080
FXUS66 KPDT 131727
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1027 AM PDT SUN SEP 13 2026
KEY MESSAGES
- ONGOING RAIN ACROSS THE REGION THROUGH THE AFTERNOON.
- GUSTY WINDS THROUGH THE AFTERNOON HOURS.
- GENERALLY DRY WITH BELOW NORMAL TEMPERATURES FOR MOST OF THE
WEEK.
UPDATE
WITH RAINFALL REPORTS REACHING OVER AN INCH IN SOME AREAS,
ADDITIONAL EVALUATION WAS MADE FOR THE POTENTIAL OF FOG
DEVELOPMENT OVERNIGHT. PATCHY FOG WAS ADDED TO ISOLATED AREAS.
CONFIDENCE IN FOG DEVELOPMENT IS LOW TO MODERATE (20-40%). NO
OTHER SIGNIFICANT UPDATES MADE TO FORECAST PACKAGE.
DISCUSSION
AN AREA OF LOW PRESSURE WAS MOVING NORTHEASTWARD ACROSS THE
REGION AND BY TONIGHT WILL BE IN SOUTHERN CANADA. DRY
NORTHWESTERLY FLOW WILL MOVE IN BEHIND THE DEPARTING LOW.
LATEST RADAR SHOWED RAIN, MAINLY ACROSS WASHINGTON, AT THIS
TIME. SOME OF THE GUIDANCE SUGGESTS THERE COULD BE A LULL IN
THE RAIN THROUGH THE MORNING HOURS ACROSS PORTIONS OF THE AREA,
ESPECIALLY THE COLUMBIA BASIN, BEFORE THE RETURN FLOW
PRECIPITATION THIS AFTERNOON. THERE IS ALSO A LOW (<20 PERCENT)
CHANCE OF A THUNDERSTORM THIS AFTERNOON, MAINLY IN WALLOWA
COUNTY. BY LATE AFTERNOON, RAIN WILL BEGIN TO WIND DOWN AND BE
OVER COMPLETELY DURING THE NIGHT. CENTRAL OREGON SHOULD RECEIVE
THE BE MOSTLY DRY, THOUGH THERE WILL BE SOME RAIN MAINLY IN THE
MORNING.
WINDS WILL BE GUSTY ESPECIALLY ACROSS THE COLUMBIA BASIN,
GORGE, SIMCOE HIGHLANDS AND FOOTHILLS OF THE NORTHERN BLUE
MOUNTAINS. WINDS ARE EXPECTED TO GUST IN THE 25 TO 30 MPH RANGE,
WITH SOME AREAS GUSTING AS HIGH AS 35 MPH. NBM PROBABILITIES OF
WIND GUSTS >= 25 MPH ARE GREATER THAN 90%. NBM PROBABILITIES OF
WIND GUSTS >=39 MPH ARE 30-40 PERCENT.
QPF VALUES TODAY RANGE FROM 1.00 INCHES PLUS IN THE WASHINGTON
CASCADES AND SURROUNDING LOCATIONS, TO AROUND 0.75 INCHES ALONG
THE CREST OF THE BLUE MOUNTAINS TO AROUND 0.25 INCHES IN MOST
LOWER ELEVATION AREAS TO LESS THAN 0.10 INCHES ACROSS CENTRAL
OREGON AND ELSEWHERE. THE ECMWF EFI SHOWS A BROAD AREA OF 80TH
TO 90TH PERCENTILE FOR QPF ACROSS A LARGE SWATH OF EASTERN
WASHINGTON. WITHIN THAT IS AN AREA OF 90TH TO 95TH PERCENTILE
FOR QPF ACROSS THE WASHINGTON COLUMBIA BASIN AND YAKIMA VALLEY
HEADING UP TOWARDS THE CASCADES AND WITHIN THAT IS AN AREA OF
95TH TO 99TH PERCENTILE. SHIFT OF TAILS IS 1 TO 2.
ANOTHER UPPER LOW WILL DROP DOWN FROM CANADA LATER TUESDAY INTO
WEDNESDAY AND COULD TRIGGER SOME SHOWERS OVER THE MOUNTAINS.
HIGH PRESSURE WILL THEN BUILD IN BEHIND THE DEPARTING LOW.
HIGH TEMPERATURES WILL STRUGGLE IN THE LOWER 60S TODAY. THIS IS
15 TO 20 DEGREES BELOW NORMAL. HIGHS WILL REBOUND INTO THE 70S
MONDAY THROUGH WEDNESDAY. THESE TEMPERATURES WILL BE ABOUT 5 TO
10 DEGREES BELOW NORMAL. BY THURSDAY AND FRIDAY, TEMPERATURES
WILL RETURN TO CLOSE TO NORMAL.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
MVFR TO VFR CONDITIONS ANTICIPATED ACROSS THE FORECAST AREA
TODAY. THE DEVELOPMENT OF ADDITIONAL RAINFALL MAY CREATE BRIEF
PERIODS OF MVFR CONDITIONS AT TERMINALS, WITH OTHERWISE VFR
CONDITIONS EXPECTED. GUSTY WIND OF 15G25KT REMAINS IN THE
FORECAST FOR MOST TERMINALS THROUGH THE EARLY EVENING, WITH
GUSTY WINDS PERSISTING AT KPSC THROUGH THE OVERNIGHT HOURS.
BRANHAM/76
PRELIMINARY POINT TEMPS/POPS
PDT 62 45 70 44 / 60 60 0 0
ALW 62 50 71 50 / 90 80 0 0
PSC 63 46 74 45 / 70 40 0 0
YKM 61 44 69 47 / 100 20 0 0
HRI 64 46 73 44 / 50 50 0 0
ELN 57 41 65 42 / 100 30 0 0
RDM 61 33 71 36 / 10 10 0 0
LGD 61 43 70 42 / 80 90 0 0
GCD 61 41 70 42 / 50 20 0 0
DLS 65 51 74 50 / 50 10 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...FLASH FLOOD WATCH UNTIL 8 PM PDT THIS EVENING FOR WAZ030.
OR...FLASH FLOOD WATCH UNTIL 8 PM PDT THIS EVENING FOR ORZ502.
UPDATE...76
DISCUSSION...77
AVIATION...76
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