544
FXUS66 KPDT 230928
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
ISSUED BY NATIONAL WEATHER SERVICE SPOKANE WA
228 AM PDT WED APR 23 2025
SHORT TERM...TODAY THROUGH FRIDAY
KEY POINTS
1. DRY AND WARM TEMPERATURES THROUGH THURSDAY
2. PRECIPITATION TO RETURN TO REGION THURSDAY AFTERNOON THROUGH
FRIDAY.
CURRENT NIGHTTIME SATELLITE SHOWS LITTLE TO NO CLOUDS OVER THE
REGION TONIGHT. THERE WILL BE A SLIGHT PATTERN SHIFT AS AN UPPER
LEVEL TROUGH WILL CONTINUE TO SWING TOWARDS THE REGION BEFORE
SHIFTING SOUTHWARD AND UNDERCUTTING THE REGION. THIS WILL ALLOW
FOR SOME WRAP AROUND MOISTURE TO PUSH INTO THE REGION FROM THE
SOUTH. HOWEVER, MODELS DO SHOW THE INFLUENCE OF THE SYSTEM TO BE
WEAK. THIS WILL STILL ALLOW SOME PRECIPITATION TO RETURN TO THE
OR CASCADES AND PORTIONS OF THE EASTERN MOUNTAINS BEFORE BECOMING
WIDESPREAD BY FRIDAY.
DRY AND WARM CONDITIONS WILL CONTINUE THROUGH TODAY AND MUCH OF
THURSDAY AHEAD OF THE WEAK PATTERN SHIFT. MODELS SHOW THE REGION
TO CONTINUE TO BE UNDER THE INFLUENCE NORTHWESTERLY FLOW ALOFT AS
AN UPPER LEVEL TROUGH CONTINUES TO PUSH TOWARDS THE REGION.
TEMPERATURES WILL CONTINUE TO BE WARM EVEN UNDER THE INFLUENCE OF
THE LOW AS WARM AIR ADVECTION PUSHES WARM AIR FROM THE SOUTH INTO
THE REGION. 70-80% OF THE RAW ENSEMBLES SHOW TEMPERATURES TODAY
TO BE IN THE MID TO UPPER 60S THROUGH THE BASIN, GORGE, YAKIMA
VALLEY AND PORTIONS OF THE FOOTHILLS OF THE NORTHERN BLUES WHILE
CENTRAL/NORTH CENTRAL OR, KITTITAS VALLEY AND THE FOOTHILLS OF
THE SOUTHERN BLUES WILL SEE LOW TO MID 60S. THURSDAY 60-80% OF THE
RAW ENSEMBLES SHOW TEMPERATURES IN THE LOWER ELEVATIONS SEEING
UPPER 60S TO LOW 70S WHILE THE MID ELEVATIONS LIKE CENTRAL OR
SEEING MID 60S. FRIDAY TEMPERATURES ARE EXPECTED TO INCREASE A FEW
DEGREES LEAVING 40-60% OF THE RAW ENSEMBLES SHOWING THE BASIN
COULD SEE TEMPERATURES IN THE MID TO HIGH 70S, 30-60% SHOWS THE
FOOTHILLS OF THE S & N BLUES WILL SEE UPPER 60S TO LOW 70S AND
50-80% SHOW N CENTRAL/CENTRAL OR WILL SEE THE MID TO HIGH 60S.
AS FOR THE PRECIPITATION, MODELS SHOW THE UPPER LEVEL SYSTEM TO
BEGIN AS A TROUGH AS IT CONTINUES TO SLIP SOUTHWARD. THE LEADING
EDGE OF THE SYSTEM WILL ALLOW FOR SOME PRECIPITATION TO MAKE ITS
WAY ACROSS THE FAR SOUTHERN PORTION OF THE CASCADES IN THE CWA
WITH 30-50% OF THE RAW ENSEMBLES ONLY SHOWING 0.01 INCHES OF RAIN
TO BEGIN THURSDAY EVENING. BY FRIDAY MODELS SHOW THE UPPER LEVEL
SYSTEM TO BECOME A BIT MORE OF A CLOSED LOW AND IT WILL MOVE A BIT
FARTHER SOUTHEAST UNDERCUTTING THE REGION. THIS WILL ALLOW FOR
THE WRAP AROUND MOISTURE TO BEGIN TO INFLUENCE THE EASTERN
MOUNTAINS AND STEADILY MOVE NORTHWARD WITH THE PRECIPITATION. 80%
OF THE RAW ENSEMBLES SHOW 0.01 INCHES OF PRECIPITATION THROUGH
CENTRAL OR AND THE EASTERN MOUNTAINS, 30-50% FOR 0,01 INCHES ALONG
THE FOOTHILLS OF THE N & S BLUES, 30-50% FOR THE WA CASCADES AND
LESS THAN 30% FOR THE BASIN.
LONG TERM...SATURDAY THROUGH WEDNESDAY
ENSEMBLE GUIDANCE IN
PRETTY GOOD AGREEMENT ON THE SYNOPTIC PATTERN THROUGH THE PERIOD.
MAIN STORY CONTINUES TO BE A BROAD CUTOFF LOW THAT WILL PASS TO
OUR SOUTH, FOLLOWED BY A WARMING TREND HEADING INTO NEXT WORK WEEK
AS HIGH PRESSURE BUILDS IN OVERHEAD. AS MODELS CONTINUE TO BRING
THIS CUTOFF LOW TO OUR SOUTH, THE PRECIP FORECAST CONTINUES TO
TREND DOWNWARD. AS A RESULT, THINKING THAT THE GREATEST IMPACT
FROM THIS SYSTEM WILL BE GUSTY WINDS, ESPECIALLY ACROSS THE
CASCADE GAPS, FOOTHILLS OF THE BLUES, AND THE GRANDE RONDE VALLEY.
THE CENTER OF THIS SYSTEM WILL ALREADY BE TO OUR SOUTH BY SATURDAY MORNING,
WITH MOST MODELS PINNING IT AROUND THE CENTRAL SIERRA NEVADA RANGE. THIS IS
NOT A PARTICULARLY IDEAL SETUP FOR ONSHORE MOISTURE ADVECTION INTO OUR
FORECAST AREA, BUT GIVEN THIS SYSTEM’S SLOW PROGRESSION, WRAPAROUND
MOISTURE WILL MAKE FOR PERSISTENT POPS ACROSS THE OREGON CASCADES AND
EASTERN MOUNTAINS, WITH THE WETTEST DAY ON SATURDAY. STILL, NBM
PROBABILISTIC GUIDANCE IS ONLY SUGGESTING ABOUT A 40-50% CHANCE FOR QPF
OVER A QUARTER OF AN INCH FOR THE EASTERN MOUNTAINS AND AROUND A 70-80% FOR
THE CASCADE CRESTS ACROSS CENTRAL OREGON. NOT A PARTICULARLY IMPRESSIVE
SYSTEM IN TERMS OF PRECIP, BUT THAT IS TO BE EXPECTED WITH THE LOW TAKING A
MORE SOUTHERLY TRACK THAN WHAT MODELS HAD INITIALLY ANTICIPATED. THE CHANCE
FOR THUNDERSTORMS HAS ALSO DECREASED AS FAVORABLE DYNAMICS ONCE AGAIN FALL
TO OUR SOUTH, BUT STILL CANNOT RULE OUT ISOLATED STORMS (20-30% CHANCE)
ACROSS THE EASTERN MOUNTAINS THANKS TO FAVORABLE OROGRAPHIC FLOW VIA
WRAPAROUND MOISTURE.
OTHERWISE, PRECIP CHANCES FALL OFF AFTER SUNDAY ONCE THE SYSTEM FULLY
EXITS THE FORECAST AREA, WITH ENSEMBLE CONSENSUS BEING THAT OF RIDGING
MOVING IN MONDAY ONWARD. AS THIS LOW MOVES IN AND WE TRANSITION BETWEEN
SYSTEMS, EXPECT A COUPLE OF GUSTY DAYS FOR OUR USUAL WIND-PRONE AREAS. IN
FACT, NBM PROBABILISTIC IS ALREADY SUGGESTING A 70-80% CHANCE FOR WIND
GUSTS TO EXCEED 45 MPH ACROSS THE KITTITAS VALLEY, COLUMBIA RIVER
GORGE, AND THE FOOTHILLS OF THE BLUE MOUNTAINS ON SATURDAY AND
SUNDAY AS THIS LOW (AND THE RIDGE TRAILING IT) INVITE A STRONG
CROSS-CASCADE PRESSURE GRADIENT. AND GIVEN HOW MUCH MODELS HAVE US
WARM UP NEXT WEEK (APPROACHING THE 80S ACROSS THE LOWLANDS BY THE
END OF THE PERIOD), WOULD NOT BE SURPRISED IF WE SEE SEVERAL WIND
ADVISORIES OVER THE WEEKEND. EVANS/74
AVIATION...12Z TAFS
VFR CONDITIONS EXPECTED. CLEAR SKIES AND
LIGHT, TERRAIN-DRIVEN WINDS LESS THAN 10 KTS WILL PREVAIL THROUGH
THE PERIOD. EVANS/74
PRELIMINARY POINT TEMPS/POPS
PDT 66 38 71 43 / 0 0 0 0
ALW 66 41 70 47 / 0 0 0 0
PSC 71 37 76 42 / 0 0 0 0
YKM 69 40 73 45 / 0 0 0 0
HRI 70 38 75 42 / 0 0 0 0
ELN 67 39 72 43 / 0 0 0 10
RDM 64 29 71 38 / 0 0 0 20
LGD 62 34 68 39 / 0 0 0 0
GCD 63 33 69 39 / 0 0 0 10
DLS 71 42 76 46 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...90
LONG TERM....74
AVIATION...74
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