898
FXUS66 KPDT 270510
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1010 PM PDT SUN OCT 26 2025
EVENING UPDATE
A CONVERGENCE ZONE HAS ESTABLISHED ITSELF ALONG
SNOQUALMIE PASS THIS EVENING, IN LIGHT OF STRONG NW FLOW THROUGH
THE CASCADES. WHILE THE LOWER ELEVATIONS OF THE FORECAST AREA WILL
DRY OUT OVERNIGHT AS THE MID-LEVEL WINDS BECOME MORE ZONAL,
POCKETS OF HEAVY SNOW ARE EXPECTED TO CONTINUE FOR THE CASCADES.
THE ONGOING WINTER WEATHER ADVISORY HAS BEEN EXTENDED TO 5 AM
MONDAY AS A RESULT. SHOULD NOTE THAT IMPACTS TO SNOQUALMIE PASS
ARE LIMITED TO RIGHT ALONG THE SUMMIT GIVEN THE BORDERLINE
TEMPERATURES, BUT ROAD CLOSURES HAVE BEEN REPORTED ALONG I-90 DUE
TO SLIDE-OFFS. TRAVEL WILL BE DIFFICULT THROUGH SANTIAM AND WHITE
PASSES AS WELL.
CONFIDENCE IS NOT SO HIGH IN ADVISORY-LEVEL SNOW FOR THE NORTHERN
BLUES, WITH ODOT ROAD OBS SUGGESTING ONLY 2 TO 4 INCHES HAVING
FALLEN ALONG TOLLGATE THIS EVENING, BUT WILL LEAVE THE CURRENT
ADVISORY IN PLACE AS THE SYNOPTIC PATTERN DOES FAVOR AT LEAST
LIGHT UPSLOPE SNOW SHOWERS THROUGH THE OVERNIGHT. OVERALL FORECAST
MESSAGING OUTSIDE MOUNTAIN SNOW REMAINS THE SAME, HOWEVER. 74
AVIATION...06Z TAFS
VFR CONDITIONS ARE EXPECTED THROUGH THE
PERIOD. LOW SCT-BKN CIGS WILL GRADUALLY CLEAR OUT HEADING INTO
MONDAY MORNING, LEAVING ALL SITES WITH PERSISTENT WESTERLY WINDS
LESS THAN 15 KTS. 74
PREV DISCUSSION... /ISSUED 333 PM PDT SUN OCT 26 2025/
DISCUSSION...TODAY THROUGH TUESDAY: BASED ON CURRENT SATELLITE AND
RADAR IMAGERY, A FRONTAL SYSTEM IS SWEEPING ACROSS THE WA/OR
CASCADES, FOOTHILLS OF THE NORTHERN BLUES-OR AND THE LOWER COLUMBIA
BASIN WITH BREEZY WINDS AND RAIN SHOWERS. MOUNTAIN SNOW WILL
CONTINUE TO LINGER THIS EVENING THROUGH TOMORROW MORNING WITH SNOW
ACCUMULATIONS UP TO 8 INCHES (>70% CHANCE). THE RAW ENSEMBLES DO
FAVOR A 40-50% PROBABILITY FOR THE NORTHERN BLUES OF WA/OR REACHING
TO 5 INCHES OVERNIGHT. ADDITIONAL SNOW MAY DEVELOP OVER THE CASCADES
BUT, MODELS HAVE SHOWN PRECIP ACTIVITY TO BE MOSTLY WET ALONG WITH
RELATIVELY WARMING TEMPERATURES THAT WOULD CAUSE ADDITIONAL SNOW TO
NOT STICK AROUND. THEREFORE, WE DECIDED TO NOT EXTEND THE WINTER
WEATHER ADVISORIES AND KEEP THEM IN EFFECT FOR THE WA/OR CASCADES
AND NORTHERN BLUES OF WA/OR UNTIL TOMORROW MORNING. BUT, THE
ADVISORY HAD TO PUSHED BACK TO 3PM THIS AFTERNOON FOR THE NORTHERN
BLUES OF OR/WA DUE TO A DELAYED ONSET FOR SNOWFALL BASED ON WEB
CAMERAS AND EARLIER OBSERVATIONS. THIS WEATHER SHOULD BEGIN TO
GRADUALLY CEASE AROUND THIS EVENING WITH LINGERING RAIN AND MOUNTAIN
SNOW AS THE TROUGHING PATTERN STARTS LEAVING OUR FORECAST AREA.
TOMORROW, WE MAY HAVE A BREAK WITH THE TROUGH LEAVING THE PACNW
AS AN UPPER LEVEL RIDGE GRADUALLY BUILDS OVER THE PACNW TUESDAY.
THE UPPER SLOPES OF WA CASCADES MAY HAVE A SLIGHT CHANCE OF SNOW
SHOWERS (<30% CHANCE) ALONG WITH THE NORTHERN BLUES OF WA/OR
THROUGH TOMORROW EVENING, THOUGH THE REMAINING LOCATIONS WILL BE
DRY. DRY CONDITIONS WILL CONTINUE THROUGH TUESDAY AS WELL.
HOWEVER, A FRONTAL SYSTEM ASSOCIATED WITH A LOW OVER THE BC
COASTLINE THAT MIGHT SWEEP ALONG THE CASCADE GAPS. CONFIDENCE IS
LOW ON THE IMPACT (<20%).
GUSTY WINDS (25-35 MPH) WILL CONTINUE THROUGH OVERNIGHT AND OVER THE
CASCADE GAPS AND FOOTHILLS BLUES OF OR. BASED ON THE NBM CONUS,
THERE IS A 30-50% PROBABILITY FOR GUSTS UP TO 35 MPH OVER THE
AFOREMENTIONED AREAS. TOMORROW WILL HAVE LIGHT TO BREEZY CONDITIONS
IN THE AFTERNOON HOURS, THOUGH DECREASES LATER IN THE DAY. MAY SEE
GUSTY WINDS (20-30 MPH) RETURN TUESDAY EVENING HOURS ACROSS THE
EASTERN MOUNTAINS (40-60% PROB).
WEDNESDAY THROUGH SUNDAY: THROUGH THURSDAY, DRY CONDITIONS WILL
PERSIST WITH AN UPPER-LEVEL RIDGE OVER THE PACNW. A ZONAL PATTERN
WILL ARRIVE FRIDAY ONWARD WITH A FRONTAL SYSTEM RETURNING AN
UNSETTLED, WET PATTERN. WINDS WILL REMAIN LIGHT THROUGH THURSDAY BUT
COULD BECOME SLIGHTLY BREEZY STARTING FRIDAY INTO THE WEEKEND (30%
CONFIDENCE). FEASTER/97
PRELIMINARY POINT TEMPS/POPS
PDT 36 54 32 58 / 70 10 0 0
ALW 38 53 35 55 / 90 10 0 10
PSC 36 57 31 54 / 40 10 0 0
YKM 29 55 30 50 / 20 0 10 20
HRI 36 57 31 55 / 40 10 0 0
ELN 28 51 26 47 / 40 10 10 20
RDM 24 51 26 63 / 30 0 0 0
LGD 31 49 26 53 / 90 20 0 0
GCD 28 49 28 57 / 80 0 0 0
DLS 39 57 38 55 / 50 20 10 20
PDT WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY UNTIL 8 AM PDT MONDAY FOR ORZ502.
WINTER WEATHER ADVISORY UNTIL 5 AM PDT MONDAY FOR ORZ509.
WA...WINTER WEATHER ADVISORY UNTIL 8 AM PDT MONDAY FOR WAZ030.
WINTER WEATHER ADVISORY UNTIL 5 AM PDT MONDAY FOR WAZ522.
SHORT TERM...74
LONG TERM....97
AVIATION...74
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