785
FXUS66 KPDT 182150
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
250 PM PDT SUN OCT 18 2026
KEY MESSAGES
- WARM AND DRY CONDITIONS THROUGH THE NEXT FEW DAYS AS AN UPPER
RIDGE PREVAILS OVER THE REGION.
- COOLER, WETTER PATTERN IN THE MIDWEEK WITH SPLIT FLOW ENTERING
THE REGION.
- LIGHT MOUNTAIN SNOW SHOWERS POSSIBLE MID TO LATE WEEK
(10-20%).
DISCUSSION
SATELLITE AND RADAR INDICATE CLEAR AND DRY CONDITIONS ACROSS THE
REGION AS UPPER LEVEL RIDGE PERSISTS AND CONTINUES TO PUSH TO
THE EAST. HIGH TEMPERATURES WILL CONTINUE TO GET WARMER THROUGH
WEDNESDAY (>90% CHANCE) WITH MAXTS CLIMBING UP TO 10 TO 15
DEGREES ABOVE CLIMATOLOGICAL AVERAGE. THE UPPER RIDGE WILL KEEP
WINDS CALM AND LIGHT WITH JUST DIURNAL DRIVEN SPEEDS THROUGH AT
LEAST MID-WEEK (70-90% CHANCE).
WEATHER BECOMES MORE ACTIVE AS A TROUGH AMPLIFY'S FROM THE GULF
OF ALASKA INTO THE PACIFIC THROUGH THE WEEK. GUIDANCE AND
CLUSTERS ARE IN GOOD AGREEMENT THAT THE TROUGH WILL DIG SOUTH
THROUGH MID-WEEK AND FORM A CUT OFF LOW JUST OFF THE SHORE OF
CALIFORNIA. IT WILL THEN MOVE ONSHORE OF CALIFORNIA (70-80%
CHANCE) THEN CONTINUE TO PUSH OFF INTO THE EAST. CLOSER TO HOME,
ANOTHER SHORTWAVE IS MOVING OFF THE COAST OF BRITISH COLOMBIA
AND INTO THE PACNW REGION THE SAME TIME AS THE CUTOFF LOW IS
MOVING ACROSS CALIFORNIA. THIS SPLIT-FLOW PATTERN WILL BRING
PRECIP CHANCES UP LATE WEDNESDAY INTO THE REST OF THE WEEK
(40-70% CHANCES) WITH IT BEING A MOSTLY RAIN DOMINANT SYSTEM.
CURRENT NBM SNOW LEVEL FORECASTS OVER THE WALLOWA'S LATE
THURSDAY THROUGH EARLY FRIDAY MORNING ADVERTISE 5500 TO 6000
FEET WITH MINIMUM SNOW HEIGHTS AROUND 4500 TO 5000 FEET. A
10-30% CHANCE OF LIGHT MOUNTAIN SNOW SHOWERS EXISTS FOR THIS
SCENARIO, WITH MORE AREAS OF A MIX OF RAIN/SHOW THROUGH THE
WALLOWA'S AND NORTHERN BLUE MOUNTAINS. DEPENDING OF THE STRENGTH
OF THE SHORTWAVE ABOVE WASHINGTON STATE/BRITISH COLOMBIA, A
STRONGER SHORTWAVE COULD BRING LIGHTER SNOW SHOWERS TO A WIDER
COVERAGE, BUT NOT ANTICIPATING ANYTHING GREATER THAN 0.05 INCHES
OF QPF (70-90% CHANCE) WITH DRY PWAT VALUES LESS THAN 0.25
INCHES. LOOKING AT THE POTENTIAL FOR WINDS, TIGHT PRESSURE
GRADIENTS DEVELOPING ACROSS THE AREA WILL BE BRING BREEZY TO
WINDY CONDITIONS ACROSS MUCH OF THE AREA (WITH THE EXCEPTION OF
CENTRAL OREGON). ELEVATED WINDS WITH GUSTS UP TO 30-35 MPH SHOWS
40-70% CHANCES ACROSS THE REGION. UPPING TO WIND ADVISORY
THRESHOLDS (45 MPH GUSTS OR GREATER) SECLUDES CHANCES TO THE
DALLES AND OTHER PARTS OF THE CASCADE GAPS WITH 20-50% CHANCES.
GUIDANCE IS IN GOOD AGREEMENT THE WEATHER SYSTEM WILL PUSH-OFF
FRIDAY WITH DRY CONDITIONS DEVELOPING WITH A SHORT-LIVED RIDGE
ENTERING THE REGION BRINGING SOME TEMPORARY RELIEF BEFORE
ANOTHER SHORTWAVE CROSSES THE REGION SATURDAY. AGREEMENT IS
SHAKY AT BEST GOING INTO THE WEEKEND WITH STRENGTH ALL OVER THE
PLACE, INCLUDING THE IMPACTS TO THE AREA. ACCORDING TO CLUSTERS,
22% BRINGS A MUCH WEAKER SOLUTION WITH A MOSTLY RAIN DOMINANT
SOLUTION, WHILE 50% ADVERTISE A STRONGER SYSTEM WITH STRONGER
COLD AIR ADVECTION. WILL NEED TO MONITOR FOR SNOW AND RAIN
IMPACTS OVER THE NEXT SEVERAL DAYS FOR THIS EVOLVING FORECAST.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
VFR CONDITIONS AND PREDOMINANTLY LIGHT, DIURNALLY AND TERRAIN-
DRIVEN WINDS OF 10 KTS OR LESS ARE EXPECTED (90% CONFIDENCE OR
HIGHER) THROUGH THE PERIOD.
PRELIMINARY POINT TEMPS/POPS
PDT 36 63 36 63 / 0 0 0 0
ALW 41 63 40 64 / 0 0 0 0
PSC 36 65 37 69 / 0 0 0 0
YKM 39 64 39 69 / 0 0 0 0
HRI 36 64 37 66 / 0 0 0 0
ELN 35 61 34 65 / 0 0 0 0
RDM 29 59 29 61 / 0 10 10 0
LGD 39 70 36 68 / 0 0 0 0
GCD 39 71 38 71 / 0 0 0 0
DLS 43 66 42 71 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...95
AVIATION...86
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