477
FXUS66 KPDT 240517
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1017 PM PDT SAT MAY 23 2026
KEY MESSAGES
1. DRY AND WARM CONDITIONS WILL PERSIST THROUGH THE WEEKEND
2. BREEZY TO WINDY THROUGH THE GAPS SATURDAY AND AGAIN MONDAY
3. PATTERN SHIFT MONDAY WILL BRING CHANCES MOUNTAIN SHOWERS
BECOMING MORE WIDESPREAD TUESDAY ONWARDS
DISCUSSION
CURRENT SATELLITE SHOWS MOSTLY CLEAR SKIES OVER THE VAST
MAJORITY OF THE REGION WITH SOME FAIR WEATHER CUMULUS
ACCUMULATING OVER THE RIDGELINES OF SOME OF THE MOUNTAINS.
TODAY WILL BE THE HOTTEST DAY OF THE WEEK WITH 80-90% OF THE NBM
RAW ENSEMBLES SHOWING THE MAJORITY OF THE REGION IN THE LOW TO
MID 80S WITH POCKETS OF HIGH 80S IN THE BASIN. BY SUNDAY
TEMPERATURES WILL BE IN THE UPPER 70S LOW 80S WITH 70-90%
PROBABILITIES. IN OFFICE DIFFERENCE CALCULATIONS FROM CLIMATE
SHOWS TEMPERATURES TO BE 10-15 DEGREES ABOVE NORMAL BY TODAY AND
SUNDAY.
AS MENTIONED ABOVE, THE BREAKDOWN OF THE RIDGE FROM NORTHWEST FLOW
TO WESTERLY FLOW WILL CAUSE A SLIGHT INCREASE IN THE WINDS,
ESPECIALLY THROUGH THE MOUNTAINS GAP AREAS. WITH THE WESTERLY OR
ZONAL FLOW, WINDS WILL BE BREEZY WITH MODELS SHOWING SUSTAINED WINDS
SPEEDS NEARING 20 MPH WITH GUSTS NEAR 30 MPH WITH 80-90% OF THE NBM
RAW ENSEMBLES IN AGREEMENT. THE LOCATIONS OF THE WINDS WILL
PRIMARILY BE THROUGH THE MOUNTAIN GAPS OF THE GORGE AND KITTITAS
VALLEY WITH 50-70% IN AGREEMENT THAT THE SOUTHERN FOOTHILLS OF THE
BLUES WILL SEE THESE WINDS AS WELL. THERE WILL BE A BRIEF SETTLING
OF THE WIND AHEAD OF THE NEXT SYSTEM THAT WILL BE ROLLING THROUGH ON
MONDAY. WINDS WILL THEN SHIFT TO THE SOUTHWEST AS THE UPPER LEVEL
TROUGH/LOW MAKES ITS WAY INTO THE REGION. AS THE FRONT MOVES INLAND,
MODELS AND IN HOUSE CALCULATIONS SHOW A TIGHTENING OF THE PRESSURE
GRADIENTS AT THE SURFACE ACROSS THE CASCADES. THIS WILL BRING
INCREASED WINDS BACK TO THE REGION LEANING MORE TOWARDS WINDY
CONDITIONS ON MONDAY THROUGH THE GORGE, KITTITAS VALLEY AND THE
SOUTHERN BLUE FOOTHILLS. NBM RAW ENSEMBLES ARE AGAIN IN 60-80%
AGREEMENT OF SUSTAINED WINDS OF 25-35 MPH WITH GUSTS OF 45-50 MPH.
WILL BE KEEPING AN EYE ON THE WINDS TO WATCH FOR THE NEED OF A
POSSIBLE ADVISORY FOR THOSE AREAS.
MONDAYS COLD FRONT WILL BRING COOLER TEMPERATURES AND PRECIPITATION
WITH TUESDAY BEING THE COOLEST DAY OF THE PERIOD. IN HOUSE
CALCULATIONS SHOW TEMPERATURES WILL DROP TO NEARLY 10-15 DEGREES
BELOW SEASONAL AVERAGES WITH THE NBM ENSEMBLES SHOWING TEMPERATURES
IN THE UPPER 50S TO LOW 60S WITH A FEW ISOLATED BASIN LOCATIONS
SEEING NEAR 70S WITH HIGH CONFIDENCE OF 70-90%. PRECIPITATION IS
EXPECTED TO RETURN TO THE CASCADES MONDAY AFTERNOON WITH 0.05 INCHES
OF RAIN POSSIBLE OVER THE 24 HOURS WITH 70-80% CONFIDENCE. MODELS
SHOW THE RAIN TO BECOME MORE WIDESPREAD TUESDAY WITH PRECIPITATION
EXPECTED ACROSS A VAST MAJORITY OF THE REGION. TUESDAYS 24 HOUR RAIN
TOTAL ARE NEAR 0.05 INCHES IN THE MOUNTAINS WITH 70-80% CONFIDENCE
ON 0.01-0.03 FOR SOME OF THE LOWER ELEVATIONS. AS THE SYSTEM
STEADILY MOVES SOUTHEAST, RAIN AMOUNTS WILL SLIGHTLY DECREASE TO
0.01-0.03 INCHES WITH 60-80% CONFIDENCE AND STEADILY DECREASE
THEREAFTER WITH MAINLY LIGHT SHOWERS EXPECTED THROUGH THE REMAINDER
OF THE WEEK.
MODELS ARE IN AGREEMENT WITH THE SYSTEM MOVING THROUGH. LOOKING AT
THE CLUSTERS, THE BIGGEST DIFFERENCE BETWEEN THE MODELS IS WHERE THE
LOW WILL GO. MANY MODELS SHOW THE UPPER LEVEL SYSTEM TO CUTOFF
AND MOVE TO THE SOUTH OF THE REGION. THIS WILL LEAD TO WRAP
AROUND PRECIPITATION AS WELL AS THE POTENTIAL FOR ISOLATED
THUNDERSTORMS BEGINNING AS EARLY AS TUESDAY. OTHER MODELS SHOW
THE UPPER LEVEL CUT OFF LOW TRACKING NORTHEAST ONLY CLIPPING THE
EASTERN PORTION OF THE REGION. REGARDLESS, NBM 12 HR
PROBABILITIES OF THUNDER SHOW 20% PROBABILITIES OF THUNDERSTORMS
ALONG THE OR CASCADES, CASCADE FOOTHILLS AND ACROSS CENTRAL OR
INTO THE OCHCO-JOHN DAY HIGHLANDS TUESDAY. BY WEDNESDAY THE
CHANCE DROP TO 15% PROBABILITIES AND SHIFT MAINLY OVER THE
EASTERN MOUNTAINS AND PORTIONS OF WALLOWA.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
VFR CONDITIONS WILL CONTINUE THROUGH SUNDAY. WINDS ARE MAINLY
10 KTS OR LESS EXCEPT AT DLS AND YKM, WHERE THERE ARE SOME
GUSTS TO AROUND 25 KTS. THESE WILL LIKELY CONTINUE FOR A FEW
MORE HOURS BEFORE DECREASING. WINDS WILL INCREASE AGAIN ON
SUNDAY AFTERNOON AND GUST TO AROUND 20 KTS, BEFORE DECREASING
DURING THE EVENING.
FIRE WEATHER
DRY AND WARM ZONAL FLOW THROUGH SUNDAY AND THEN
SOUTHWEST FLOW MONDAY AS AN UPPER LEVEL TROUGH/LOW MOVES INTO THE
REGION. DAYTIME RHS WILL BE AT THEIR LOWEST OVER WEEKEND WITH THE
LOWEST RHS WILL BE SUNDAY WITH WIDESPREAD TEENS AND LOW 20%. RHS
TOMORROW WILL BE IN THE LOW TO MID TEENS THROUGH CENTRAL OR AND THE
OCHCO-JOHN DAY HIGHLAND WITH POCKETS ALONG THE SOUTHERN BLUES AND IN
THE BASIN. 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 AS WELL AS THE BASIN WITH 15-20 MPH WINDS.
THIS PUTS THIS AREA OF THE REGION IN ELEVATED FIRE WEATHER CONCERNS
WHERE THE OVERALL FIRE ENVIRONMENT SUGGESTS A MODERATE HIGH RISK FOR
SIGNIFICANT FIRES (5-19% PROBABILITIES).
PRELIMINARY POINT TEMPS/POPS
PDT 50 82 51 83 / 0 0 0 0
ALW 55 82 57 84 / 0 0 0 0
PSC 52 86 54 86 / 0 0 0 0
YKM 50 85 53 78 / 0 0 0 0
HRI 53 84 54 83 / 0 0 0 0
ELN 48 77 49 73 / 0 0 0 0
RDM 41 84 46 81 / 0 0 0 0
LGD 46 82 48 87 / 0 0 0 10
GCD 43 84 46 87 / 0 0 0 0
DLS 53 83 54 77 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...90
AVIATION...77
FIRE WEATHER...99
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