FXUS66 KPDT 252237
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
235 PM PST WED NOV 25 2009
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...VERY WINDY CONDITIONS
IN THE SOUTHERN GRANDE RONDE VALLEY HAVE DECREASED SLIGHTLY SINCE
THEIR PEAK AN HOUR OR TWO AGO. NONETHELESS...THE PRESSURE AND
TEMPERATURE DIFFERENCES BETWEEN THE BAKER AND GRANDE RONDE VALLEYS
ARE EXPECTED TO CONTINUE UNTIL A COLD FRONT APPROACHES LATE THURSDAY
NIGHT. AS SUCH THE WIND ADVISORY HAS BEEN EXTENDED THROUGH 7 PM
THURSDAY EVENING AND MAY NEED TO BE EXTENDED AGAIN. THE TIMING OF
THE COLD FRONT REMAINS UNCERTAIN AND IT MAY NOT ARRIVE UNTIL
FRIDAY MORNING. THURSDAY WINDS WILL INCREASE SOMEWHAT IN THE REST
OF THE GRANDE RONDE VALLEY AND ALSO IN THE SOUTHERN PORTION OF THE
WALLOWA VALLEY AROUND JOSEPH. THERE IS POTENTIAL FOR DOWNSLOPE
ACCELERATION INTO THE SOUTHERN WALLOWA VALLEY BUT AT THIS TIME LESS
THAN ADVISORY WIND SPEEDS ARE EXPECTED.
COMPUTER MODELS HAVE TRENDED SLOWER AND WEAKER WITH THE APPROACHING
COLD FRONTAL SYSTEM. THE SYSTEM IS BRINGING A STREAM OF ABUNDANT
MOISTURE ACROSS THE EAST PACIFIC THAT WILL SLOWLY TRANSITION ACROSS
THE INTERIOR PACIFIC NORTHWEST TONIGHT THROUGH FRIDAY. THE
PRECIPITATION SHOULD BE IN THE FORM OF RAIN FOR MOST LOCATIONS
THURSDAY...AND EITHER RAIN OR A RAIN SNOW MIX THURSDAY NIGHT. THEN
AS COOLER AIR ARRIVES FRIDAY SNOW LEVELS WILL FALL...AND BY SATURDAY
MORNING FALL TO 1500 TO 2500 FEET MSL. THE RELATIVELY HIGH SNOW
LEVELS EXPECTED THURSDAY NIGHT AND FRIDAY MORNING MEANS BELOW
ADVISORY SNOW AMOUNTS ARE EXPECTED. 80
.LONG TERM...SATURDAY THROUGH WEDNESDAY...A RIDGE WILL START TO
REBUILD OFF THE PACIFIC NORTHWEST COAST BEHIND THE DEPARTING TROUGH
SYSTEM. A SECOND DISTURBANCE WILL KEEP A CHANCE OF PRECIPITATION
GOING IN THE HIGHER TERRAIN ON SATURDAY BEFORE DRIER AIR MOVES IN BY
SUNDAY AS THE RIDGE STRENGTHENS. WITH CLEARING SKIES AND LIGHTER
WINDS...PATCHY FOG WILL BE POSSIBLE ALONG THE AREA RIVERS SUNDAY AND
MONDAY MORNINGS. MODELS THEN INDICATE A TROUGH WITH A COLD FRONT
WILL MOVE THROUGH THE REGION ON MONDAY. THIS TROUGH WILL BRING
COLDER AIR AND LOWERING SNOW LEVELS. PRECIPITATION DOES NOT APPEAR
TO BE HEAVY WITH THIS FASTER MOVING SYSTEM...SO DO NOT ANTICIPATE
ANY HEAVY SNOW IN THE HIGHER TERRAIN AT THIS TIME. THE REGION WILL
THEN BE UNDER A NORTHERLY FLOW TUESDAY AND WEDNESDAY WITH COOLER
TEMPERATURES AND DRIER CONDITIONS. DMH
&&
.AVIATION...00Z TAFS...VFR CONDITIONS WILL MOSTLY PREVAIL FOR THE
NEXT 24 HOURS. HIGH CLOUDS WILL CONTINUE TO INCREASE AHEAD OF THE
NEXT WEATHER DISTURBANCE TONIGHT AND INTO TOMORROW. PATCHY FOG WILL
AGAIN BE POSSIBLE LATE TONIGHT AND INTO TOMORROW MORNING AT
KDLS...KPSC...KALW AND KYKM. MVFR CEILINGS AND VISIBILITIES ARE
POSSIBLE IN THESE LOCATIONS...THOUGH HIGHER CLOUDS MAY KEEP
CONDITIONS FROM DROPPING INTO THE IFR CATEGORY. A CHANCE OF SHOWERS
IS POSSIBLY NEAR KDLS AND KYKM AS THE NEXT SYSTEM BEGINS TO MOVE
ACROSS THE CASCADES THURSDAY AFTERNOON AND EVENING. DMH
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 35 50 42 47 / 0 0 40 50
ALW 37 48 43 48 / 0 0 40 50
PSC 33 47 43 48 / 0 0 40 20
YKM 31 44 39 46 / 10 40 50 20
HRI 32 49 43 49 / 0 0 40 30
ELN 34 44 36 44 / 10 60 60 30
RDM 29 51 38 41 / 0 0 50 50
LGD 30 44 32 38 / 0 0 20 60
GCD 32 49 34 39 / 0 0 20 50
DLS 35 51 43 48 / 0 20 70 40
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY UNTIL 7 PM PST THURSDAY FOR ORZ049.
WA...NONE.
&&
THREAT INDEX
THURSDAY : 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
$$
80/84/84
