784
FXUS66 KPDT 201748
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
948 AM PST THU NOV 20 2025
.UPDATED AVIATION DISCUSSION.
AVIATION...18Z TAFS
VFR CONDITIONS CURRENTLY ACROSS MOST SITES,
WITH MVFR CONDITIONS FOR KALW DUE TO REDUCED CEILINGS OF 3KFT. THE
LOWERED CEILINGS FOR KALW WILL LIKELY PERSIST INTO THE EARLY
AFTERNOON BEFORE INCOMING HIGH PRESSURE FROM THE WEST ALLOWS FOR
IMPROVEMENT ACROSS ALL SITES. 15-25KFT CEILINGS WILL BE THE CASE
THIS EVENING, WITH WINDS STAYING LIGHT AND BELOW 6 KTS FOR ALL
SITES. 75
PREV DISCUSSION
/ISSUED 340 AM PST THU NOV 20 2025/
DISCUSSION...OVERNIGHT WATER VAPOR IMAGERY DEPICTS A CLOSED LOW
DESCENDING DOWN TOWARD SOUTHERN CALIFORNIA, WITH OUR FORECAST AREA
BEING CLIPPED BY ITS NORTHEASTWARD FLANK. LIGHT SHOWERS HAVE
CIRCULATED ACROSS WESTERN OREGON AND INTO THE EAST SLOPES OF THE
CASCADES AS A RESULT, HOWEVER GIVEN THIS LOW'S TRAJECTORY, MOISTURE
IS RELATIVELY PALTRY OVERALL, SO PRECIP IMPACTS ASSOCIATED WITH THIS
SYSTEM ARE EXPECTED TO BE MINIMAL. THE NORTHERLY FLOW ALOFT
ASSOCIATED WITH THE FORWARD FLANK OF THIS SYSTEM MAY PROVIDE SOME
LIGHT SHOWER ACTIVITY ACROSS THE EASTERN MOUNTAINS AND INTO THE
FOOTHILLS (30-40% CHANCE), BUT ACCUMULATIONS ARE EXPECTED TO BE A
COUPLE HUNDREDTHS AT BEST.
FOR THE REST OF THURSDAY, THE PACNW WILL TRANSITION INTO A MORE
RIDGE-LIKE PATTERN THROUGH THE WEEKEND, MAKING FOR A RELATIVELY DRY
FORECAST. THERE IS A 'DIRTY' COMPONENT TO THE RIDGE, WITH MODELS
SUGGESTING ENOUGH MOISTURE TRANSPORT TO SUPPORT LOW-END SHOWER
CHANCES (20-40%) ACROSS THE CENTRAL WA CASCADES, HOWEVER QPF WILL BE
LIMITED UNTIL AROUND SUNDAY EVENING, WHEN MODELS TRY TO BRING IN A
BROAD TROUGH THROUGH THE FORECAST AREA. SHOULD NOTE THAT ENSEMBLE
GUIDANCE DOESN'T SHOW PARTICULARLY STRONG AGREEMENT ON THE AMPLITUDE
OF THIS TROUGH, BUT THAT OVERALL GUIDANCE SUGGESTS THAT THIS SUNDAY
NIGHT INTO MONDAY TIMEFRAME LOOKS TO BE THE AREA'S NEXT BEST CHANCE
FOR AREA-WIDE PRECIP. THIS SYSTEM DOES LOOK TO BRING IN ENOUGH COLD
AIR TO DROP SNOW LEVELS DOWN TO AROUND 2500-3000 FT FOR THE CENTRAL
WASHINGTON CASCADES, WHERE THE BULK OF PRECIP IS EXPECTED TO OCCUR.
THIS WOULD SUPPORT SNOW AT SNOQUALMIE PASS, BUT FORECASTED AMOUNTS
ARE LIGHT (ONLY A COUPLE OF INCHES) AS THIS TROUGH LOOKS TO BE
PRETTY QUICK-MOVING. STILL, THIS LOOKS TO BE THE MOST SIGNIFICANT
SYNOPTIC-LEVEL FEATURE ACROSS ENSEMBLE GUIDANCE FOR THE NEXT WEEK,
SO FOCUS WILL BE ON THIS POTENTIAL TROUGH OVER THE COMING DAYS.
PATCHY FOG MAY DEVELOP THIS WEEKEND DUE TO THE RIDGE PATTERN, BUT
OTHERWISE OUR LOWLANDS ARE NOT ANTICIPATED TO SEE IMPACTFUL
SENSIBLE WEATHER OVER THE NEXT 4-5 DAYS. ENSEMBLES DIVERGE IN
SOLUTIONS BEYOND THE MIDWEEK NEXT WEEK DUE TO THE PROGRESSIVE
NATURE OF THE SYNOPTIC PATTERN, SO FORECAST CONFIDENCE IS
UNFORTUNATELY TOO LOW (15-25%) IN PREDICTING HOW THANKSGIVING WILL
SHAPE UP THIS FAR OUT. 74
PRELIMINARY POINT TEMPS/POPS
PDT 47 29 50 31 / 40 0 0 0
ALW 44 34 49 36 / 40 10 10 0
PSC 49 30 48 31 / 20 0 0 0
YKM 51 28 48 30 / 30 0 0 0
HRI 49 30 48 31 / 30 0 0 0
ELN 47 27 47 31 / 30 0 10 10
RDM 47 21 51 24 / 20 0 0 0
LGD 47 29 50 29 / 60 10 0 0
GCD 47 29 50 29 / 70 0 0 0
DLS 52 34 50 37 / 40 0 0 10
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
DISCUSSION...74
AVIATION...75
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