FXUS66 KPDT 041141 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
340 AM PST FRI DEC 4 2009
UPDATED AVIATION DISCUSSION
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...THE FIRST OF A COUPLE
OF SIGNIFICANT COLD FRONTS IS CURRENTLY MOVING NORTH TO SOUTH ACROSS
THE FORECAST AREA AND HAS JUST MOVED SOUTH OF THE OREGON/WASHINGTON
BORDER WITHIN THE LAST HOUR OR SO. SOME MID AND HIGH CLOUDS AHEAD OF
THE FRONT HAS BEEN PUSHED TO THE SOUTH OF THE COLUMBIA RIVER AND
CONTINUES TO BE PUSHED TO THE SOUTH-SOUTHEAST. THIS COLD FRONT
CONTAINS VERY LITTLE MOISTURE AND THE MOST THAT CAN BE EXPECTED FROM
IT IS A FEW LIGHT SNOW SHOWERS OR FLURRIES OVER THE NORTHERN BLUE
MOUNTAINS AND WASHINGTON CASCADE EAST SLOPES THIS MORNING. A COLD
NORTHERLY FLOW WILL SETTLE IN OVER THE REGION LATER TODAY AND
TONIGHT WITH CONTINUED COLD ADVECTION INTO THE REGION FROM THE
NORTH. TEMPERATURES WILL HAVE DIFFICULTY GETTING OUT OF THE 30S
TODAY AND SATURDAY...EVEN IN THE LOWEST ELEVATIONS. A SECONDARY COLD
FRONT ORIGINATING FROM ARCTIC REGIONS WILL DROP DOWN INTO THE
PACIFIC NORTHWEST BY LATE SATURDAY INTO SATURDAY NIGHT. IN ADDITION
A CLOSED UPPER LOW PRESSURE SYSTEM FROM ABOUT 850-700MB AND HIGHER
WILL ALSO DROP DOWN OVER THE CWA. CIRCULATION AROUND THIS LOW WILL
HELP TO TRANSPORT SOME PACIFIC MOISTURE INTO THE REGION OVER THE
DOME OF ARCTIC AIR. AS SUCH CAN EXPECT A BETTER CHANCE FOR SNOW
SHOWERS SATURDAY AND SATURDAY NIGHT. HAVE TRENDED THE POPS UPWARDS
FOR EACH PERIOD AS A RESULT...THOUGH STILL NOT CONVINCED THERE WILL
BE ENOUGH MOISTURE FOR WINTER STORM OR EVEN ADVISORY CRITERIA TO BE
MET...BUT PERHAPS A JUST A FEW INCHES IN THE MOUNTAINS AND A LIGHT
COATING TO PERHAPS AN INCH IN THE LOWER VALLEYS AND COLUMBIA BASIN.
THE MAIN FEATURE WILL BE THE VERY COLD AIR...COLDEST OF THE SEASON
SO FAR...WHICH WILL SETTLE INTO THE REGION BY LATE SATURDAY NIGHT
AND PERSIST INTO THE EXTENDED PERIOD. 88
.LONG TERM...SUNDAY THROUGH THURSDAY...AN UPPER LEVEL LOW WILL MOVE
FROM BRITISH COLUMBIA TO WESTERN OREGON SUNDAY. THIS WILL BRING A
WIDESPREAD CHANCE OF SNOW TO EASTERN WASHINGTON AND OREGON...WITH
SHOWERS LINGERING IN OREGON MONDAY. COLD NORTHERLY FLOW WILL REMAIN
OVER THE AREA TUESDAY. UPPER LEVEL FLOW WILL BECOME MORE NORTHWEST
WEDNESDAY AND THURSDAY WITH COLD AIR TRAPPED IN THE COLUMBIA BASIN.
A SERIES OF DISTURBANCES IN THE NORTHWEST FLOW WILL BRING VARYING
CHANCES OF WINTER PRECIPITATION WEDNESDAY AND THURSDAY. COONFIELD
&&
.AVIATION...12Z TAFS...LOW CLOUDS CONTINUE TO LINGER ACROSS
KPDT...KYKM...KALW...AND KPSC. EXPECT THAT THESE LOW CIGS WILL
DIMINISH IN THE LATE MORNING HOURS AS WESTERLY WINDS INCREASE BEHIND
A DRY FRONT. THE WINDS SHOULD MIX OUT MOST OF THE LOW CLOUDS. 76
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 37 17 33 18 / 10 20 20 30
ALW 40 20 36 18 / 10 20 20 30
PSC 38 18 38 18 / 10 10 10 20
YKM 40 16 37 21 / 10 10 10 20
HRI 40 15 35 18 / 10 10 10 20
ELN 40 18 37 15 / 10 10 10 20
RDM 42 10 36 11 / 10 20 20 20
LGD 36 20 31 17 / 10 30 30 40
GCD 39 18 33 12 / 10 20 20 40
DLS 39 22 40 19 / 10 20 20 20
&&
.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
$$
88/76/76
