000 FXUS66 KOTX 201049 AFDOTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 249 AM PST WED FEB 20 2008 .SYNOPSIS... STRONG UPPER LEVEL RIDGING WILL REMAIN OVER THE INLAND NORTHWEST THROUGH THE END OF THE WORK WEEK. THIS SHOULD KEEP THE WEATHER PRIMARILY DRY HOWEVER A COUPLE OF WEAK FRONTS WILL PASS THROUGH THE RIDGE POSSIBLY PRODUCING SOME VERY LIGHT PRECIPITATION. THE RIDGE WILL BREAK DOWN BY THE WEEKEND WITH A WETTER PATTERN ENSUING. && .DISCUSSION... TODAY AND TONIGHT...LOOKS LIKE A FAIRLY QUIET PERIOD. ONLY FEATURE ON SATELLITE THIS MORNING WAS NEGATIVELY TILTED BAND OF MID/HIGH CLOUDS EXTENDING FROM THE SOUTHERN TIP OF VANCOUVER ISLAND TOWARD THE NE CORNER OF OREGON. THIS IS WHATS LEFT OF AN OLD FRONTAL BOUNDARY WHICH LOOKED MUCH MORE IMPRESSIVE 24-30 HOURS AGO WHEN IT WAS OFF THE COAST. LOOKS LIKE THE LONGWAVE RIDGE...CURRENTLY CENTERED OVER NORTH IDAHO AND WESTERN MONTANA HAS SAPPED MUCH OF ITS STRENGTH. AS SUCH...IT LOOKS LIKE A NON-PLAYER FOR TODAYS WEATHER...OTHER THAN TO BRING VARIABLE CLOUDS TO THE REGION. LOOKS LIKE PRECIPITATION CHANCES FROM THE REMNANTS OF THIS FRONT SHOULD BE MINIMAL...ESPECIALLY CONSIDERING IT WENT OVER WESTERN WA EARLIER TONIGHT AND DROPPED VIRTUALLY NOTHING. MAIN FORECAST PROBLEM FOR TODAY WILL BE WHAT TO MAKE OF FOG. THUS FAR...FOG FORMATION HAS BEEN SOMEWHAT MINIMAL...AT LEAST ACCORDING TO THE CONVENTIONAL 4KM FOG PRODUCT. FORTUNATELY THE 1KM FOG PRODUCT FROM THE MODIS POLAR ORBITER DEPICTED A MUCH NICER PICTURE WITH AREAS OF FOG OVER THE VALLEYS IN NORTH IDAHO EAST OF COEUR D'ALENE AS WELL AS SOME BY PRIEST LAKE AND NORTH OF DEER PARK. THERE WAS ALSO ANOTHER POCKET OF FOG BETWEEN RITZVILLE AND SPRAGUE IN THE EASTERN COLUMBIA BASIN. SUSPECT THAT MUCH LIKE YESTERDAY THIS FOG WILL BURN OFF BETWEEN 18Z-20Z BASED ON SIMILAR TEMPERATURE PROFILES AND INVERSION STRENGTHS. STAGNANT CONDITIONS BENEATH THIS INVERSION WILL ALSO SPELL THE CONTINUATION OF THE AIR STAGNATION ADVISORY. FOR TONIGHT MIN TEMPS WILL BE LARGELY DEPENDANT ON ELEVATED CLOUD COVERAGE. SINCE THE OFFSHORE FRONT WONT IMPACT THE INLAND NW UNTIL THURSDAY WE SUSPECT THE MODEL CLOUD GRIDS ARE OVERBLOWN. AS SUCH WE HAVE DECIDED TO UNDERCUT MOS AND MODEL TEMPS OVER MOST VALLEY LOCATIONS. FOG AGAIN COULD BECOME A CONCERN LATE. FX THURSDAY THROUGH FRIDAY NIGHT...THE MID LEVEL RIDGE IS NUDGED SLOWLY EAST THIS PERIOD. SPLIT FLOW WILL DIRECT MOST OF THE SHORTWAVE ENERGY TO OUR NORTH AND SOUTH WITH THE LEFTOVERS STRETCHED QUITE THIN. MODELS ARE SLOWER MOVING THE RIDGE EAST SO POPS HAVE BEEN TRIMMED BACK FOR THURSDAY. KEPT JUST A SLIGHT CHANCE IN THE CASCADES FOR LIGHT EASTERLY UPSLOPE FLOW. A STRONGER SHORTWAVE SWINGS THROUGH THE REGION ON FRIDAY ALONG WITH DEEPER MOISTURE. THE 850-500MB LAPSE RATES INCREASE OVER THE SOUTHEAST ZONES AS THE COLD POOL RIDES OVER THE AREA BUT OROGRAPHIC LIFT IS RATHER WEAK. THE STRONGEST FORCING REMAINS TO OUR SOUTH BUT MUCH OF THE FORECAST AREA COULD SEE SOME LIGHT QPF WITH THIS TROUGH PASSAGE. SATURDAY THROUGH WEDNESDAY...THE REGION TRANSITIONS TO SOUTHWEST FLOW WITH THE BEST CHANCE OF PRECIP SUNDAY NIGHT/MONDAY AS A CLOSED LOW OFF THE CALIFORNIA COAST APPROACHES THE FORECAST AREA. BY TUESDAY A RIDGE BUILDS WITH MINOR IMPULSES RIDING OVER THE TOP...MAINLY IMPACTING THE NORTHERN ZONES. TEMPERATURES WILL CONTINUE NEAR SEASONAL NORMALS THROUGH MIDWEEK. /KELCH && .AVIATION... STAGNANT PATTERN WILL CONTINUE THROUGH 06Z THU. MAIN AVIATION CONCERN WILL BE FORMATION OF STRATUS/FOG AND RESULTANT IFR/LIFR CIGS/VSBYS. SUSPECT COVERAGE WILL SIMILAR TO THIS MORNING...WHICH WAS MAINLY LOCAL AND CONFINED TO THE NORTHEASTERN COLUMBIA BASIN AND THE VALLEYS NORTH OF THE COLUMBIA BASIN. BEST CHANCES BASED ON WIND PATTERNS AND CURRENT MOISTURE PLACE THE GREATEST RISK OVER COE SFF AND GEG BUT FAR FROM CERTAIN THIS WILL OCCUR. IF FOG FORMS IT COULD BE SLOW TO BURN OFF WITH FAIRLY STRONG INVERSIONS AND LIGHT BOUNDARY LAYER WINDS. FOR NOW WE WILL BURN IT OFF AROUND 19Z. && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 41 25 41 28 42 31 / 0 0 0 20 30 20 COEUR D'ALENE 40 24 42 28 41 32 / 0 0 0 20 40 20 PULLMAN 43 27 44 33 44 33 / 0 0 0 20 30 20 LEWISTON 49 30 49 35 51 36 / 0 0 0 10 30 20 COLVILLE 45 24 46 24 45 30 / 0 0 0 20 30 20 SANDPOINT 40 22 42 23 41 33 / 0 0 0 10 40 30 KELLOGG 44 24 43 27 42 31 / 0 10 0 10 40 30 MOSES LAKE 43 25 43 27 44 27 / 0 0 10 30 20 20 WENATCHEE 44 31 45 29 46 32 / 0 0 10 30 20 20 OMAK 37 22 39 25 41 25 / 0 0 10 30 20 30 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...AIR STAGNATION ADVISORY UNTIL 12 PM PST THURSDAY FOR NORTHERN PANHANDLE. WA...AIR STAGNATION ADVISORY UNTIL 12 PM PST THURSDAY FOR EAST SLOPES NORTHERN CASCADES...NORTHEAST MOUNTAINS...OKANOGAN HIGHLANDS...OKANOGAN VALLEY...SPOKANE AREA. && $$ ----------------------------------------------------------------------
