105
FXUS66 KPDT 101751
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1051 AM PDT TUE MAR 10 2026
KEY MESSAGES
- LIGHT TO MODERATE SNOW ACCUMULATIONS CONTINUE IN THE CASCADES
THIS MORNING, WITH ANOTHER ROUND ALONG THE OREGON CASCADE
CREST AND IN THE WASHINGTON BLUE MOUNTAINS TONIGHT THROUGH
WEDNESDAY.
- ATMOSPHERIC RIVER WILL PRODUCE HEAVY SNOW ACCUMULATIONS IN THE
WASHINGTON CASCADES LATE TUESDAY THROUGH THURSDAY NIGHT.
- STRONG WINDS MAY DEVELOP ACROSS THE COLUMBIA BASIN AND HIGH
MOUNTAIN RIDGES/PEAKS WEDNESDAY NIGHT INTO THURSDAY AS COLD
FRONT APPROACHES AND LOW LEVEL JET DEVELOPS.
DISCUSSION
TODAY THROUGH FRIDAY NIGHT: THE PACNW WILL BE
SITUATED UNDER AN ACTIVE, NEAR ZONAL FLOW ALOFT THROUGH THE REST
OF THE WORKWEEK. TODAY THROUGH TONIGHT, LIGHT TO LOCALLY
MODERATE SNOW BANDS WILL DEVELOP ALONG THE CASCADE CREST AND THE
NORTHERN BLUES AS A SHORTWAVE TROUGH TO THE NORTH CLIPS THE
REGION. SNOW LEVELS WILL BE WELL BELOW PASS LEVEL ACROSS THE
CASCADES AND BLUES, ALLOWING SNOW ACCUMULATIONS IN THESE AREAS.
HOWEVER, HI-RES ENSEMBLES SHOW THAT THE BULK OF THE
PRECIPITATION IN THE BLUES WILL BE FOCUSED IN THE WA PORTION OF
THE MOUNTAIN RANGE. WINTER WEATHER ADVISORIES HAVE BEEN ISSUED
FOR THE OR CASCADE EAST SLOPES AND THE WA NORTHERN BLUES THROUGH
TOMORROW AFTERNOON AND EVENING.
BY TOMORROW, THE FIRST WAVE OF AN ATMOSPHERIC RIVER WILL REACH
THE PACNW, INCREASING PRECIPITATION ALONG THE CASCADE CREST,
WITH PERSISTENT LIGHT TO MODERATE PRECIP ALONG THE NORTHERN
BLUES AND EAGLE CAPS. THE AR WILL CONTINUE TO PUSH A MODERATE
PLUME OF MOISTURE INTO THE REGION THURSDAY, RESULTING IN MORE
LIGHT TO MODERATE PRECIPITATION RATES ACROSS THE MOUNTAIN ZONE.
BUT BY FRIDAY, A SECOND WAVE IN THE AR WILL RESULT IN ANOTHER
ROUND OF MODERATE TO HEAVY PRECIP IN THE MOUNTAINS THROUGHOUT
FRIDAY. AT THE BEGINNING OF THE AR PERIOD, SNOW LEVELS WILL
START OFF BELOW PASS LEVEL ACROSS THE REGION, BUT WILL RISE TO
AT LEAST ABOVE 4.5KFT LATE WEDNESDAY AS WARM AIR ADVECTS INTO
THE REGION WITH THE ARRIVAL OF SURFACE WARM FRONT AND STRONG
LOW-LEVEL JET. A COLD FRONT SAGGING SOUTH INTO WA WILL BRING
SNOW LEVELS BACK DOWN TO 2.5KFT TO 4KFT ACROSS THE CENTRAL WA
CASCADE CREST THURSDAY THROUGH FRIDAY, WHILE SNOW LEVELS WILL
GENERALLY BE ABOVE 4KFT TO 5.5KFT ACROSS THE REMAINDER OF THE
FORECAST AREA. THE AR COMBINED WITH THE LOW SNOW LEVELS ACROSS
THE WA CASCADES WILL RESULT IN HEAVY SNOW ACCUMULATIONS OVER A
THREE DAY PERIOD ENDING FRIDAY MORNING. AS FOR HOW HEAVY ARE
ACCUMULATIONS, THE NBM IS INDICATING A 85-95% CHANCE OF SNOW
ACCUMULATIONS GREATER THAN 2 FEET AT SNOQUALMIE AND WHITE PASS
THROUGH FRIDAY MORNING, WITH CHANCES OF 3 FEET AROUND 40-60%. AS
FOR SANTIAM PASS AND THE NORTHERN BLUES, CHANCES OF SEEING SNOW
ACCUMULATIONS OF AT LEAST 12 INCHES THROUGH A THREE DAY PERIOD
ENDING FRIDAY MORNING ARE ONLY 40-60%, THOUGH THE BEST CHANCE
WILL BE THROUGH WEDNESDAY AFTERNOON WHEN SNOW LEVELS ARE STILL
AT OR BELOW THE SURFACE.
IN THE LOWER ELEVATIONS, SNOW LEVELS WILL GENERALLY BE ABOVE THE
SURFACE, RESULTING IN LIGHT RAIN ACCUMULATIONS THROUGHOUT THE
WEEK. RAIN SHADOWING ON THE LEE SIDE OF THE CASCADES WILL LIMIT
THE AMOUNT OF PRECIPITATION MOST AREAS WILL SEE (0.05 TO 0.15
INCHES), BUT PORTIONS OF THE BLUE MOUNTAIN FOOTHILLS WILL SEE
0.25 TO 0.45 INCHES OF RAIN THROUGH THURSDAY NIGHT, WITH AN
ADDITIONAL 0.1 TO 0.2 INCHES FRIDAY (CONFIDENCE 60-80%).
THE AFOREMENTIONED COLD FRONT AND IT'S PARENT SURFACE LOW WILL
ALSO BRING THE POTENTIAL FOR STRONG WINDS ACROSS THE COLUMBIA
BASIN AND ADJACENT VALLEYS/FOOTHILLS LATE WEDNESDAY THROUGH
THURSDAY MORNING. THE COLD FRONT PASSAGE WILL ALSO COINCIDE
WITH A STRONG 850MB JET (55-65KTS) DEVELOPING OVER THE COLUMBIA
BASIN WEDNESDAY NIGHT. THERE IS A CHANCE (55-75%) THAT THESE
STRONG WINDS WILL MIX DOWN INTO THE LOWER ELEVATIONS, ESPECIALLY
IN WIND PRONE AREAS ACROSS NORTH CENTRAL OR, SIMCOE HIGHLANDS,
AND THE COLUMBIA BASIN. A HIGH WIND WATCH IS IN EFFECT FOR THESE
AREAS WEDNESDAY EVENING THROUGH THURSDAY MORNING.
SATURDAY THROUGH MONDAY: THERE IS GOOD AGREEMENT AMONGST
ENSEMBLE CLUSTER GUIDANCE THAT A RIDGE BUILDING OFFSHORE WILL
PUSH THE AR NORTH OF THE REGION, BRINGING A MOMENTARY RESPITE
FROM HEAVY PRECIPITATION IN THE MOUNTAINS. SUNDAY THROUGH MONDAY,
PERSISTENT LIGHT RAIN/SNOW WILL REDEVELOP ACROSS THE CASCADE
CREST AND NORTHERN BLUES AS A WEAK AR ROUNDS THE TOP OF THE
OFFSHORE RIDGE(CONFIDENCE 45-65%). LAWHORN/82
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
MOSTLY VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. LIGHT RAIN
WILL DEVELOP AT SITE DLS AFTER 00Z, WITH CIGS POTENTIALLY
LOWERING TO MVFR AFTER 03Z-06Z. RAIN WILL ALSO BE POSSIBLE AT
KALW/KPDT/KRDM/KBDN AFTER 05Z, KYKM AFTER 12Z AND KPSC AFTER
15Z, HAVE INDICATED THE LIKELIEST TIMES USING PROB30. WINDS WILL
INCREASE TO 12-17KTS WITH GUSTS 20-25KTS AFTER 20Z. WINDS WILL
WEAKEN AT SITES DLS/YKM TO LESS THAN 10KTS THIS EVENING, WITH
WINDS CONTINUING AT 10KTS TO 15KTS AT SITES PDT/RDM/BDN/ALW/PSC
THROUGH 18Z TOMORROW. GUSTS TO AROUND 21KTS WILL PERSIST AT
SITE BDN AFTER 04Z. PERRY/83
PRELIMINARY POINT TEMPS/POPS
PDT 46 34 57 47 / 20 40 50 50
ALW 46 37 55 47 / 30 50 70 70
PSC 52 37 58 49 / 0 20 20 40
YKM 48 28 54 41 / 20 40 60 80
HRI 50 36 59 49 / 10 30 30 40
ELN 44 27 45 36 / 30 50 70 80
RDM 41 28 54 39 / 10 20 30 30
LGD 40 29 48 42 / 50 50 80 80
GCD 40 28 52 43 / 40 20 40 30
DLS 49 36 53 47 / 50 80 80 80
PDT WATCHES/WARNINGS/ADVISORIES
WA...HIGH WIND WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING FOR WAZ026-028-029-521.
WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 PM PDT
WEDNESDAY FOR WAZ030.
WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 5 AM PDT
FRIDAY FOR WAZ522.
OR...HIGH WIND WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING FOR ORZ044-507-508-510.
WINTER WEATHER ADVISORY UNTIL 5 PM PDT WEDNESDAY FOR ORZ509.
DISCUSSION...82
AVIATION...83
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