991
FXUS66 KPDT 231106
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
406 AM PDT WED SEP 23 2026
KEY MESSAGES
- NEAR TO ABOVE NORMAL TEMPERATURES WITH DRY CONDITIONS THROUGH
THURSDAY
- WIDESPREAD SHOWERS AND BREEZY TO WINDY CONDITIONS DEVELOP LATE
THURSDAY THROUGH FRIDAY
- SPLIT FLOW EMERGING MONDAY BRINGING LIGHT WINDS AND DRY
CONDITIONS
DISCUSSION
LITTLE TO TALK ABOUT ACROSS THE REGION TONIGHT,
WITH NIGHTTIME SATELLITE IMAGERY ONLY SHOWING DECKS OF CIRRUS
SPREADING EAST OF THE CASCADES.
TODAY THROUGH SATURDAY: MOSTLY QUIET CONDITIONS WITH NEAR TO
ABOVE NORMAL TEMPERATURES WILL PREVAIL TODAY AND TOMORROW AS THE
PACNW SITS UNDERNEATH A WEST TO SOUTHWEST FLOW ALOFT. DURING
THURSDAY, FLOW ALOFT WILL INCREASE FROM THE SOUTHWEST AS AN
UPPER TROUGH WITH AN ATTENDANT SURFACE LOW SWING TOWARDS THE
PACNW. SOUTHERLY WINDS THROUGH THE GRAND RONDE VALLEY AND
NORTH/SOUTH VALLEYS IN WALLOWA COUNTY WILL INCREASE TO AROUND
15-25 MPH WITH GUSTS UP TO 35 MPH AHEAD OF THE TROUGH/LOW
THURSDAY AFTERNOON.
LATE THURSDAY, SHOWER ACTIVITY WILL INCREASE ACROSS THE CASCADE
CREST AS THE UPPER TROUGH AND SURFACE LOW CONTINUE TO APPROACH
THE PACNW. RAIN SHOWERS WILL THEN SPREAD EASTWARD ACROSS THE
REMAINDER OF THE FORECAST AREA EARLY SATURDAY MORNING INTO THE
AFTERNOON AS THE TROUGH AND REMNANTS OF THE LOW CONTINUE EAST.
THERE WILL BE A 60-90% CHANCE OF AT LEAST MEASURABLE RAIN
ACROSS MUCH OF THE FORECAST AREA FRIDAY, WITH A 40-60% CHANCE OF
0.25 INCHES IN THE NORTHERN BLUES AND A 50-80% CHANCE OF 0.5
INCHES ALONG THE CASCADE CREST AND EAST SLOPES. IN ADDITION TO
PRECIPITATION, THE UPPER TROUGH AND SURFACE LOW PASSAGE WILL
BRING INCREASING WESTERLY WINDS ACROSS THE FORECAST AREA. WINDS
WILL BE 15-30 MPH WITH GUSTS 35-50 MPH THROUGH THE CASCADE GAPS
AND INTO THE COLUMBIA BASIN, WITH WINDS 15-20 MPH AND GUSTS UP
TO 35 MPH ELSEWHERE. SURFACE WINDS WILL BE SUPPORTED BY A
40-50KT LOW LEVEL JET THAT WILL MIX DOWN ACROSS PORTIONS OF THE
COLUMBIA BASIN FRIDAY AFTERNOON, WITH MOD-HIGH CONFIDENCE
(65-80%) THAT WIND ADVISORIES WILL BE NEEDED.
SHOWER ACTIVITY AND WINDY CONDITIONS WILL DIMINISH OVERNIGHT
FRIDAY INTO SATURDAY AS THE UPPER TROUGH EXITS THE REGION TO
THE NORTHEAST. WEAK BROAD TROUGHING WILL DEVELOP OFFSHORE THE
PACNW SATURDAY, PLACING THE REGION UNDER WEAK FLOW ALOFT. THIS
WILL RESULT IN DRY AND COOL CONDITIONS WITH LIGHT WINDS SATURDAY
(CONFIDENCE 60-75%). LAWHORN/82
SUNDAY THROUGH TUESDAY: SUNDAY AFTERNOON INTO MONDAY HAS THE
TROUGH ARRIVING AT THE COAST, CENTERING WITHIN CALIFORNIA. MODEL
MEMBERS ARE IN AGREEMENT FOR THE TIMING AND POSITION OF THE
TROUGH. AFTER LANDFALL OF THE TROUGH, A SPLIT FLOW WILL EMERGE
AS TROUGH MOVES SOUTH OF THE PACIFIC NW. IMPACTS WILL BE MINIMAL
BRINGING LIGHT WINDS AND DRY CONDITIONS. ENSEMBLE MEMBERS ARE
IN SLIGHT DISAGREEMENT WITH THE PROGRESSION OF THE TROUGH IN
CALIFORNIA, WITH THE GLOBAL AND CANADIAN MEMBERS HAVING IT
LINGER TILL TUESDAY AFTERNOON, WHILE THE EUROPEAN MEMBER HAS IT
LEAVE MONDAY NIGHT. MONDAY INTO TUESDAY ENSEMBLE MEMBERS SHOW
INCREASING MOUNTAIN SHOWERS WITH OFFSHORE TROUGHING, WHILE
DETERMINISTIC FORECASTS SHOWS A LOW PRESSURE SYSTEM WITH
POSSIBLE COLD FRONT PASSAGE. CONFIDENCE IN TIMING AND EXTENT OF
SHOWERS IS LOW (15% CONFIDENCE). NEAR TO BELOW NORMAL
TEMPERATURE CONDITIONS ARE EXPECTED FROM SUNDAY INTO TUESDAY.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
DLS/PDT/RDM/BDN: VFR CONDITIONS LIKELY TO CONTINUE OVER THE TAF
PERIOD. NO RISK OF HIGH WINDS, LOW CLOUD BASE, OR LOW
VISIBILITY PRESENT FOR THE TAF PERIOD.
YKM/ALW/PSC: VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. WINDS
WILL BE LIGHT AND DIURNALLY DRIVEN. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 74 46 77 52 / 0 0 0 10
ALW 75 52 78 56 / 0 0 0 0
PSC 77 47 78 51 / 0 0 0 20
YKM 74 48 74 53 / 0 0 0 70
HRI 77 47 78 51 / 0 0 0 20
ELN 69 42 69 47 / 0 0 0 80
RDM 73 39 80 44 / 0 0 0 70
LGD 78 47 85 52 / 0 0 0 0
GCD 80 47 87 52 / 0 0 0 0
DLS 76 50 77 54 / 0 0 0 80
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...07/82
AVIATION...07/82
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