300
FXUS66 KPDT 281044
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
244 AM PST SUN DEC 28 2025
KEY POINTS
1. A HIGH PRESSURE RIDGE WILL DOMINATE THROUGH MID-WEEK
2. FOG WILL BE THE MAIN CONCERN THROUGH MID-WEEK
3. LIKELY RETURN OF PRECIPITATION LATE NEXT WEEK
DISCUSSION
CURRENT SATELLITE SHOWS NO RETURNS OVER THE REGION
WITH NIGHTTIME SATELLITE SHOWING MOSTLY HIGH CLOUDS IN THE AREA THAT
ARE QUICKLY MOVING SOUTHWARD. NORTHWEST FLOW ALOFT IS ADVECTING
COOLER AIR INTO THE REGION TONIGHT WHICH WILL BRING OVERNIGHT
TEMPERATURES INTO THE TEENS TO LOW 20S IN MOST AREAS WITH ONLY THE
BASIN, FOOTHILLS AND THE GORGE SEEING TEMPERATURES IN THE UPPER 20S.
MODELS SHOW THE WEAK SHORTWAVE THAT CAME THROUGH LAST NIGHT TO BE
MOSTLY OUT OF THE REGION LEAVING NORTHWEST FLOW ALOFT. AS STATED
ABOVE, THIS WILL BRING BELOW AVERAGE TEMPERATURES TO THE REGION
OVERNIGHT AND THROUGH TOMORROW. BY SUNDAY MORNING, THE LEADING EDGE
OF THE UPPER LEVEL RIDGE WILL BEGIN MOVING OVER THE REGION. MODELS
ARE IN FORM AGREEMENT AND SHOW THE HIGH PRESSURE WILL DOMINATE THE
REGION THROUGH THE MID-WEEK WITH STEADILY INCREASING TEMPERATURES.
HOWEVER, CLIMATE SHOWS THAT THE BASIN AND FOOTHILLS WILL REMAIN
SLIGHTLY BELOW NORMAL SEASONAL TEMPERATURES WHILE ELSEWHERE WILL SEE
SLIGHTLY ABOVE AVERAGE. 100% OF ALL RAW ENSEMBLES SHOW THAT ALL
LOCATIONS WILL BE BELOW 40 DEGREES SUNDAY, EVERYWHERE EXCEPT CENTRAL
OR ON MONDAY WHILE STEADILY INCREASING TO THE EASTERN MOUNTAINS
TUESDAY AND WEDNESDAY. TEMPERATURES WILL BE STEADY IN THE UPPER 30S
TO LOW 40S FOR MOST LOCATIONS THROUGH WEDNESDAY WITH 40-60% OF THE
ENSEMBLES HAVING CENTRAL OR IN THE UPPER 40S TO LOW 50S BY
WEDNESDAY.
PATTERN RECOGNITION COUPLE WITH THE COLD POOLING FROM THE NORTHWEST
FLOW ALOFT, POINTS TO THE TYPICAL WINTER SET UP FOR FOG TO FORM.
WHILE HREF AND OTHER GUIDANCE SUGGESTS LOW POTENTIAL FOR FOG SUNDAY
(10-30% CHANCES) WE CAN NOT RULE OUT THE POTENTIAL FOR FOG TO FORM
IN THE PRONE AREAS THROUGH THE WEEK AND WITH COOLER TEMPERATURES,
CHANCES OF FREEZING FOG IS LIKELY. HOWEVER, TIMING ON IF AND WHEN
FOG WILL DEVELOP IS LOW/MODERATE AT BEST (30-50% CONFIDENCE)
BY THURSDAY MODELS SHOW AN UPPER LEVEL LOW SWEEPING SOUTHWARD OF THE
REGION AND BREAKING DOWN THE RIDGE. SOUTHWESTERLY FLOW ALOFT WILL
BRING IN WARM AIR ADVECTION AND MOISTURE BACK TO THE REGION. MODELS
SHOW THAT TEMPERATURES WILL STEADILY INCREASE THURSDAY THROUGH THE
WEEKEND BRING THE AREA BACK INTO 5-10 DEGREES ABOVE SEASONAL
AVERAGE. RAW ENSEMBLES SHOW THE VAST MAJORITY OF THE REGION TO BEGIN
SEEING TEMPERATURE IN THE UPPER 30S TO LOW 40S BY THE WEEKEND. 90
AVIATION...12Z TAFS
VFR CONDITIONS EXPECTED TO PERSIST THROUGH
THE PERIOD. WINDS WILL BE MOSTLY DIURNALLY DRIVEN BELOW 6KTS WITH
CIGS 5KFT AND ABOVE. 90
PRELIMINARY POINT TEMPS/POPS
PDT 37 24 36 22 / 10 0 0 0
ALW 36 26 35 25 / 0 0 0 0
PSC 37 23 36 22 / 0 0 0 0
YKM 36 23 36 21 / 0 0 0 0
HRI 37 24 35 22 / 0 0 0 0
ELN 31 21 32 21 / 0 10 0 0
RDM 40 21 43 20 / 0 0 0 0
LGD 36 23 39 26 / 0 0 0 0
GCD 38 23 43 25 / 0 0 0 0
DLS 41 29 38 27 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...90
AVIATION...90
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