939
FXUS66 KPDT 212331
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
431 PM PDT THU MAY 21 2026
KEY MESSAGES
1. DRY AND WARM CONDITIONS WILL PERSIST THROUGH THE WEEK
2. BREEZY TO WINDY THROUGH THE GAPS SUNDAY
3. PATTERN SHIFT SUNDAY WILL BRING CHANCES MOUNTAIN SHOWERS BECOMING
MORE WIDESPREAD MONDAY ONWARDS
DISCUSSION
CURRENT SATELLITE SHOWS MOSTLY CLEAR SKIES OVER THE REGION WITH A
FEW CUMULUS CLOUDS BEGINNING TO BUBBLE UP THROUGH PORTIONS OF
CENTRAL OR. HIGH PRESSURE OVER THE REGION WILL KEEP THE REGION UNDER
DRY AND CONTINUED WARMING CONDITIONS THROUGH THE WEEK WITH
TEMPERATURES TODAY LINGERING IN THE MID 70S AND LOW 80S (90%
PROBABILITIES).
MODELS SHOW THE UPPER LEVEL RIDGE TO REMAIN OVER THE REGION THROUGH
AT LEAST SUNDAY MORNING AHEAD OF A PATTERN SHIFT. TEMPERATURES WILL
CONTINUE TO WARM THROUGH THE PERIOD WITH TEMPERATURES PEAKING
SATURDAY. RAW NBM ENSEMBLES SHOW TEMPERATURES TO BE IN THE UPPER 70S
TO LOW 80S STARTING TOMORROW WITH 70-90% PROBABILITIES. BY SATURDAY
TEMPERATURES WILL BE IN THE LOW TO MID 80S WITH 70-90%
PROBABILITIES. IN OFFICE DIFFERENCE CALCULATIONS FROM CLIMATE SHOWS
TEMPERATURES TO BE 5 TO 10 DEGREES ABOVE SEASONAL NORMAL TODAY AND
TOMORROW BEFORE REACHING 10-15 DEGREES ABOVE NORMAL BY SATURDAY.
WITH THE UPPER LEVEL LOW PRESSURE SYSTEM EXPECTED TO ARRIVE SUNDAY
EVENING, IN HOUSE MODEL GUIDANCE IS SHOWING A TIGHTENING OF THE
PRESSURE GRADIENTS ALONG THE CASCADES. THIS WILL LEAD TO INCREASED
WINDS THROUGH THE CASCADE GAPS AND ALONG THE FOOTHILLS OF THE
SOUTHERN BLUES. NBM RAW ENSEMBLES SHOW THE SUSTAINED WINDS OF NEAR
25 MPH THROUGH THESE AREAS WITH 60-80% PROBABILITIES THROUGH THE
GORGE AND KITTAS VALLEY AND 20-40% PROBABILITIES ACROSS THE
FOOTHILLS OF THE SOUTHERN BLUES.
SUNDAY IS WHEN THE MODELS SHOW THE NEXT SYSTEM WILL MAKE ITS WAY
INTO THE PACNW. DETERMINISTIC MODELS ARE IN RELATIVELY FORM AGREEMENT
WITH A SHIFT IN THE PATTERN. HOWEVER, ENSEMBLES CLUSTERS SHOW THERE
TO BE A DEVIANCE IN THE AMPLITUDE OF THE UPPER LEVEL LOW PRESSURE
SYSTEM. 80% OF THE ENSEMBLES CLUSTERS ARE IN AGREEMENT WITH A BIT OF
A DEEPER TROUGH COMING ACROSS THE REGION SUNDAY. WITH THAT SAID,
MODELS ARE SHOWING INCREASED CHANCES OF MOUNTAIN PRECIPITATION
SUNDAY AS WELL AS INCREASED WINDS. MODELS SHOW SUNDAY NIGHT COULD
SEE SOME LIGHT PRECIPITATION OVER THE CASCADES BEFORE BECOMING MORE
WIDESPREAD MONDAY AND TUESDAY. MODELS SHOW UPWARDS OF 0.15-0.20
INCHES OF RAIN ACROSS THE BLUES WITH 50-60% PROBABILITIES AND NEAR
0.3-0.4 INCHES ALONG THE CASCADES WITH 40-50% PROBABILITIES. WITH
THE SYSTEM, TEMPERATURES ARE EXPECTED TO DROP TO THE LOW TO MID 70S.
90
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
LIGHT 5 TO 15 MPH WINDS CONTINUE THROUGH ALL SITES. EXPECTING
VFR CONDITIONS TO CONTINUE THROUGH THE FORECAST PERIOD, WITH NO
SIGNIFICANT CIG OR VIS ISSUES EXPECTED.
FIRE WEATHER
DRY AND WARM CONDITIONS WILL PERSIST THROUGH THE WEEKEND WITH A
PATTERN SHIFT EXPECTED SUNDAY EVENING. DAYTIME RHS HIGHEST OVER THE
NEXT THREE DAYS AHEAD OF THE UPPER LEVEL LOW. RHS FRIDAY WILL BE IN
THE LOW TO MID TEENS THROUGH CENTRAL OR AND THE OCHCO-JOHN DAY
HIGHLANDS. POCKETS OF LOW RHS ALONG THE SOUTHERN BLUES AND IN THE
BASIN. SATURDAY RHS WILL BECOME MORE WIDESPREAD ACROSS THE REGION
WITH LOW RHS ACROSS THE VAST MAJORITY OF THE LOWER ELEVATIONS.
SUNDAY IS THE HIGHEST DAY OF CONCERN, ESPECIALLY IN THE KITTITAS
VALLEY WHERE RHS WILL BE IN THE LOW TO MID 20% AND WINDS WILL BE
BETWEEN 15-25 MPH. THIS PUTS THIS AREA OF THE REGION IN MODERATE
FIRE WEATHER CONCERNS.
PRELIMINARY POINT TEMPS/POPS
PDT 46 80 49 83 / 0 0 0 0
ALW 50 80 53 83 / 0 0 0 0
PSC 48 85 52 88 / 0 0 0 0
YKM 51 84 53 87 / 0 0 0 0
HRI 48 83 52 85 / 0 0 0 0
ELN 47 78 50 79 / 0 0 0 0
RDM 41 81 44 83 / 0 0 0 0
LGD 42 77 45 82 / 0 0 0 0
GCD 39 80 43 85 / 0 0 0 0
DLS 54 85 54 82 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...90
AVIATION...95
FIRE WEATHER...90
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