547
FXUS66 KPDT 220953
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
253 AM PDT SUN MAR 22 2026
KEY MESSAGES
1. DRY AND COOL CONDITIONS THROUGH EARLY IN THE WEEK
2. AT OR NEAR SEASONAL AVERAGE TEMPERATURES
3. A PATTERN CHANGE WILL BRING BACK CHANCES OF LOWLAND RAIN,
MOUNTAIN SNOW AND BREEZY CONDITIONS
DISCUSSION
CURRENT SATELLITE SHOWS MOSTLY CLEAR SKIES OVER THE REGION WITH SOME
MID-LEVEL CLOUDS MOVING INTO CENTRAL OR. MODELS SHOW WEST FLOW ALOFT
USHERING IN THE DRY AIR MASS OVER THE REGION. WITH THE LACK OF
CLOUD COVER AND THE COLD AIR MASS COMING IN, TEMPERATURES COULD DROP
TO FREEZING ACROSS PORTIONS OF CENTRAL OR AND THE FOOTHILLS OF THE
BLUES AS WELL AS THE SIMCOE HIGHLANDS AND ADJACENT VALLEYS. MODELS
ARE IN FORM AGREEMENT THIS PATTERN WILL PERSIST THROUGH MONDAY.
THE WESTERLY FLOW ALOFT HAS BROUGHT IN DRY AND COOLER AIR LAST NIGHT
AND OVERNIGHT. DRY AND COOL CONDITIONS WILL BRING TEMPERATURES BACK
TO NEAR SEASONAL NORMAL WITH NBM RAW ENSEMBLES SHOWING HIGHS TO BE
IN THE LOW TO MID 50S ACROSS MUCH OF THE REGION WITH LOW 60S IN
CENTRAL OR AND ISOLATED SPOTS IN THE BASIN (60-70% CONFIDENCE). BY
SUNDAY TEMPERATURES WILL SLOWLY INCREASE, HOWEVER, STILL REMAINING
NEAR SEASONAL WITH TEMPERATURES ACROSS MUCH OF THE REGION SEEING THE
LOW 60S (60-80% CONFIDENCE) THROUGH MIDWEEK.
MODELS ARE IN FORM AGREEMENT THAT BY TUESDAY/TUESDAY NIGHT AN UPPER
LEVEL LOW WILL TRACK TO THE NORTH OF THE REGION BRINGING A FRONTAL
SYSTEM ACROSS THE REGION. INCREASED CHANCES OF PRECIPITATION WILL
OCCUR WITH NBM RAW ENSEMBLES SHOWING 0.50-1 INCH OF PRECIPITABLE
WATER ALONG THE CASCADES. WITH THE SNOW LEVELS ABOVE 4000 FEET
TUESDAY, MUCH OF THE PRECIPITATION WILL FALL AS RAIN. THE LOWLANDS
WILL SEE 0.02-0.05 INCHES OF RAIN TUESDAY WITH 60-70% OF THE NBM RAW
ENSEMBLES IN AGREEMENT. AS WE MOVE INTO WEDNESDAY AND EARLY THURSDAY
AND THE FRONT PASSES THE REGION, GRIDDED MODELS SHOW THE SNOW LEVELS
TO DROP TO BELOW 2000 FEET AND MODELS SHOW A CONTINUED PLUME OF
MOISTURE PUSHING INTO THE REGION. THIS WILL BRING SNOW ACCUMULATIONS
OF 2.5-5 INCHES ALONG THE I-90 CORRIDOR WEDNESDAY WITH 70-80%
CONFIDENCE. THE BLUES WILL SEE ONLY 0.01-0.05 INCHES ABOVE 4000 FEET
(60% CONFIDENCE) AND THE LOWER ELEVATIONS WILL REMAIN DRY.
NOT ONLY WILL THIS FRONT BRING PRECIPITATION, IT WILL ALSO BRING
BREEZY CONDITIONS BACK TO THE AREA. NBM RAW ENSEMBLES SHOW 60-80%
PROBABILITIES OF THE REGION SEEING GUSTY WINDS OF 25-30 MPH BOTH
TUESDAY AND WEDNESDAY AS THE FRONT PASSES OVER
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
VFR CONDITIONS PREVAIL
FOR ALL SITES. WINDS WILL BE LESS THAN 12 KTS FOR MOST SITES. KPSC
MAY SEE NORTHERLY WINDS OF 13 KTS OR HIGHER THROUGH 08Z (30%
CONFIDENCE). FEASTER/97
HYDROLOGY
RIVER FLOODING FROM SNOWMELT AND PREVIOUS RAINFALL IS ONGOING
FOR THE YAKIMA AND NACHES RIVERS IN SOUTH-CENTRAL WASHINGTON.
THESE RIVERS HAVE CRESTED, OR WILL CREST THIS AFTERNOON, FOR
MOST LOCATIONS IN THE YAKIMA AND KITTITAS VALLEYS. LOCATIONS
DOWNSTREAM TOWARDS THE EASTERN END OF THE YAKIMA VALLEY AND THE
LOWER COLUMBIA BASIN HAVE YET TO CREST, AND THE YAKIMA AT KIONA
IS FORECAST TO CREST BETWEEN LATE SUNDAY AFTERNOON AND EARLY
MONDAY MORNING.
LOOKING AHEAD, SEVERAL FORECAST POINTS ALONG THE YAKIMA AND
NACHES RIVERS, INCLUDING THOSE AT EASTON, CLIFFDELL, NACHES, AND
PERHAPS UMTANUM, ARE THEN ANTICIPATED TO REMAIN ABOVE ACTION
STAGE THROUGH THE WEEK ACCORDING TO THE LATEST FORECASTS FROM
THE NORTHWEST RIVER FORECAST CENTER IN PORTLAND.
PRELIMINARY POINT TEMPS/POPS
PDT 57 34 60 44 / 0 0 0 10
ALW 57 37 60 47 / 0 0 0 10
PSC 60 35 63 45 / 0 0 0 10
YKM 56 34 60 42 / 0 0 0 10
HRI 60 34 63 45 / 0 0 0 10
ELN 53 31 55 38 / 0 0 0 10
RDM 60 31 64 42 / 0 0 0 10
LGD 58 35 64 45 / 0 0 0 10
GCD 61 37 65 45 / 0 0 0 10
DLS 61 38 62 45 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...90
AVIATION...97
HYDROLOGY...86
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