621
FXUS66 KPDT 171805
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1105 AM PDT SUN MAY 17 2026
KEY MESSAGES
- PERIODIC LIGHT MOUNTAIN SHOWERS THROUGH TUESDAY
- SLIGHT CHANCE OF ISOLATED THUNDERSTORMS THIS AFTERNOON OVER
NORTHEAST OR MOUNTAINS, WITH LOW CHANCE OVER THE WA CASCADES
- DRY AND WARMING TREND THROUGH THE REMAINDER OF THE WEEK
DISCUSSION
TODAY THROUGH TUESDAY: SATELLITE IMAGERY THIS EARLY MORNING
SHOWS CLOUDY CONDITIONS ACROSS THE OR HALF OF THE FORECAST
AREA, WHILE SCATTERED MID LEVEL CLOUD DECKS ARE ACROSS PORTIONS
OF SOUTHEAST WA. MEANWHILE, RADAR SHOWS WIDELY SCATTERED LIGHT
SHOWERS ACROSS SOUTHEAST WA, WHILE SURFACE OBSERVATIONS INDICATE
SHOWERS ARE IMPACTING PORTIONS OF CENTRAL OR AT THIS TIME.
TODAY, THE UPPER TROUGH OVER THE REGION WILL BE PULLED SOUTH AND
EAST BY A SHORTWAVE DIVING DOWN NORTHERLY FLOW ALOFT. BY MID-
MORNING, SCATTERED SHOWER ACTIVITY WILL BE LIMITED TO THE HIGHER
PEAKS/CRESTS OF THE MOUNTAINS IN NORTHEAST OR, WITH A SLIGHT
CHANCE (15-20%) OF ISOLATED THUNDERSTORMS FORMING IN THIS AREA
BY THE EARLY AFTERNOON. THERE IS A LOW CHANCE (~10%) THAT AN
ISOLATED SHOWER/THUNDERSTORM MAY DEVELOP ALONG THE WA CASCADE
CREST THIS AFTERNOON.
MONDAY INTO TUESDAY, THE PACNW WILL COME UNDER THE INFLUENCE OF
AN UPPER RIDGE DEVELOPING OFFSHORE, WITH THE REGION UNDER A
NORTHWEST FLOW ALOFT. WEAK SHORTWAVES WILL SLIDE DOWN THE
NORTHWESTERLY FLOW ALOFT BOTH DAYS, WHICH WILL BRING SLIGHT
CHANCES (10-15%) OF SHOWERS TO THE WA CASCADES, BLUES AND
WALLOWAS. OTHERWISE, THE REMAINDER OF THE FORECAST AREA WILL
REMAIN DRY WITH A GRADUAL WARMING TREND, AND DIURNALLY DRIVEN
WEST TO NORTHWEST WINDS THROUGH THE CASCADE GAPS.
WEDNESDAY THROUGH SATURDAY: THERE REMAINS GOOD AGREEMENT AMONGST
ENSEMBLE CLUSTER GUIDANCE IN THE REGION REMAINING UNDER THE
INFLUENCE OF THE UPPER RIDGE OFFSHORE THROUGH THURSDAY
AFTERNOON. ANOTHER SHORTWAVE TROUGH IS ADVERTISED TO SLIDE DOWN
NORTHWESTERLY FLOW THURSDAY EVENING THROUGH FRIDAY MORNING,
PRODUCING SLIGHT CHANCES (10-20%) OF MOUNTAIN SHOWERS. AFTER THE
TROUGH EXIT FRIDAY MORNING, THE FORECAST AREA WILL COME UNDER
THE INFLUENCE OF THE UPPER RIDGE OFFSHORE, RETURNING TO DRY
CONDITIONS THAT WILL PERSIST INTO SATURDAY.
OTHERWISE, DIURNALLY DRIVEN BREEZY WINDS THROUGH THE CASCADE
GAPS WILL CONTINUE, WITH STRONGEST WINDS OVERLAPPING WITH THE
TROUGH PASSAGE THURSDAY. A GRADUAL WARMING TREND IN THE LOWER
ELEVATIONS WILL RESULT IN A RETURN OF AFTERNOON TEMPERATURES IN
THE UPPER 70S TO MID 80S BY THURSDAY. CONFIDENCE IN THE
FORECAST DURING THIS PERIOD IS MODERATE (55-65%). LAWHORN/82
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
VFR CONDITIONS ARE FORECAST AT ALL SITES FOR THE NEXT 24 HRS.
SOME LOW STRATOCUMULUS (2.5-3KFT) THIS MORNING IN THE VICINITY
OF BDN/RDM/ALW PRESENTS THE BEST CHANCE OF TEMPORARY MVFR CIGS.
WINDS WILL BE GUSTY FOR THE REMAINDER OF THIS MORNING INTO THE
EVENING HOURS, WITH STRONGEST WINDS OF 12-17 KTS ACCOMPANIED BY
GUSTS OF 20-25 KTS FORECAST AT DLS/RDM/BDN/YKM. ELSEWHERE,
SUSTAINED WINDS OF 12KTS OR LESS ARE FORECAST, AND HAVE OMITTED
A MENTION OF GUSTS SINCE GUSTS ARE ANTICIPATED TO REMAIN IN THE
RANGE OF 12-18 KTS.
VERY LOW CHANCES (5-10 PERCENT) OF RAIN SHOWERS ARE FORECAST FOR
YKM/PSC/ALW/PDT LATER THIS AFTERNOON AND EVENING.
SOME HIGH CLOUD IS FORECAST TO OVERSPREAD THE REGION BY LATER
THIS EVENING AND MONDAY MORNING.
PRELIMINARY POINT TEMPS/POPS
PDT 64 39 69 42 / 0 0 0 0
ALW 63 43 69 46 / 0 0 0 0
PSC 71 42 75 45 / 0 0 0 0
YKM 71 42 74 44 / 0 0 0 0
HRI 69 41 73 44 / 0 0 0 0
ELN 65 39 68 40 / 0 10 10 10
RDM 60 29 68 31 / 0 0 0 0
LGD 55 33 64 36 / 10 0 0 0
GCD 55 30 65 34 / 20 0 0 0
DLS 68 44 73 45 / 0 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...82
AVIATION...86
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