FXUS66 KPDT 281148 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
348 AM PST SAT NOV 28 2009
UPDATED AVIATION DISCUSSION
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...THESE PERIOD OF TIME WILL
BE DOMINATED BY RIDGE OF HIGH PRESSURE. THE RIDGE IS CURRENTLY OFF
THE WEST COAST BUT WILL NUDGE INLAND OVER THE NEXT COUPLE OF DAYS. A
LITTLE BIT OF WARM AIR ADVECTION WILL CLIP WESTERN WASHINGTON
MEANING A FEW RAIN SHOWERS COULD REACH THE WASHINGTON CASCADES LATE
TODAY AND OVERNIGHT BEFORE THE RIDGE AXIS MOVES INTO THE PACIFIC
NORTHWEST AND SHIFTS THE WARM AIR ADVECTION NORTH INTO CANADA. A
LITTLE BIT OF CLOUDS...MAINLY MID AND HIGH LEVEL...WILL COME ALONG
WITH THIS WARM AIR ADVECTION FOR THE REST OF THE FORECAST AREA.
DEVELOPING INVERSIONS UNDER THE WARM AIR ADVECTION WILL MEAN THE
DEVELOPMENT AND SPREAD OF NOCTURNAL FOG FORMATION OVER THE NEXT
COUPLE OF NIGHTS.
.LONG TERM...MONDAY THROUGH FRIDAY. THE EXTENDED MODELS ARE NOT IN
VERY GOOD AGREEMENT AFTER TUESDAY MORNING..SO LIMITED CHANGES WERE
MADE TUESDAY THROUGH FRIDAY. AN UPPER LEVEL RIDGE WILL BE OVER THE
AREA MONDAY. SUBSIDENCE FROM THE RIDGE WILL KEEP EASTERN WASHINGTON
AND OREGON DRY WITH PATCHY FOG TRAPPED BELOW STRONG SURFACE
INVERSIONS MONDAY. A WEAK SYSTEM WILL MOVE TO THE NORTH THROUGH THE
RIDGE MONDAY NIGHT AND TUESDAY. THIS SYSTEM MAY TRIGGER A FEW
SHOWERS IN HIGHER TERRAIN. AFTER THIS THE UPPER LEVEL RIDGE WILL
REBUILD OVER THE PACIFIC NORTHWEST WITH A CUTOFF LOW UNDERCUTTING
THE RIDGE WEDNESDAY. THURSDAY AND FRIDAY ECMWF AND GFS MODELS ARE
OUT OF SYNC. THE GFS ENSEMBLE RUNS ALSO SHOW WIDE SPREAD. DID NOT
CHANGE CURRENT FORECAST BASED ON THE UPPER LEVEL RIDGE REMAINING
OVER THE AREA. THIS KEEPS THE FORECAST MAINLY DRY WITH SEASONAL
TEMPERATURES AND PATCHY FOG IN THE COLUMBIA BASIN AND VALLEYS.
COONFIELD
&&
.AVIATION...12Z TAFS...VFR CONDITIONS ARE GENERALLY EXPECTED FOR THE
NEXT 24 HOURS EXCEPT AT KPSC. PATCHY FOG WILL GET THICKER AROUND
KPSC WITH PREVAILING IFR/LIFR CONDITIONS BY SUNRISE. FOG WILL BREAK
UP 17-19Z. INCREASING MID AND HIGH CLOUDS DURING THE AFTERNOON.
PATCHY FOG WILL REDEVELOP TONIGHT AT KPSC. PATCHY FOG IS POSSIBLE
AFTER 29/09Z AT KYKM. SURFACE WINDS WILL BE LESS THAN 10 KTS. 76
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 46 32 47 33 / 0 0 0 0
ALW 47 35 48 33 / 0 0 0 0
PSC 46 30 47 29 / 0 0 0 0
YKM 44 30 47 28 / 0 0 0 0
HRI 47 29 47 28 / 0 0 0 0
ELN 44 32 47 30 / 10 10 0 0
RDM 45 23 47 26 / 0 0 0 0
LGD 42 27 43 31 / 0 0 0 0
GCD 42 30 44 33 / 0 0 0 0
DLS 49 33 49 33 / 0 10 0 0
&&
.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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