426
FXUS66 KPDT 211721
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1021 AM PDT SAT MAR 21 2026
KEY MESSAGES
1. TEMPERATURES WILL RETURN TO NEAR SEASONAL AVERAGES
2. DRY AND COOLER CONDITIONS THROUGH MONDAY NIGHT
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
PREDOMINANTLY VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.
SOME LOW CLOUDS ARE LINGERING AT PDT/ALW/RDM/BDN THIS MORNING IN
THE WAKE OF LAST NIGHT'S COLD FRONTAL PASSAGE. CAN'T ENTIRELY
RULE OUT TEMPORARY MVFR (RDM/BDN) OR HIGH-END IFR (PDT/ALW) CIGS
THIS MORNING INTO THE EARLY AFTERNOON, BUT CONFIDENCE IS LOW
(20-30 PERCENT). SKIES WILL BECOME MOSTLY CLEAR FOR ALL SITES BY
THIS EVENING, FOLLOWED BY INCREASING HIGH-LEVEL CLOUD OVERNIGHT
INTO SUNDAY MORNING.
WINDS OF 10-15 KTS WITH GUSTS OF 15-25 KTS ARE FORECAST AT ALL
SITES TODAY, THEN LIGHT VARIABLE OR TERRAIN-DRIVEN WINDS ARE
ANTICIPATED OVERNIGHT INTO EARLY SUNDAY MORNING. 86
DISCUSSION...ISSUED 406 AM PDT SAT MAR 21 2026
CURRENT RADAR SHOWS A FEW RETURNS OVER THE CASCADES AND THE
BLUES AS THE REMNANTS OF THE ATMOSPHERIC RIVER REMAIN OVER THE
AREA. CURRENT GROUND OBSERVATIONS SHOW THAT THE LAST HOUR THESE
RETURNS HAVE ONLY PUT DOWN BETWEEN 0.01-0.02 INCHES OF RAIN.
RAIN IS EXPECTED TO CONTINUE OVER THE MOUNTAINS THROUGH TODAY
(SATURDAY) WITH RAIN ACCUMULATIONS NEARING 0.05-0.1 INCHES IN
THE OR CASCADES AND THE EASTERN MOUNTAINS THROUGH 11 PM TONIGHT
(70-90% CONFIDENCE). RADAR COUPLED WITH MODELS SHOW THE MAJORITY
OF THE PERCEPTION WILL CONTINUE A SOUTHWEST TRAJECTORY OVER THE
OR CASCADES AND BLUE MOUNTAINS BEFORE TAPERING OFF SATURDAY
NIGHT.
MODELS SHOW A WEAK COLD FRONT MOVING ACROSS THE REGION LATE LAST
NIGHT AND THROUGH THIS MORNING. THIS WILL BRING WITH IT
INCREASED CLOUD COVER AS WELL AS COOLER TEMPERATURES. IN HOUSE
COMPARISONS SHOW THAT TEMPERATURES WILL DECREASE NEARLY 20
DEGREES FROM YESTERDAY WITH TEMPERATURES AT OR NEAR SEASONAL
NORMAL. WITH THAT SAID, NBM RAW ENSEMBLES AS WELL AS HREF RAW
ENSEMBLES SHOW 80-90% CONFIDENCE THAT THE BASIN, YAKIMA, THE
GORGE AND CENTRAL OR SEEING TEMPERATURES IN THE MID TO UPPER 50S
SATURDAY WHILE ELSEWHERE WILL SEE UPPER 40S TO LOW 50S WITH
EVEN COOLER TEMPERATURES ALONG THE HIGHER TERRAINS. SUNDAY BOTH
RAW ENSEMBLES SETS SHOW TEMPERATURES TO BE EVEN COOLER WITH
70-80% OF THE AFOREMENTIONED AREAS SEEING LOW TO MID 50S WITH
ISOLATED LOCATIONS IN CENTRAL OR AND THE BASIN SEEING MID TO
UPPER 50S. AFTER SUNDAY, MODELS SHOW A SLOW WARM UP THROUGH THE
BEGINNING OF NEXT WEEK.
MODELS SHOW PERSISTENT COOL AND DRY WEATHER THROUGH MONDAY NIGHT
AS SOUTHWEST FLOW ALOFT CONTINUES OVER THE AREA. THIS WILL
SLOWLY BRING TEMPERATURES UP THROUGH THE BEGINNING OF THE WEEK.
MODELS ALSO SHOW THAT PRECIPITATION WILL BE LACKING WITH THE
SOUTHWEST FLOW KEEPING THE REGION DRY AHEAD OF A PATTERN CHANGE
WITH AN UPPER LEVEL SHORTWAVE BRINGING IN INCREASED CHANCES OF
PRECIPITATION, BREEZY WINDS AND A RETURN TO COOLER CONDITIONS.
HYDROLOGY...ISSUED 236 PM PDT FRI MAR 20 2026
THE CASCADE SLOPE BASINS HAVE RECEIVED THE BULK OF THE
PRECIPITATION THAT WILL BE IMPACTING RIVER FORECASTS OVER THE
WEEKEND. ALL TRIBUTARIES WITH MOUNTAIN HEADWATERS WILL CONTINUE
TO RUN HIGH. FORECAST POINTS ALONG THE NACHES AND YAKIMA RIVERS
WILL BE THE MOST IMPACTED BY THE SURGE OF MOUNTAIN RUNOFF AS
SEVERAL OF THESE POINTS ENTER INTO FLOOD BY SATURDAY, IF NOT
ALREADY IN FLOOD LIKE THE NACHES AT NACHES. THE YAKIMA RIVER AT
EASTON IS FORECAST TO REACH JUST OVER THE 52.1 FT LEVEL, (ABOUT
1 FT OVER MODERATE FLOOD) BUT HAS A 30% CHANCE OF REACHING 52FT.
AT KIONA, THE RIVER IS FORECAST TO REACH THE 13.9 FT LEVEL, BUT
HAS A 10% CHANCE OF REACHING 14 FT. RUSSELL/71
PRELIMINARY POINT TEMPS/POPS
PDT 58 30 57 33 / 80 0 0 0
ALW 58 34 57 37 / 90 0 0 0
PSC 66 33 60 34 / 50 0 0 0
YKM 63 29 56 33 / 0 0 0 0
HRI 62 32 60 33 / 70 0 0 0
ELN 54 29 52 30 / 0 0 0 0
RDM 59 24 60 29 / 20 0 0 0
LGD 56 28 58 34 / 80 0 0 0
GCD 58 29 60 35 / 60 0 0 0
DLS 60 34 61 37 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...90
AVIATION...86
HYDROLOGY...71
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