FXUS66 KPDT 271633
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
835 AM PST FRI NOV 27 2009
.UPDATE...THE COLD FRONT CONTINUES TO MOVE SLOWLY EAST ACROSS
EASTERN OREGON AND WASHINGTON. A DISTURBANCE CURRENTLY LOCATED OVER
THE WILLAMETTE VALLEY HELPED TO ENHANCE PRECIPITATION ACROSS PARTS
OF THE COLUMBIA BASIN AND THE OREGON FOOTHILLS THIS MORNING. THIS
DISTURBANCE WILL TRACK SOUTHEAST AND MAY BRING SCATTERED SHOWERS TO
CENTRAL OREGON LATER THIS MORNING. EXPECT RAIN TO CONTINUE ACROSS
THE BLUE MOUNTAINS AND EASTWARD DURING THE DAY TODAY. CONDITIONS ARE
DRYING ACROSS CENTRAL WASHINGTON AND HAVE UPDATED THE ZONES TO
INDICATE THIS. THE TEMPERATURES ACROSS THE BLUE MOUNTAIN FOOTHILLS
MAY BE COOLER THIS AFTERNOON THAN PREVIOUSLY FORECASTED AS CLOUDS
WILL BE SLOW TO DEPART TODAY. MAY BE UPDATING LATER THIS MORNING TO
ADJUST HIGH TEMPERATURES TODAY IN THE FOOTHILLS. HIGH PRESSURE WILL
BUILD INTO THE AREA TONIGHT FOR DECREASING SHOWERS AND COOLER
OVERNIGHT TEMPERATURES. DMH
&&
.PREV DISCUSSION... /ISSUED 332 AM PST FRI NOV 27 2009/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT...A SLOW MOVING COLD
FRONT CONTINUES TO MOVE ACROSS THE FORECAST AREA THIS MORNING. MAIN
FRONTAL PRECIPITATION BAND STRETCHES FROM NORTHERN CALIFORNIA ACROSS
EASTERN OREGON TO FAR EASTERN WASHINGTON AND THE IDAHO PANHANDLE.
PRECIPITATION ALONG THE EAST SLOPES OF THE CASCADES HAS DECREASED TO
SHOWERS AT THIS TIME. AS THE FRONT CONTINUES TO SLOWLY MOVE EAST WE
WILL SEE THIS TRANSITION FROM A STEADY PRECIPITATION TO SHOWERS ON A
WEST TO EAST PROGRESSION. THE FRONT WON'T EXIT THE FORECAST AREA
UNTIL LATE THIS AFTERNOON SO AREAS EAST OF JOHN DAY AND MEACHAM WILL
SEE A STEADY PRECIPITATION UNTIL THIS AFTERNOON BEFORE TURNING OVER
TO SHOWERS. OTHER THAN A FEW LINGERING SHOWERS NEAR THE IDAHO
BORDER EARLY TONIGHT THE OVERNIGHT PERIOD LOOKS TO BE DRY AS HIGH
PRESSURE BUILDS BACK OVER THE REGION FROM OFF THE PACIFIC OCEAN.
THIS HIGH PRESSURE WILL DOMINATE THE WEATHER ON SATURDAY FOR MOST OF
THE FORECAST AREA. HOWEVER...A WARM FRONT WILL BE CLIPPING WESTERN
WASHINGTON SO COULD SEE SOME LIGHT RAIN AND SNOW NEAR THE SNOQUALMIE
PASS AREA OTHERWISE JUST SOME MID AND HIGH LEVEL CLOUDS ON
SATURDAY.
LONG TERM...SUNDAY THROUGH THURSDAY. AN UPPER LEVEL RIDGE WILL
BUILD OVER THE PACIFIC NORTHWEST SUNDAY. AN UPPER LEVEL TROUGH WILL
APPROACH THE PACIFIC NORTHWEST MONDAY..AND FLATTEN THE RIDGE AS IT
MOVES THROUGH MONDAY NIGHT WITH A CHANCE OF RAIN AND MOUNTAIN SNOW.
THE UPPER RIDGE WILL REBUILD OFFSHORE AREA TUESDAY AND MOVE SLOWLY
EAST OVER WASHINGTON AND OREGON WEDNESDAY AND THURSDAY. NORTHWEST
FLOW MAY KEEP A FEW SHOWERS IN THE NORTHEAST OREGON MOUNTAINS
TUESDAY. THE GFS AND ECMWF HAVE VERY DIFFERENT TIMING AND TRACK OF A
CUTOFF LOW UNDERCUTTING THE RIDGE...WITH THE GFS MOVING THE CUTOFF
OVER OREGON AND THE ECMWF MOVING IT THROUGH CALIFORNIA. WITH WIDELY
DIFFERENT SOLUTIONS MADE NO CHANGES TO CURRENT EXTENDED FORECAST
BASED ON THE RIDGE MAINTAINING ITSELF. KEPT PARTLY CLOUDY SKIES WITH
PATCHY FOG DEVELOPING IN THE COLUMBIA BASIN AND ADJACENT VALLEYS
WEDNESDAY AND THURSDAY.
AVIATION...12Z TAFS...MVFR CONDITIONS WILL BE PREVALENT THIS
MORNING AT ALL TAF SITES EXCEPT KRDM DUE TO RAIN/FOG ASSOCIATED WITH
A VERY SLOW MOVING FRONTAL SYSTEM. IFR IS POSSIBLE AT TIMES UNTIL
18Z. CEILINGS AND VISIBILITY WILL GRADUALLY IMPROVE FROM WEST TO
EAST. STEADY RAIN WILL TAPER OFF TO SHOWERS DURING THE
MORNING...ENDING BY THE AFTERNOON. CLEARING SKIES THIS AFTERNOON AND
EVENING WILL ALLOW FOG TO REDEVELOP NEAR KPSC...AND POSSIBLY KDLS
AND KALW. 76
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 46 30 46 32 / 50 10 0 0
ALW 47 32 47 35 / 60 10 0 0
PSC 50 29 46 30 / 20 10 0 0
YKM 50 25 46 29 / 10 0 0 0
HRI 49 29 46 29 / 30 10 0 0
ELN 48 27 46 32 / 10 0 0 10
RDM 44 25 45 23 / 30 10 0 0
LGD 44 27 40 27 / 80 10 0 0
GCD 43 26 40 29 / 70 10 0 0
DLS 50 33 48 33 / 30 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
TODAY : GREEN
SATURDAY : GREEN
SUNDAY : GREEN
GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
$$
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