212
FXUS66 KPDT 062234
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
234 PM PST THU NOV 6 2025
DISCUSSION
KEY MESSAGES:
1. WET AND BREEZY TO WINDY THIS EVENING INTO FRIDAY
2. MOSTLY DRY LATE FRIDAY INTO THE MIDDLE OF NEXT WEEK
3. TIMING UNCERTAINTY IN WEATHER SYSTEM LATE NEXT WEEK
AFTERNOON SATELLITE IMAGERY SHOWS A CLOSED LOW TRACKING NORTHEAST
INTO THE NORTHERN END OF VANCOUVER ISLAND, WITH A SURFACE COLD
FRONT EXTENDING FROM VANCOUVER ISLAND TO OFFSHORE OF NW CA.
ALOFT, A SHORTWAVE IS EVIDENT WEST OF THE OR/WA COAST. THE
SHORTWAVE AND SURFACE COLD FRONT WILL COME ONSHORE LATER THIS
EVENING THROUGH THE OVERNIGHT HOURS, USHERING IN WIDESPREAD
PRECIPITATION AND BREEZY TO WINDY SOUTHWESTERLY THEN WESTERLY
WINDS. REGARDING WIND POTENTIAL, THE 12Z HREF, NAM, AND GFS ALL
PLACE A 8-12 HPA PRESSURE DIFFERENCE ACROSS THE REGION FROM PDX TO
GEG, ALONG WITH A 40-50 KT LOW-LEVEL JET OVER THE COLUMBIA
PLATEAU. IF FRONTAL PASSAGE WERE DURING THE DAYTIME WITH A WELL-
MIXED BOUNDARY LAYER, THIS WOULD BE ENOUGH TO WARRANT A WIND
ADVISORY FOR MUCH OF THE LOWER ELEVATIONS. THAT SAID, DUE TO THE
NOCTURNAL NATURE OF THE EVENT, HAVE OPTED TO HOLD OFF ON ISSUING
ANY WIND HIGHLIGHTS FOR COLD FRONTAL PASSAGE DUE TO BARELY
INSUFFICIENT (50-70 PERCENT) CONFIDENCE IN A SHORT PERIOD (1-4
HOURS) OF ADVISORY-LEVEL GUSTS (45-55 MPH FOR WIND-PRONE
LOCATIONS WITHIN THE EASTERN COLUMBIA RIVER GORGE, LOWER COLUMBIA
BASIN, NORTH-CENTRAL OREGON, AND THE FOOTHILLS OF THE BLUE
MOUNTAINS. CONFIDENCE IS VERY HIGH (70-95 PERCENT) IN WIDESPREAD
GUSTS OF 30-40 MPH FOR THE AFOREMENTIONED AREAS.
WHILE MOUNTAIN SNOW IS FORECAST TONIGHT INTO FRIDAY MORNING AS
SNOW LEVELS DROP BEHIND THE COLD FRONT, ONLY LIGHT AMOUNTS (1 INCH
OR LESS) ARE FORECAST FOR MOUNTAIN PASSES, EXCEPT FOR WHITE PASS
IN WA WHICH IS FORECAST TO RECEIVE 3-5 INCHES OF SNOW OVERNIGHT.
UPSLOPE SHOWERS WILL PERSIST ALONG THE CASCADE CREST AND PERHAPS
THE HIGHEST TERRAIN OF THE NORTHERN BLUE MOUNTAINS THROUGH MUCH
OF FRIDAY, WITH OTHERWISE DRY CONDITIONS ACROSS THE FORECAST
AREA. BREEZY TO LOCALLY WINDY WESTERLY WINDS ARE FORECAST THROUGH
THE CASCADE GAPS UNTIL MID-AFTERNOON FRIDAY WHEN PRESSURE
GRADIENTS RELAX.
DRY WEATHER IS FORECAST LATE FRIDAY THROUGH THE WEEKEND AS AN
UPPER-LEVEL RIDGE OF HIGH PRESSURE BUILDS OVERHEAD (95 PERCENT
CONFIDENCE). MAY (60 PERCENT CONFIDENCE) SEE THE RETURN OF SOME
FOG IN LOW-LYING SPOTS OF THE LOWER ELEVATIONS SATURDAY AND
SUNDAY, ESPECIALLY DURING THE MORNING HOURS.
LATE MONDAY, THERE IS MEDIUM-HIGH (30-70 PERCENT) CONFIDENCE IN A
WEAK SHORTWAVE TRACKING ACROSS THE PACIFIC NORTHWEST. THIS WAVE
WOULD PRODUCE SOME LIGHT PRECIPITATION (TRACE TO A COUPLE TENTHS
OF AN INCH) ALONG THE CASCADE CREST AND HIGHEST ELEVATIONS OF THE
NORTHERN BLUE MOUNTAINS. BEST CHANCES (50-70 PERCENT) FOR
PRECIPITATION WILL BE ALONG THE WA CASCADE CREST, WITH LOWEST
CHANCES (15-30 PERCENT) FOR THE NORTHERN BLUE MOUNTAINS.
LOOKING AHEAD, CLUSTERS OF ENSEMBLE MEMBERS INDICATE SIGNIFICANT
UNCERTAINTY IN THE EVOLUTION OF AN OFFSHORE CLOSED LOW IN THE
WED/THU TIME PERIOD OF NEXT WEEK. AS OF THE 12Z ENSEMBLE RUNS, DRY
CONDITIONS ARE FAVORED (70 PERCENT OR MORE OF ENSEMBLE MEMBERS)
TUESDAY THROUGH WEDNESDAY, WITH A RETURN OF PRECIPITATION MORE
LIKELY BY THE THU/FRI PERIOD AS ENSEMBLE MEAN 500-HPA FIELDS SHOW
THE TROUGH MOVING OVER THE PACIFIC NORTHWEST.
AVIATION...00Z TAFS
THE WEATHER FOR THE TERMINALS OVER THE
NEXT 18 TO 24 HOURS CAN BE CHARACTERIZED WITH INCREASING RAIN
CHANCES FROM WEST TO EAST AND PEAKING THIS EVENING (3Z-6Z).
CEILINGS STAY ABOVE MVFR THRESHOLDS (4-5KFT AGL MOSTLY) WITH THE
BEST OPPORTUNITY TO HAVE CEILINGS AS LOW AS 3000 FT AGL NEAR DLS
AND YKM. THE COLD FRONT SWEEPS THROUGH THE REGION OVERNIGHT WITH
RAINS LINGERING A BIT LONGER AT ALW BEFORE CLEARING ON FRIDAY. AN
UPTICK IN WIND SPEEDS BEHIND TO COLD FRONT IS OF HIGH CONFIDENCE
(90%) WITH PEAK WESTERLY WIND GUSTS BETWEEN 25-30 KNOTS OVERNIGHT.
PRELIMINARY POINT TEMPS/POPS
PDT 40 55 32 54 / 90 10 0 0
ALW 43 54 36 53 / 100 20 0 0
PSC 42 58 30 51 / 90 0 0 0
YKM 36 56 30 52 / 90 0 0 0
HRI 42 58 32 52 / 80 10 0 0
ELN 34 50 28 48 / 100 10 0 0
RDM 34 52 26 59 / 80 10 0 0
LGD 38 52 29 54 / 100 40 0 0
GCD 40 52 29 59 / 90 40 0 0
DLS 43 57 37 55 / 100 30 10 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...86
AVIATION...71
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