760
FXUS66 KPDT 261832
AFDPDT
AREA FORECAST DISCUSSION...UPDATED AVIATION.
NATIONAL WEATHER SERVICE PENDLETON OR
1032 AM PST FRI DEC 26 2025
DISCUSSION
KEY MESSAGES:
1. WIDESPREAD LIGHT PRECIPITATION PERSISTS TODAY.
2. SIGNIFICANT MOUNTAIN SNOWFALL TODAY THROUGH EARLY SATURDAY.
*WINTER ADVISORIES IN EFFECT*
3. DRIER AND COOLER CONDITIONS EARLY IN THE WEEK.
A WEAK UPPER TOUGH/SURFACE COLD FRONTAL SYSTEM IS POSITIONED
ALONG THE PAC NW COAST THIS MORNING. AND POISED TO LIFT INLAND
THROUGH TODAY AND TONIGHT BRINGING PRECIPITATION ACROSS THE
REGION, AND WINDY CONDITIONS OVERNIGHT AND EARLY SATURDAY.
WINTER WEATHER ADVISORIES STILL LOOKS GOOD FOR THE SNOQUALMIE
PASS AREAS OF THE WA CASCADES AS THE PROBABILITY FOR EXCEEDANCE OF
8 AND 12 INCH SNOWFALL THROUGH 15Z SATURDAY IS AT AROUND 90 AND
40 PERCENT RESPECTIVELY, AND FOR 8 OR MORE INCHES AT THE SANTIAM
PASS IN THE OREGON CASCADES, THE PROBABILITY AROUND 63 PERCENT.
LIKEWISE AT TOLLGATE OR, ABOUT 50%, BOTH WELL BELOW AN 80% TRIGGER
FOR WINTER STORM WARNINGS. AS FAR AS WIND GOES, THE BREEZY TO
MARGINALLY WINDY CONDITIONS FOLLOWING THE PRECIPITATION SHOULD
LAST THROUGH THE OVERNIGHT FRIDAY INTO EARLY DAY SATURDAY BUT
FALL BELOW THE WIND ADVISORY CRITERION OF SUSTAINED WINDS UP
AROUND 26 KNOTS OR MORE. WITH HIGH PRESSURE SETTLING IN OVER THE
FOLLOWING DAYS, (SUNDAY AND BEYOND) INVERSIONS DIURNALLY WILL BE
A RISK TO TRAVELERS AT TIMES. ONE AREA PRONE IS THE I-84 AND OTHER
HIGHWAYS OF THE BLUE MOUNTAIN FOOTHILLS AND LOWER COLUMBIA BASIN,
AS WELL AS OTHER VALLEYS OF SOUTH CENTRAL WASHINGTON WHERE THE
PROBABILITY FOR FOG SHOWS UP AT AROUND 20-40% THESE PROBABILITIES
HAVE TRIGGERED THE MENTION OF SOME PATCHY AND AREAS OF FOG EARLY
TO MID WEEK, IN WHAT OTHERWISE LOOKS TO BE A RELATIVELY UNEVENTFUL
WEATHER PERIOD.
AVIATION...18Z TAFS
LIMITED AVIATION CONCERNS GENERALLY THE NEXT
24-HRS WITH THE NEAR-TERM FOCUSED ON SUB-VFR AT KYKM AND KALW. THE
FORMER REVOLVING AROUND FOG/STRATUS AND THE LATTER REVOLVING AROUND
PASSING RAIN AND LOW CLOUDS. LATEST RADAR DISPLAY SHOWS AREA OF RAIN
AND MOUNTAIN SNOW MOVING INTO EASTERN WA AND EXTREME NORTHEAST OR
ASSOCIATED WITH AN SHORTWAVE TROUGH LIFTING NORTHEASTWARD. BACK EDGE
OF PRECIP IS WELL DEFINED AND WILL BE ENDING AT KALW SHORTLY/OVER
THE NEXT 30 MINS. OTHERWISE, SATELLITE SHOWS LOW STRATUS ENTRENCHED
IN THE UPPER YAKIMA VALLEY. CURRENT THINKING IS DAYTIME MIXING WILL
BE SUFFICIENT TO ERODE THE FOG/STRATUS BY 21Z GIVEN LATEST GUIDANCE,
HOWEVER, MODELS HAVE BEEN HANDLING IT POORLY THUS CONFIDENCE IS
MODERATE (50-70%).
AN UNSETTLED PATTERN REMAINS AND WILL DOMINATE THE REGION WITH AN
UPPER TROUGH PRESENTLY OVER THE WEST COAST. NEXT EMBEDDED SHORTWAVE
TROUGH CURRENTLY OVER VANCOUVER ISLAND WILL BE MOVING INTO THE
INTERIOR NW EARLY TONIGHT WITH ITS ATTENDANT COLD PROMOTING PRECIP
AND BREEZY TO LOCALLY WINDY CONDITIONS. GUSTS 25 KTS OR MORE LIKELY
(OVER 60%) AT KPSC, KPDT, KDLS, AND KALW BETWEEN 3-12 UTC TONIGHT
WITH PEAK GUSTS ANTICIPATED AS HIGH AS 30-35 KTS. KYKM EXPECTED TO
SEE LIMITED WINDS AND GUSTS IN COMPARISON (PEAK GUSTS 20-25 KTS).
OTHERWISE, KPDT, KALW, AND KDLS TERMINALS WILL SEE THE BEST CHANCES
FOR RAIN AFTER 00Z TONIGHT (OVER 60%) WITH LOWER CHANCES (UNDER 30%)
FOR PRECIP AT THE CENTRAL OR TERMINALS AND KYKM.
PRELIMINARY POINT TEMPS/POPS
PDT 48 30 40 23 / 80 70 50 0
ALW 47 31 38 25 / 90 90 60 0
PSC 47 30 42 21 / 80 50 10 0
YKM 44 24 40 20 / 40 30 0 0
HRI 48 31 43 23 / 80 60 20 0
ELN 38 23 34 18 / 50 40 0 0
RDM 44 24 38 18 / 40 30 10 0
LGD 44 28 33 20 / 70 90 80 0
GCD 43 28 34 20 / 70 80 70 0
DLS 46 34 44 30 / 80 70 20 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY UNTIL 7 AM PST SATURDAY FOR ORZ502-509.
WA...WINTER WEATHER ADVISORY UNTIL 7 AM PST SATURDAY FOR WAZ030-522.
DENSE FOG ADVISORY UNTIL NOON PST TODAY FOR WAZ026-027.
DISCUSSION...71
AVIATION...90
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