429
FXUS66 KPDT 121157
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
457 AM PDT SUN APR 12 2026
KEY MESSAGES
- CHANCES OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TODAY,
ALBEIT CHANCES ARE NOT AS GREAT AS YESTERDAY.
- A SECONDARY SYSTEM WILL CONTINUE THE EXPERIENCED WET PATTERN,
WITH A SHORT DRY BREAK ON TUESDAY.
- COOLING TREND CONTINUES FOR THE NEXT FEW DAYS, BRINGING
TEMPERATURES 5-10 DEGREES BELOW SEASONAL AVERAGE.
DISCUSSION
THE UPPER LEVEL LOW THAT IS ASSOCIATED WITH THE UNSETTLED
WEATHER PATTERN IS AT/NEAR THE NORTHERN CALIFORNIA COAST,
CONTINUING THE WET PATTERN WE'VE EXPERIENCED THE PAST FEW DAYS.
OVERNIGHT RADAR SHOWS LIGHT POP-UP SHOWERS THROUGH THE COLUMBIA
BASIN WITH A MORE WIDESPREAD BAND AREA JUST SOUTHEAST OF THE
REGION IN THE BAKER CITY AREA. GUIDANCE CONTINUES TO SHOW A
LARGE SWATH OF PRECIPITATION WILL CONTINUE TO MOVE NORTH INTO
THE REGION, INCREASING POP CHANCES ACROSS THE REGION BY 50-70%
SUNDAY GOING INTO MONDAY. THIS WILL BE A MORE RAIN DOMINATED
SYSTEM, WITH LIGHT TO MODERATE SNOW FALLING IN THE CASCADE
CREST, AND PARTS OF THE SOUTHERN BLUES.
CHANCES OF THUNDERSTORMS WILL BE GREATEST IN THE EASTERN PART
OF THE REGION, SPECIFICALLY IN THE WALLOWAS IN THE AFTERNOON TO
LATE AFTERNOON HOURS SUNDAY. WHILE THERE'S ENOUGH CAPE (250-500
J/KG) IS AVAILABLE, SUFFICIENT HEATING IS LESS COMPARED TO
YESTERDAY AND HREF ENSEMBLE PAINTBALLS DON'T SUPPORT WIDESPREAD
THUNDERSTORM ACTIVITY. THUS, THUNDERSTORM CHANCES WERE CAPPED AT
15-20 PERCENT CHANCES TO ACCOUNT FOR UNCERTAINTY IN WIDESPREAD
DEVELOPMENT. ANY CONVECTION CHANCES WILL DROP OUT GOING INTO
TUESDAY AS WE GO INTO A QUICK DRY BREAK.
NBM CLUSTERS ARE IN GREAT AGREEMENT THAT THE TROUGH WILL PASS
BY MONDAY, ALLOWING A WEAK RIDGE TO BRING ZONAL FLOW INTO THE
AREA. AFTERWARDS, GENERAL CONSENSUS WILL BRING A TROUGH FROM THE
BRITISH COLUMBIA/GULF OF ALASKA REGION DOWN INTO THE PACNW LATE
TUESDAY/EARLY WEDNESDAY. LOOKING AT CLUSTERS FOR THE TUESDAY
EVENING TIMEFRAME, 100% OF MEMBERS KEEPS THE BASIN/BLUE
MOUNTAINS DRY, BUT 75% WANT TO INTRODUCE LIGHT TO MODERATE SNOW
FALL RATES INTO THE WASHINGTON CASCADES.
CLUSTERS ARE REMAINING IN GOOD AGREEMENT WITH THE SECOND TROUGH
WILL CONTINUE TO BRING MODERATE SNOW FALLS TO THE CASCADES AND
NORTHERN BLUE MOUNTAINS ALONG WITH LIGHT RAIN ACROSS THE VALLEY
THROUGH WEDNESDAY. SNOW TOTAL VIA THE NBM ADVERTISE 7-10" OF
SNOW IN SNOQUALMIE AND OTHER GENERAL PASSES, WHILE DISPLAYING
5-8" IN NORTHERN BLUE MOUNTAINS. CHANCES OF ISSUING AN ADVISORY
IN PARTS OF THE CASCADES AND NORTHERN BLUE MOUNTAINS INCREASE,
BUT WILL BE RE-ASSESED OVER THE NEXT 24-HOURS.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
THE WEATHER SYSTEM ASSOCIATED WITH WET WEATHER OVER THE PAST FEW
DAYS CONTINUES TO BRING LIGHT TO MODERATE RAIN AT THE TAF
SITES. VFR CONDITIONS ARE INITIATING WITH THE 12Z TAFS, BUT WILL
SEE CHANCES OF MVFR CONDITIONS FROM MODERATE RAIN SHOWERS
INCREASE GOING INTO THE LATER MORNING HOURS FOR ALL SITES
(EXCEPT FOR PSC). WINDY CONDITIONS WILL DEVELOP IN DLS AND ALW
IN THE AFTERNOON TO LATE AFTERNOON HOURS THAT WILL PRO-LONG
THROUGH THE REST OF THE 12Z PERIOD.
PRELIMINARY POINT TEMPS/POPS
PDT 58 44 59 38 / 80 80 40 0
ALW 60 46 59 42 / 80 80 50 0
PSC 66 47 68 42 / 50 60 10 0
YKM 67 44 65 37 / 30 20 0 0
HRI 62 45 64 41 / 70 70 20 0
ELN 64 43 56 36 / 20 20 0 0
RDM 52 35 54 29 / 80 70 10 0
LGD 55 41 52 36 / 90 90 70 20
GCD 51 37 51 33 / 90 90 80 10
DLS 62 46 60 42 / 60 50 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...95
AVIATION...95
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