FXUS66 KPDT 051010
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
210 AM PST SAT DEC 5 2009
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...A SERIES OF WAVES IN A
NORTHERLY FLOW ALOFT IS CONTINUING TO DRAW IN COLDER AIR INTO THE
FORECAST AREA WITH EACH ONE BEING A BIT COLDER THAN THE PREVIOUS.
THE NEXT IS CURRENTLY PUSHING SOUTH ACROSS CENTRAL WASHINGTON STATE
INTO NORTH CENTRAL OREGON. THIS IS PRODUCING A FEW SNOW FLAKES OVER
THE FORECAST AREA THIS MORNING...BUT NOT ENOUGH FOR ANY
ACCUMULATION. THE GENERAL TREND IS FOR AVAILABLE ATMOSPHERIC
MOISTURE FOR SNOW ALSO INCREASE WITH EACH SUCCESSIVE WAVE IN THE
NORTHERLY FLOW. A STRONGER AND COLDER PUSH OF ARCTIC AIR IS PROGGED
TO MOVE INTO THE FORECAST AREA TONIGHT AND SUNDAY MORNING. A CLOSED
UPPER LOW PRESSURE SYSTEM WILL ALSO DEVELOP WITH THIS NEXT WAVE AND
SLIDE SOUTHWARD OVER WESTERN OREGON. THIS WILL PUT EASTERN OREGON
AND SOUTHEAST WASHINGTON IN A NORTHEAST WRAP AROUND BAROCLINIC FLOW
WITH BETTER CIRCULATION OF SOME PACIFIC MOISTURE INTO THE REGION.
THIS COMBINED WITH INCREASING LIFT CAUSED BY THE DOME OF ARCTIC AIR
AS WELL AS SOME OROGRAPHIC LIFT WILL CAUSE A BETTER CHANCE OF SNOW
SHOWERS TONIGHT AND EARLY SUNDAY. THOUGH IT STILL IS UNLIKELY THAT
ADVISORY OR WARNING AMOUNTS OF SNOW WILL OCCUR THERE MAY BE AS MUCH
AS A COATING TO AN INCH IN THE LOWER ELEVATIONS WITH GREATER
AMOUNTS...PERHAPS A FEW INCHES...IN THE MOUNTAINS...ESPECIALLY THE
BLUES AND WALLOWA MOUNTAINS...AND AGAINST THE EAST SLOPES OF THE
CASCADES. BITTER COLD ARCTIC AIR WILL REMAIN IN PLACE OVER THE CWA
THROUGH SUNDAY INTO MONDAY AND THE EARLY PART OF THE EXTENDED
FORECAST PERIOD. WILL REFRESH A SPECIAL WEATHER STATEMENT LATER THIS
MORNING FOR THE COLD AIR DUE TO ARRIVE ALONG WITH SOME LIGHT SNOW. 88
.LONG TERM...MONDAY THROUGH FRIDAY...MONDAY AND TUESDAY COLD
NORTHERLY UPPER LEVEL FLOW WILL KEEP SOME SNOW SHOWERS IN UPSLOPE
AREAS OF OREGON. UPPER LEVEL FLOW WILL BECOME MORE NORTHWEST
WEDNESDAY THROUGH FRIDAY. COLD AIR WILL REMAIN TRAPPED BELOW STRONG
SURFACE INVERSIONS IN THE COLUMBIA BASIN. TEMPERATURES WILL SLOWLY
MODERATE IN OTHER AREAS AS THE ARCTIC AIR MASS BECOMES
MODIFIED...BUT TEMPERATURES WILL REMAIN UNSEASONABLY COLD IN ALL
LOCATIONS THROUGH THE PERIOD. A SERIES OF DISTURBANCES IN THE
NORTHWEST FLOW WILL BRING VARYING CHANCES OF WINTER PRECIPITATION
DURING WEDNESDAY THROUGH FRIDAY. COONFIELD
&&
.AVIATION...06Z TAFS...MVFR AND OCCASIONAL IFR CONDITIONS ARE LIKELY
ACROSS THE AREA TONIGHT DUE TO LOW CEILINGS. HOWEVER...A COLD FRONT
IS FORECAST TO SWEEP ACROSS THE REGION...AND CEILINGS SHOULD
GRADUALLY RISE DURING THE DAY SATURDAY. OCCASIONAL LIGHT SNOW
SHOWERS WILL BE POSSIBLE DURING THE NEXT 24 HOURS. WINDS WILL
REMAIN LESS THAN 10 KTS. 82
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 29 17 25 11 / 20 40 40 20
ALW 30 20 27 13 / 20 40 30 20
PSC 32 14 29 10 / 10 20 20 10
YKM 32 14 29 8 / 10 60 20 10
HRI 32 16 29 9 / 10 20 20 10
ELN 31 13 27 7 / 10 60 20 10
RDM 32 9 25 5 / 10 20 40 40
LGD 28 16 26 9 / 20 40 30 20
GCD 31 13 26 7 / 20 30 40 40
DLS 32 19 30 15 / 10 50 30 20
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
TODAY : GREEN
SUNDAY : GREEN
MONDAY : 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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