537
FXUS66 KPDT 252302
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
401 PM PDT SAT APR 25 2026
.UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- NEAR-FREEZING OVERNIGHT/SUNDAY MORNING IN THE COLUMBIA BASIN
AND ALONG THE BLUE MOUNTAIN FOOTHILLS
- SLIGHT CHANCE OF SHOWERS EACH DAY THROUGH TUESDAY, MAINLY
OVER THE MOUNTAINS
- GRADUALLY WARMING TO NEAR OR ABOVE NORMAL THROUGH NEXT WEEK
DISCUSSION
WATER VAPOR IMAGERY SHOWS A COUPLE UPPER-LEVEL LOWS OVER OR NEAR
THE CONUS THIS AFTERNOON. THE MOST IMPRESSIVE LOW IS A DEEP
CLOSED LOW OVER THE CANADIAN PRAIRIES AND NORTHERN GREAT PLAINS.
MEANWHILE, A WEAKER LOW IS LOCATED JUST OFFSHORE OF CENTRAL
CALIFORNIA. A SHORTWAVE TROUGH EMBEDDED WITHIN NORTHERLY FLOW
ALOFT ON THE WEST SIDE OF THE AFOREMENTIONED DEEP CLOSED LOW IS
SLIDING SOUTH OVER THE PACIFIC NORTHWEST. UNDER THE SHORTWAVE,
CLEAR TO PARTLY SKIES ARE PRESENT ACROSS THE LOWER ELEVATIONS,
WHILE THE MOUNTAINS HAVE SEEN SCATTERED TO NUMEROUS CUMULUS
DEVELOP. A FEW ISOLATED SHOWERS ARE EVIDENT WITHIN THE CUMULUS
FIELD, BUT NOT ANTICIPATING ANY ROBUST CONVECTION TODAY GIVEN
THE LACK OF ANY DEEP CAPE PROFILES.
TONIGHT INTO SUNDAY MORNING, THERE IS A LOW-MEDIUM PROBABILITY
OF OBSERVING FREEZING TEMPERATURES AGAIN ACROSS THE COLUMBIA
BASIN AND ALONG THE BLUE MOUNTAIN FOOTHILLS. THE BEST CHANCES
(30-60 PERCENT) LIE IN THE PENDLETON AREA WITH LOWER (20-40
PERCENT) CHANCES EXTENDING OUTWARD ACROSS THE REST OF THE
AFOREMENTIONED REGION INCLUDING THE YAKIMA AND KITTITAS VALLEYS.
GIVEN THAT FORECAST CLOUD COVER FROM CAMS IS IN THE FEW-BKN
RANGE, CONFIDENCE IS A BIT LOWER IN A WIDESPREAD FREEZE COMPARED
TO THIS MORNING WHEN MOSTLY CLEAR TO CLEAR SKIES WERE PRESENT,
AND HAVE HELD OFF ON ISSUING ANY FREEZE HEADLINES. HAVE INCLUDED
A MENTION OF FROST IN THE FORECAST FOR AREAS WITH TEMPERATURES
NEAR OR BELOW FREEZING, THOUGH.
LOOKING AHEAD, ENSEMBLE NWP GUIDANCE IS IN AGREEMENT THAT
ADDITIONAL WEAK SHORTWAVES WILL DIVE SOUTHWARD THROUGH SUNDAY,
PROVIDING ADDITIONAL WEAK FORCING FOR SHOWERS, MAINLY OVER THE
MOUNTAINS WITH LOWER CHANCES (10 PERCENT OR LESS) EXTENDING
ACROSS THE LOWLANDS. FLOW ALOFT LOOKS TO TURN MORE
NORTHWESTERLY BY MONDAY AND TUESDAY, WITH A COUPLE SHORTWAVES
AND WEAK DIURNALLY DRIVEN INSTABILITY (CAPE OF 500 J/KG OR LESS)
PROVIDING IMPETUS FOR ISOLATED TO SCATTERED SHOWERS, MAINLY
OVER THE MOUNTAINS.
WEDNESDAY THROUGH THE REMAINDER OF THE WEEK, ENSEMBLE CLUSTER
ANALYSIS SHOWS 500-HPA HEIGHTS RISING TO NEAR OR ABOVE NORMAL
OVER THE PACIFIC NORTHWEST AND VICINITY, WITH ROUGHLY 80-90
PERCENT OF MEMBERS PLACING DRY CONDITIONS REGION-WIDE. ROUGHLY
HALF OF MEMBERS DO SHOW HINTS OF A TROUGH OR CLOSED LOW MOVING
OVER SOUTHERN CANADA OR THE NORTHERN TIER LATE THURSDAY OR
FRIDAY, BUT CONFIDENCE IN IT PROVIDING PRECIPITATION TO THE
FORECAST AREA IS LOW (10-20 PERCENT). 86
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
VFR CONDITIONS CURRENTLY AT ALL SITES, WHICH WILL STAY THE
COURSE THROUGH THE PERIOD. WINDS WILL STAY LIGHT AND BELOW 10 KTS,
WITH BROKEN CEILINGS OF 25KFT THIS EVENING, DROPPING TO 10-15KFT
FOR KDLS/KYKM/KRDM/KBDN SUNDAY AFTERNOON. 75
PRELIMINARY POINT TEMPS/POPS
PDT 33 62 39 64 / 0 0 10 10
ALW 38 62 42 65 / 0 10 10 20
PSC 36 67 40 70 / 0 0 10 0
YKM 37 67 38 69 / 0 10 10 0
HRI 34 66 40 68 / 0 0 0 0
ELN 33 62 36 62 / 0 10 10 10
RDM 26 59 29 61 / 0 0 0 0
LGD 30 57 33 59 / 0 10 10 40
GCD 28 56 32 58 / 0 10 10 40
DLS 40 69 43 67 / 0 10 10 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...86
AVIATION...75
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