527
FXUS66 KPDT 030546
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1046 PM PDT WED SEP 2 2026
KEY MESSAGES
- AN UPPER LEVEL LOW WILL MOVE ONSHORE THURSDAY AND REMAIN OVER
THE PACIFIC NORTHWEST THROUGH MUCH OF THE WEEKEND.
- WIDESPREAD SHOWER CHANCES THROUGH EARLY THURSDAY, WITH
ISOLATED THUNDERSTORM CHANCES EACH AFTERNOON THROUGH FRIDAY.
LOW (<30) SHOWER AND THUNDERSTORM CHANCES, MAINLY OVER THE
MOUNTAINS THROUGH THE HOLIDAY WEEKEND.
- BELOW NORMAL TEMPERATURES THROUGH THE REMAINDER OF THE WEEK
AND INTO THE WEEKEND.
DISCUSSION
AN AREA OF LOW PRESSURE OFF THE BRITISH COLUMBIA COAST WILL MOVE
SOUTHEASTWARD AND INLAND OVER WASHINGTON AND OREGON ON THURSDAY.
THIS UPPER LOW WILL KEEP THE WEATHER UNSETTLED OVER THE NEXT FEW
DAYS.
AS THIS LOW APPROACHES, STRONG SOUTHERLY FLOW AHEAD OF IT WILL
BRING A FAIRLY WIDESPREAD RAINFALL ACROSS THE REGION THIS
EVENING INTO EARLY THURSDAY. MOST LOCATIONS, EXCEPT THE
COLUMBIA BASIN AND POSSIBLY CENTRAL OREGON SHOULD GET WETTING
RAIN AND THE MOUNTAIN LOCATIONS SHOULD GET SIGNIFICANTLY MORE,
WITH MOUNTAIN LOCATIONS RECEIVING AT LEAST 0.25 INCHES AND
POSSIBLY 0.50 INCHES OR MORE. AS THE LOW MOVES ACROSS THE REGION
THURSDAY AND FRIDAY, THE PRECIPITATION WILL LARGELY BE CONFINED
TO THE MOUNTAINS, WHERE ADDITIONAL WETTING RAINS ARE POSSIBLE.
THE HIGHEST RAIN TOTAL LOOK TO BE FOR AREAS FROM THE NORTHERN
BLUE MOUNTAINS EASTWARD. WITH INSTABILITY FROM THE UPPER LOW IN
PLACE, ISOLATED (<20%) THUNDERSTORMS ARE POSSIBLE, MAINLY OVER
THE MOUNTAINS. OVER THE HOLIDAY WEEKEND, PRECIPITATION CHANCES
STILL EXIST BUT WILL BE LOWER, GENERALLY (<30%).
FINALLY, BY MONDAY, THE LOW BEGINS TO MOVE EASTWARD AND DRIER
WEATHER WILL MOVE IN FROM LATER MONDAY THROUGH THE MIDWEEK
PERIOD.
WINDS WILL ALSO GUST 20 TO 30 MPH THIS AFTERNOON AND EVENING AS
THE LOW APPROACHES.
HIGH TEMPERATURES WILL MAINLY BE IN THE 60S AND 70S THROUGH THE
WEEKEND. THIS IS 7 TO 10 DEGREES BELOW NORMAL ON AVERAGE. LOWS
WILL MAINLY BE IN THE 40S, WITH SOME 30S AS WELL, WHICH ARE ALSO
ABOUT 7 TO 10 DEGREES BELOW NORMAL. THE ECMWF EFI INDICATES
SOME AREAS MAINLY IN CENTRAL OREGON WHERE DEPARTURES ARE BELOW
NORMAL ARE GREATER THAN THE 90TH PERCENTILE WITH SOME LOCATIONS
EVEN IN THE 95TH PERCENTILE BELOW NORMAL FOR HIGH TEMPERATURES.
BY MIDWEEK, TEMPERATURES RETURN CLOSER TO NORMAL.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
AN UPPER-LEVEL LOW WILL GENERATE UNSETTLED WEATHER ACROSS THE
FORECAST AREA THROUGH THE PERIOD. WIDESPREAD RAIN WILL LIKELY
(70-90 PERCENT CONFIDENCE) PERSIST INTO THE NIGHT AT
PDT/ALW/PSC WITH RAIN EXPECTED TO TAPER OFF OVER THE NEXT
SEVERAL HOURS AT DLS/RDM/BDN/YKM.
CONFIDENCE IN PERSISTENT MVFR CIGS/VSBYS WAS TOO LOW (<50%) TO
INCLUDE IN THE 06Z TAFS, BUT PERIODS OF RA OR +RA AT PDT/ALW MAY
(30-50% CHANCE PER 00Z HREF GUIDANCE) RESULT IN TEMPORARY MVFR
CONDITIONS (CIGS AND/OR VSBYS) OVERNIGHT. CHANCES OF SUB-VFR
CONDITIONS ARE LOW (<30%) ELSEWHERE.
INCLUDED SOME PROB30 GROUPS FOR SHOWERS OR RAIN THURSDAY
AFTERNOON AND EVENING FOR ALL SITES EXCEPT PSC/YKM.
SUSTAINED WINDS OF 10 KTS OR LESS ARE FORECAST THROUGH THE
PERIOD, BUT ANTICIPATING PERIODIC GUSTS OF 12-18 KTS AT BDN/RDM
DURING THE MID/LATE MORNING AND EARLY AFTERNOON.
PRELIMINARY POINT TEMPS/POPS
PDT 49 68 42 68 / 90 10 40 30
ALW 52 69 46 68 / 100 20 40 30
PSC 51 73 43 73 / 80 0 10 20
YKM 48 70 45 71 / 50 10 10 20
HRI 50 71 43 71 / 80 0 20 10
ELN 45 66 40 66 / 70 30 20 40
RDM 39 64 31 63 / 90 20 40 50
LGD 49 66 41 66 / 100 80 80 60
GCD 47 63 39 65 / 100 80 70 40
DLS 51 70 47 72 / 80 30 30 20
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...77
AVIATION...86
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