FXUS66 KOTX 062329
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
329 PM PST SUN DEC 6 2009
.SYNOPSIS...
BLUSTERY NORTH-NORTHEAST WINDS AND BITTERLY COLD TEMPERATURES WILL
CONTINUE ACROSS THE INLAND NORTHWEST THROUGH THE REMAINDER OF THE
WEEKEND. SLIGHTLY WARMER...BUT STILL DRY AND COLD CONDITIONS WILL
PERSIST THROUGH MUCH OF NEXT WEEK...WITH THE NEXT CHANCE OF
ACCUMULATING SNOW ARRIVING IN TIME FOR NEXT WEEKEND.
&&
.DISCUSSION...
...BITTERLY COLD AND BREEZY TONIGHT...
TONIGHT...SATELLITE INDICATES A WEST TO EAST ORIENTED WEAKENING
UPPER TROUGH DRAPED OVER THE NORTHWESTERN UNITED STATES. SURFACE
ANALYSIS REVEALS A STRONG ARCTIC SURFACE HIGH PRESSURE CENTERED
OVER SOUTHERN SASKATCHEWAN THIS AFTERNOON...WITH A TIGHT PRESSURE
GRADIENT ON IT'S WESTERN FLANK INDICATING THE COLD ARCTIC AIR
BANKED AGAINST THE BITTERROOTS AND CANADIAN ROCKIES. THE GRADIENT
ORIENTATION IS VERY FAVORABLE FOR A STRONG ARCTIC BLEED THROUGH
THE PURCELL TRENCH...WITH WINDS AT SANDPOINT SUSTAINED IN THE MID
20S AND GUSTING INTO THE MID 30 MPH RANGE ALL DAY. WITH THE AIR
MASS VERY DRY WITH BARELY A TENTH OF AN INCH OF PRECIPITABLE WATER
AVAILABLE AND NO SYNOPTIC LIFT...PRECIPITATION IS NOT A FACTOR
TONIGHT.
WINDS AND TEMPERATURES AND THEIR MARRIAGE INTO WIND CHILL
TEMPERATURES IS THE PRIMARY WEATHER ISSUE. BOTH THE NAM AND GFS
INDICATE THE STRONG GRADIENT WILL LOOSEN UP SLIGHTLY
OVERNIGHT...WITH THE NAM SUGGESTING A LARGER WIND DECREASE THAN
THE GFS...BUT THE GRADIENT WILL ESSENTIALLY REMAIN IN PLACE
PROVIDING AT LEAST BREEZY CONDITIONS THROUGH OUT THE BASIN AND
MOUNTAIN GAP ZONES THROUGH THE NIGHT. THESE WINDS...AND A LACK OF
LOW ELEVATION SNOW COVER WILL RETARD RADIATIONAL COOLING DESPITE
CLEARING SKIES. THIS WILL LIKELY KEEP TEMPERATURES FROM PLUNGING
MUCH FURTHER THAN THE SINGLE DIGITS AT MOST LOCATIONS. ANALYSIS OF
EXPECTED OVERNIGHT WINDS AND TEMPERATURES YIELDS POTENTIAL WIND
CHILL READINGS IN THE MID TEENS BELOW ZERO...NOTHING TO SCOFF AT
BUT NOT QUITE ACHIEVING THE NECESSARY -20 TO JUSTIFY A WIND CHILL
WARNING. THUS THE INHERITED WIND CHILL WATCH HAS BEEN CANCELLED.
THE CURRENT WIND ADVISORIES WILL REMAIN IN EFFECT FOR THE EVENING
HOURS WITH SOME ABATEMENT EXPECTED AFTER SUNSET...BUT STILL BREEZY
TO WINDY THROUGH THE NIGHT AT MOST LOCATIONS. /FUGAZZI
MONDAY THROUGH WEDNESDAY...NORTHERLY FLOW THE RESULT OF LARGE
BLOCKING RIDGE PARKED OFF THE WEST COAST ALLOWS A GENERALLY DRY
AND COLD FORECAST TO CONTINUE INTO TUESDAY. WEAK NUISANCE WAVE
HAVING NO REAL SIGNIFICANT TAP INTO ANY MOISTURE FROM THE PACIFIC
IS EXPECTED TO TRAVERSE SOUTHWARD ON THE EASTERN EDGE OF THE
OFFSHORE RIDGE AND MAY ALLOW FOR EXTREMELY LIGHT SNOW TO OCCUR
OVER THE IDAHO PANHANDLE AND NORTHEAST MOUNTAINS OF WASHINGTON
TUESDAY NIGHT AND WEDNESDAY...AND WHAT IS MEANT BY LIGHT IS LESS
THAN ONE INCH OVER THE MOUNTAINS AND TRACE AMOUNTS AT BEST IN THE
VALLEYS. TEMPERATURES MODERATE DURING THIS PERIOD AS THE BLOCKING
RIDGE OFF THE COAST GETS UNDERCUT WITH DISTURBANCES RUNNING
THROUGH ITS MIDSECTION BUT WITH TRAJECTORIES TOO FAR SOUTH TO BE
OF NOTE TO AFFECT SENSIBLE WEATHER OVER EASTERN WASHINGTON AND
NORTHERN IDAHO. MJO APPEARS TO HAVE PEAKED/MOVED EAST OF THE
DATELINE WHICH MEANS IT IS NOW NOT IN POSITION TO AID IN
REINFORCEMENT OF THE OFFSHORE LONGWAVE BLOCKING RIDGE...SO IT
MAKES SENSE THAT DISTURBANCES WILL HAVE A BETTER SHOT UNDERCUTTING
IT AND/OR SLIDING DOWN ITS PERIPHERY SOMEWHAT CLOSER TO ITS RIDGE
AXIS WHICH IS WHAT IS CALLED FOR TUESDAY NIGHT AND WEDNESDAY BUT
STILL NOTHING SPECTACULAR AS FAR AS SNOW AMOUNTS GO...ADDITIONALLY
THE NORTHERLY FLOW WILL CONTINUE TO FAVOR FORECAST TEMPERATURES
THAT ARE CONSIDERABLY ON THE COLD SIDE OF WHAT WOULD BE CONSIDERED
NORMAL FOR THIS TIME OF YEAR. /PELATTI
...A CHANGE IN THE WEATHER PATTERN EXPECTED BY THE END OF THE WEEK...
WEDNESDAY NIGHT THROUGH SUNDAY...AFTER A COUPLE MORE DAYS OF COLD
AND DRY WEATHER...THE UPPER LEVEL PATTERN WILL CHANGE AS THE EASTERN
PACIFIC RIDGE STARTS TO DISINTEGRATE AND IS REPLACED BY A TROUGH.
MEDIUM RANGE MODELS ARE CONSISTENT IN BRINGING PRECIPITATION TO THE
REGION BY FRIDAY NIGHT. POPS START A TREND TOWARD CLIMO FOR THE
WEEKEND. THE SOUTHERN STREAM JET STARTS TO UNDERCUT THE RIDGE
ALLOWING VORTICITY TO STREAM INTO THE REGION. MOIST ISENTROPIC
UPGLIDE STARTS TO SPREAD ACROSS THE INLAND NORTHWEST ON SATURDAY AND
CONTINUES THROUGH THE WEEKEND. SOUTHWEST MID LEVEL FLOW WILL TRY TO
PUSH SOME WARMER AIR ACROSS THE FORECAST AREA. AT THE
SURFACE...EASTERLY WINDS WILL TEND TO KEEP THE COLD AIR BANKED UP
AGAINST THE CASCADES WITH THE POTENTIAL FOR SOME MIXED PRECIPITATION
IN THE WESTERN VALLEYS AS 850MB TEMPS CREEP ABOVE 0C SUNDAY NIGHT.
IT IS MUCH TOO EARLY FOR ANY CERTAINTY IN FORECASTING PRECIPITATION
TYPES BUT MODEL SOUNDINGS INDICATE THE POTENTIAL IS THERE. FOR NOW
THE WEATHER GRIDS WILL SHOW SNOW ONLY. TEMPERATURES WILL START OUT
AROUND 20 DEGREES BELOW SEASONAL NORMALS AND THEN START A GRADUAL
CLIMB TOWARD NORMAL VALUES WITH HIGH TEMPERATURES REACHING THE LOW
TO MID 30S FOR MOST VALLEY LOCATIONS BY SUNDAY. /KELCH
&&
.AVIATION...
STRONG EASTERLY WINDS CURRENTLY GUSTING AT 25 TO 35 KNOTS WILL
BEGIN TO DIMINISH THIS EVENING WITH FURTHER ABATEMENT OVERNIGHT.
WINDS AT MOST TAF SITES WILL BE 14 KTS OR LESS AFTER 10Z. WINDS AT
KCOE EXPECTED TO REMAIN GUSTY THRU 18Z MONDAY AS FLOW IS FUNNELED
DOWN THE PURCELL TRENCH. BLSN OVER THE WATERVILLE PLATEAU MAY
BRIEFLY CAUSE REDUCED VISIBILITIES IN THE KEAT AREA THIS EVENING.
OTHERWISE VFR CONDITIONS EXPECTED AT ALL TAF SITES THRU 00Z
TUESDAY WITH VARYING DEGREES OF MID LEVEL CLOUDS AND HIGH CIRRUS
LAYERS. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 6 15 1 12 5 15 / 0 0 0 0 0 0
COEUR D'ALENE 5 14 1 13 4 14 / 0 0 0 0 0 0
PULLMAN 4 15 5 12 2 16 / 0 0 0 0 0 0
LEWISTON 12 20 7 17 9 22 / 0 0 0 0 0 0
COLVILLE 8 17 2 15 8 16 / 0 0 0 0 10 10
SANDPOINT 1 9 -2 8 3 12 / 0 0 0 0 10 10
KELLOGG 2 9 0 8 3 11 / 0 0 0 0 10 10
MOSES LAKE 10 21 4 18 4 20 / 0 0 0 0 0 0
WENATCHEE 10 18 -2 17 4 23 / 0 0 0 0 0 0
OMAK 7 18 -1 19 6 21 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR COEUR D'ALENE
AREA...IDAHO PALOUSE.
WIND ADVISORY UNTIL 7 PM PST THIS EVENING BELOW 3000 FEET FOR
NORTHERN PANHANDLE.
WA...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR SPOKANE AREA...
WASHINGTON PALOUSE.
WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR MOSES LAKE AREA...
UPPER COLUMBIA BASIN.
&&
$$
