Winter Weather in Washington, January 16, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
947 AM PST TUE JAN 16 2007

.SYNOPSIS...HIGH PRESSURE ALOFT WILL WEAKEN SLIGHTLY TODAY WITH A
PASSING DISTURBANCE BRINGING LIGHT ACCUMULATIONS OF SNOW TO MUCH
OF THE REGION. FOR THE REMAINDER OF THE WEEK CONDITIONS WILL
REMAIN COLD AND MAINLY DRY.

&&

.DISCUSSION...
REST OF TODAY...SATELLITE INDICATES A HIGHLY MERIDIONAL UPPER LEVEL
TROUGH MOVING ONSHORE INTO THE WESTERN US THIS MORNING. THIS TROUGH
IS SPLITTING ITS ENERGY WITH THE LIONS SHARE EXPECTED TO PASS
WELL SOUTH OF THE FORECAST AREA...WITH THE NORTHERN BRANCH OF THE
SPLIT BRUSHING THE FORECAST AREA TO THE NORTH. BETWEEN THESE TWO
DYNAMIC REGIONS A STRETCHING MID LEVEL COLD FRONT IS DRAGGING
THROUGH THE CASCADES THIS MORNING. RADAR AND SATELLITE SUGGEST THIS
BAROCLINIC REGION WILL REMAIN STRONG ENOUGH TO ENHANCE A MODERATE
FETCH OF PRECIPITABLE WATER INTO LIGHT SNOW AS IT BREAKS OUT INTO
THE COLUMBIA BASIN DURING THE AFTERNOON TODAY. THE STRETCHING AND
WEAKENING NATURE OF THIS FRONTAL BAND SUGGESTS ANY ACCUMULATION
WILL BE GENERALLY LESS THAN 1 INCH EXCEPT OVER HIGHER
TERRAIN NEAR THE CASCADES CREST. VERY DRY MID LEVEL AIR MASS NOTED
ON SPOKANE RAOB THIS MORNING SUGGESTS IT WILL TAKE A WHILE FOR THE
DRY LAYER TO BE WIPED OUT BEFORE PRECIPITATION BEGINS OVER THE
EASTERN ZONES...WITH A LIKELY ONSET NEAR OR AFTER 5 PM THIS
AFTERNOON. THUS FOR TODAY IMPENDING ZONE UPDATE WILL INCREASE POPS
OVER THE WESTERN ZONES FOR A LOW ACCUMULATION LIGHT SNOW EVENT
DURING THE DAY TODAY...AND CUT BACK POPS INTO THE SLIGHT CHANCE
CATEGORY OVER THE EAST TO ACCOUNT FOR THIS MOISTENING PROCESS
BEFORE LIGHT SNOW COMMENCES THIS EVENING WHEN CURRENT HIGHER POPS
ARE JUSTIFIED. OTHERWISE MINOR TWEAKS TO EXPECTED HIGH TEMPERATURES
BASED ON CURRENT OBSERVATIONS AND TRENDS. UPDATE TO STATE FORECAST
PRODUCT ALSO EXPECTED SHORTLY TO ADD AIR STAGNATION HEADLINE FOR THE
YAKIMA AREA. /FUGAZZI

&&

.AVIATION...STRATUS CEILINGS DAMMED AGAINST THE E SLOPES OF THE
CASCADES FROM KEAT N TO KOMK TODAY...ALONG WITH DEVELOPING SNOW FOR
ALL SITES...WILL BE THE AREAS OF FOCUS AS FAR AS AVIATION WX...WITH
MVFR VIS/CEILINGS WIDESPREAD. PACIFIC COLD-FRONT NOW MOVING SLOWLY E
ACROSS WRN WA AND THE CASCADES WILL BEGIN TO PRODUCE LIGHT SNOW ALOFT
WHICH...IF HEAVY ENUF...WILL ACT TO MIX THRU THE SFC STRATUS AND
RAISE CEILINGS TO VFR LEVELS FROM KEAT TO KOMK. HOWEVER...ONCE THE
LOW LEVELS MOISTEN FROM THE FALLING SNOW...EXPECT VIS AND CEILINGS TO
DECREASE ONCE AGAIN INTO THE MVFR OR OCNL IFR FOR THE REST OF TODAY.
THIS SNOW AND MVFR/IFR WX WILL ADVANCE SLOWLY E THRU ERN WA...
REACHING THE SPOKANE REGION BY 01Z WED. FOLLOWING FRONTAL PASSAGE
THIS EVENING...STRATUS WILL BECOME WIDESPREAD...ESPECIALLY ACROSS THE
PALOUSE/LEWISTON AND SPOKANE AREA...PRODUCING IFR CEILINGS AND MVFR
VSBY. STRATUS AND/OR FOG TO LAST THRU AT LEAST 18Z WED. BZ

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        23  10  23  12  22  14 /  20  60  30   0  10  10
COEUR DALENE  21  12  24  10  23  13 /  20  60  30  10  10  10
PULLMAN        29  14  26  16  25  18 /  10  40  30  10  10  10
LEWISTON       30  16  31  19  30  22 /  10  20  20  10  10  10
COLVILLE       21   9  23  10  22  11 /  60  40  30   0  10  10
SANDPOINT      20  10  23   9  23  11 /  40  60  30  10  10  10
KELLOGG        22  12  24  12  23  16 /  20  50  30  10  10  10
MOSES LAKE     24  11  25  12  26  18 /  40  20   0   0  10  10
WENATCHEE      24  13  26  13  25  19 /  60  20   0   0  10  10
OMAK           20   9  23   8  24  15 /  60  20   0   0  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&