394
FXUS66 KPDT 221738
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
938 AM PST MON DEC 22 2025
AVIATION...18Z TAFS
ALL SITES EXCEPT FOR THE DLS WILL PREVAIL
WITH VFR CONDITIONS THROUGH OUT THE PERIOD. WINDS REMAIN LIGHT AND
VARIABLE WITH BREEZY CONDITIONS IN BDN EXPECTED TO DEVELOP AROUND
21Z THROUGH 01Z WITH GUSTS AS HIGH AS 20 TO 30 MPH. THE DLS IS THE
ONLY SITE OF CONCERN WITH CONDITIONS FLIPPING THROUGH MVFR TO LIFR
THROUGHOUT THE MORNING. FOG REMAINS WITH NOT VERY MUCH MIXING THAT
WOULD LIFT IT TO VFR CONDITIONS. LEVELS ARE EXPECTED TO IMPROVE
CLOSE TO MVFR AS WE GO THROUGH THE AFTERNOON HOURS, BUT THE CHANCE
REMAINS FOR SUB-MVFR CONDITIONS (5 TO 15 PERCENT CHANCE)
DEPENDING ON RAIN AND ADDITIONAL FOG ROLLING THROUGH.
PREV DISCUSSION
/ISSUED 400 AM PST MON DEC 22 2025/
DISCUSSION...
SOUTHWESTERLY FLOW WILL PREVAIL ACROSS THE PACIFIC NORTHWEST TODAY
AS ONE SYSTEM EXITS THE REGION. DRYING WILL MOVE OVER THE AREA AND
THE ONLY PRECIPITATION EXPECTED WILL BE OVER THE CASCADES.
ANOTHER WEAK SYSTEM WILL BRING A RENEWED SHOT OF LIGHT SNOW OVER
THE CASCADES TONIGHT BUT AMOUNTS SHOULD BE AROUND 2 INCHES AT
PASS LEVEL. THE REMAINDER OF THE AREA WILL REMAIN DRY INTO
TUESDAY. HOWEVER, LATER TUESDAY, MOISTURE WILL MOVE UP FROM THE
SOUTH AND BRING PRECIPITATION TO THE SOUTHERN HIGHLANDS AND BLUE
MOUNTAINS AND WALLOWA MOUNTAINS. THIS MOISTURE WILL THEN MOVE
NORTHWESTWARD ACROSS THE REGION.
IN THE MEANTIME, ADDITIONAL MOISTURE WILL MOVE NORTH FROM
CALIFORNIA DURING THE DAY ON WEDNESDAY. MOST AREAS WILL SEE AT
LEAST SOME PRECIPITATION, WITH THE MOUNTAINS GETTING SNOW AND THE
LOWER ELEVATIONS RECEIVING RAIN. BY WEDNESDAY AFTERNOON INTO
WEDNESDAY NIGHT, THE MOISTURE MOVES OUT AND MOST AREAS WILL DRY
OUT. THEN THERE IS AT LEAST ANOTHER SHOT OF PRECIPITATION...ALBEIT
LIGHTER...ACROSS THE AREA ON CHRISTMAS DAY, AS A LOW MOVES
NORTHWARD OFF THE CALIFORNIA AND OREGON COASTS THEN MOVES INLAND
AND WEAKENS AND EVENTUALLY DISSIPATES.
IT IS POSSIBLE THAT ADDITIONAL WINTER WEATHER HEADLINES MAY BE
NEEDED FOR THE WASHINGTON CASCADES, ESPECIALLY AT SOME POINT FOR
THE TUESDAY NIGHT WEDNESDAY TIME FRAME, DEPENDING ON WHAT LATER
GUIDANCE SHOWS, HOWEVER, RIGHT NOW, GUIDANCE IS BELOW WINTER
WEATHER ADVISORY THRESHOLDS...GENERALLY AROUND 3 INCHES. ALSO, IT
IS POSSIBLE, IF NOT PROBABLE THAT THERE WILL BE LIGHT < 1 INCH
ACCUMULATION IN THE KITTITAS VALLEY AND NEARBY AREAS, AND ON
FRIDAY IN THE WALLOWA VALLEY.
PRECIPITATION CHANCES LINGER INTO FRIDAY...LIGHT IN THE LOWER
ELEVATIONS AND A BIT HEAVIER FOR THE MOUNTAINS...BUT BY LATER
FRIDAY, HIGH PRESSURE WILL BUILD IN FROM THE WEST AND
PRECIPITATION WILL COME TO AN END WITH DRY WEATHER EXPECTED FOR
THE WEEKEND.
ON WEDNESDAY, AS PRESSURE GRADIENT STRENGTHENS DUE TO A SURFACE
LOW MOVING NORTHWARD OFF THE COAST, WINDS ARE EXPECTED TO
INCREASE. THERE IS STILL SOME UNCERTAINTY AS TO JUST HOW MUCH.
SOME OF THE GUIDANCE IS STRONGER THAN OTHERS, BUT THERE IS A
POSSIBILITY OF GUSTY WINDS, ESPECIALLY ACROSS THE ELEVATED
TERRAIN, AND WIND HEADLINES MAY ULTIMATELY BE NEEDED. THE ECMWF
EFI IS NOT ESPECIALLY FOCUSED ON ANY SPECIFIC AREA AT THIS TIME.
IT JUST HAS 0.8 TO 0.9 ANOMALIES ACROSS A WIDE SWATH OF WESTERN,
SOUTH- CENTRAL AND A PORTION OF EASTERN OREGON.
PRELIMINARY POINT TEMPS/POPS
PDT 49 33 45 34 / 10 0 30 60
ALW 49 37 45 38 / 20 10 40 70
PSC 49 32 45 35 / 10 0 10 80
YKM 41 28 41 32 / 0 30 0 70
HRI 49 32 44 34 / 10 0 20 70
ELN 37 24 36 29 / 10 40 0 70
RDM 47 25 44 29 / 10 0 30 50
LGD 44 32 43 37 / 30 10 70 40
GCD 46 33 46 38 / 20 10 90 40
DLS 46 36 44 37 / 20 60 10 80
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...FREEZING FOG ADVISORY UNTIL 11 AM PST THIS MORNING FOR WAZ026.
SHORT TERM...77
LONG TERM....77
AVIATION...95
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