321
FXUS66 KPDT 172121
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
221 PM PDT SAT MAY 17 2025
SHORT TERM
TONIGHT THROUGH MONDAY NIGHT...AN UPPER TROUGH WILL MOVE EASTWARD
ACROSS THE REGION THROUGH SUNDAY. AS IT DOES, AN UPPER LOW ILL
DROP DOWN FROM CANADA ON SUNDAY AND INTO THE GREAT BASIN SUNDAY
NIGHT. UPPER LEVEL RIDGING WILL MOVE OVER THE AREA EARLY MONDAY.
ZONAL FLOW WILL ALLOW FOR A WEAK SYSTEM TO BRING PRECIPITATION,
ON MONDAY INTO MONDAY NIGHT.
ANY SHOWERS THUNDERSTORMS SHOULD MOVE EASTWARD OVERNIGHT AND
MAINLY JUST IMPACT THE EASTERN MOUNTAINS, AND SOME OF THE CASCADES
ON SUNDAY. ALSO, AS THE TROUGH MOVES AND LOW DROPS DOWN, SNOW
LEVELS WILL DECREASE TO AS LOW AS 3500 FEET IN SOME AREAS. THERE
COULD BE A COUPLE OF INCHES OF SNOW ALONG THE CREST OF THE BLUE
MOUNTAINS, BUT DUE TO WARM ANTECEDENT CONDITIONS SIGNIFICANT
ACCUMULATIONS AT PASS LEVEL IS NOT ANTICIPATED.
WINDS WILL BE GUSTY ON SUNDAY. A WIND ADVISORY HAS ALREADY BEEN
ISSUED FOR THE KITTITAS VALLEY WITH WIND GUSTS EXPECTED IN THE 50
TO 55 MPH RANGE, WHILE MANY OTHER AREAS, AS THE SIMCOE HIGHLANDS,
FOOTHILLS OF THE BLUE MOUNTAINS AND PORTIONS OF THE COLUMBIA BASIN
WILL GUST 25 TO 35 MPH AND MOST AREAS WILL GUST TO AT LEAST 25
MPH.
NBM WIND GUST PROBABILITIES TO 39 MPH ON SUNDAY ARE >90 PERCENT
ACROSS THE AREAS MENTIONED ABOVE. HOWEVER, WIND GUSTS >=47 MPH ARE
GENERALLY 30 TO 50% OVER THESE AREAS EXCEPT FOR THE KITTITAS
VALLEY, WHERE IT IS 90%.
LOW TEMPERATURES MONDAY MORNING WILL BE ON AVERAGE AROUND 5
DEGREES, AND IN SOME AREAS CLOSER TO 10 DEGREES BELOW NORMAL,
ESPECIALLY IF THE SKY CLEARS OUT AND THE WINDS DROP OFF. LOCATIONS
IN THE GRAND RONDE VALLEY COULD BE CLOSE TO FREEZING, AND THIS
WILL HAVE TO BE MONITORED. BUT IF CLOUDS REMAIN LONGER OR WINDS
STAY ELEVATED, THEN TEMPERATURES WON'T BE A COOL AS FORECAST.
LONG TERM
TUESDAY THROUGH SATURDAY...A GENERAL WESTERLY FLOW WILL REMAIN
OVER THE AREA THROUGH THE WEEK. ANOTHER WEAK SYSTEM WILL BRING
RAIN, MAINLY TO THE MOUNTAINS TUESDAY AFTERNOON. RIDGING THEN
BUILDS IN FOR TUESDAY NIGHT INTO WEDNESDAY BEFORE ANOTHER SYSTEM
BRINGS ANOTHER SHOT OF PRECIPITATION, MAINLY FOR THE MOUNTAINS
LATE WEDNESDAY INTO EARLY THURSDAY. DRY SOUTHWESTERLY FLOW IS
EXPECTED FOR FRIDAY, BEFORE ANOTHER SYSTEM APPROACHES FOR
SATURDAY. OVERALL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH THE
PERIOD, THOUGH THERE ARE SOME MINOR TIMING DIFFERENCES WITH
RESPECT TO THE INDIVIDUAL FEATURES.
AVIATION
18Z TAFS...CONDITIONS ARE GENERALLY VFR, WITH SOME MVFR MIXED IN,
AS AN AREA OF SHOWERS MOVES THROUGH MAINLY EASTERN PORTIONS OF THE
REGION. CONDITIONS SHOULD THEN IMPROVE TO VFR EVERYWHERE. THERE IS
STILL A LOW CHANCE (20%) OF THUNDERSTORMS THIS AFTERNOON. LATEST
SATELLITE SHOWS CLEARING ACROSS PORTIONS OF CENTRAL OREGON AND THE
WESTERN COLUMBIA BASIN BUT MOST OTHER AREAS REMAIN CLOUDY. IF WE
AREAS REMAIN CLOUDY, THUNDERSTORM DEVELOPMENT SHOULD REMAIN MUTED.
THEREFORE, HAVE OPTED NOT TO PUT ANY THUNDERSTORM MENTIONS IN THE
INDIVIDUAL TAF SITES UNTIL WE SEE IF/WHEN DEVELOPMENT OCCURS.
OTHERWISE, EXPECT GUSTY WINDS AT ALL SITES EXCEPT YKM/ALW/PSC
TODAY. WINDS SHOULD GUST TO AROUND 25 KTS. WINDS SHOULD DECREASE
TO AROUND 10 TO 15 KTS OVERNIGHT AT DLS/PDT/RDM/BDN. WINDS SHOULD
INCREASE EVERYWHERE ON SUNDAY BY LATE MORNING AND BECOME GUSTY TO
AROUND 25 KTS.
PRELIMINARY POINT TEMPS/POPS
PDT 44 61 39 66 / 50 20 0 50
ALW 44 60 42 64 / 90 30 10 50
PSC 45 67 40 70 / 70 10 0 30
YKM 41 65 38 69 / 10 0 0 30
HRI 44 66 41 70 / 40 10 0 40
ELN 41 59 38 65 / 10 0 0 40
RDM 34 57 33 67 / 10 0 0 10
LGD 39 53 33 64 / 70 30 10 40
GCD 37 53 32 65 / 70 20 10 30
DLS 46 63 43 66 / 10 0 0 40
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...WIND ADVISORY FROM 8 AM TO 8 PM PDT SUNDAY FOR WAZ026.
SHORT TERM...77
LONG TERM....77
AVIATION...77
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