225
FXUS66 KPDT 092211
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
311 PM PDT FRI OCT 9 2026
.UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- BREEZY TO WINDY WESTERLY WINDS ACCOMPANIED BY PATCHY BLOWING
DUST THIS AFTERNOON AND EVENING. WIND ADVISORY IN EFFECT FOR
KITTITAS VALLEY.
- NEAR- TO SUB-FREEZING MORNING TEMPERATURES SATURDAY ACROSS
MUCH OF THE REGION. FREEZE WARNINGS IN EFFECT FOR CENTRAL
OREGON AND WALLOWA VALLEY.
- WIDESPREAD NEAR- TO SUB-FREEZING MORNING TEMPERATURES CONTINUE
EARLY NEXT WEEK ACROSS THE LOWER ELEVATIONS.
DISCUSSION
SATELLITE IMAGERY SHOWS NOTABLE TROUGHING OVER THE PACIFIC
NORTHWEST REGION THIS AFTERNOON: AN UPPER-LEVEL CLOSED LOW IS
CENTERED OVER EASTERN BRITISH COLUMBIA; MEANWHILE, A SECOND
VORTICITY MAXIMUM IS DIVING SOUTHWARD ALONG THE ALASKA PANHANDLE
AND NORTHWEST BRITISH COLUMBIA. A COLD FRONT IS DRAPED ACROSS
OUR FORECAST AREA, AND WIDESPREAD BREEZY TO WINDY WESTERLY WINDS
ARE PRESENT AT THE SURFACE. MOST AREAS HAVE OBSERVED SUB-
ADVISORY WINDS IN THE 15-25 MPH RANGE WITH GUSTS OF 30-40 MPH.
HOWEVER, ESPECIALLY WIND-PRONE LOCATIONS ACROSS THE COLUMBIA
PLATEAU WILL CONTINUE TO SEE SUSTAINED WINDS OF 25-35 MPH WITH
GUSTS OF 40-55 MPH INTO THIS EVENING (80% CONFIDENCE). OPTED
TO ISSUE A WIND ADVISORY FOR THE KITTITAS VALLEY, VALID THROUGH
9 PM PDT THIS EVENING, WHERE ADVISORY-LEVEL WINDS HAVE BEEN MOST
WIDESPREAD. PATCHY TO LOCALIZED AREAS OF BLOWING DUST HAVE BEEN
OBSERVED ACROSS THE COLUMBIA PLATEAU FROM LATE THIS MORNING
THROUGH EARLY AFTERNOON, AND WILL LIKELY CONTINUE INTO THIS
EVENING (80% CONFIDENCE). HAVE ISSUED A SPECIAL WEATHER
STATEMENT FOR THE THREAT OF BLOWING DUST, BUT AREAL COVERAGE AND
INTENSITY OF VISIBILITY DROPS THUS FAR HAS BEEN TOO LOW TO
WARRANT A BLOWING DUST ADVISORY.
THE COLD FRONTAL PASSAGE WILL BE DRY FOR MOST AREAS, WITH LOW-
MEDIUM (20-50%) CHANCES OF A WETTING RAIN (0.10") FOR THE
NORTHERN BLUE MOUNTAINS AND OREGON CASCADES. ELSEWHERE, A
WETTING RAIN HAS ALREADY OCCURRED THIS MORNING INTO EARLY
AFTERNOON IN THE WASHINGTON CASCADES.
A COLDER, DRY AIR MASS (PWATS OF 0.4" OR LESS) IS FORECAST IN
THE WAKE OF THIS AFTERNOON'S COLD FRONTAL PASSAGE, WHICH WILL
LEAD TO SOME POTENTIAL FOR OVERNIGHT FREEZING TEMPERATURES.
CONFIDENCE IN AREAS OR WIDESPREAD NEAR- OR SUB-FREEZING
TEMPERATURES IS HIGHEST (70-90%) FOR CENTRAL OREGON AND WALLOWA
VALLEY; FREEZE WARNINGS ARE IN EFFECT FOR THOSE ZONES.
ELSEWHERE, CONFIDENCE IN SUB-FREEZING TEMPERATURES IS MEDIUM
(40-70%) IN THE GRANDE RONDE VALLEY, JUST A BIT TOO LOW TO ISSUE
A WARNING. IN THE COLUMBIA BASIN AND SURROUNDING VALLEYS,
CONFIDENCE IN REACHING FREEZING TEMPERATURES IS LOW (5-30%),
HIGHEST FOR THE KITTITAS AND YAKIMA VALLEYS WHERE SKIES ARE
EXPECTED TO BE MOSTLY CLEAR OVERNIGHT. ON THE SUBJECT OF CLOUD
COVER, LINGERING CLOUDS AND NORTHWEST WINDS ARE THE TWO
VARIABLES THAT HAVE THE POTENTIAL TO SPOIL THE FORECAST
OVERNIGHT FREEZE IN NORTHEAST OREGON.
THE AFOREMENTIONED UPPER-LEVEL SYSTEMS ARE EXPECTED (99%
CONFIDENCE) TO TRACK SOUTHWARD OVER THE PACIFIC NORTHWEST
SATURDAY THROUGH SUNDAY, FACILITATING ADDITIONAL COLD AIR
ADVECTION INTO THE REGION. WHILE LINGERING CLOUD COVER AND
BREEZY NORTH TO NORTHEAST WINDS ASSOCIATED WITH THE LOW-
PRESSURE SYSTEM REMAIN SOURCES OF UNCERTAINTY, THE REGION WILL
SEE CONTINUED CHANCES OF NEAR- OR SUB-FREEZING MORNING LOWS
SUNDAY. DUE TO FORECAST LIGHTER WINDS AND MOSTLY CLEAR TO CLEAR
SKIES, THE BEST CHANCE OF WIDESPREAD FREEZING MORNING LOWS FOR
THE LOWER ELEVATIONS IS MONDAY AND TUESDAY MORNINGS, AND
ADDITIONAL FREEZE WATCHES OR WARNINGS MAY BE ISSUED IN THE
COMING DAYS.
WARMER, MOSTLY DRY CONDITIONS ARE THEN FORECAST BY MID-WEEK AS
ENSEMBLE GUIDANCE INDICATES AN UPPER-LEVEL RIDGE WILL LIKELY
DEFLECT ANY NOTABLE WEATHER SYSTEMS TO THE NORTH (60-80%
CHANCE).
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
VFR CONDITIONS THROUGHOUT ALL SITES, WHICH IS HIGHLY LIKELY (GREATER
THAN 70%) TO CONTINUE THROUGH THE TAF PERIOD. REDUCED VISIBILITY
FROM PATCHY BLOWING DUST IS POSSIBLE AT SOME TERMINALS, WITH
THE BEST CHANCE BEING KALW. BREEZY WINDS CURRENTLY OCCURRING
THROUGHOUT MOST SITES, WITH GUSTS OF AROUND 20-35 KNOTS.
WINDS ARE HIGHLY LIKELY (GREATER THAN 70% CHANCE) TO WEAKEN
THROUGHOUT THE TAF PERIOD. THERE'S CURRENTLY MODERATE CONFIDENCE
THAT WINDS WILL TRANSITION TO TYPICAL PATTERNS BY 16Z (30-60%
CHANCE), ALTHOUGH SOME SITES MAY TRANSITION AS EARLY AS AROUND
12Z. CLOUDS ARE ALSO VERY LIKELY TO WEAKEN ALONGSIDE WINDS
(GREATER THAN 70% CHANCE), WITH CLOUDS LIMITED TO AT OR ABOVE 25
KFT AFTER 12Z FOR MOST SITES.
PRELIMINARY POINT TEMPS/POPS
PDT 35 58 33 56 / 20 0 0 10
ALW 39 58 36 57 / 30 0 0 10
PSC 38 63 37 61 / 0 0 0 0
YKM 36 61 39 60 / 0 0 20 0
HRI 38 61 36 60 / 10 0 0 0
ELN 32 54 32 55 / 0 20 30 0
RDM 27 54 24 51 / 0 0 0 20
LGD 31 54 32 51 / 30 0 0 10
GCD 32 55 28 51 / 20 0 0 0
DLS 42 62 40 64 / 0 0 10 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL 9 PM PDT THIS EVENING FOR WAZ026.
OR...FREEZE WARNING FROM 1 AM TO 10 AM PDT SATURDAY FOR ORZ050-511.
DISCUSSION...86
AVIATION...21/75
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