FXUS66 KPDT 152310 AAA
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
310 PM PST TUE DEC 15 2009
UPDATED AVIATION DISCUSSION
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...A FRONT CONTINUES TO
MOVE INTO THE AREA THIS AFTERNOON. A GENEROUS TAP OF WARM MOIST AIR
IS FEEDING THE FRONT AND HAS BEEN CREATING RAIN AND FREEZING RAIN
ACROSS THE AREA. NUMEROUS WARNINGS AND ADVISORIES REMAIN IN EFFECT.
SEE PDXWSWPDT FOR DETAILS. SLOWLY THE COLD AIR AT THE SURFACE IN THE
OREGON COLUMBIA BASIN IS ERODING AND MANY AREAS HAVE CLIMBED ABOVE
FREEZING. THE WASHINGTON COLUMBIA BASIN AND COLUMBIA GORGE REMAINS
NEAR OR BELOW FREEING FOR THE MOST PART AND BELIEVE THAT IT WILL
REMAIN SO THIS EVENING. AS PRECIPITATION IS EXPECTED TO CONTINUE
THIS EVENING...THOSE AREAS ARE EXPECTED TO SEE FURTHER FREEZING RAIN
SO HAVE ISSUED AN ICE STORM WARNING FOR THE WASHINGTON COLUMBIA
BASIN AND COLUMBIA GORGE THROUGH 10 PM THIS EVENING. OVERNIGHT THE
RAIN WILL TAPER OFF AND TEMPERATURES SHOULD RISE OR REMAIN
STATIONARY OVER MOST OF THE AREA. THIS WILL HELP ALLEVIATE THE
POTENTIAL FOR FLOODING IN THE BLUE MOUNTAIN FOOTHILLS AS RAIN AND
MELTED SNOW RUN OFF FROZEN GROUND. HOWEVER...UPSLOPE WESTERLY WINDS
INTO THE BLUE MOUNTAINS WILL CONTINUE TO CREATE SNOW IN THE BLUE
MOUNTAINS THROUGH THE NIGHT ALTHOUGH THE SNOW LEVEL WILL RISE TO
4500 FEET SO A WINTER STORM WARNING AND WINTER WEATHER ADVISORIES
WILL REMAIN IN EFFECT FOR VARIOUS PORTIONS OF THE BLUE MOUNTAINS.
TOMORROW AND WEDNESDAY WILL SEE A CONTINUED SOUTHWEST FLOW INTO THE
REGION. IMPULSES IN THE FLOW WILL KEEP A CHANCE OF MAINLY RAIN WITH
MOUNTAINS SNOW ABOVE 4500 FEET. TEMPERATURES WILL BE IN THE UPPER
30S TO MID 40S TOMORROW AND AROUND FREEZING WEDNESDAY NIGHT. RAIN
WILL GRADUALLY REDUCE IN INTENSITY AND WILL AMOUNT TO AROUND ONE
TENTH IN THE LOWER ELEVATIONS WITH TWO TENTHS OF PRECIPITATION IN
THE MOUNTAINS ON WEDNESDAY AND AGAIN WEDNESDAY NIGHT. PERRY
.LONG TERM...THURSDAY THROUGH SATURDAY NIGHT...MODELS ARE IN
RELATIVELY GOOD AGREEMENT WITH ANOTHER WEATHER SYSTEM MOVING INTO
THE REGION THURSDAY NIGHT. THIS WILL BRING A CHANCE OF PRECIPITATION
TO THE REGION WITH SNOW ABOVE 3000 FEET. A SECOND DISTURBANCE WILL
APPROACH THE SOUTHERN OREGON AND NORTHERN CALIFORNIA COAST ON FRIDAY
AND PUSH INTO THE REGION OVERNIGHT AND INTO SATURDAY. THIS WILL
BRING ANOTHER CHANCE OF PRECIPITATION TO THE REGION. MODELS START TO
DISAGREE BEHIND THIS SYSTEM WITH THE GFS BRINGING A TROUGH WITH
COLDER AIR INTO THE REGION SATURDAY NIGHT...WHILE THE EUROPEAN
STRENGTHENS THE RIDGE OFF SHORE. HAVE LOWERED PRECIPITATION CHANCES
SATURDAY NIGHT AS BOTH MODELS INDICATE A DECREASE IN THE THREAT FOR
PRECIPITATION...BUT HAVE KEPT TEMPERATURES NEAR NORMAL DUE TO THE
UNCERTAINTY IN THE MODELS. DMH
SUNDAY THROUGH TUESDAY...AN UPPER LEVEL RIDGE WILL MOVE OVER EASTERN
WASHINGTON AND OREGON SUNDAY WITH DRY CONDITIONS EXCEPT NEAR THE
CASCADES. SUNDAY NIGHT THROUGH TUESDAY A SERIES OF DISTURBANCES
ROTATING AROUND AN UPPER LEVEL LOW OFF THE COAST WILL MOVE OVER THE
PACIFIC NORTHWEST...KEEPING A CHANCE OF PRECIPITATION OVER EASTERN
WASHINGTON AND OREGON. MODEL TIMING HAS BEEN INCONSISTENT AND
ENSEMBLE SPREAD IS HIGH. THIS GIVES A LOW CONFIDENCE IN TIMING AND
STRENGTH...SO KEPT A BROAD BRUSH CHANCE MOUNTAINS AND SLIGHT CHANCE
VALLEYS THROUGH THE PERIOD. COONFIELD
&&
.AVIATION...00Z TAFS...A WEATHER DISTURBANCE CONTINUES TO SPREAD
RAIN ACROSS NORTHEAST OREGON AND SOUTHEAST WASHINGTON THIS
AFTERNOON. A FEW LOCATIONS IN THE COLUMBIA BASIN MAY CONTINUE TO SEE
FREEZING RAIN...IMPACTING POTENTIALLY KYKM AND KPSC BEFORE SWITCHING
TO RAIN LATER THIS EVENING. CEILINGS AND VISIBILITIES WILL DECREASE
AGAIN LATE TONIGHT AND INTO THE MORNING INTO THE MVFR CATEGORY
ACROSS THE REGION UNDER MIST. ANOTHER DISTURBANCE WILL SPREAD MORE
SHOWERS INTO THE AREA IN THE EARLY MORNING HOURS BEFORE TAPERING OFF
WEDNESDAY LATE MORNING. DMH
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 34 41 32 41 / 70 50 50 20
ALW 35 42 35 42 / 70 50 50 20
PSC 30 40 32 41 / 70 30 30 20
YKM 27 36 29 37 / 70 40 40 20
HRI 32 41 32 41 / 70 40 40 20
ELN 27 35 28 37 / 80 50 60 30
RDM 33 45 30 45 / 60 40 50 30
LGD 35 39 30 40 / 60 60 50 20
GCD 35 40 30 42 / 60 40 40 20
DLS 32 41 33 42 / 80 60 70 30
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...ICE STORM WARNING UNTIL 10 PM PST THIS EVENING FOR ORZ044.
WINTER WEATHER ADVISORY UNTIL 6 PM PST THIS EVENING FOR ORZ050.
WINTER WEATHER ADVISORY UNTIL 10 AM PST WEDNESDAY FOR ORZ503.
WINTER STORM WARNING UNTIL 10 AM PST WEDNESDAY FOR ORZ502.
FREEZING RAIN ADVISORY UNTIL 7 PM PST THIS EVENING FOR ORZ041.
WA...WINTER STORM WARNING UNTIL 6 PM PST THIS EVENING FOR WAZ026-027-
501-502.
ICE STORM WARNING UNTIL 10 PM PST THIS EVENING FOR WAZ028.
WINTER WEATHER ADVISORY UNTIL 10 AM PST WEDNESDAY FOR WAZ030.
FREEZING RAIN ADVISORY UNTIL 7 PM PST THIS EVENING FOR WAZ024.
&&
THREAT INDEX
WEDNESDAY : YELLOW
THURSDAY : GREEN
FRIDAY : 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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