418
FXUS66 KPDT 252250
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
350 PM PDT FRI SEP 25 2026
KEY MESSAGES
- SHOWERS AND BREEZY CONDITIONS REMAIN THROUGH THIS AFTERNOON AND
INTO THE EVENING HOURS.
- WIND ADVISORIES ARE STILL IN EFFECT THIS AFTERNOON FROM THE
KITTITAS AND YAKIMA VALLEY'S TO THE LOWER COLUMBIA BASIN.
- DRY AND LIGHT WIND CONDITIONS RETURN OVER THE WEEKEND; LOW
CHANCE FOR FREEZING TEMPERATURES SATURDAY NEAR WALLOWA VALLEY.
DISCUSSION
CURRENT SATELLITE AND RADAR IMAGERY SHOW SHOWERS IMPACTING OUR
FORECAST AREA AS THE SURFACE LOW MOVED ONSHORE THIS MORNING. THIS
SYSTEM BROUGHT BANDS OF LIGHT RAIN TO THE EASTERN SLOPES OF THE
CASCADES, WITH SOME SHOWERS STILL PRESENT IN THE CENTRAL AND
NORTHEAST PORTIONS OF THE FORECAST AREA.
SHOWERS AND BREEZY CONDITIONS SHOULD DIMINISH LATER TONIGHT AS THE
UPPER-LEVEL TROUGH EXITS FURTHER NORTHEAST OUT OF OUR FORECAST AREA.
POST-FRONTAL SHOWERS WILL CONTINUE THIS AFTERNOON INTO THE EARLY
EVENING HOURS AND THE BREEZY WIND CONDITIONS SHOULD DIE DOWN AND
BECOME MORE LIGHT BY EARLY SATURDAY MORNING. DETERMINISTIC AND
ENSEMBLE GUIDANCE CONTINUE TO BE IN GOOD AGREEMENT OF A WEAK BROAD
SHORTWAVE DEVELOPING OFFSHORE THE PACNW ALONG THE CALIFORNIA COAST
SATURDAY MORNING, THEN GLIDING THROUGH THE AREA OVER SUNDAY
(CONFIDENCE 75-80%). ALTHOUGH PROBABILISTIC GUIDANCE DEPICTS SOME
VORTICITY ADVECTION ALOFT ASSOCIATED WITH THE UPPER-LEVEL TROUGH,
THERE DOESN'T SEEM TO BE EFFICIENT MOISTURE AND LOW-LEVEL JET
FLOW FAVORING THE DEVELOPMENT OF PRECIPITATION FOR OUR AREA
(CONFIDENCE 50-60%).
MODEL GUIDANCE CONTINUES TO SUPPORT BELOW NORMAL TEMPERATURES THIS
WEEKEND ACROSS THE REGION, WITH AFTERNOON HIGH IN THE LOW-MID 60S
SATURDAY AND HIGH 60S TO LOW 70S SUNDAY. PER HIRES MODELS, THERE IS
A LOW CHANCE FOR FREEZING TEMPERATURES IN AND NEAR WALLOWA VALLEY,
BUT LOOKS TO BE CONFINED TO THE WALLOWA MOUNTAINS(CONFIDENCE 15-
20%).
FOR MONDAY, PROBABILISTIC GUIDANCE IS IN GOOD AGREEMENT THAT MOSTLY
ZONAL FLOW WILL RETURN OVER THE PACNW BRINGING DRY AND LIGHT WIND
CONDITIONS TO THE FORECAST AREA. WHILE AN UPPER-LEVEL TROUGH AND
ATTENDANT LOW-PRESSURE SYSTEM DEVELOPS IN ALASKA AND NORTHERN
BRITISH COLUMBIA WHICH, PER MODEL GUIDANCE, SHOULD STAY MORE
NORTHWEST OF THE PACNW. ALONG WITH THIS TROUGH IS SOME EMBEDDED
SHORTWAVES WHICH MIGHT BRING PRECIPITATION CHANCES TUESDAY AS IT
SHIFTS SOUTHEASTWARD(CONFIDENCE 65-80%). AMES/01
TUESDAY THROUGH THURSDAY: MODELS SHOW THE SYNOPTIC PATTERN TO
BE IN A MORE ZONAL FLOW REGIME. A SHORTWAVE WILL MOVE THROUGH
THE ZONAL FLOW BRINGING MOUNTAIN SHOWERS AND BREEZY CONDITIONS
TUESDAY. 60-80% OF THE RAW NBM ENSEMBLES SHOW THERE TO BE A
60-80% CHANCE OF ANOTHER 0.10-0.25 INCHES OF RAIN ALONG THE
CENTRAL WA CASCADES TUESDAY. NOT ONLY WILL THERE BE MOUNTAIN
RAIN, BUT MODELS SHOW A SLIGHT TIGHTENING OF THE PRESSURE
GRADIENTS AT THE SURFACE. THIS WILL BRING BREEZY CONDITIONS
THROUGH THE COLUMBIA GORGE AS WELL AS ALONG THE FOOTHILLS OF THE
SOUTHERN BLUES. NBM RAW ENSEMBLES SHOW A 60-70% PROBABILITY OF
SEEING SUSTAINED WINDS NEAR 15 MPH WITH GUSTS TO NEAR 30 MPH.
WEDNESDAY MODELS SHOW THE POTENTIAL FOR SOME LINGERING SHOWERS ALONG
THE CASCADES BEFORE THE SYNOPTIC PATTERN BEGINS TO SHIFT BY
WEDNESDAY AFTERNOON. 40-60% OF THE NBM RAW ENSEMBLES SHOW AN
ADDITIONAL 0.05-0.10 INCHES OF RAIN THROUGH WEDNESDAY AFTERNOON. BY
WEDNESDAY AFTERNOON, MODELS SHOW THE LEADING EDGE OF THE NEXT SYSTEM
BEGINNING TO DIG SOUTHWARDS INTO THE REGION. HOWEVER, THE MODELS
BEGIN TO DIFFER IN WHAT THAT SYSTEM WILL ULTIMATELY BE. EURO REMAINS
WITH ZONAL FLOW THROUGH THURSDAY WHILE THE GFS BRINGS IN THE LEADING
EDGE OF A TROUGH. EITHER SOLUTION SHOWS TEMPERATURES TO BE AT OR
SLIGHTLY BELOW NORMAL WITH COOLER TEMPERATURES THROUGH THURSDAY AND
DRY CONDITIONS. 90
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
VFR CONDITIONS PREVAIL. WINDS ARE STILL GUSTY BUT WINDS ARE
TRENDING DOWN OVERALL THOUGHOUT THE REGION. AN OCCATIONAL GUST
IN THE HIGHER ELEVATIONS CANNOT BE RULED OUT. TOMORROW WINDS
SHOULD BE RELATIVELY CALM WITH SPEEDS UNDER 10 KTS WITH LITTLE
TO NO IMPACTFUL GUSTS FORECASTED AT THIS TIME.
KPSC IS URRENTLY UNDER A AIRPORT WEATHER WARNING UNTILL 5PM
PDT. HIGHEST WINDS SO FAR AROUND 51 MPH/44 KTS
PRELIMINARY POINT TEMPS/POPS
PDT 39 64 37 65 / 0 0 0 0
ALW 45 65 42 66 / 0 0 0 0
PSC 42 68 41 71 / 0 0 0
0
YKM 40 64 41 67 / 0 0 0 0
HRI 42 67 40 69 / 0 0 0 0
ELN 36 60 36 63 / 10 0 0 0
RDM 32 63 33 63 / 0 0 0 0
LGD 37 64 38 68 / 0 0 0 0
GCD 37 67 40 70 / 0 0 0 0
DLS 45 68 45 71 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR WAZ024-027>029-
521.
OR...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR ORZ041-044-507-
508-510.
WIND ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR ORZ511.
DISCUSSION...01/90
AVIATION...18
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