201
FXUS66 KPDT 241152
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
452 AM PDT FRI OCT 24 2025
UPDATED FOR AVIATION
AVIATION
12Z TAFS...VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH THE TAF
PERIOD. -RA IS EXPECTED TO MOVE INTO ALL TAF SITES LATER THIS
AFTERNOON/EVENING. IF THE RAIN IS HEAVY ENOUGH THERE COULD BE
SOME LOCAL MVFR CONDITIONS.
WINDS WILL INCREASE DURING THE AFTERNOON AND EVENING, ESPECIALLY
FOR BDN/RDM WHERE WINDS WILL GUST TO AROUND 30 KTS AND ELSEWHERE
WILL SEE GUSTS IN THE 20 TO 25 KT RANGE.
PREV DISCUSSION
/ISSUED 347 AM PDT FRI OCT 24 2025/
DISCUSSION...TODAY THROUGH MONDAY MORNING: UPPER LEVEL TROUGHING
HAS DEVELOPED OFF THE PACNW COAST TONIGHT, WITH SATELLITE AND
COASTAL RADAR IMAGERY SHOWING A LEADING COLD FRONT JUST OFF THE
OLYMPIC PENINSULA.
THE COLD FRONT WILL PASS OVER THE PACNW THROUGH THIS EVENING, WITH
THE FRONTAL PASSAGE EAST OF THE CASCADE CREST COINCIDING WITH A
SHORTWAVE TROUGH PIVOTING AROUND THE PARENT TROUGH THIS AFTERNOON
AND EVENING TODAY. MODERATE TO HEAVY RAIN AND HIGH ELEVATION SNOW
WILL DEVELOP ACROSS THE MOUNTAINS TODAY, WHILE THE LIGHT TO
MODERATE RAINFALL IN THE LOWER ELEVATIONS WILL BE ASSOCIATED WITH
THE FRONTAL BOUNDARY PASSAGE THROUGH THIS EVENING. BESIDES
INCREASING PRECIPITATION CHANCES, THE LOWER ELEVATIONS WILL SEE
BREEZY TO WINDY SOUTH/SOUTHWEST WINDS DEVELOPING WITH AND BEHIND
THE COLD FRONT PASSAGE(MOVING WEST TO EAST), WHICH WILL BE AIDED
BY 35-50KT LOW LEVEL JET DEVELOPING AS THE SHORTWAVE TROUGH
APPROACHES LATE THIS MORNING. THE STRONGEST SOUTHWESTERLY GUSTS OF
40-55MPH WILL OCCUR WITH THE INITIAL FRONTAL PASSAGE, AS THE
FRONTAL BOUNDARY WILL ALLOW FOR THE LOW LEVEL JET WINDS TO MORE
EASILY MIX DOWN TO THE SURFACE. THE HIGHEST WINDS ARE EXPECTED
ACROSS AREAS SUSCEPTIBLE TO STRONG SOUTH/SOUTHWEST WINDS, WHICH
INCLUDES CENTRAL AND NORTH CENTRAL OR, WESTERN PORTIONS OF THE
SOUTHERN BLUE MOUNTAIN FOOTHILLS, SIMCOE HIGHLANDS, SOUTHERN
PORTIONS AND RIDGETOPS OF THE YAKIMA VALLEY, LOWER COLUMBIA BASIN
OF WA, AND THE NORTHERN BLUE MOUNTAIN FOOTHILLS OF WA. WIND
ADVISORIES HAVE BEEN ISSUED FOR THIS AFTERNOON AND LATE EVENING
FOR THESE AREAS. OTHERWISE, GUSTS OF 25-35MPH ARE EXPECTED
ELSEWHERE.
THE NEXT SERIES OF SHORTWAVE TROUGHS WILL ARRIVE SATURDAY MORNING
AND SUNDAY LATE MORNING, THOUGH THIS TIME A SURFACE LOW WILL BE
LOCATED WITH THE SHORTWAVE TROUGH SATURDAY AND WEAK COLD FRONT
SUNDAY. FOR SATURDAY BOTH LOW PRESSURE FEATURES WILL SWING ACROSS
THE PACNW, RESULTING IN ANOTHER DAY OF WIDESPREAD PRECIPITATION
CHANCES AS WELL AS BREEZY TO WINDY SOUTHWEST WINDS ACROSS THE
REGION. CONFIDENCE IS MODERATE-HIGH (60-80%) THAT WIND GUSTS OF
40-55MPH WILL BE MORE WIDESPREAD ACROSS THE LOWER ELEVATIONS WITH
STRONG WINDS ALONG MOUNTAIN RIDGETOPS AS ANOTHER LOW LEVEL JET
(35-60KTS) DEVELOPS FROM CENTRAL OR TO THE COLUMBIA BASIN, WHICH
WILL ALSO COINCIDE WITH A FRONTAL BOUNDARY LIFTING NORTHEAST
ACROSS THE FORECAST AREA. ANOTHER ROUND OF WIND HIGHLIGHTS ARE
LIKELY FOR SATURDAY (CONFIDENCE 65-80%). AS FOR SUNDAY, BREEZY
WINDS WILL REDEVELOP ACROSS THE LOWER ELEVATIONS, HOWEVER THE
WEAKER FRONT AND LACK OF STRONG LOW LEVEL JET WINDS WILL PRECLUDE
THE NEED FOR YET ANOTHER ROUND OF WIND HIGHLIGHTS ACROSS THE AREA
AS WIND GUSTS WILL GENERALLY BE 25-40 MPH ACROSS THE FORECAST
AREA.
BY SUNDAY NIGHT, THE LAST SHORTWAVE TROUGH WILL EXIT THE PACNW
WITH NORTHWEST FLOW ALOFT DEVELOPING IN IT'S WAKE. LIGHT UPSLOPE
PRECIPITATION WILL CONTINUE ACROSS THE CASCADE CREST AND THE
NORTHERN BLUE MOUNTAINS, WHILE DRIER CONDITIONS WILL BEGIN TO
SETTLE IN ELSEWHERE. BREEZY CONDITIONS WILL ALSO BE ON THE DOWN
TREND THROUGH SUNDAY EVENING, WITH A RETURN TO LIGHT TO LOCALLY
BREEZY WINDS LATE MONDAY MORNING.
INCLUDING THE INITIAL FRIDAY SYSTEM THIS SERIES OF SYSTEMS WILL
BRING PERSISTENT PRECIPITATION CHANCES TO THE MOUNTAINS (65-95%)
AND LOWER ELEVATIONS (45-80%) THROUGH MONDAY MORNING. THE
HEAVIEST PRECIPITATION WILL COINCIDE WITH A WEAK TO MODERATE
ATMOSPHERIC RIVER (70-90% CHANCE OF IVT > 250 KG/M/S) THAT WILL
ARRIVE WITH THE COLD FRONT PASSAGE TONIGHT, AND WILL PUSH OFF TO
THE SOUTH OF THE FORECAST AND WEAKEN BY LATE SATURDAY AFTERNOON
(CONFIDENCE 70-90%). WHILE LOWER ELEVATION LOCATIONS WILL SEE
MOSTLY RAIN THROUGHOUT THE WEEKEND, SNOW LEVELS WILL GRADUALLY
DROP TO PASS LEVEL SATURDAY AND PERSIST THROUGH MONDAY AS THE
TROUGH PERSISTS OVERHEAD. THIS WILL RESULT IN MODERATE TO LOCALLY
HEAVY SNOWFALL IN THE MOUNTAINS, WITH HIGH CONFIDENCE (80-95%) OF
6 TO 10 INCHES OF SNOW ACCUMULATIONS ACROSS SANTIAM/WHITE PASSES
AND ACROSS THE NORTHERN BLUES ABOVE 4500FT, WITH MOD-HIGH
CONFIDENCE (60-80%) IN SNOW AMOUNTS BETWEEN 3-7 INCHES AT PASS
LEVEL IN SNOQUALMIE PASS(CHANCES 60-80% ALONG RIDGES IN THE PASS).
OTHERWISE, AREAS ON THE OUTSKIRTS OF BEND AND ALONG THE US97
CORRIDOR DOWN TO LA PINE MAY SEE THEIR FIRST SNOWFALL OF THE YEAR,
WITH MODERATE CONFIDENCE (55-70%) OF ACCUMULATIONS BETWEEN 1 TO 4
INCHES SATURDAY NIGHT.
MONDAY AFTERNOON THROUGH THURSDAY: MODERATE-HIGH CONFIDENCE
(65-80%) THAT WEAK RIDGING WILL DEVELOP OVER THE PACNW LATE MONDAY
INTO TUESDAY, WITH A WEAK WARM FRONT LIFTING ACROSS THE REGION.
THROUGH TUESDAY, A MAJORITY OF ENSEMBLE GFS AND ECMWF MEMBERS
FAVOR LIGHT RAIN AND HIGH ELEVATION SNOW CONTINUING ACROSS THE
CASCADE CREST, WITH ~50% OF MEMBERS FAVORING LIGHT PRECIPITATION
DEVELOPING ACROSS THE BLUES AND PORTIONS OF THE COLUMBIA BASIN AS
THE WARM FRONT LIFTS NORTH. DISAGREEMENT GROWS AMONGST ENSEMBLE
MEMBERS WEDNESDAY WITH DISAGREEMENT SURROUNDING THE POSITION AND
TIMING OF A SHORTWAVE TROUGH PASSAGE, WITH MEMBERS EITHER
FAVORING JUST CASCADE PRECIPITATION (SHORTWAVE SWINGS NORTHEAST)
OR CASCADE AND EASTERN MOUNTAIN PRECIPITATION (SHORTWAVE SLIDES
ALONG OR/WA BORDER). DISAGREEMENT CONTINUES AS ABOUT 55% OF
MEMBERS FAVOR RIDGING OVERHEAD WHILE THE REMAINING MEMBERS FAVOR
TROUGHING OFFSHORE AND RIDGING TO THE EAST. THE LATTER WOULD
RESULT IN CONTINUED PRECIP CHANCES ACROSS THE CASCADE CREST WHILE
THE FORMER WOULD KEEP CONDITIONS DRY. LAWHORN/82
AVIATION...PREVIOUS DISCUSSION...06Z TAFS...VFR CONDITIONS
CONTINUE AND WILL PREVAIL GOING FORWARD. ACTIVE WEATHER WITH
PERIODS OF RAIN SHOWERS AND GUSTY WINDS WILL START TO IMPACT SITES
GOING THROUGH LATE MORNING HOURS TOMORROW THROUGH EARLY
AFTERNOON. DLS/YKM WILL SEE PRECIPITATION ENTER THE AREA AT AROUND
18Z, WITH SOME OTHER SITES (RDM/BDN/PSC) RECEIVING PROB30 GROUPS
IN THE LATE AFTERNOON HOURS DUE TO THE AXIS DIRECTION OF THE
SYSTEM.
WINDS WILL START OUT LIGHT AND VARIABLE BUT WILL BECOME BREEZIER
AS WE HEAD THROUGH THE LATER MORNING AND EARLY AFTERNOON HOURS
WITH MOST SITES DEVELOPING 15-25 KNOT GUSTS BY THE LATE AFTERNOON.
SUB-VFR CONDITIONS ARE POSSIBLE (5-15% CHANCE) WITH SOME OF THE
HEAVIER RAIN BANDS POSSIBLY BRINGING <6 MILE VISIBILITY AND/OR LOW
CIG DECKS.
PRELIMINARY POINT TEMPS/POPS
PDT 68 43 61 39 / 10 70 100 40
ALW 68 46 61 42 / 10 70 100 60
PSC 64 40 62 40 / 20 60 90 30
YKM 62 36 54 35 / 70 70 100 60
HRI 65 42 62 40 / 20 60 90 30
ELN 57 31 50 30 / 70 80 90 70
RDM 68 37 55 30 / 40 70 90 70
LGD 67 43 57 33 / 0 80 100 60
GCD 70 44 57 33 / 0 80 100 40
DLS 63 42 58 43 / 80 90 100 80
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY FROM 8 AM SUNDAY TO 8 AM PDT MONDAY FOR
ORZ502.
WIND ADVISORY FROM 11 AM THIS MORNING TO 11 PM PDT THIS EVENING
FOR ORZ508-510-511.
WINTER WEATHER ADVISORY FROM 8 PM SATURDAY TO 2 AM PDT MONDAY
FOR ORZ509.
WA...WINTER WEATHER ADVISORY FROM 8 AM SUNDAY TO 8 AM PDT MONDAY FOR
WAZ030.
WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS EVENING
FOR WAZ027-028-521.
WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 11 PM PDT THIS EVENING
FOR WAZ029.
WINTER WEATHER ADVISORY FROM 11 PM SATURDAY TO 11 PM PDT SUNDAY
FOR WAZ522.
SHORT TERM...82
LONG TERM....82
AVIATION...77
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