830
FXUS66 KPDT 251750
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1050 AM PDT FRI SEP 25 2026
KEY MESSAGES
- WIDESPREAD RAIN SHOWERS AND BREEZY TO WINDY CONDITIONS WILL
DEVELOP THROUGHOUT TODAY, WITH AN ISOLATED THUNDERSTORM OR TWO
IN THE WASHINGTON CASCADES
- WIND ADVISORIES IN EFFECT TODAY FROM CENTRAL OREGON TO THE
LOWER COLUMBIA BASIN
- DRY CONDITIONS AND LIGHT WINDS RETURN OVER THE WEEKEND, THEN A
RETURN OF PERIODIC LIGHT SHOWERS IN THE CASCADES NEXT WEEK
DISCUSSION
SATELLITE AND RADAR IMAGERY TONIGHT SHOW A
SURFACE LOW AND UPPER TROUGH SWINGING INTO THE PACNW, WITH A
COLD FRONT PUSHING A BAND OF RAIN ACROSS THE CASCADE EAST
SLOPES.
TODAY THROUGH SUNDAY: THE NORTH/SOUTH ORIENTED BAND OF RAIN
LEADING THE COLD FRONT AND SURFACE LOW WILL CONTINUE TO PUSH
EAST THIS MORNING AND EXIT IN THE AFTERNOON. POST FRONTAL
SHOWERS WILL CONTINUE ACROSS THE CASCADE CREST AND EAST SLOPES
THANKS TO SUPPORT FROM THE UPPER TROUGH PASSAGE, BUT WILL
DIMINISH THROUGH THE EVENING HOURS AS THE TROUGH EXITS TO THE
NORTHEAST. THERE REMAINS A WIDESPREAD 60-90% CHANCE OF AT LEAST
MEASURABLE RAIN ACROSS MUCH OF THE FORECAST AREA TODAY, WITH
ONLY A 30-45% CHANCE OF 0.25 INCHES IN THE NORTHERN BLUES AND A
65-95% CHANCE OF 0.5 INCHES ALONG THE CASCADE CREST AND EAST
SLOPES. IN ADDITION TO PRECIPITATION, THE UPPER TROUGH AND
SURFACE LOW PASSAGE WILL BRING INCREASING WEST TO SOUTHWEST
WINDS ACROSS THE FORECAST AREA. WINDS WILL BE 25-35 MPH WITH
GUSTS 35-50 MPH THROUGH THE CASCADE GAPS, CENTRAL OR, AND INTO
THE COLUMBIA BASIN AND ADJACENT FOOTHILLS/VALLEYS. WINDS 15-25
MPH AND GUSTS UP TO 35 MPH ARE EXPECTED IN MOST OTHER LOCATIONS,
WITH STRONGER WINDS ALONG THE CASCADE CREST. SURFACE WINDS WILL
BE SUPPORTED BY A 40-50KT LOW LEVEL JET THAT WILL MIX DOWN
ACROSS PORTIONS OF THE COLUMBIA BASIN THIS AFTERNOON. WIND
ADVISORIES ARE IN EFFECT ACROSS CENTRAL/NORTH CENTRAL OR,
COLUMBIA BASIN/GORGE, YAKIMA VALLEY, AND THE BLUE MOUNTAIN
FOOTHILLS FROM 8AM TO 11PM TODAY.
SHOWER ACTIVITY AND WINDY CONDITIONS WILL DIMINISH TONIGHT INTO
SATURDAY AS THE UPPER TROUGH AND SURFACE LOW EXIT TO THE
NORTHEAST. DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUE TO
DEPICT WEAK BROAD TROUGHING DEVELOPING OFFSHORE THE PACNW
SATURDAY, THEN SLIDING ACROSS THE REGION THROUGH SUNDAY. THE
TROUGH PASSAGE WILL LACK MOISTURE AND MID TO UPPER LEVEL JET
SUPPORT, RESULTING IN DRY CONDITIONS WITH LIGHT WINDS. IT WILL
HOWEVER CONTINUE TO SUPPORT BELOW NORMAL TEMPERATURES ACROSS THE
REGION, WITH AFTERNOON HIGHS IN THE 60S. WHILE WIDESPREAD
OVERNIGHT FREEZING TEMPERATURES (OUTSIDE OF THE MOUNTAIN ZONES)
ARE NOT EXPECTED TO DEVELOP, AREAS OF THE WALLOWA VALLEY AND
CENTRAL OR WILL SEE A 25-65% CHANCE OF FREEZING MORNING
TEMPERATURES SATURDAY. THE MAKE OR BREAK FOR FREEZING
TEMPERATURES WILL BE CLOUD COVER IN THE OVERNIGHT AND EARLY
MORNING HOURS, THOUGH CONFIDENCE IS LOW (25-35%) IN EXTENT OF
CLOUD COVER FOR TOMORROW MORNING.
MONDAY THROUGH THURSDAY: ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT
OF MOSTLY ZONAL FLOW DEVELOPING OVER THE PACNW AS AN UPPER
TROUGH DEVELOPS OVER AK AND NORTHERN BC AND RIDGING OUT IN THE
EASTERN PACIFIC THROUGH TUESDAY. WHILE MONDAY WILL REMAIN MOSTLY
DRY, ENSEMBLE CLUSTER SOLUTIONS HINT AT A SHORTWAVE AND
ATTENDANT WEAK FRONTAL PASSAGE BRINGING LIGHT RAIN SHOWERS TO
THE CASCADE CREST AND EAST SLOPES THROUGHOUT TUESDAY, THOUGH
ABOUT 30-45% OF CLUSTER MEMBERS BRING LIGHT RAIN TO THE NORTHERN
BLUES LATTER HALF OF TUESDAY. WINDS ARE FAVORED TO REMAIN LIGHT
TO LOCALLY BREEZY WITH THE SYSTEM PASSAGE TUESDAY (CONFIDENCE
60-65%).
DISAGREEMENT GROWS AMONGST ENSEMBLE MEMBERS MID WEEK IN THE
EVOLUTION OF THE SYNOPTIC PATTERN. SOLUTIONS RANGE FROM RIDGING
WEDNESDAY THEN UPPER TROUGH PASSAGE THURSDAY TO SLOW MOVING
TROUGHING WEDNESDAY INTO THURSDAY. EITHER SOLUTIONS WOULD FAVOR
MORE MOUNTAIN PRECIPITATION, BUT WITH PLENTY OF DISAGREEMENT
AMONGST THE MEMBERS, CONFIDENCE IS LOW (20-25%) IN EXTENT,
TIMING, AND AMOUNTS OF PRECIPITATION NEXT WEEK.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
VFR CONDITIONS PREVAIL WIDESPREAD WITH HIGH WINDS OVER MUCH OF THE
REGION TODAY WITH ALL TAF SITES WITHIN A GENERAL WIND ADVISORY.
WINDS PEAKING 30-40 KTS, WINDIEST AT KDLS AND KPDT. HOWEVER,
CONFIDENCE IN PEAK GUSTS IS MODERATE (50%) OWING TO DIFFERENCES
BETWEEN RAW AND BIAS CORRECTED GUIDANCE WITH POTENTIAL FOR LOWER
PEAK GUSTS THAN FORECAST. SUB-VFR CEILINGS EXIST IN THE HIGHER
ELEVATIONS WHERE CLOUD BASES ARE INTERSECTING OR LOWER TO THE
SURFACE. WINDS SHOULD BEGIN TO SUBSIDE AROUND 02Z SATURDAY. WIDE
SPREAD RAIN HAS KEPT THE CEILING HEIGHT RELATIVELY LOW
THROUGHOUT MOST OF THE AREA
KPSC: CURRENTLY UNDER A AIRPORT WEATHER WARNING BETWEEN 1700Z AND
1100Z FRIDAY. GUSTS ARE EXPECTED TO BE BETWEEN 38-43KTS.
PRELIMINARY POINT TEMPS/POPS
PDT 69 39 64 37 / 90 0 0 0
ALW 69 45 65 42 / 90 0 0 0
PSC 72 42 68 41 / 80 0 0 0
YKM 65 40 64 41 / 20 0 0 0
HRI 72 42 67 40 / 90 0 0 0
ELN 61 36 60 36 / 60 10 0 0
RDM 59 32 63 33 / 10 0 0 0
LGD 66 37 64 38 / 60 0 0 0
GCD 66 37 67 40 / 60 0 0 0
DLS 66 45 68 45 / 50 10 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR WAZ024-027-521.
WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR WAZ028-029.
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...82
AVIATION...18
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