069
FXUS66 KPDT 281716
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1016 AM PDT MON APR 28 2025
.UPDATED AVIATION DISCUSSION.
AVIATION...18Z TAFS
VFR CONDITIONS CURRENTLY AT ALL SITES, WHICH
WILL STAY THE COURSE THROUGH THE PERIOD. THE ONLY EXCEPTION WILL BE
KPDT/KALW WHICH WILL EXPERIENCE MVFR CONDITIONS DUE TO REDUCED
CEILINGS OF 2500FT TUESDAY MORNING. THIS IS IN RESPONSE TO A WEAK
WEATHER SYSTEM THAT WILL ALSO BRING LIGHT MORNING RAIN THE KPDT/KALW
THROUGH THE MORNING HOURS AND BRIEFLY IN THE MORNING FOR KPSC.
BREEZY WINDS WITH GUSTS OF 15-25KTS OVER KPDT/KALW THIS AFTERNOON,
WITH HIGHER GUSTS BETWEEN 25-35KTS FOR KDLS THROUGH THE PERIOD. 75
PREV DISCUSSION
/ISSUED 249 AM PDT MON APR 28 2025/
SHORT TERM...TODAY THROUGH WEDNESDAY...THE STRONGEST OF THE BREEZY
WINDS THAT FLOWED THROUGH THE CASCADE GAPS ON SUNDAY WILL SUBSIDE
THIS MORNING, HOWEVER WITH A PROGRESSIVE SYNOPTIC PATTERN OVERHEAD,
EXPECT GUSTS TO REMAIN ELEVATED IN THE 25-35 MPH RANGE FOR THE GORGE
AND KITTITAS VALLEYS DURING THE DAY BOTH TODAY AND TUESDAY.
NOTICEABLE BREEZES WILL PREVAIL ELSEWHERE IN THE BASIN AND INTO
CENTRAL OREGON DURING THE DAYTIME HOURS AS WELL WITH GUSTS UP TO 25
MPH AT TIMES. OTHERWISE THE WEATHER WILL REMAIN CLEAR AND DRY UNTIL
TUESDAY.
LATE MONDAY OVERNIGHT INTO TUESDAY, AN UPPER-LEVEL WAVE WILL CLIP US
TO OUR NORTHEAST, PROVIDING FOR A CHANCE OF PRECIP FOR MOST OF THE
FORECAST AREA. THIS WAVE HAS TRACKED A BIT MORE SOUTHWARD ACROSS THE
LATEST MODEL RUNS, RESULTING IN AN UPTICK IN THE PRECIP FORECAST,
PRIMARILY FOR THE EASTERN MOUNTAINS. STILL NOT EXPECTING THIS SYSTEM
TO BE A HEAVY-HITTER, BUT NBM PROBABILISTIC GUIDANCE HAS UPPED
PROBABILITIES OF AT LEAST A TENTH OF AN INCH OF LIQUID PRECIP
FALLING OVER THE NORTHERN BLUES UP TO THE 70-80% RANGE, WITH SIMILAR
AMOUNTS OVER THE CRESTS OF THE CASCADES AS WELL. PRECIP IS LESS
IMPRESSIVE ACROSS THE LOWLANDS, HOWEVER, AMOUNTING TO ONLY A FEW
HUNDREDTHS, WITH SHADOWING PREVALENT OVER CENTRAL OREGON AND THE
GORGE, GIVEN THE SYSTEM'S TRACK.
DRY NORTHERLY FLOW THEN BUILDS IN ON WEDNESDAY AHEAD OF A RIDGE SET
TO MOVE OVER THE FORECAST AREA BY THE END OF THE WORK WEEK. WE'LL
SEE A STEADY WARMING TREND ACROSS THE REGION AS A RESULT, WITH HIGHS
WELL INTO THE 80S POSSIBLE AS A WELCOMING GIFT FROM MAY'S ARRIVAL.
EVANS/74
LONG TERM...THURSDAY THROUGH MONDAY...SENSIBLE WEATHER CONCERNS
THROUGH THE EXTENDED FORECAST CONTINUE TO FOCUS ON THE PASSAGE OF
AN UPPER LOW FEATURE FRIDAY THROUGH THE WEEKEND THAT WILL PRODUCE
SHOWERS AND A SLIGHT CHANCE (<25%) OF ISOLATED THUNDERSTORMS AT
TIMES. BREEZY CONDITIONS AND COOLER CONDITIONS WILL ALSO DEVELOP
WITH THE TROUGH PASSAGE OVER THE WEEKEND.
THURSDAY THROUGH EARLY FRIDAY, THE PACNW WILL CONTINUE TO BE UNDER
THE INFLUENCE OF AN UPPER LEVEL RIDGE PASSING OVERHEAD, RESULTING
IN DRY AND WARM CONDITIONS AREA-WIDE. A WARMING TREND UNDER THE
UPPER RIDGE WILL RESULT IN AFTERNOON TEMPERATURES WARMING INTO THE
UPPER 70S TO MID 80S ACROSS THE LOWER ELEVATIONS OF THE FORECAST
AREA THURSDAY AND FRIDAY (CONFIDENCE 75-90%).
THURSDAY NIGHT, ENSEMBLE CLUSTER GUIDANCE REMAINS IN GREAT
AGREEMENT THAT THE UPPER RIDGE WILL BEGIN TO TRAVERSE THE ROCKIES,
WITH AN UPPER LEVEL TROUGH AND COLD FRONT BOUNDARY SWINGING
TOWARDS THE PACNW. THE UPPER TROUGH WILL DEVELOP A SLIGHT NEGATIVE
TILT AS IT APPROACHES THE PACNW COAST FRIDAY MORNING WITH A
LEADING SOUTH-SOUTHWEST FLOW ALOFT. WIDESPREAD SHOWERS WILL
DEVELOP IN THE AFTERNOON FROM SOUTHWEST TO NORTHEAST ACROSS THE
FORECAST AREA AS THE UPPER TROUGH CONTINUES TO APPROACH THE
PACNW(CONFIDENCE 65-75%). THE NEGATIVE TILT AND SOUTHWEST FLOW
ALOFT WILL ALSO LEAD TO INCREASING INSTABILITY ACROSS THE EASTERN
MOUNTAINS AND CENTRAL OR, RESULTING IN SLIGHT CHANCES (15-25%) OF
ISOLATED TO WIDELY SCATTERED THUNDERSTORMS DEVELOPING FRIDAY
AFTERNOON. BREEZY WINDS (GUSTS 25-35MPH) WILL DEVELOP WITH THE
APPROACH AND SUBSEQUENT PASSAGE OF THE COLD FRONT FRIDAY AFTERNOON
INTO THE OVERNIGHT HOURS (CONFIDENCE 65-75%).
LATE FRIDAY NIGHT INTO SUNDAY, THE UPPER TROUGH WILL SLOWLY PUSH
ACROSS THE PACNW, RESULTING IN PERSISTENT RAIN AND HIGH MOUNTAIN
SNOW SHOWERS ACROSS THE CASCADES AND THE EASTERN MOUNTAINS
(CONFIDENCE 60-75%). HOWEVER, AS THE UPPER TROUGH AXIS APPROACHES
THE CASCADE CREST SATURDAY AFTERNOON, RAIN SHOWERS WILL RETREAT TO
THE CASCADES AND EASTERN MOUNTAINS WITH DRY CONDITIONS PERSISTING
IN THE LOWER ELEVATIONS THROUGH SUNDAY (CONFIDENCE 55-70%).
BREEZY WINDS (GUSTS 20-40MPH) THROUGH THE CASCADE GAPS AND INTO
THE COLUMBIA BASIN AND PORTIONS OF NORTH CENTRAL OR WILL PERSIST
INTO SATURDAY AND SUNDAY, WITH THE STRONGEST WINDS EXPECTED
SATURDAY AFTERNOON THROUGH THE KITTITAS VALLEY AND EASTERN
COLUMBIA RIVER GORGE. OVERALL, ENSEMBLE GUIDANCE REMAINS IN GOOD
AGREEMENT WITH PROGRESSION OF THE UPPER TROUGH IN SATURDAY
AFTERNOON, THOUGH SOME DIFFERENCES IN TIMING/STRENGTH BEGIN TO
PRESENT THEMSELVES THE SECOND HALF OF SATURDAY. SATURDAY NIGHT
INTO SUNDAY, THE DISAGREEMENT ONLY GROWS AMONGST ENSEMBLE CLUSTER
MEMBERS, AS 48% OF MEMBERS FAVOR THE TROUGH TRANSITIONING INTO A
CLOSED LOW SATURDAY NIGHT, WITH 39% OF MEMBERS FAVORING THE CLOSED
LOW FORMING SUNDAY AFTERNOON. IN REGARDS TO THE CLOSED LOW,
DISAGREEMENT IS PRESENT ON IT'S POSITION, WITH ENSEMBLE CLUSTER
SOLUTIONS RANGING FROM SOUTHERN CA TO CENTRAL CA/SOUTHERN NV; IN
REGARDS TO IMPACTS, THE FURTHER SOUTH THE CLOSED LOW, THE DRIER
THE CONDITIONS ACROSS THE FORECAST AREA. OVERALL, CONFIDENCE IS
MODERATE (50-60%) THAT SHOWERS WILL CONTINUE OVER THE MOUNTAIN
AREAS SATURDAY NIGHT THROUGH SUNDAY AFTERNOON, WITH BREEZY
CONDITIONS OVER THE LOWER ELEVATIONS.
SUNDAY AFTERNOON INTO MONDAY, CONFIDENCE IS MODERATE (40-50%)
THAT THE UPPER LOW WILL MOVE EAST OF THE REGION, RESULTING IN
MOSTLY DRY CONDITIONS ACROSS THE FORECAST AREA. ENSEMBLE MEMBERS
DO FAVOR VERY LIGHT SHOWERS CONTINUING ACROSS THE CASCADES AND
EASTERN MOUNTAINS THROUGH MONDAY AS SOUTHWEST FLOW ALOFT DEVELOPS
OVER THE PACNW. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 70 48 68 42 / 0 10 70 0
ALW 69 50 67 44 / 0 20 80 0
PSC 75 49 74 41 / 0 10 50 0
YKM 75 49 73 40 / 10 30 10 0
HRI 73 50 72 42 / 0 10 60 0
ELN 67 48 65 41 / 0 30 20 0
RDM 69 41 65 32 / 0 10 20 0
LGD 67 44 60 37 / 0 10 80 0
GCD 68 42 61 36 / 0 10 60 0
DLS 68 50 68 42 / 0 20 20 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...74
LONG TERM....82
AVIATION...75
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