139
FXUS66 KPDT 261258 AAB
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
500 PST THU NOV 26 2009
UPDATED AVIATION DISCUSSION
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
A COLD FRONT CONTINUES TO
BE STALLED ALONG THE PACIFIC NORTHWEST COAST THIS MORNING LEAVING
THE FORECAST AREA UNDER A RIDGE FOR THE TIME BEING. THIS FRONT WILL
BEGIN TO SLOWLY MOVE EASTWARD TODAY BRINGING SOME PRECIPITATION TO
THE CASCADES BY AFTERNOON. THE FRONT WILL PUSH EAST OF THE CASCADES
OVERNIGHT SPREADING PRECIPITATION INTO FAR NORTHEAST OREGON BY
EARLY SATURDAY MORNING. PRECIPITATION WILL MAINLY BE IN THE FORM OF
RAIN WITH SNOW LEVELS ORIGINALLY AROUND 6000 TO 8000 FEET EVENTUALLY
LOWERING TO 3000 TO 4000 FEET BY SATURDAY. PRECIPITATION WILL TURN
TO SHOWERS BEHIND THE PASSAGE OF THE FRONT. A FEW SHOWERS WILL
LINGER OVER NORTHEAST OREGON INTO SATURDAY NIGHT. SNOW SIGNIFICANT
SNOW ACCUMULATIONS EXPECTED WITH THIS SYSTEM. TODAYS HIGH
TEMPERATURES SHOULD BE ABOUT THE SAME AS YESTERDAYS. SOME COOL AIR
WILL CONTINUED TO BE TRAPPED IN THE COLUMBIA BASIN AND SOME MORNING
PATCHY FOG IS LIKELY. SOUTHERLY WINDS WILL INCREASE TODAY IN MOST
AREAS OTHER THAN THE BASIN THEN SWITCH TO WESTERLY TONIGHT BEHIND
THE COLD FRONTAL PASSAGE. THE GRANDE RONDE VALLEY WILL CONTINUE TO
BE UNDER A WIND ADVISORY THROUGH THIS EVENING.
LONG TERM...SATURDAY THROUGH WEDNESDAY
A WARM FRONT WILL BRUSH
THE PACIFIC NORTHWEST SATURDAY. THIS SYSTEM MAY BRING PRECIPITATION
IN THE HIGHER TERRAIN...PARTICULARLY NEAR THE CASCADES. SATURDAY
NIGHT A RIDGE WILL BUILD OVER THE PACIFIC NORTHWEST. SUBSIDENCE FROM
THE RIDGE WILL BRING DRIER AIR AND LIGHT WINDS. WITH CLEARING SKIES
AND LIGHTER WINDS...PATCHY FOG WILL DEVELOP ALONG THE AREA RIVERS
SUNDAY AND MONDAY MORNINGS. A WEAK TROUGH WILL FLATTEN THE RIDGE AND
BRING SOME PRECIPITATION AND LOWERING SNOW LEVELS MONDAY. THIS
SYSTEM WILL MOVE THROUGH QUICKLY...SO DO NOT EXPECT HEAVY SNOW IN
THE HIGHER TERRAIN. TUESDAY AND WEDNESDAY THE UPPER LEVEL RIDGE WILL
REBUILD OFFSHORE WITH DRY NORTHERLY FLOW OVER EASTERN WASHINGTON AND
OREGON. COONFIELD
AVIATION...12Z
VRF OR MVFR CONDITIONS WILL MOSTLY PREVAIL FOR THE
NEXT 18 HOURS. HIGH CLOUDS WILL CONTINUE TO INCREASE AHEAD OF THE
NEXT WEATHER DISTURBANCE. PATCHY FOG WILL PERSIST THIS MORNING AT
KDLS...KPSC...KYKM...KALW AND KPDT. MVFR VISIBILITIES ARE LIKELY AND
IFR VISIBILITIES AND CEILINGS ARE POSSIBLE KDLS AND KPSC. THE HIGHER
CLOUDS WILL ALSO DELAY IMPROVEMENT IN VISIBILITY. RAIN IS LIKELY
NEAR KDLS AND KYKM THURSDAY EVENING AS THE NEXT SYSTEM BEGINS TO
MOVE ACROSS THE CASCADES. RAIN SHOWERS WILL BE POSSIBLE AT THE
REMAINING TAF SITES BY THURSDAY EVENING. WINDS WILL REMAIN LIGHT.
76
PRELIMINARY POINT TEMPS/POPS
PDT 51 40 49 31 / 0 60 30 10
ALW 46 42 50 34 / 0 60 40 10
PSC 47 41 53 29 / 0 50 20 10
YKM 46 35 50 28 / 30 60 20 0
HRI 47 39 52 29 / 0 50 20 10
ELN 45 34 46 29 / 50 60 20 10
RDM 57 33 43 26 / 10 50 20 10
LGD 47 37 41 30 / 0 40 60 20
GCD 56 37 40 31 / 0 50 60 10
DLS 47 41 50 34 / 20 60 20 10
PDT WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR ORZ049.
WA...NONE.
THREAT INDEX
TODAY : GREEN
FRIDAY : GREEN
SATURDAY : 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
91/76/76
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