FXUS66 KOTX 281030
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
230 AM PST SAT NOV 28 2009
.SYNOPSIS...
CLOUDS WILL INCREASE TODAY AND PORTIONS OF NORTHERN WASHINGTON AND
FAR NORTHERN IDAHO WILL EXPERIENCE SOME LIGHT SNOW THIS AFTERNOON
AND THIS EVENING. HIGH PRESSURE WILL BE THE DOMINANT WEATHER
FEATURE OVER THE PACIFIC NORTHWEST FOR MOST OF NEXT WEEK. LOOK FOR
MAINLY DRY WEATHER AND CHILLY TEMPERATURES.
&&
.DISCUSSION...
TODAY AND TONIGHT....CLOUDS WILL SPILL INTO EASTERN WASHINGTON
TODAY...OVER THE TOP OF A FLAT UPPER LEVEL RIDGE. THE HIGH LEVEL
JET WILL BE DIRECTED INTO NORTHERN BRITISH COLUMBIA TODAY AND
TONIGHT...AND THE HEART OF DEEP SUBTROPICAL MOISTURE FETCH WILL BE
WELL NORTH OF THE SPOKANE FORECAST AREA. WARM ADVECTION IN THE MID
TROPOSPHERE SHOULD BE SUFFICIENT TO PRODUCE SOME LIGHT
PRECIPITATION IN THE CASCADES AND THE MOUNTAINS ALONG THE CANADIAN
BORDER. THE 00Z AND 06Z RUNS OF THE NAM AGGRESSIVELY GENERATE
PRECIPITATION OVER NORTHEAST WASHINGTON AND NORTHERN IDAHO THIS
AFTERNOON AND THIS EVENING...WITH AS MUCH AS A QUARTER OF AN INCH
QPF AROUND COEUR D'ALENE. THE GFS AND ECMWF GENERATE MUCH LESS AND
APPEAR TO BE MORE REASONABLE GIVEN THE LIMITED AMOUNT OF DEEP
LAYER MOISTURE AND WEAK ISENTROPIC ASCENT. SINCE ANY PRECIPITATION
THAT FALLS WILL BE VERY LIGHT...CHANCES HAVE BEEN MAINLY LIMITED
TO 30 PERCENT OR LESS IN THE MOUNTAINS. FLURRIES OR SPRINKLES
POSSIBLE THIS AFTERNOON AND EVENING IN THE SPOKANE/COEUR D'ALENE
AREA.
FOR THIS MORNING...A BANK OF LOW CLOUDS AND FOG OVER THE PALOUSE
WILL SPREAD NORTH INTO THE SPOKANE AREA. AS OF 09Z...THE FOG
CHANNEL SHOWED AN ARC OF STRATUS AND FOG FROM EAST OF MOSCOW TO
RITZVILLE TO THE TRI-CITIES. BOUNDARY LAYER WIND PROGS FROM THE
NAM...GFS...AND RUC BECOME SOUTH OR SOUTHWESTERLY BETWEEN 09Z AND
12Z AND HOLD A SOUTHERLY TRAJECTORY THROUGH THE DAY. DESPITE
DEWPOINT DEPRESSIONS OF 3-6F IN THE SPOKANE AREA...LOOK FOR THE
ADVECTION OF LOW CLOUDS AND FOG INTO THE REGION BETWEEN 3AM AND
7AM...WITH AREAS OF LIMITED VISIBILITIES LIKELY THROUGH NOON.
/GKOCH
SUNDAY THROUGH MONDAY NIGHT...THE REGION WILL BE UNDER AN UPPER
LEVEL RIDGE WITH MAINLY DRY CONDITIONS AND TEMPERATURES A BIT WARMER
THAN NORMAL. AS THE UPPER RIDGE BUILDS AND LOW LEVEL INVERSIONS
STRENGTHEN...THE THREAT OF VALLEY FOG AND LOW STRATUS WILL INCREASE.
BY MONDAY MORNING CLEARING SKIES AND LIGHT WINDS WILL ALLOW AREAS OF
FOG TO FORM IN MOST VALLEYS AND ACROSS MUCH OF THE BASIN. THE
EXCEPTION WILL BE THE PALOUSE WHERE EASTERLY DOWNSLOPING WINDS
SHOULD KEEP THE FOG AT BAY. A WEAK DISTURBANCE WILL CLIP THE
NORTHERN TIER MONDAY NIGHT BRINGING SOME LIGHT PRECIPITATION. ANY
ACCUMULATING SNOW WILL BE CONFINED TO THE MOUNTAINS.
TUESDAY THROUGH SATURDAY...THE REGION WILL CONTINUE UNDER THE
INFLUENCE OF THE UPPER RIDGE THROUGH AT LEAST THURSDAY. AN UPPER
TROUGH WILL APPROACH THE PACIFIC NORTHWEST BY THE END OF THE
WORKWEEK. MEDIUM RANGE MODELS LACK CONSISTENCY IN THE TIMING AND
STRENGTH OF THE TROUGH AS IT TRACKS THROUGH THE REGION. AS
CONFIDENCE REMAINS LOW...WILL CONTINUE THE TREND OF LOW END POPS
ACROSS THE MTS. TEMPERATURES WILL BE ON A COOLING TREND WITH
READINGS BELOW NORMAL POSSIBLE BY THE WEEKEND. /KELCH
&&
.AVIATION...
LOW CLOUDS AND FOG IN THE PULLMAN AREA WILL SPREAD NORTH INTO THE
SPOKANE AND COEUR D'ALENE AREAS BETWEEN 11Z AND 14Z. CEILINGS WILL
LIKELY BE 500 FEET OR LESS...AND VISIBILITIES OF 2 MILES OR LESS
WILL BE POSSIBLE THROUGH 20Z. TEMPORARY VISIBILITY RESTRICTIONS
FROM FOG MAY ALSO SPREAD AS FAR WEST AS MOSES LAKE THIS MORNING.
/GKOCH
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 36 31 40 31 41 29 / 10 10 0 0 0 10
COEUR D'ALENE 36 31 39 32 43 30 / 20 20 10 0 10 20
PULLMAN 37 30 43 32 44 31 / 10 10 0 0 0 10
LEWISTON 43 32 48 34 47 34 / 0 10 0 0 0 10
COLVILLE 36 32 40 33 42 31 / 20 20 10 10 10 30
SANDPOINT 35 30 36 32 39 30 / 20 20 20 10 10 30
KELLOGG 33 31 36 32 41 29 / 20 20 20 10 10 20
MOSES LAKE 41 31 45 32 43 29 / 0 10 0 0 0 0
WENATCHEE 43 34 48 34 44 33 / 0 10 0 0 0 10
OMAK 40 31 43 33 44 30 / 10 10 0 0 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
