018
FXUS66 KPDT 022125
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
225 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 /18Z TAFS THROUGH 18Z THURSDAY/
REGIONAL RADAR SHOWS RAIN TO THE NORTHEAST AND WEST OF THE AREA
RESULTING FROM AN UPPER TROUGH MOVING INLAND. RDM AND BDN
SHOULD ALREADY BE SEEING -SHRA AND VFR TO MVFR CEILINGS TODAY
WHILE THUNDER RISK REMAINS MORE PROBABLE OVER THE HIGHER
TERRAIN/MOUNTAIN AREAS. -SHRA AND MVFR CONDITIONS SHOULD SPREAD
EASTWARD OVER THE VALLEY TERMINALS AND INTO THE COLUMBIA BASIN
PDT/ALW/PSC AS WELL TONIGHT AS THE SYSTEM EVOLVES EASTWARD.
PRELIMINARY POINT TEMPS/POPS
PDT 45 68 42 67 / 90 20 30 30
ALW 49 68 47 68 / 100 30 40 40
PSC 47 72 46 72 / 80 0 10 30
YKM 47 70 48 71 / 40 10 10 20
HRI 47 71 46 71 / 90 0 20 20
ELN 43 66 42 67 / 60 30 20 40
RDM 37 64 35 63 / 80 20 50 50
LGD 46 65 42 65 / 90 70 80 70
GCD 44 63 41 65 / 100 70 80 40
DLS 50 69 50 71 / 80 30 30 30
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...77
AVIATION...71
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