379
FXUS66 KPDT 121750
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1050 AM PDT SAT SEP 12 2026
KEY MESSAGES
- DRY MUCH OF TODAY, THEN RAIN DEVELOPING LATE THIS
AFTERNOON/EARLY THIS EVENING. ISOLATED THUNDERSTORMS THIS
EVENING.
- WIDESPREAD RAIN TONIGHT INTO SUNDAY.
- BREEZY TO WINDY ACROSS THE COLUMBIA GORGE, COLUMBIA BASIN,
KITTITAS VALLEY AND BLUE MOUNTAIN FOOTHILLS THIS EVENING
THROUGH SUNDAY MORNING.
- DRY MONDAY THROUGH THE REST OF THE UPCOMING WEEK.
DISCUSSION
AN AREA OF LOW PRESSURE OFF THE COAST OF OREGON AND WASHINGTON
IS MOVING SOUTHEASTWARD, THIS LOW MOVE ONSHORE LATE THIS
EVENING/OVERNIGHT.
AS THE LOW MOVES CLOSER, RAIN IS EXPECTED TO DEVELOP FROM WEST
TO EAST DURING THE EVENING HOURS. RAIN WILL BECOME WIDESPREAD
OVERNIGHT INTO SUNDAY MORNING BEFORE DECREASING FROM WEST TO
EAST DURING THE AFTERNOON AND EVENING ON SUNDAY AS THE LOW MOVES
NORTHEASTWARD TOWARDS SOUTHERN CANADA.
THE RAIN SHOULD BE OVER BY EARLY MONDAY. DRY WEATHER IS THEN
EXPECTED FOR THE REMAINDER OF THE WEEK, THOUGH A SECOND TROUGH
DROPPING DOWN TUESDAY NIGHT INTO WEDNESDAY WILL HAVE TO BE
WATCHED, IT HAS LITTLE MOISTURE WITH IT.
MODEL GUIDANCE IS STILL NOT IN GREAT AGREEMENT WITH RESPECT TO
RAINFALL AMOUNTS. HOWEVER, THERE IS SOLID AGREEMENT THAT THE
MOUNTAINS WILL GET THE HIGHEST AMOUNTS, AND MOST, IF NOT ALL
AREAS WILL RECEIVE DECENT RAINS AND SHOULD GET WETTING RAINS.
IT DOES APPEAR THAT THE HIGHER AMOUNTS WILL BE OVER THE
WASHINGTON CASCADES AND NEARBY AREAS, BUT EXACTLY HOW MUCH THE
MODELS ARE IN DISAGREEMENT OVER, THOUGH THERE IS AGREEMENT ON 1
INCH PLUS. OVER THE BLUE MOUNTAINS, THERE IS A BIT MORE
VARIABILITY WITH AMOUNTS RANGING FROM 0.50 INCH TO OVER AN INCH.
NBM PROBABILITIES OF 24 HOUR RAINFALL AMOUNTS >=0.50 INCHES ARE
HIGH ACROSS MUCH OF THE REGION, GENERALLY GREATER THAN 60%,
THOUGH CURRENT QPF AMOUNTS ACROSS THE BASIN ARE LESS THAN 0.50
INCHES. ACROSS THE MOUNTAIN AREAS THEY ARE >80%. NBM
PROBABILITIES >=1 INCH ARE HIGHEST IN THE WASHINGTON CASCADES
(>80 PERCENT), THOUGH MORE VARIABILITY IS SHOWN ACROSS THE BLUE
MOUNTAINS AND OTHER EASTERN MOUNTAINS WHERE PERCENTAGES VARY
FROM 30 TO ABOUT 50 PERCENT.
THERE IS ALSO A LOW (<20%) CHANCE OF THUNDERSTORMS THIS EVENING
AND OVERNIGHT. DEPENDING ON THUNDERSTORM DEVELOPMENT, THE
POTENTIAL EXISTS FOR FLOODING OVER THE BURN SCARS ASSOCIATED
WITH THE PARADISE AND HAGEN FIRES SO FLOOD WATCHES ARE IN
EFFECT FOR THESE AREAS.
WINDS WILL ALSO INCREASE THIS EVENING AND BECOME GUSTY AND
CONTINUE THROUGH SUNDAY ACROSS THE COLUMBIA GORGE, BASIN,
KITTITAS VALLEY AND FOOTHILLS OF THE BLUE MOUNTAINS. WINDS GUSTS
WILL BE IN THE 25 TO 30 MPH RANGE WITH GUSTS POSSIBLY AS HIGH
AS 40 MPH. NBM PROBABILITIES OF WIND GUSTS >=25 MPH ARE 90%
ACROSS MUCH OF THE REGION. HOWEVER, WIND GUSTS >=39 MPH ARE 50%
OR HIGHER ACROSS PORTIONS OF THE BASIN AND BLUE MOUNTAIN
FOOTHILLS. WIND GUSTS >=48 MPH ARE 20 TO 40 PERCENT.
THE COMBINATION OF THE GUSTY WINDS AND RAIN WILL CREATE WIND
SWEPT RAIN AT TIMES ACROSS PORTIONS OF THE AREA.
HIGH TEMPERATURES TODAY WILL BE A COUPLE OF DEGREES BELOW
NORMAL. HOWEVER, ON SUNDAY, HIGHS WILL BE 15 TO 20 DEGREES
BELOW NORMAL, AND WILL STRUGGLE IN THE LOWER 60S...AND IN SOME
AREAS MAY NOT GET OUT OF THE 50S. HIGHS WILL SLOWLY WARM UP
THROUGH THE WEEK, INTO THE 70S, (BUT WILL STILL BE BELOW
NORMAL), BUT BY FRIDAY AND SATURDAY WILL BE CLOSE TO NORMAL.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
VFR CONDITIONS ARE EXPECTED THROUGH THE FIRST 6 HOURS OF THE
FORECAST PERIOD. WINDS WILL BEGIN TO INCREASE FROM THE NORTHWEST
LATER THIS AFTERNOON AND INTO THIS EVENING, WITH BREEZY
CONDITIONS PREVAILING THROUGH THE MORNING ON SUNDAY. LIGHT RAIN
IS EXPECTED TO MOVE INTO THE REGION LATE TONIGHT, WITH THE
HIGHEST CONFIDENCE OF RAIN OCCURRING AT THE NORTHERN SITES.
ALONG WITH THE LIGHT RAIN, LOWER CIGS WILL FILTER INTO THE AREA,
WITH MVFR CONDITIONS SETTING IN BETWEEN 09Z AND 12Z AND
PERSISTING THROUGH THE REMAINDER OF THE FORECAST PERIOD.
PRELIMINARY POINT TEMPS/POPS
PDT 76 46 63 44 / 0 100 70 40
ALW 79 51 63 50 / 0 100 80 70
PSC 80 48 64 46 / 0 90 80 30
YKM 76 50 62 45 / 0 100 100 10
HRI 79 47 65 46 / 0 100 60 30
ELN 72 44 57 41 / 0 100 100 20
RDM 71 36 61 33 / 10 90 10 0
LGD 81 45 62 43 / 0 90 60 60
GCD 81 44 61 40 / 0 90 40 10
DLS 77 52 66 51 / 20 100 60 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...FLASH FLOOD WATCH FROM 5 PM PDT THIS AFTERNOON THROUGH SUNDAY
EVENING FOR WAZ030.
OR...FLASH FLOOD WATCH FROM 5 PM PDT THIS AFTERNOON THROUGH SUNDAY
EVENING FOR ORZ502.
DISCUSSION...77
AVIATION...99/JTC
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