296
FXUS66 KPDT 272152
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
252 PM PDT SUN SEP 27 2026
KEY MESSAGES
- PATCHY FROST/FREEZING TEMPERATURES POSSIBLE IN CENTRAL OREGON
AND KITTITAS VALLEY TONIGHT.
- WARMER HIGH TEMPERATURES THROUGH THE WEEK WITH ZONAL/SPLIT
FLOW ALOFT.
- SHOWERS (50-70% CHANCE) DEVELOPING ALONG THE CASCADES TUESDAY
WITH A SHORTWAVE PASSING THROUGH BRITISH COLOMBIA.
DISCUSSION
RADAR ADVERTISING LIGHT RETURNS ACROSS AS A LOW PRESSURE SYSTEM
CENTERED AROUND NORTHERN CALIFORNIA ADVECTS MOISTURE ACROSS THE
BLUE AND EASTERN MOUNTAINS THROUGH THIS AFTERNOON. THE EXITING
OF THE LOW PRESSURE SYSTEM WILL BRING CALM, CLEAR CONDITIONS
ACROSS THE REGION OVERNIGHT, ALLOWING COOLER LOWS TONIGHT WITH
THE POSSIBILITY OF FREEZING TEMPERATURES IN THE KITTITAS VALLEY,
CENTRAL OREGON, AND OTHER LOW SHELTERED VALLEYS. CONFIDENCE
ISN'T TOO GREAT (ONLY 20-40% CHANCE) THAT FREEZING TEMPERATURES
WILL LINGER IN THESE PARTS LONG ENOUGH TO WARRANT FREEZE
WARNINGS. IT'S POSSIBLE WITH A RE-ASSESSMENT LATER TODAY/TONIGHT
THAT WE MIGHT ISSUE FREEZE WARNINGS FOR ALL OR SOME OF THESE
AREAS BASED ON IF GUIDANCE IS STILL ALIGNED OR NOT. FOR NOW, WE
DECIDED TO HOLD OFF AS OF NOW.
THE LOW WILL CONTINUE TO PUSH OFF TO THE EAST THROUGH THE
REMAINDER OF THE DAY, ALLOWING MORE ZONAL FLOW TO TAKE PLACE AS
A TROUGH DIGS DOWN FROM BRITISH COLOMBIA AND A RIDGE PUSHES EAST
JUST UNDERNEATH IT. THIS SET-UP WILL ALLOW MODERATE TO HEAVY
SHOWERS TO DEVELOP IN THE CASCADE REGION (MOSTLY ON THE
WASHINGTON STATE SIDE) THROUGH TUESDAY, WITH THE MAXIMUM
POTENTIAL LOCATED AROUND SNOQUALMIE. DECENT CHANCE (50-70%)
WE'LL SEE WETTING RAINS AROUND THE SNOQUALMIE AREA WITH QPF'S
ADVERTISING UP TO A HALF AN INCH POSSIBLE THROUGH TUESDAY AND
WEDNESDAY.
AS WE HEAD LATER INTO THE WEEK, GUIDANCE IS IN GOOD AGREEMENT
(80-90% CHANCE) THAT THE RIDGE JUST OFFSHORE WILL CONTINUE TO
PUSH EAST, DROPPING OFF POP'S ON THE LATER HALF OF THE WEEK. THE
RIDGE AXIS WILL AMPLIFY HEADING ONSHORE BRINGING WARMER WEATHER
WITH HIGHS INTO THE LOW TO HIGH 70S THROUGH THE WEEK, WITH
CALMER WINDS. ALTHOUGH TIMING IS A BIT ROUGH WITH GUIDANCE, THE
GENERAL PICTURE IS THE SAME THAT WE'LL BE IN A MOSTLY DRY
PATTERN WITH CALM TO ELEVATED WINDS THROUGH THE WEEK.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
VFR CONDITIONS WILL PERSIST THROUGH THE FORECAST PERIOD. WINDS
WILL BE LIGHT AND VARIABLE THROUGH THE PERIOD WITH MAINLY HIGH
CLOUDS.
PRELIMINARY POINT TEMPS/POPS
PDT 38 71 45 76 / 0 0 0 0
ALW 43 72 52 75 / 0 0 0 0
PSC 37 75 46 77 / 0 0 0 0
YKM 39 73 47 73 / 0 0 0 0
HRI 36 74 48 76 / 0 0 0 0
ELN 31 68 43 65 / 0 0 0 20
RDM 30 71 35 75 / 0 0 0 0
LGD 38 72 39 76 / 0 0 0 0
GCD 37 72 40 76 / 0 0 0 0
DLS 42 75 48 73 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...95
AVIATION...90
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