228
FXUS66 KPDT 162229
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
329 PM PDT SAT MAY 16 2026
KEY MESSAGES
- MOUNTAIN SNOW SHOWERS CONTINUE THROUGH THIS EVENING
- SLIGHT CHANCE OF THUNDERSTORMS THIS AFTERNOON, MAINLY COLUMBIA
BASIN AND BLUE MOUNTAIN FOOTHILLS
- MOSTLY DRY AND WARMING CONDITIONS MONDAY THROUGH FRIDAY
DISCUSSION
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED
ACROSS THE FORECAST AREA TODAY AS THE COMBINATION OF DAYTIME
HEATING AND COOLER TEMPERATURES ALOFT UNDER AN UPPER-LEVEL LOW
HAVE FACILITATED STEEPENING LOW- AND MID-LEVEL LAPSE RATES. BEST
CHANCES (15-25 PERCENT) OF THUNDER WILL BE ACROSS THE LOWER
COLUMBIA BASIN AND ALONG THE BLUE MOUNTAIN FOOTHILLS THIS
AFTERNOON AND EVENING, WITH LOWER (10-15 PERCENT) CHANCES FOR
THE CASCADES AND BLUES OF NORTHEAST OREGON AND FAR SOUTHEAST
WASHINGTON. SMALL HAIL, GUSTY OUTFLOW WINDS, AND CLOUD-TO-GROUND
LIGHTNING CONSTITUTE THE MAIN HAZARDS WITH THUNDERSTORMS TODAY.
LOSS OF DAYTIME HEATING SHOULD PUT A DAMPER ON THE MORE ROBUST
CONVECTION BY LATE EVENING, BUT FORCING FROM A SHORTWAVE
ROUNDING THE BASE OF THE UPPER LOW SHOULD KEEP MOUNTAIN SNOW
SHOWERS GOING INTO THE OVERNIGHT HOURS (80 PERCENT CONFIDENCE).
ADDITIONAL SNOW ACCUMULATIONS OF A TRACE TO SEVERAL INCHES ARE
FORECAST FOR THE CASCADES AND BLUE MOUNTAINS THIS EVENING INTO
THE OVERNIGHT HOURS.
WIDESPREAD BREEZY TO WINDY WESTERLY WINDS THIS AFTERNOON HAVE
FLIRTED WITH ADVISORY CRITERIA FOR PORTIONS OF THE LOWER
COLUMBIA BASIN, EASTERN COLUMBIA RIVER GORGE, AND BLUE MOUNTAIN
FOOTHILLS, BUT CONFIDENCE IN SUSTAINED ADVISORY CRITERIA ACROSS
A BROAD ENOUGH REGION WAS TOO LOW (50 PERCENT) TO WARRANT THE
ISSUANCE OF ANY WIND HEADLINES. WINDS WILL SLACKEN OVERNIGHT.
WHILE NO HEADLINES FOR FREEZING TEMPERATURES HAVE BEEN ISSUED,
THERE IS LOW (10-40 PERCENT) CONFIDENCE IN NEAR- TO SUB-FREEZING
MORNING LOWS IN THE YAKIMA AND KITTITAS VALLEYS, LOWER COLUMBIA
BASIN, AND BLUE MOUNTAIN FOOTHILLS SUNDAY MORNING. ELSEWHERE,
CONFIDENCE IS HIGHER (40-60 PERCENT) FOR THE GRANDE RONDE
VALLEY, SIMCOE HIGHLANDS, AND NORTH-CENTRAL OREGON. HAVE
INCLUDED A MENTION OF FROST IN THE FORECAST FOR THE
AFOREMENTIONED AREAS FOR MESSAGING. SHOULD CLOUD COVER CLEAR
MORE QUICKLY THAN FORECAST THIS EVENING, AND WINDS SLACKEN
EARLIER THAN ANTICIPATED, TEMPERATURES WILL HAVE THE POTENTIAL
TO DROP BELOW WHAT IS FORECAST.
MONDAY THROUGH FRIDAY, WARMING TEMPERATURES AND MOSTLY DRY
CONDITIONS ARE FORECAST REGION-WIDE AS AN UPPER-LEVEL RIDGE OF
HIGH PRESSURE WILL LIKELY (80-90 PERCENT CHANCE) DOMINATE THE
WEATHER. A COUPLE WEAK SHORTWAVES PASSING THROUGH NORTHWESTERLY
FLOW ALOFT MAY FACILITATE SOME SHOWERS FOR THE MOUNTAINS, BUT
POPS ARE LOW (GENERALLY 5-15 PERCENT, EXCEPT 15-25 PERCENT FOR
THE NORTHERN BLUES ON MONDAY). THE ALTERNATE, LESS-LIKELY
SCENARIO (10-15 PERCENT CHANCE PER 12Z ENSEMBLE CLUSTER
ANALYSIS) IS FOR A CLOSED LOW TO DIVE SOUTH FROM CANADA AND
PLACE THE REGION UNDER COOL, SHOWERY WEATHER BETWEEN WEDNESDAY
AND THURSDAY.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
WIDESPREAD SHOWERS AND ISOLATED THUNDER STORMS CONTINUE THROUGH
THE REGION. EXPECTING CONVECTION COVERAGE TO DECREASE AS WE GET
CLOSER TO SUNSET HOURS, SO NOT EXPECTING ANY THUNDERSTORM
IMPACTS AT THE SITES (ALTHOUGH PSC HAS A SMALL 5 TO 15% CHANCE
OF A PASSING STORM THROUGH 03Z). MAJORITY OF THE RAIN WILL MOVE
OUT OF THE AREA BY 03Z, WITH MOSTLY DRY CONDITIONS BY 06Z. SOME
OF THESE SHOWERS CAN BRING GUSTY 20-30 KNOT GUST WITH TEMPORARY
MVFR CONDITIONS DEVELOPING (5 TO 15% CHANCE). VFR CONDITIONS
EXPECTED OVER THE NEXT 24-HOURS, EXCEPT FOR THE SMALL CHANCE
MENTIONED EARLIER.
PRELIMINARY POINT TEMPS/POPS
PDT 36 62 39 69 / 30 10 0 0
ALW 40 62 42 69 / 50 10 0 0
PSC 38 70 41 75 / 20 0 0 0
YKM 37 71 41 74 / 0 0 0 0
HRI 36 68 40 73 / 20 0 0 0
ELN 34 64 38 68 / 0 0 0 0
RDM 26 60 28 68 / 20 0 0 0
LGD 33 54 33 64 / 60 10 0 0
GCD 31 54 31 65 / 60 10 0 0
DLS 39 67 43 73 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
WAZ522.
OR...WINTER WEATHER ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
ORZ509.
DISCUSSION...86
AVIATION...95
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