514
FXUS21 KWNC 301800
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 30 2025
SYNOPSIS: PREVAILING MID-LEVEL LOW PRESSURE OVER THE NORTHERN PACIFIC IS
ANTICIPATED TO MAINTAIN AN INCREASED RISK OF HEAVY PRECIPITATION, HIGH
ELEVATION SNOWFALL, AND HIGH WINDS TO PORTIONS OF THE NORTHWESTERN CONTIGUOUS
U.S. (CONUS). SURFACE LOW DEVELOPMENT IN THE LEE OF THE ROCKIES MAY BRING
PERIODS OF HIGH WINDS ACROSS PORTIONS OF THE GREAT PLAINS AND MISSISSIPPI
VALLEY.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE PACIFIC NORTHWEST AND
NORTHERN CALIFORNIA, FRI-MON, NOV 7-10.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADE MOUNTAINS, FRI-MON, NOV 7-10.
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN ROCKIES, FRI-MON, NOV 7-10.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE PACIFIC NORTHWEST AND NORTHERN
CALIFORNIA, FRI-MON, NOV 7-10.
SLIGHT RISK OF HIGH WINDS FOR THE NORTH-CENTRAL CONUS, FRI-SUN, NOV 7-9.
DETAILED SUMMARY
FOR SUNDAY NOVEMBER 02 - THURSDAY NOVEMBER 06:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY NOVEMBER 07 - THURSDAY NOVEMBER 13: LATE NEXT WEEK, DYNAMICAL MODEL
ENSEMBLE GUIDANCE CONTINUES TO FEATURE ANOMALOUS 500-HPA TROUGHING OVER THE
NORTHEASTERN PACIFIC, WITH DOWNSTREAM RIDGING CENTERED OVER THE WESTERN AND
CENTRAL U.S., AND POSITIVE HEIGHT DEPARTURES EXTENDING INTO CENTRAL CANADA.
COMPARED TO YESTERDAY, BOTH THE GEFS AND ECMWF ENSEMBLES SHOW STRONGER POSITIVE
MID-LEVEL HEIGHT ANOMALIES OVER THE WESTERN CONUS EARLY IN THE PERIOD, WITH
MUCH OF THE SHORTWAVE ENERGY LOCATED EAST OF THE BUILDING RIDGE AXIS. AS A
RESULT, THE ENHANCED ONSHORE FLOW AND ASSOCIATED HEAVY PRECIPITATION RISK
FAVORED LATE IN WEEK-1 IS EXPECTED TO SUBSIDE, AT LEAST PERHAPS TEMPORARILY,
BEFORE ADDITIONAL TROUGHING REAPPROACHES THE WEST COAST LATER IN THE PERIOD.
THE GEFS IS MORE BULLISH WITH THIS OUTCOME, WHILE THE ECMWF FAVORS AN ANOMALOUS
RIDGE THAT RETROGRADES AND LATER AMPLIFIES OVER THE INTERIOR WEST, WHICH MAY
AMELIORATE THE THREAT OF DISTURBED WEATHER BY THE MIDDLE OF THE PERIOD. GIVEN
MODEL DIFFERENCES IN THE EVOLUTION OF THE MID-LEVEL HEIGHT PATTERN, THERE IS
ADDED UNCERTAINTY IN THE OUTLOOK OVER THE WESTERN CONUS. EAST OF THE ROCKIES,
THE PATTERN LOOKS TO BE FAIRLY PROGRESSIVE AND MUTED. THOUGH, SHOULD MORE
RIDGING BECOME MORE AMPLIFIED ACROSS THE WEST PER THE ECMWF, THIS COULD FORCE
MORE TROUGHING DOWNSTREAM AND PROMOTE MORE UNSETTLED WEATHER ACROSS PORTIONS OF
THE EASTERN CONUS TOWARDS THE MIDDLE OF NOVEMBER.
INTEGRATED VAPOR TRANSPORT (IVT) TOOLS CONTINUE TO INDICATE ELEVATED CHANCES
FOR VALUES EXCEEDING 250 KG/M/S OVER THE WEST COAST WITH THE HIGHEST CHANCES
NOW WITHIN THE WEEK-1 PERIOD. TIED TO THE POTENTIALLY RELOADING TROUGH, ANOTHER
UPTICK IN THESE SIGNALS IS EVIDENT EARLY IN WEEK-2, WHICH IS SUPPORTED IN THE
RAW DAILY PRECIPITATION TOOLS DEPICTING INCREASED MEAN PRECIPITATION AMOUNTS,
AS WELL AS INCREASED CHANCES FOR AMOUNTS EXCEEDING AN INCH SHIFTING SOUTHWARD
INTO WESTERN OREGON AND NORTHERN CALIFORNIA. GIVEN THIS, AND PROBABILISTIC
EXTREMES TOOL (PET) GUIDANCE CONTINUING TO DEPICT 20-30% CHANCES FOR 3-DAY
AMOUNTS EXCEEDING THE 85TH PERCENTILE, A SLIGHT RISK OF HEAVY PRECIPITATION
REMAINS POSTED FOR NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST, WITH AN
ACCOMPANYING SLIGHT RISK OF HIGH ELEVATION SNOW POSTED OVER THE CASCADES AND
PARTS OF THE NORTHERN ROCKIES, BOTH REMAINING VALID THROUGH NOV 10. ANY HEAVY
PRECIPITATION IS LIKELY TO LEAD TO INCREASED STREAMFLOWS AND POSSIBLY ISOLATED
URBAN FLOODING WITHIN THE HIGHLIGHTED PRECIPITATION AREA. BASED ON THE PETS
DEPICTING INCREASED CHANCES FOR WIND SPEEDS EXCEEDING THE 85TH PERCENTILE, A
SLIGHT RISK OF HIGH WINDS ALSO REMAINS ISSUED FOR THE PACIFIC NORTHWEST AND
NORTHERN CALIFORNIA FOR THE SAME PERIOD.
ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE ENERGY PROPAGATING ACROSS THE
INTERIOR WEST, SURFACE LOW DEVELOPMENT IN THE LEE OF ROCKIES REMAINS FAVORED,
THOUGH BOTH THE GEFS AND ECMWF ENSEMBLES DEPICT A CONSIDERABLY MORE NORTHERLY
SOLUTION OF THIS SURFACE FEATURE RELATIVE TO YESTERDAY. WHAT REMAINS CONSISTENT
IN THE GUIDANCE IS A LACK OF RETURN FLOW FROM THE GULF TO SUPPLY A HEAVY
PRECIPITATION RISK, WHICH IS SUPPORTED IN THE RAW AND CALIBRATED TOOLS.
HOWEVER, AS THE MEAN LOW DEEPENS, PERIODS OF STRONG WINDS ARE POSSIBLE AND A
SLIGHT RISK REMAINS POSTED FOR NOV 7-9 WHERE PETS INDICATE INCREASED CHANCES
FOR WIND SPEEDS EXCEEDING THE 85TH PERCENTILE. GIVEN A SURFACE LOW TRACK THAT
IS NOW CLOSER TO THE GREAT LAKES, COVERAGE FOR THE SLIGHT RISK AREA IS SHIFTED
ACCORDINGLY, AND IS MORE FOCUSED OVER A BROAD AREA OF THE NORTH-CENTRAL CONUS.
DOWNSTREAM OF THE MEAN SURFACE LOW, MEAN SURFACE HIGH PRESSURE IN THE WAKE OF A
COLD FRONT IS FAVORED TO BUILD AND BRING A BRIEF PERIOD OF COLDER TEMPERATURES
OVER THE MID-ATLANTIC AND THE NORTHEAST EARLY IN WEEK-2. RAW TEMPERATURE TOOLS
FROM THE GEFS AND ECMWF CONTINUE TO TREND COOLER, WITH THE ECMWF PET BEING MOST
PRONOUNCED WITH THE COLD POTENTIAL SHOWING SIGNALS PEAKING ON DAYS 8 AND 9 IN
PERCENTILE SPACE. ALTHOUGH THESE SIGNALS TRANSLATE INTO MINIMUM TEMPERATURES
POTENTIALLY FALLING INTO THE TEENS (DEG F) OVER NORTHERN NEW ENGLAND AND
UPSTATE NEW YORK, NO CORRESPONDING TEMPERATURE HAZARDS ARE POSTED DUE TO MANY
AREAS ALREADY HAVING EXPERIENCED THEIR FIRST AUTUMN FROST AND/OR FREEZE, WITH
ACTUAL TEMPERATURES REMAINING ABOVE WINTER THRESHOLDS. WITH SOME INCREASED
TROPOSPHERIC MOISTURE IN PLACE, THE ENHANCED NORTHWESTERLY FLOW ALOFT MAY
PRODUCE PERIODS OF ACCUMULATING SNOW, WITH LAKE EFFECT SNOW ALSO POSSIBLE.
NO HAZARDS ARE ISSUED OVER ALASKA. PERIODS OF HIGH WINDS AND LOCALLY HEAVY
PRECIPITATION ARE POSSIBLE OVER THE SOUTHEAST ASSOCIATED WITH ANOMALOUS
MID-LEVEL TROUGHING SHIFTING EASTWARD FROM THE BERING STRAIT, HOWEVER PETS SHOW
PRECIPITATION AMOUNTS AND WIND SPEEDS LIKELY REMAINING BELOW HAZARD THRESHOLDS.
FORECASTER: NICK NOVELLA
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