658
FXUS66 KPDT 271712
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1012 AM PDT SUN APR 27 2025
MORNING UPDATE
A WIND ADVISORY WILL BE IN EFFECT TODAY FOR THE
EASTERN COLUMBIA RIVER GORGE OF OR/WA AND KITTITAS VALLEY FROM 2 PM
TO 11 PM PST WITH GUSTS EXPECTED UP TO 50 MPH AND SUSTAINED WINDS OF
25-35 MPH. UPSTREAM STRONG INVERSION WERE PRESENT AT SLE AND UIL
BASED ON THE 12Z SOUNDINGS WITH A MARINE STRATUS LAYER UNDERNEATH
SHOWN FROM SATELLITE IMAGERY. AND LOOKING AT THE 925 MB WINDS, WE DO
SEE A PEAK OF 39 KTS (ABOUT 45 MPH) OVER THE EASTERN CR GORGE.
TEMPERATURE AND PRESSURE GRADIENTS WILL ALSO STRENGTHEN THROUGH THE
DAY AS WELL. PRIOR TO THIS AFTERNOON, WIND GUSTS MAY REACH TO A
BORDERLINE OF 45 MPH. HOWEVER, CONFIDENCE IN WINDS EXCEEDING TO 45
MPH WILL BE 70-90% WITH THESE FAVORABLE CONDITIONS. FEASTER/97
AVIATION...18Z TAFS
VFR CONDITIONS ARE FORECAST FOR ALL
STIES THROUGH THE VALID PERIOD. BREEZY TO WINDY SOUTHWESTERLY TO
NORTHWESTERLY WINDS (DEPENDING ON SITE) ARE FORECAST THROUGH MUCH OF
THE PERIOD, STRONGEST THIS AFTERNOON AND EVENING. OTHERWISE, MOSTLY
CLEAR SKIES ARE FORECAST TODAY, WITH MEDIUM (60%) CONFIDENCE IN FEW-
SCT CLOUDS AT 7-10 KFT LATE AFTERNOON INTO THE OVERNIGHT HOURS AT
PDT/ALW/PSC/YKM. PLUNKETT/86
PREV DISCUSSION
/ISSUED 245 AM PDT SUN APR 27 2025/
SHORT TERM...TODAY THROUGH TUESDAY
PRECIP CHANCES WILL LARGELY
MOVE OUT OF OUR AREA TODAY AS A CUTOFF LOW TO OUR SOUTH SLOWLY
MEANDERS ITS WAY TOWARD THE ROCKIES. WALLOWA COUNTY MAY GET
CLIPPED BY SOME LINGERING WRAP-AROUND MOISTURE (15-25%) THIS
AFTERNOON, BUT OTHERWISE EXPECT A DRY FORECAST THROUGH MONDAY AS
DRY NORTHERLY FLOW FILTERS INTO THE FORECAST AREA. ON THE BACK END
OF THIS DEPARTING CUTOFF LOW, PRESSURE GRADIENTS WILL TIGHTEN,
MAKING FOR ANOTHER BLUSTERY DAY, ESPECIALLY THROUGH THE CASCADE
GAPS AND FOOTHILLS OF THE BLUE MOUNTAINS. PRESSURE GRADIENTS
AREN'T QUITE WHERE WE'D LIKE TO SEE THEM TO NECESSITATE A WIND
ADVISORY, BUT SHOULD NOTE THAT THE COLUMBIA RIVER GORGE AND
KITTITAS VALLEY ARE EXPECTED TO SEE WIND GUSTS APPROACH AT LEAST
40 MPH AT TIMES THIS AFTERNOON AND EARLY EVENING (60-70%).
CONFIDENCE IS JUST NOT HIGH ENOUGH FOR WINDS TO EXCEED MUCH
FURTHER BEYOND THAT. EXPECT GUSTS IN THE 15-30 MPH RANGE ACROSS
THE REST OF THE FORECAST AREA.
AFTER A QUIET MONDAY, MODELS CLIP US WITH A WEAK SHORTWAVE TO OUR
NORTHWEST AROUND LATE TUESDAY MORNING. MODELS ARE AGGRESSIVE WITH
POPS (WIDESPREAD 30-50%, HIGHER ACROSS THE EASTERN MOUNTAINS), BUT
LESS SO WITH QPF. MUCH OF THIS SYSTEM'S MOISTURE LIES TO OUR
NORTHWEST, SO NOT ANTICIPATING MUCH WITH THIS SYSTEM OUTSIDE OF SOME
LIGHT RAIN SHOWERS, WITH HEAVIEST AMOUNTS OVER THE EASTERN MOUNTAINS
OF OREGON. RIDGING THEN STARTS TO MOVE IN HEADING INTO WEDNESDAY,
KICKING OFF A WARMING TREND HEADING INTO THE START OF MAY.
EVANS/74
LONG TERM...WEDNESDAY THROUGH SUNDAY
SENSIBLE WEATHER CONCERNS
THROUGH THE EXTENDED FORECAST WILL MAINLY INVOLVE THE PASSAGE OF
AN UPPER TROUGH ACROSS THE PACNW FRIDAY INTO THE WEEKEND, WHICH WILL
BRING PERIODS OF RAIN AND HIGH MOUNTAIN SNOW SHOWERS AND A THREAT
OF ISOLATED TO WIDELY SCATTERED THUNDERSTORMS.
THE MID WEEK WILL START WITH UPPER LEVEL RIDGING BUILDING ACROSS
THE PACNW, WITH THE INFLUENCE OF THE RIDGE PERSISTING INTO EARLY
FRIDAY MORNING. UNDER THE UPPER RIDGE, TEMPERATURES WILL
EXPERIENCE A WARMING TREND INTO THE UPPER 70S TO MID 80S ACROSS
THE LOWER ELEVATIONS OF THE FORECAST AREA THURSDAY AFTERNOON
(CONFIDENCE 70-90%). OTHERWISE, A DRY AIRMASS WILL FILTER INTO
THE REGION AND LIGHT WINDS WITH LOCALLY BREEZY AFTERNOONS WILL
PREVAIL UNDERNEATH THE UPPER RIDGE.
THURSDAY NIGHT, ENSEMBLE CLUSTER GUIDANCE IS 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 NEGATIVE TILT AS IT
APPROACHES THE PACNW COAST FRIDAY MORNING WITH A LEADING SOUTH-
SOUTHWEST FLOW ALOFT. WIDESPREAD SHOWERS WILL DEVELOP BY THE
AFTERNOON FROM SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA AS
THE UPPER TROUGH CONTINUES TO APPROACH THE PACNW(CONFIDENCE
60-75%). THE NEGATIVE TILT AND SOUTHWEST FLOW ALOFT WILL ALSO
LEAD TO INCREASING INSTABILITY ACROSS THE EASTERN MOUNTAINS,
RESULTING IN CHANCES (15-30%) OF ISOLATED TO WIDELY SCATTERED
THUNDERSTORMS DEVELOPING FRIDAY AFTERNOON. BREEZY WINDS (GUSTS
25-40MPH) WILL DEVELOP WITH THE APPROACH AND SUBSEQUENT PASSAGE
OF THE COLD FRONT FRIDAY AFTERNOON INTO THE OVERNIGHT HOURS
(CONFIDENCE 65-80%).
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 50-70%). HOWEVER, AS THE UPPER TROUGH AXIS APPROACHES
THE CASCADE CREST SATURDAY AFTERNOON, RAIN SHOWERS ACROSS THE
LOWER ELEVATIONS WILL TAPER OFF WITH DRY CONDITIONS PERSISTING
INTO 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.
OVERALL, ENSEMBLE CLUSTER GUIDANCE IS IN GOOD AGREEMENT WITH THE
PROGRESSION OF THE UPPER TROUGH THROUGH SATURDAY, THOUGH SOME
DIFFERENCES IN TIMING OF THE TROUGH PASSAGE ARE PRESENT AMONGST
MEMBERS. LOOKING AT SUNDAY, DISAGREEMENT DOES INCREASE AMONGST MEMBERS
ON WHEN/WHERE THE UPPER TROUGH TRANSITIONS INTO A CUT-OFF UPPER
LOW IN THE GREAT BASIN, WITH ABOUT 40% OF MEMBERS DEPICTING
SHOWERS PERSISTING INTO SUNDAY AFTERNOON, AND THE REMAINING 60%
PUSHING SHOWERS OUT OF THE FORECAST AREA BY THE AFTERNOON HOURS.
LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 70 43 71 48 / 0 0 0 10
ALW 70 46 69 50 / 0 10 0 20
PSC 78 45 75 49 / 0 0 0 20
YKM 75 45 76 50 / 0 0 0 20
HRI 74 44 74 49 / 0 0 0 10
ELN 69 45 68 47 / 0 0 0 30
RDM 65 32 69 41 / 0 0 0 10
LGD 65 40 67 43 / 10 0 0 10
GCD 66 37 69 41 / 0 0 0 10
DLS 65 44 68 49 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS EVENING
FOR ORZ041.
WA...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS EVENING
FOR WAZ024-026.
MORNING UPDATE...97
SHORT TERM...74
LONG TERM....82
AVIATION...86
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