598
FXUS21 KWNC 291816
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 29 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.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE PACIFIC NORTHWEST AND
NORTHERN CALIFORNIA, THU-MON, NOV 6-10.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADE MOUNTAINS, THU-MON, NOV 6-10.
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN ROCKIES, THU-MON, NOV 6-10.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE PACIFIC NORTHWEST AND NORTHERN
CALIFORNIA, THU-MON, NOV 6-10.
SLIGHT RISK OF HIGH WINDS FOR THE CENTRAL AND SOUTHERN HIGH PLAINS, FRI-SUN,
NOV 7-9.
DETAILED SUMMARY
FOR SATURDAY NOVEMBER 01 - WEDNESDAY NOVEMBER 05:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY NOVEMBER 06 - WEDNESDAY NOVEMBER 12: TOWARDS THE MIDDLE OF NEXT
WEEK, THERE IS FAIR AGREEMENT BETWEEN THE 0Z GEFS AND 0Z ECMWF ENSEMBLES
FEATURING A PAIR OF ANOMALOUS 500-HPA TROUGHS OVER THE NORTHEASTERN PACIFIC AND
EASTERN NORTH AMERICA, WITH ANOMALOUS RIDGING CENTERED OVER THE CENTRAL U.S.
AND EXTENDING INTO CANADA. CONSISTENT WITH PREVIOUS ENSEMBLE GUIDANCE, THE
ECMWF FAVORS A MORE AMPLIFIED SOLUTION OF THESE MEAN MID-LEVEL FEATURES, WHERE
THERE CONTINUES TO BE STRONGER SIGNS FOR ANOTHER ROUND OF ONSHORE FLOW AND
POTENTIAL ATMOSPHERIC RIVER (AR) ACTIVITY OVER THE NORTHWESTERN CONUS COMPARED
TO THE GEFS. LATER IN THE PERIOD, ENSEMBLES GENERALLY FAVOR THE PATTERN
BECOMING MORE PROGRESSIVE, PARTICULARLY WITH THE MEAN MID-LEVEL RIDGING
SHIFTING EASTWARD WITH TIME AND KEEPING ANY ANOMALOUS COLD AND HEAVY
PRECIPITATION RISKS AT BAY EAST OF THE ROCKIES. HOWEVER, THE ECMWF FAVORS MUCH
OF THE ANOMALOUS TROUGHING TO PERSIST OVER THE NORTHEASTERN PACIFIC, WHICH
COULD BRING A RENEWED RISK OF AR ACTIVITY OVER THE WESTERN CONUS LATER IN
NOVEMBER.
THE LATEST INTEGRATED VAPOR TRANSPORT (IVT) TOOLS FROM THE GEFS AND ECMWF
ENSEMBLE INDICATE THE HIGHEST CHANCES FOR VALUES EXCEEDING 250 KG/M/S FROM 40N
TO 50N BEGIN LATE IN WEEK-1 AND INTO EARLY WEEK-2. THE ONSET OF INCREASED
PRECIPITATION AMOUNTS IS SUPPORTED IN THE WPCS DAY 7 QPF OVER NORTHERN
CALIFORNIA AND THE PACIFIC NORTHWEST. FOR DAYS 8-10 (NOV 6-8), PROBABILISTIC
EXTREMES TOOLS (PETS) MAINTAIN 20-30% CHANCES FOR AMOUNTS EXCEEDING THE 85TH
PERCENTILE, WITH THE HEAVY PRECIPITATION POTENTIAL (20-30% CHANCES FOR 3-DAY
AMOUNTS EXCEEDING 2 INCHES) BECOMING MORE FOCUSED OVER THE PACIFIC NORTHWEST
EARLY IN WEEK-2. TOWARDS THE MIDDLE PORTION OF WEEK-2, RAW TOOLS DEPICT SOME OF
THE HIGHER DAILY TOTALS RETURNING TO THE SOUTH OVER PARTS OF WESTERN OREGON AND
NORTHERN CALIFORNIA ASSOCIATED WITH ADDITIONAL TROUGHING ENCROACHING THE WEST
COAST. WHILE THIS IS LESS SUPPORTED IN THE GEFS IVT TOOL, THE GEFS PET DOES
MAINTAIN ELEVATED PRECIPITATION SIGNALS IN PERCENTILE SPACE THROUGH DAY 12 (NOV
10). THEREFORE, TO BETTER CAPTURE THE EVOLUTION OF AR POTENTIAL, A SLIGHT RISK
OF HEAVY PRECIPITATION REMAINS POSTED FOR NORTHERN CALIFORNIA AND THE PACIFIC
NORTHWEST, AND AN ACCOMPANYING SLIGHT RISK OF HIGH ELEVATION SNOW IS POSTED
OVER THE CASCADES AND PARTS OF THE NORTHERN ROCKIES, BOTH VALID FOR NOV 6-10.
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.
TIED TO THE STRONG RIDGING FAVORED DOWNSTREAM, NO WEATHER RELATED HAZARDS ARE
POSTED FOR THE INTERIOR WEST. THE ECMWF ENSEMBLE IS SHOWING STRONGER SUPPORT
FOR SHORTWAVE ENERGY PROPAGATING INTO THE GREAT PLAINS, FAVORABLE FOR LEE
CYCLOGENESIS LATER NEXT WEEK. INCREASED PRECIPITATION AMOUNTS ARE EVIDENT
ACROSS THE LOWER AND MIDDLE MISSISSIPPI VALLEY BY DAYS 9 AND 10, HOWEVER THESE
AMOUNTS REMAIN PRETTY MEAGER AT THIS TIME, LIKELY DUE TO THE LACK OF GOOD
RETURN FLOW FROM THE GULF. THOUGH, EPISODES OF HIGH WINDS ARE POSSIBLE, AS THE
RAW AND CALIBRATED ECMWF TOOLS DEPICT INCREASED CHANCES FOR WINDS EXCEEDING THE
85TH PERCENTILE AND 20KTS ACROSS THE CENTRAL AND SOUTHERN PLAINS. THEREFORE, A
SLIGHT RISK OF HIGH WINDS IS POSTED FOR NOV 7-9.
COMPARED TO YESTERDAY, DEEPER MEAN TROUGHING FAVORED OVER THE CANADIAN
MARITIMES MAY LEAD TO ADDITIONAL SHORTWAVE ENERGY OVER NORTHEASTERN CONUS, AND
POTENTIALLY BRING ANOTHER ROUND OF ENHANCED NORTHWESTERLY FLOW AND COLDER
TEMPERATURES INTO THE EASTERN U.S. RAW TEMPERATURE TOOLS FROM THE GEFS AND
ECMWF HAVE TRENDED COOLER, WITH ECMWF PET BEING MOST PRONOUNCED WITH THE COLD
POTENTIAL, WITH THE SIGNALS PEAKING ON DAYS 9 AND 10. HOWEVER, 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.
OVER SOUTHERN ALASKA, PERIODS OF HIGH WINDS AND LOCALLY HEAVY PRECIPITATION ARE
POSSIBLE ASSOCIATED WITH ANOMALOUS MID-LEVEL TROUGHING SHIFTING EASTWARD FROM
THE BERING STRAIT EARLY IN WEEK-2. HOWEVER, NO HAZARDS ARE POSTED OVER ALASKA
DUE TO WEAKER TROUGHING FAVORED IN THE GEFS AS WELL AS DECREASED SIGNALS IN THE
PETS OVER THE SOUTHEAST RELATIVE TO YESTERDAY.
FORECASTER: NICK NOVELLA
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