FXUS66 KPDT 280337
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
740 PM PST FRI NOV 27 2009
.UPDATE...THE COLD FRONT AND ITS ASSOCIATED PRECIPITATION HAVE MOVED
EAST OF THE AREA. SKIES WILL BECOME MOSTLY CLEAR TONIGHT...ALLOWING
TEMPERATURES TO FALL BELOW FREEZING IN MOST LOCATIONS. THIS
RADIATIONAL COOLING WILL ALSO AID IN THE FORMATION OF PATCHY
FOG...ESPECIALLY IN THE RIVER VALLEYS OF THE COLUMBIA BASIN. HIGH
CLOUDS WILL BEGIN MOVING INTO THE REGION BY SATURDAY MORNING AS A
STORM SYSTEM APPROACHES WESTERN CANADA. HOWEVER...A STRONG RIDGE OF
HIGH PRESSURE IN THE EASTERN PACIFIC SHOULD KEEP MOST OF THE LOCAL
AREA DRY THROUGH MID-WEEK. 82
&&
.PREV DISCUSSION... /ISSUED 330 PM PST FRI NOV 27 2009/
SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...SATELLITE IMAGERY SHOWS
THE SHARP BACKSIDE OF THE COLD FRONT MOVING INTO THE BLUE MOUNTAINS
CURRENTLY. A WEATHER DISTURBANCE MOVING SOUTHEAST BEHIND THE FRONT
IS SPREADING ISOLATED TO SCATTERED SHOWERS ACROSS CENTRAL OREGON.
BOTH OF THESE SYSTEMS ARE EXPECTED TO MOVE OUT OF THE AREA THIS
EVENING AND OVERNIGHT. SHOWERS WILL BE ON THE DECREASE WITH DRIER
CONDITIONS EXPECTED BY SATURDAY. SKIES ARE CLEARING RAPIDLY BEHIND
THE TWO SYSTEMS WHICH WILL LEAD TO COLD OVERNIGHT LOWS. SOME PATCHY
FOG AND FREEZING FOG IS POSSIBLE LATE TONIGHT AND INTO SATURDAY
MORNING IN THE LOWER ELEVATIONS OF THE COLUMBIA BASIN...PARTICULARLY
NEAR THE BIG RIVERS (COLUMBIA...YAKIMA AND WALLA WALLA RIVERS). A
RIDGE OF HIGH PRESSURE WILL BUILD AND MOVE INLAND THROUGH THE
WEEKEND...PUSHING WEATHER SYSTEMS TO THE NORTH. A SYSTEM ON SATURDAY
MAY BRUSH THE CENTRAL WASHINGTON CASCADES WITH A SLIGHT CHANCE OF
PRECIPITATION MOVING EAST OF THE CREST. ELSEWHERE...INCREASING
CLOUDS WILL BE THE MAIN AFFECT OF THE PASSING SYSTEMS. MOIST LOWER
LEVELS WITH LIGHTER WINDS WILL LEAD TO THE SPREAD OF PATCHY FOG AND
FREEZING FOG OVERNIGHT SUNDAY MORNING AND SUNDAY NIGHT LEADING INTO
MONDAY MORNING. DMH
LONG TERM...MONDAY THROUGH FRIDAY. THE EXTENDED MODELS ARE NOT IN
VERY GOOD AGREEMENT SO LIMITED CHANGES WERE MADE TO THIS FORECAST
PACKAGE. EURO AND GFS AGREE ON THE UPPER LEVEL RIDGE OVER THE AREA
MONDAY WITH A WEAK SYSTEM PASSING BY TO THE NORTH MONDAY NIGHT AND
TUESDAY. AFTER THIS THE MODELS ARE OUT OF SYNC WITH THE POSITIONS OF
UPPER RIDGES AND UPPER LOWS. FOR NOW WENT WITH THE UPPER RIDGE
SCENARIO WHICH WAS ADVERTISED BY BOTH MODELS YESTERDAY. THIS KEEPS
THE FORECAST MAINLY DRY WITH SEASONAL TEMPERATURES AND AREAS OF
OVERNIGHT FOG IN THE COLUMBIA BASIN AND VALLEYS. 94
AVIATION...00Z TAFS. PRECIPITATION HAS ENDED ACROSS ALL TAF SITES
WITH THE EXCEPTION OF RDM WHERE A FEW SHOWERS WILL CONTINUE INTO
EARLY EVENING. CONDITIONS ARE IMPROVING WITH CEILINGS AND VISIBILITY
RISING INTO THE VFR RANGE. SURFACE WINDS 5-10 KT THROUGH THE
EVENING. SOME AREAS OF FOG COULD DEVELOP OVERNIGHT IN THE COLUMBIA
BASIN AND VALLEYS WITH THE RECENT RAIN AND CLEARING SKIES. ANY FOG
THAT DEVELOPS WILL DISSIPATE SATURDAY MORNING. A WARM FRONT PASSING
BY TO THE NORTH WILL BRING INCREASING MID AND HIGH LEVEL CLOUDS
DURING THE AFTERNOON. CEILINGS WILL BE 100-200.
94
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 29 44 32 44 / 10 0 0 0
ALW 31 45 35 45 / 10 0 0 0
PSC 25 46 30 45 / 10 0 0 0
YKM 23 45 28 46 / 0 0 0 0
HRI 26 45 29 45 / 10 0 0 0
ELN 25 45 30 47 / 0 0 10 0
RDM 21 44 23 46 / 10 0 0 0
LGD 29 40 25 44 / 10 0 0 0
GCD 30 40 29 45 / 10 0 0 0
DLS 31 48 33 48 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
SATURDAY : 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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