548
FXUS66 KPDT 121120
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
320 AM PST MON JAN 12 2026
UPDATED AVIATION DISCUSSION
PREV DISCUSSION
/ISSUED 226 AM PST MON JAN 12 2026/
DISCUSSION
RADAR AND SATELLITE IMAGERY TONIGHT SHOWS SHOWERS
FOCUSED ALONG THE CENTRAL WA CASCADE CREST, WHILE MID TO UPPER
LEVEL CLOUDS DRIFT ACROSS THE REMAINDER OF THE FORECAST AREA.
AT THE SURFACE, BREEZY TO LOCALLY WINDY CONDITIONS PERSIST
THROUGH THE SOUTHERN GRANDE RONDE VALLEY, AND ALONG THE IMMEDIATE
BLUE MOUNTAIN FOOTHILLS.
TODAY: THE FLATTENED RIDGE OVER WESTERN CONUS WILL BEGIN ITS SLOW
TREK POLEWARD TODAY, PUSHING THE LAST OF THE PRECIPITATION ALONG
THE WA CASCADES NORTH AND OUT OF THE REGION LATE THIS EVENING.
AS THE RIDGE RESTRENGTHENS OVERHEAD, THE SURFACE PRESSURE
GRADIENT BETWEEN THE COLUMBIA BASIN AND TREASURE VALLEY WILL
GRADUALLY WEAKEN THROUGHOUT TODAY, AND IN TURN REDUCING WINDS
ALONG THE BLUE MOUNTAIN FOOTHILLS AND THROUGH THE SOUTHERN GRANDE
RONDE VALLEY. BREEZY WINDS (GUSTS 30-40MPH) WILL CONTINUE LATE
THIS AFTERNOON THROUGH TOMORROW AFTERNOON.
TUESDAY THROUGH SUNDAY: THE UPPER LEVEL RIDGE OVER THE WESTERN
CONUS WILL CONTINUE TO AMPLIFY POLEWARD TUESDAY, BRINGING A
RETURN TO AREA-WIDE DRY AND STAGNANT CONDITIONS. THE RIDGE WILL
BRIEFLY FLATTEN AGAIN WEDNESDAY AS A SHORTWAVE SLIDES INTO BC TO
THE NORTH, BUT PRECIPITATION WILL REMAIN WELL NORTH OF THE PACNW.
WINDS ALOFT WILL BEGIN TO TURN NORTHERLY BEHIND THE EXIT OF THE
SHORTWAVE WEDNESDAY, BRINGING WITH IT THE START OF AN ARCTIC
AIRMASS FILTERING INTO COLUMBIA BASIN, AND WITH IT COOLER
TEMPERATURES IN THE LOWER ELEVATIONS. ENSEMBLE GUIDANCE IS IN
AGREEMENT THAT THE RIDGE AXIS WILL THEN SETUP OFFSHORE AND REMAIN
THERE THROUGH THE WEEKEND AS IT RESTRENGTHENS, PLACING THE
EASTERN HALF OF WA/OR UNDER A NORTHERLY FLOW ALOFT. AN ARCTIC
AIRMASS WILL ADVECT FURTHER SOUTH ACROSS THE FORECAST AREA UNDER
THE NORTHERLY FLOW ALOFT, RESULTING IN A COOLING TREND ACROSS THE
NORTHERN TWO-THIRDS OF THE FORECAST AREA. IN ADDITION, LOW LEVEL
INVERSIONS ACROSS THE COLUMBIA BASIN AND ADJACENT VALLEYS WILL
STRENGTHEN UNDER THE STABLE CONDITIONS AND DRY AIR ALOFT,
PROMOTING THE DEVELOPMENT OF WIDESPREAD LOW LEVEL STRATUS AND
DENSE FOG/FREEZING FOG THAT WILL IMPACT THE AREA BEGINNING AS
LATE AS THURSDAY (CONFIDENCE 50-75%). LAWHORN/82
AVIATION...12Z TAFS
VFR CONDITIONS WILL PREVAIL WITH LIGHT WINDS
AND FEW-OVC HIGH CLOUDS FOR ALL SITES. FEASTER/97
PRELIMINARY POINT TEMPS/POPS
PDT 57 34 54 30 / 10 0 0 0
ALW 55 39 52 33 / 10 0 0 0
PSC 54 34 51 30 / 10 0 0 0
YKM 52 36 52 33 / 0 0 0 0
HRI 55 32 51 30 / 10 0 0 0
ELN 48 37 49 30 / 10 10 0 0
RDM 54 27 57 25 / 0 0 0 0
LGD 47 32 50 32 / 0 0 0 0
GCD 52 32 56 33 / 0 0 0 0
DLS 52 36 51 33 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY UNTIL NOON PST TODAY FOR ORZ049.
WA...NONE.
SHORT TERM...82
LONG TERM....82
AVIATION...97
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