FXUS66 KOTX 271043
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
243 AM PST FRI NOV 27 2009
.SYNOPSIS...
RAIN WILL COME TO AN END THIS MORNING OVER MOST OF EASTERN
WASHINGTON AND NORTHERN IDAHO. MANY PLACES WILL EXPERIENCE
SUNSHINE BY THE AFTERNOON. WEAK HIGH PRESSURE WILL BRING MAINLY
DRY CONDITIONS TO THE INLAND NORTHWEST THIS WEEK. A WEAK FRONTAL
SYSTEM MAY BRING SOME LIGHT PRECIPITATION TO THE REGION MONDAY
NIGHT INTO TUESDAY...BUT THE REMAINDER OF THE WEEK SHOULD BE
CHILLY...BUT DRY.
&&
.DISCUSSION...
TODAY AND TONIGHT...EARLY MORNING WATER VAPOR IMAGERY SHOWS AN
ELONGATED...POSITIVELY TILTED UPPER TROUGH MOVING THROUGH THE
PACIFIC NORTHWEST. AS OF 10Z...THE MAIN VORTICITY CENTER WAS
MOVING TOWARD NORTHERN CALIFORNIA AND SOUTHERN OREGON. AHEAD OF
THE UPPER TROUGH...DEEP MOIST ISENTROPIC ASCENT HAS BEEN PRODUCING
RAIN OVER THE COLUMBIA BASIN THROUGH EASTERN WASHINGTON INTO THE
PANHANDLE. THE NAM AND GFS SHOW BETWEEN 25-35KTS OF SOUTHWESTERLY
FLOW ON THE 295K THETA SURFACE. THE PRESSURE ADVECTION IS
SUFFICIENT OVERWHELM THE CASCADE RAIN SHADOW. AS OF 10Z...MOSES
LAKE RECEIVED ABOUT 0.3 INCHES OF RAIN...AND WENATCHEE RECEIVED
ABOUT A 0.1 INCH. THESE TYPICALLY DRY PLACES WILL LIKELY RECEIVE
AS MUCH RAIN AS PLACES LIKE SPOKANE AND PULLMAN WHICH ARE USUALLY
WETTER.
PRECIPITATION WILL MAINLY OCCUR THIS MORNING FOR THE MAJORITY OF
THE SPOKANE FORECAST AREA. AS THE TROUGH AXIS PUSHES THROUGH
EASTERN WASHINGTON...MUCH DRIER AIR WILL BE USHERED INTO THE
REGION FROM THE NORTH. BOTH THE NAM AND GFS FORECAST STRONG MID
LEVEL DRY ADVECTION BEHIND THE 700MB TROUGH AXIS. THE DRY AIR IS
CERTAINLY ON THE WAY. THE 00Z RAOB AT CYLW OVER SOUTHERN BRITISH
COLUMBIA HAD A DEWPOINT DEPRESSION OF 26C AT 700MB. DEEP LAYER
NORTHERLY FLOW SHOULD BE STRONG ENOUGH TO ERODE MOST OF THE POST
FRONTAL STRATUS THIS AFTERNOON...EXCEPT FOR LINGERING
STRATOCUMULUS OVER THE MOUNTAINS OF THE CENTRAL AND SOUTHERN
PANHANDLE. THERE IS A HIGH LIKELIHOOD THAT LOW CLOUDS AND FOG WILL
REDEVELOP OVERNIGHT OVER THE PALOUSE AND SPOKANE AREA. BOUNDARY
LAYER PROGS FROM BOTH THE NAM AND GFS SUGGEST FOG OR STRATUS
REDEVELOPING BETWEEN 06-12Z BETWEEN PULLMAN AND SPOKANE AND
EXPANDING NORTHWARD ALONG THE COLUMBIA RIVER AND THE VALLEYS OF
NORTHEAST WASHINGTON. /GKOCH
SATURDAY THROUGH THURSDAY...A SHORT-WAVE RIDGE BUILDS IN BEFORE
THE NEXT SYSTEM MOVES BY MONDAY NIGHT...THEN ANOTHER RIDGE AMPLIFIES
NEAR THE COAST TUESDAY AND USHERS IN COOLER AIR. A WEAK WARM FRONT
LEADS IN THE RIDGE SATURDAY. A NW FLOW AND WEAK ISENTROPIC ASCENT
WILL PROVIDE A RISK FOR LIGHT SNOW SHOWERS OVER THE MOUNTAIN ZONES
SATURDAY INTO EARLY SUNDAY...BEFORE DRIER AIR REDUCES THIS RISK TO
JUST THE MOUNTAINS THEMSELVES. A VALLEY STRATUS AND FOG THREAT
WITH ACCOMPANY THE BUILDING RIDGE. THE NEXT SYSTEM SWINGS ONTO
THE COAST MONDAY AND PASSES MONDAY NIGHT. GUIDANCE HAS TRENDED
FURTHER NORTH WITH THIS FEATURE...SO POPS WERE REDUCED A TAD.
EITHER WAY THIS WILL BRING THE NEXT CHANCE OF RAIN AND SNOW. THE
SYSTEM SWINGS EAST BY TUESDAY AND A RIDGE REBUILDS...SHRINKING
THE MAIN PRECIPITATION CHANCES TO THE IDAHO MTNS. TEMPERATURES ARE
ALSO EXPECTED TO DIP NEAR OR SLIGHTLY BELOW NORMAL WITH THE
DEVELOPING NNW FLOW...ESPECIALLY OVER THE NORTHEAST CWA. MODELS
CONTINUE TO WAVER ON THE EXTENT OF THE COOLING. 00Z MODELS TRENDED
SLIGHTLY WARMER THAN PREVIOUS RUNS. WE WILL HAVE TO WATCH THE
DEPTH OF THE CANADIAN AIR TO SEE HOW EFFICIENTLY IT CAN PRESS
WEST OF THE DIVIDE. /JCOTE
&&
.AVIATION...
A STRONG PACIFIC MOISTURE TAP AND MEANDERING FRONTAL BOUNDARY WILL
WREAK HAVOC WITH CIGS AND VIS THROUGH FRI MORNING AT MOST SITES. AN
UPPER LEVEL SYSTEM WILL GRADUALLY WEAKEN AND MOVE INLAND
OVERNIGHT...ALLOWING THE FRONTAL BOUNDARY TO SLOWLY SHIFT EASTWARD
BY MORNING. HOWEVER...BEFORE IT DOES...AREAS OF +RA ALONG THE
FRONTAL BAND WILL CONTINUE WITH CEILINGS GENERALLY INVOF 1500 TO
2500 FEET AT MOST LOCATIONS. SKIES SHOULD SCATTER OUT BEHIND THE
FRONT LATE FRIDAY FROM WEST TO EAST. /FRIES
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 40 27 36 28 38 33 / 90 10 10 10 10 0
COEUR D'ALENE 41 28 37 29 39 33 / 100 10 20 20 10 0
PULLMAN 42 29 37 28 39 33 / 90 10 10 10 0 0
LEWISTON 47 33 44 30 47 34 / 80 10 10 0 0 0
COLVILLE 42 28 38 31 39 34 / 30 0 30 20 10 10
SANDPOINT 39 24 35 29 35 33 / 80 10 30 30 20 10
KELLOGG 37 27 34 28 36 32 / 100 20 30 30 20 10
MOSES LAKE 45 24 42 28 43 34 / 20 0 10 0 0 0
WENATCHEE 47 32 44 33 46 35 / 10 0 10 0 0 0
OMAK 46 26 42 29 44 34 / 10 0 10 0 10 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
