701
FXUS66 KPDT 240516
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1016 PM PDT THU APR 23 2026
KEY MESSAGES
- BREEZY WINDS LINGER TODAY.
*WIND ADVISORY ACTIVE*
- COOLING INTO FRIDAY, FREEZING MORNING TEMPERATURES SATURDAY
- LIGHT MOUNTAIN SHOWERS SUNDAY, INCLUDING FOOTHILLS ON MONDAY.
UPDATE
DRY AIR AND WEAK WINDS WILL BRING ABUNDANT RADIATION COOLING TO
BRING FREEZING TEMPERATURES ACROSS PARTS OF THE COLUMBIA BASIN,
NORTHERN BLUE MOUNTAINS, AND KITTITAS VALLEY FRIDAY NIGHT INTO
SATURDAY MORNING.
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY VERY LIGHT RETURNS
ACROSS NORTHERN COLUMBIA AND WALLOWA COUNTIES UNDER MOSTLY CLEAR TO
PARTLY CLOUDY SKIES. THIS IS IN RESPONSE TO AN UPPER LEVEL TROUGH TO
OUR NORTHEAST THAT WILL STRENGTHEN AND EXTEND SOUTH, BRINGING A COLD
FRONT PASSAGE OVERNIGHT TONIGHT BEFORE SLOWLY PUSHING EAST OVER THE
WEEKEND. THE FRONTAL PASSAGE WILL BRING BREEZY WINDS FOR THE
REMAINDER OF THE EVENING, AS WELL AS COOLER TEMPERATURES FRIDAY AS
HIGHS ARE EXPECTED TO PEAK IN THE UPPER 50S TO LOW 60S ACROSS LOWER
ELEVATIONS OF THE COLUMBIA BASIN AND CENTRAL OREGON. CURRENT WIND
GUSTS ACROSS MUCH OF THE AREA ARE BETWEEN 15-25 MPH AND WILL
CONTINUE TO SLOWLY SUBSIDE THROUGH THE REMAINDER OF THE EVENING.
HOWEVER, AREAS ALONG THE EAST SLOPES OF THE WASHINGTON CASCADES,
PRIMARILY THROUGH THE KITTITAS VALLEY, WILL EXPERIENCE MORE
PROLONGED AND HEIGHTENED GUSTS OF BETWEEN 35-45 MPH. THUS, A
WIND ADVISORY HAS BEEN ISSUED ACROSS THE KITTITAS VALLEY UNTIL 9
PM THIS EVENING AS GUSTS OF UP TO 50 MPH WILL BE POSSIBLE.
THE COLD FRONT WILL PASS TO OUR SOUTH ON FRIDAY AS THE UPPER
LEVEL TROUGH CONTINUES TO DIP SOUTH, PROVIDING NORTHERN FLOW
ALOFT. THIS WILL BRING COOLER TEMPERATURES ON FRIDAY UNDER SUNNY
SKIES. THESE CLEAR SKIES WILL PERSIST THROUGH THE DAY AND INTO
SATURDAY, ALLOWING EFFICIENT RADIATIONAL COOLING TO OCCUR AS
SURFACE HIGH PRESSURE SLIDES IN BEHIND THE COLD FRONT. AS A
RESULT, FRIGID MORNING TEMPERATURES ARE EXPECTED AS MORNING LOWS
WILL DIP INTO THE UPPER 20S TO LOW 30S ACROSS THE LOWER COLUMBIA
BASIN AND CENTRAL OREGON. CONFIDENCE IN THESE FREEZING SATURDAY
MORNING TEMPERATURES IS HIGH AS THE NBM ADVERTISES A 70-90%
CHANCE THROUGH CENTRAL OREGON AND UNION COUNTY (BEND, REDMOND,
MADRAS, JOHN DAY), WITH A 40-70% CHANCE OVER THE BLUE MOUNTAIN
FOOTHILLS AND KITTITAS VALLEY (ELLENSBURG, PENDLETON, WALLA
WALLA, HEPPNER, CONDON) OF EXPERIENCING MORNING TEMPERATURES OF
32 DEGREES OR LOWER. THERE IS EVEN A 45-65% CHANCE OF CENTRAL
OREGON AND UNION COUNTY DIPPING INTO THE UPPER 20S SATURDAY
MORNING VIA THE NBM.
THE UPPER LEVEL TROUGH WILL CONTINUE TO DIP SOUTH AS AN
EMBEDDED SHORTWAVE APPROACHES FROM THE NORTHWEST ON SUNDAY,
BRINGING A RETURN TO MOUNTAIN RAIN AND HIGH ELEVATION SNOW
CHANCES TO THE AREA SUNDAY AND MONDAY. THE TROUGH WILL DIP SOUTH
AND TAP INTO SLIGHT MOISTURE SUNDAY TO BRING A 25-35% CHANCE OF
SHOWERS TO THE CASCADES, BLUE MOUNTAINS, AND JOHN DAY HIGHLANDS
SUNDAY, WITH MINIMAL AMOUNTS EXPECTED (<0.05"). THE SHORTWAVE
ARRIVES ON MONDAY TO ENHANCE RAIN CHANCES (30-50%) AND EXTEND
ALONG THE BLUE MOUNTAIN FOOTHILLS AND THE JOHN DAY BASIN
(20-40%). MONDAY'S RAIN AMOUNTS ARE STILL EXPECTED TO BE MINIMAL
AS THE ECWMF AI ENSEMBLE AND GFS ENSEMBLES SHOWCASE
PRECIPITABLE WATER AMOUNTS OF BETWEEN 0.25-0.45" (80-90% OF
NORMAL). RAIN AMOUNTS OVER HIGHER TERRAIN ACROSS THE BLUE
MOUNTAINS AND ELKHORNS MAY REACH A WETTING RAIN (0.10" OR MORE),
BUT LOWER ELEVATIONS ARE LIKELY TO STAY WELL BELOW THAT AMOUNT
WITH VERY LITTLE (LESS THAN 0.02") ALONG THE FOOTHILLS. SNOW
LEVELS WILL HOVER BETWEEN 5000-6000 FEET SUNDAY AND MONDAY.
THE TROUGH BEGINS TO MOVE EAST INTO MONDAY, OPENING THE DOOR TO
A SLOW MOVING UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE
TUESDAY ONWARD. THIS WILL BRING DRY AND WARMING CONDITIONS
ACROSS THE AREA AS HIGH TEMPERATURES REACH INTO THE UPPER 70S TO
LOW 80S THROUGH THE LOWER COLUMBIA BASIN ON FRIDAY. THE NBM
SUGGESTS A 45-60% CHANCE OF HIGH TEMPERATURES REACHING 80
DEGREES OR ABOVE FOR THE TRI-CITIES AREA, YAKIMA, AND THE
DALLES, AND A 20-30% CHANCE FOR WALLA WALLA AND HERMISTON
FRIDAY. CONFIDENCE IN THESE CHANCES ARE RATHER LOW AS ENSEMBLE
MEMBERS STRUGGLE WITH THE STRENGTH OF THE INCOMING SHORTWAVE
THAT ENHANCES SOUTHWEST UPPER LEVEL FLOW TO ADVECT A WARMER
AIRMASS INTO THE REGION LATE IN THE WEEK. CURRENTLY, 51% OF
ENSEMBLE MEMBERS SHOWCASE THE PRESENT RIDGE EFFECTIVELY SHEARING
THE INCOMING SHORTWAVE NORTH VERSUS THE RIDGE SHIFTING EAST AND
BREAKING DOWN AS THE SHORTWAVE PUSHES INLAND EARLIER. EITHER
WAY, THE OVERALL PATTERN ALIGNS WITH WARMING AND DRYING
CONDITIONS THROUGH THE WORKWEEK AFTER LIGHT MOUNTAINS SHOWERS
MONDAY. 75
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
VFR CONDITIONS PREVAIL WITH DRY CONDITIONS PERSISTING. WINDS
WILL BE LIGHT IN GENERAL. STILL A BIT BREEZY IN PDT WITH 20 KNOT
GUSTS GOING THROUGH THE AREA, BUT WILL DECREASE GOING INTO THE
LATER MORNING HOURS. OTHERWISE, NO CIG OR VIS LEVELS EXPECTED TO
DROP BELOW VFR STATUS.
PRELIMINARY POINT TEMPS/POPS
PDT 60 35 55 31 / 10 30 0 0
ALW 60 36 57 35 / 30 40 0 0
PSC 68 37 61 31 / 10 20 0 0
YKM 66 37 61 34 / 0 0 0 0
HRI 66 37 60 31 / 0 20 0 0
ELN 60 33 56 31 / 0 0 0 0
RDM 63 29 57 24 / 0 0 0 0
LGD 54 34 51 28 / 20 60 10 0
GCD 59 33 52 28 / 0 0 0 0
DLS 65 41 63 37 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...FREEZE WARNING FROM MIDNIGHT FRIDAY NIGHT TO 8 AM PDT SATURDAY
FOR WAZ026-028-029.
OR...FREEZE WARNING FROM MIDNIGHT FRIDAY NIGHT TO 8 AM PDT SATURDAY
FOR ORZ044-507.
UPDATE...95
DISCUSSION...75
AVIATION...95
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