .SYNOPSIS... AMPLIFIED PATTERN ACROSS NORTH AMERICA WITH TROUGH OVER EASTERN CANADA INTO GREAT LAKES WHILE RIDGES RESIDE OVER GULF OF MEXICO COAST AND FM WEST CONUS COAST INTO WESTERN CANADA. VIGOROUS SHORTWAVE OVER GULF OF ALASKA LOOKS TO MATERIAL ITSELF INTO A CLIPPER SYSTEM ACROSS UPR MI ON FRIDAY. SOUTHERN STREAM SYSTEM IS MOVING INTO THE LOWER GREAT LAKES ATTM WHILE TAIL END OF THAT SYSTEM IS PRODUCING SEVERE STORMS OVER THE ARKLATEX REGION. OVER THE LAKE SUPERIOR REGION...COLDER AIR SPILLING IN FM MANITOBA AND ONTARIO (H85 TEMPS OF -19C AT CWPL) IS RESULTING IN A RETURN TO LK EFFECT SNOWS AFTER BRIEF SPELL OF WARMER TEMPERATURES THIS LAST WEEKEND. A SHORTWAVE...NOT PRODUCING ANY SNOW...YET SIGNALING AN INCREASE IN MOISTURE...IS MOVING FM SOUTHERN MANITOBA INTO NORTHERN MN. && .DISCUSSION... MAIN CONCERN IS LK EFFECT THROUGH WED. SATELLITE AND RADAR INDICATES LK EFFECT IS BEGINNING TO INCREASE. COOLEST CLOUD TOPS...TO -19C...OVER SCNTRL LK SUPERIOR INTO NCNTRL UPR MI. LK EFFECT OVR WESTERN LK SUPERIOR IS STRUGGLING...LIKELY DUE TO WIDESPREAD ICE COVERAGE AS SEEN ON MODIS IMAGE FM 2/24. MQT VWP SHOWS RETURNS TO 5.5KFT WITH A WIND DIRECTION FM THE NORTH FM THE SFC THROUGH H85. SFC HIGH OVR PLAINS REALLY DOES NOT ARRIVE UNTIL LATER WED NIGHT INTO THU AND THUS...BLYR WINDS REMAIN FM THE NORTH OR NORTH-NORTHWEST THROUGH THIS PERIOD. INSTABILITY INCREASES WHERE THERE IS OPEN WATER ON LK SUPERIOR AS H85 TEMPS FALL TO -20C BY 00Z WED. AS SHORTWAVE OVR NORTHERN MN SWINGS TO THE SOUTHWEST OF THE AREA TODAY...INVERSIONS INCREASE TO AROUND 800MB BEFORE FALLING BACK TO 850MB TONIGHT. SOUNDINGS INDICATE THAT ALL OF THE CLOUD WILL RESIDE WITHIN IDEAL ZONE FOR DEVELOPING DENDRITES AND A FLUFFIER SNOW...PERHAPS WITH SNOW TO WATER RATIOS TO 30:1. HIGHER RESOLUTION MODELS (NAM12...RUC13...LOCAL WRF) SHOWING VERY GOOD AGREEMENT IN AREA OF LOWER LEVEL CONVERGENCE FOCUSING OVR EXTREME EAST MARQUETTE COUNTY (EAST OF SKANDIA) INTO ALGER COUNTY. DAYTIME DISRUPTION IN INDIVIDUAL SNOW BANDS COULD OCCUR FOR A GOOD PART OF THE DAYTIME HOURS BUT BY THIS EVENING ENHANCED LOW LEVEL CONVERGENCE AND VERY FAVORABLE SNOW GROWTH HAVE POTENTIAL TO PRODUCE ADVY AMOUNTS. LEFT MARQUETTE OUT OF ADVY FOR NOW SINCE BY 00Z WED WINDS ARE ALREADY SHIFTING MORE NW...WHICH SHOULD FOCUS HEAVIER SNOW INTO ALGER COUNTY. FAR EASTERN MARQUETTE COUNTY COULD EEK INTO SOME HIGHER SNOW TOTALS THOUGH AND THIS WILL HAVE TO BE EVALUATED LATER ON. IN ADDITION TO RAISING INVERSION HEIGHTS TODAY...SHORTWAVE MOVING IN FM THE WEST COULD ALSO TRIGGER SOME VERY LIGHT SYNOPTIC SNOW TOWARD THE WI BORDER...ESPECIALLY THIS AFTN. GRADUAL COLD AIR ADVECTION THROUGH THE DAY RESULTS IN TEMPS STAYING STEADY IN THE WEST AND SLOWLY FALLING IN THE CENTRAL AND EAST. LK EFFECT CONTINUES WED INTO WED NIGHT...MAINLY IN THE NW FLOW SNOWBELT OF ALGER/NORTHERN SCHOOLCRAFT AND WESTERN LUCE COUNTY. LOWERING INVERSION AND DRIER AIR WORKING IN BENEATH INVERSION SHOULD START TO DIMINISH THE SNOW SHOWERS. ARRIVAL OF MUCH MORE ANTICYLONIC FLOW AND WINDS BACKING TO THE SW BY LATE WED NIGHT/THU MORNING WILL SPELL THE END TO THE LK EFFECT. WINDS BECOMING LIGHT INLAND ON WED NIGHT WITH PWAT MINIMUM OVERHEAD SHOULD ALLOW TEMPS TO FALL WELL BELOW ZERO. USED THE ADJMAV GUIDANCE AS IT WAS NEAR LOWER END OF MOS GUIDANCE. SHORTWAVE OVER PACIFIC TOPS WESTERN NORTH AMERICA RIDGE THU AND DIGS TOWARD UPR GREAT LAKES THU NIGHT. MODELS INCONSISTENT ON EXACT PLACEMENT OF SFC LOW...BUT ARE IN GENERAL AGREEMENT IN WHERE STRONGEST WARM AIR ADVECTION AND ISENTROPIC LIFT SWATH OF PCPN DEVELOPS. LATEST GFS AND ECMWF AGREE PRETTY WELL. ECMWF PREFERRED BY HPC. A WIDEPSREAD SNOW IS EXPECTED THU NIGHT INTO EARLY FRIDAY. SOUNDINGS INDICATE THAT SNOW GROWTH IS FAVORABLE WITH LARGE AREA OF LIFT OCCURRING IN THE -12C TO -18C TEMP LAYER AND TEMPS AT BOTTOM OF CLOUD ONLY AS WARM AS -10C. QPF FM GFS/ECMWF UP TO A QUARTER OF AN INCH. WITH FAVORABLE SNOW GROWTH...COULD SEE SNOW AMOUNTS REACH TOWARD ADVY. INCREASED POPS TO LIKELY ON THU NIGHT...BUT NO OTHER CHANGES WERE MADE BEYOND THAT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... INFLUX OF DRIER AIR IN NRN MN/SRN ONTARIO AS SHOWN ON 00Z INL RAOB/ RECENT TAMDAR SDNG FM YQT AS WELL AS ACYC FLOW AT H85 HAS CAUSED VFR CONDITIONS AT CMX INTO THE OVERNGT. DESPITE THESE NEGATIVES...LONGER FETCH/FVRBL NLY UPSLOPE FLOW HAS PERSISTED THE SC MVFR CIG AT SAW. WITH WEAKENING DRY ADVECTION LATER TNGT...SUSPECT MVFR CIG WL DVLP AT CMX WHILE STEADIER SHSN THAT RESTRICT VSBY TO MVFR RANGE COMMENCE AT SAW. BEST CHC FOR MORE FREQUENT SHSN AND LOWER VSBY... MVFR AT CMX/IFR AT SAW...WL BE TUE MRNG INTO THE AFTN WHEN DIGGING SHRTWV DRAGS COLDER LLVL AIR INTO THE UPR LKS AND INVRN BASE LIFTS TO 5-6K FT. ARRIVAL OF THE COLDER AIR WL ALSO RESULT IN GUSTY WINDS AT TIMES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT NORTHERLY WINDS TO DOMINATE THROUGH WEDNESDAY. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE OVER THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS WILL RESULT IN WINDS TO 30 KT FROM THIS AFTERNOON INTO TONIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TODAY INTO WED AS COLDER AIR MOVES IN. AS THE LOW MOVES E ON WED THE NORTHERLY GRADIENT WILL SLACKEN AS WINDS QUICKLY DIMINISH BLO 20 KT BY LATE WED. SRLY WINDS WILL INCREASE TO 25 TO 30 KT BY LATE THU AND THU NIGHT AS ANOTHER CLIPPER SYSTEM DIVES INTO THE NRN PLAINS. GALES ARE POSSIBLE BY LATE FRIDAY AS NORTHWEST WINDS STRENGTHEN BEHIND THE DEPARTING CLIPPER LOW PRES. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY THROUGH 7 AM EST WEDNESDAY MIZ006. LAKE SUPERIOR...NONE. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING FROM 7 AM TUESDAY TO 7 PM EST WEDNESDAY FOR LMZ248-250. && $$ SYNOPSIS/DISCUSSION...JLA MARINE...JLB AVIATION...KC ---------------------------------------------------------------------- 000 FXUS63 KMQT 030918 AFDMQT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 418 AM EST MON MAR 3 2008 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE SNOW POTENTIAL TODAY AND TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER EASTERN NEW MEXICO CONNECTED BY A TROUGH THAT EXTENDS NORTHEAST TO A LOW OVER NORTHERN MANITOBA. RIDGES ARE OVER QUEBEC AND ALBERTA. WEAK SHORTWAVE ARE BEING EJECTED OUT AHEAD OF THE CENTRAL NORTH AMERICAN TROUGH AND ARE OVER THE FORECAST AREA AND OVER NORTHERN MINNESOTA AND ONTARIO. SURFACE ANALYSIS DEPICTS A LOW OVER NORTHEAST ONTARIO...WITH A COLD FRONT STRETCHING SOUTHWEST THROUGH THE FORECAST AREA. HIGH CENTERS ARE DEVELOPING OVER SASKATCHEWAN AND CENTRAL ROCKIES. THE TROUGH OVER MINNESOTA WILL SWEEP INTO THE FORECAST AREA TODAY AS THE NORTHERN ONTARIO LOW SHIFTS INTO HUDSON BAY. THE COLD FRONT WILL REACH EASTERN ONTARIO BY NOON AND WESTERN QUEBEC BY LATE AFTERNOON WHILE THE SASKATCHEWAN HIGH SHIFT INTO THE NORTHERN PLAINS. THE NORTHERLY FLOW CONTINUES BEHIND THE FRONTAL SYSTEM AND WILL BE ENHANCED BY THE HIGH DRAWING COLDER AIR OUT OF CENTRAL CANADA INTO THE UPPER GREAT LAKES REGION. Q-VECTOR CONVERGENCE WILL CONTINUE TO BE STRONG ENOUGH OVER THE AREA TODAY TO SUPPORT KEEPING SOME SNOW GOING. BUFKIT SHOWING SNOW GROWTH AREAS ONLY HAVE MODERATE TO LIGHT MOISTURE AVAILABLE. FORECAST SOUNDINGS SHOWING CONSIDERABLE DRY COLD AIR MOVING INTO THE AREA BETWEEN 850MB AND 400MB. FORECAST SOUNDINGS SHOW BY 18Z THAT THE SYSTEM SNOWS WILL BE OUT OF THE AREA. A POOL OF VERY COLD AIR OVER NORTHERN MANITOBA WILL SHIFT INTO WESTERN ONTARIO THIS AFTERNOON. THE THERMAL TROUGH ACCOMPANYING THIS POOL OF COLD AIR WILL LOWER THE 875MB TEMPERATURE OVER LAKE SUPERIOR TO -14C TO -19C...WHICH IS COLD ENOUGH TO BRING LES TO THE FORECAST AREA. THUS LES SHOULD DEVELOP OVER THE WEST THIS MORNING AND SPREAD EAST IMPACTING THE AREAS MOST OFTEN AFFECTED BY LES WITH A NORTHWEST FLOW. RECENT MODIS SATELLITE VISIBLE IMAGERY AND THE ICE CENTER ANALYSIS DEPICTIONS SUGGEST THAT THAT THERE IS CONSISERABLE AMOUNT OF ICE ON THE WEST END OF THE LAKE WHICH WOULD LIMIT AFFECTIVE FETCH AND THUS SNOWFALL. THE SHORTWAVE WILL MOVE EAST TONIGHT REACHING WESTERN QUEBEC LATE. THE SURFACE HIGH WILL SPREAD INTO THE FORECAST AREA TONIGHT. WINDS WILL VEER NORTH AND WEAKEN. THE 850MB THERMAL TROUGH WILL SHIFT ACROSS WEST AND CENTRAL LAKE SUPERIOR PRODUCING DELTA-T'S AS HIGH AS 20C. THUS WILL KEEP LES GOING OVER THE NORTHERN PART OF THE FORECAST AREA. THE NEXT SYSTEM WILL SLIDE OUT OF ALBERTA INTO THE NORTHERN PLAINS LATE TONIGHT WHILE THE LOW OVER THE SOUTHERN PLAINS WILL RACE THROUGH THE MIDDLE MISSISSIPPI RIVER VALLEY. PLAN TO KEEP LES GOING OVER THE FORECAST AREA. THE SURFACE WINDS WILL VEER EAST ON TUESDAY AS THE HIGH OVER THE AREA SHIFT EAST INTO QUEBEC AND THE MISSISSIPPI RIVER VALLEY LOW LIFT NORTHEAST INTO WEST VIRGINIA. THE SURFACE RIDGE ASSOCIATED WITH THE QUEBEC HIGH WILL REMAIN OVER THE FORECAST AREA. THE MID LEVEL LOW WILL MOVE OUT OF THE SOUTHERN PLAINS INTO SOUTHERN INDIANA. A WEAK SHORTWAVE WILL MOVE INTO THE NORTHERN PLAINS. THE MID LEVEL SHORTWAVE ROTATING THROUGH THE BASE OF A MID LEVEL LOW WILL SHIFT INTO NORTHERN WISCONSIN. THUS LOOKING FOR AN INCREASE IN Q-VECTOR CONVERGENCE OVER THE UPPER GREAT LAKES REGION. THE SURFACE HIGH WILL RELOCATE OVER CENTRAL QUEBEC...WHILE A LOW CENTER MOVES OUT OF THE UPPER MISSISSIPPI RIVER VALLEY INTO WESTERN LAKE SUPERIOR. THUS LOOKING FOR AN INCREASE IN CHANCE OF SNOW OVER THE WESTERN U.P. THE MID LEVEL LOW WILL LIFT INTO QUEBEC ON WEDNESDAY...WHILE ANOTHER LOW DEEPENS OVER HUDSON BAY DEVELOPING INTO A LONGWAVE TROUGH. A SHORTWAVE SWEEPING THROUGH THE BASE OF THE LOW WILL SHIFT INTO THE FORECAST AREA. THE SURFACE LOW WILL WEAKEN AS IT TRACKS THROUGH THE UPPER GREAT LAKES. THERE WILL BE SOME ISENTROPIC ASCENT OVER THE AREA ACCOMPANYING THIS WEAK SYSTEM. A CHANCE OF OF LIGHT SNOW STILL LOOKS GOOD. THE WEAK SURFACE LOW WILL TREK TO EASTERN ONTARIO ON THURSDAY. ANOTHER THERMAL TROUGH WILL DROP OUT OF CENTRAL CANADA IN THE WAKE OF THIS LOW AND CUASE DELTA-T'S OF AROUND 23C GENERATING LES OVER THE NORTHERN U.P. SOME WRAP AROUND LOW LEVEL MOISTURE WILL BLANKET THE REST OF THE AREA STILL GIVE A CHANCE OF SNOW SHOWERS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... UPSLOPE WRLY FLOW AND BLO FREEZING SFC TEMPS WILL RESULT IN FREEZING DRIZZLE/FOG AT KCMX FOR THE NEXT COUPLE HRS...UNTIL COLDER AIR TURNS PCPN TO ALL SNOW BY 09Z. LOOK FOR LES AND BLOWING SNOW TO LEAD TO IFR VSBYS AT KCMX UNTIL WINDS SUBSIDE THIS EVENING AND MVFR VSBY PREVAILS. WITH LIGHT RAIN/DRIZZLE FALLING OVER SNOWPACK...IFR CONDITIONS HAVE DEVELOPED AT KSAW WITH UPSLOPE SRLY FLOW. WITH THE ONSET OF CAA BEHIND THE COLD FRONT...STILL LOOK FOR DZ/RA TO TRANSITION TO SN BY 07Z AT KSAW. CIGS AND VSBYS AT KSAW SHOULD QUICKLY IMPROVE BY 10Z IN MODERATE DRIER WRLY FLOW BEHIND THE FRONT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS LOW PRESSURE OVER HUDSON BAY CONTINUES TO THE NORTHEAST...EXPECT HIGH PRESSURE OVER SASKATCHEWAN THIS MORNING TO MOVE TO NEAR UPPER MICHIGAN BY TUESDAY MORNING. PLAN ON NORTHWEST GALES INTO THIS AFTERNOON IN THE STRONG COLD ADVECTION/SHARP PRESSURE GRADIENT IN ADVANCE OF THE ARCTIC HIGH PRESSURE. HEAVY FREEZING SPRAY WILL ALSO DEVELOP WITH ARRIVAL OF COLDER AIR. WINDS WILL GRADUALLY DIMINISH THIS AFTERNOON WITH PASSAGE OF PRESSURE RISE CENTER AND THEN OVERNIGHT WITH THE APPROACH OF THE RIDGE. BUT HEAVY FREEZING SPRAY WILL LINGER LONGER WITH CONTINUED INFLUX OF ARCTIC AIR. AS THIS HIGH DRIFTS INTO QUEBEC ON WEDNESDAY...A LOW PRESSURE SYSTEM WILL MOVE TO SOUTHERN MINNESOTA. LOOK FOR THIS LOW TO MOVE INTO THE UPPER GREAT LAKES ON THURSDAY AND WEAKEN. ON FRIDAY...HIGH PRESSURE WILL BUILD INTO THE UPPER MISSISSIPPI RIVER VALLEY. NORTH WINDS MAY REACH 25 TO 30 KNOTS THURSDAY INTO FRIDAY BETWEEN THE DEPARTING LOW AND ADVANCING HIGH. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING UNTIL 4 PM TUESDAY FOR LSZ266-267. HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST TUESDAY FOR LSZ162-263. HEAVY FREEZING SPRAY WARNING UNTIL 7AM TUESDAY FOR LSZ162-263. HEAVY FREEZING SPRAY WARNING FROM 1 PM THIS AFTERNOON TO 7AM EST TUESDAY FOR LSZ264. LAKE MICHIGAN...NONE. && $$ DISCUSSION...DLG AVIATION...VOSS MARINE...KC