766
FXUS21 KWNC 241839
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 24 2025
SYNOPSIS: FOLLOWING THE CURRENT WEEK'S HEAVY PRECIPITATION FORECAST FOR THE
PACIFIC NORTHWEST, ADDITIONAL HEAVY PRECIPITATION IS LIKELY THERE EARLY WEEK-2,
POSSIBLY STRETCHING SOUTHWARD INTO PART OF NORTHERN CALIFORNIA. PRECIPITATION
COULD FALL IN THE FORM OF HEAVY SNOW IN THE HIGHER ELEVATIONS OF THE NORTHERN
CASCADES. FARTHER EAST, THERE MAY BE A COUPLE EPISODES OF HEAVY SNOW IN THE
NORTHERN AND CENTRAL ROCKIES THROUGH NOV 4. STRONG SURFACE LOW PRESSURE SHOULD
BE HEADED AWAY FROM THE EASTERN CONUS PRIOR TO WEEK-2, POTENTIALLY LEAVING HIGH
WINDS IN ITS WAKE ACROSS THE NORTHEASTERN QUARTER OF THE CONUS. MEANWHILE, A
COLD CANADIAN AIRMASS MOVING INTO THE SOUTHEAST PRIOR TO WEEK-2 COULD ALLOW
TEMPERATURES TO DROP BELOW 40 DEG. F BEFORE MODERATING. SOUTHEASTERN ALASKA HAS
AN ELEVATED RISK OF HAZARDOUS PRECIPITATION AND WINDS WITH MID-LEVEL LOW
PRESSURE POTENTIALLY TRACKING ONE OR MORE SURFACE LOW PRESSURE SYSTEMS THROUGH
THE REGION.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST,
SAT, NOV 1.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS NORTHERN CALIFORNIA AND THE PACIFIC
NORTHWEST, SAT-SUN, NOV 1-2.
SLIGHT RISK OF HEAVY SNOW ACROSS THE NORTHERN CASCADES SAT-SUN, NOV 1-2
SLIGHT RISK OF HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES,
SAT-TUE, NOV 1-4.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE PACIFIC NORTHWEST, SAT-SUN,
NOV 1-2.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF NORTHWESTERN MONTANA, SAT, NOV 1.
SLIGHT RISK OF HIGH WINDS FOR THE NORTHEAST, MID-ATLANTIC, CENTRAL
APPALACHIANS, AND EASTERN GREAT LAKES, SAT, NOV 1.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE SOUTHEAST,
SAT-SUN, NOV 1-2.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS SOUTHEAST ALASKA, SAT-FRI, NOV 1-7.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF SOUTHEASTERN ALASKA, SAT-FRI, NOV
1-7.
DETAILED SUMMARY
FOR MONDAY OCTOBER 27 - FRIDAY OCTOBER 31:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY NOVEMBER 01 - FRIDAY NOVEMBER 07: STORMY WEATHER IN THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA DURING WEEK-1 IS EXPECTED TO CONTINUE INTO
EARLY WEEK-2 WHILE SLOWLY WINDING DOWN. A LONGWAVE TROUGH OVER THE NORTHEASTERN
PACIFIC IS FORECAST TO AMPLIFY AND MOVE TOWARD THE WEST COAST IN LATE OCTOBER.
MODEL CONTINUITY IS GOOD ON THE TIMING OF HEAVY PRECIPITATION, WHICH LOOKS TO
BE WINDING DOWN SLIGHTLY EARLIER IN WEEK-2 THAN IT APPEARED YESTERDAY. THIS IS
CONSISTENT WITH A SLIGHT REDUCTION IN HEAVY PRECIPITATION SIGNALS IN THE TOOLS,
BUT EVEN SO, THE INTEGRATED VAPOR TRANSPORT TOOL (IVT) TOOLS DERIVED FROM THE
ECENS AND GEFS SHOW A GREATER THAN A 60 PERCENT CHANCE THAT IVT VALUES EXCEED
250 KG/M/S ACROSS THE PACIFIC NORTHWEST ON NOV 1. BASED ON THE EVOLVING
LONGWAVE PATTERN, THE IVT TOOL, AND A BLEND OF THE GEFS/ECENS PROBABILISTIC
EXTREMES TOOLS (PETS) HAVING NEARLY A 40 PERCENT CHANCE OF 3-DAY PRECIPITATION
AMOUNTS EXCEEDING THE 85TH PERCENTILE, A MODERATE RISK OF HEAVY PRECIPITATION
IS MAINTAINED FOR NORTHWESTERN OREGON AND WESTERN WASHINGTON FOR NOV 1. TODAY,
THIS AREA HAS BEEN EXPANDED INTO THE WASHINGTON CASCADES, WHERE PRECIPITATION
PETS ARE MORE ROBUST THAN YESTERDAY. WIDESPREAD RIVER FLOORING IS NOT
ANTICIPATED AT THIS TIME, SO FOR NOW, NO FLOODING HAZARD IS POSTED. BUT
SCATTERED AREAS OF URBAN FLOODING ARE POSSIBLE, AND A FEW SMALLER RIVERS MAY
OVERTOP THEIR BANKS. GIVEN REDUCED SIGNALS IN THE PETS AND RAW MODEL OUTPUT,
AND THE EXPECTATION THAT THE STORM SYSTEM MAY WIND DOWN A BIT EARLIER THAN IT
APPEARED YESTERDAY, THE MODERATE RISKS FOR BOTH HIGH WINDS AND HEAVY SNOW IN
THE PACIFIC NORTHWEST HAVE BEEN REMOVED. ADDITIONALLY, SNOW LEVELS MAY BE
RELATIVELY HIGH IN THE NORTHERN CASCADES WITH THE STORM SYSTEM BRINGING AN
INCURSION OF MILD PACIFIC AIR, JUSTIFYING THE EXPANSION OF A MODERATE HEAVY
PRECIPITATION RISK INTO THE WASHINGTON CASCADES ALONG WITH REMOVAL OF A
MODERATE HEAVY SNOW RISK. SLIGHT RISKS FOR BOTH HIGH WINDS AND HEAVY SNOW ARE
MAINTAINED, HOWEVER, ALTHOUGH ENDING ONE DAY EARLIER THAN FORECAST YESTERDAY IN
CONCERT WITH THE SLIGHT HEAVY PRECIPITATION RISK.
FARTHER EAST, A SLIGHT RISK OF HEAVY SNOW IS MAINTAINED ACROSS THE NORTHERN AND
CENTRAL ROCKIES. PET SIGNALS ARE WEAK, BUT THE RAW DETERMINISTIC AND
PROBABILISTIC OUTPUT FROM NUMEROUS MODELS SHOW HEAVY SNOW FALLING ON THIS
REGION. OF THE MODELS THAT BRING HEAVY SNOW INTO THE REGION, MOST NOW SHOW A
SECOND EPISODE OF HEAVY SNOW DROPPING SOUTHWARD OUT OF THE CANADIAN ROCKIES,
KEEPING THE SLIGHT HEAVY SNOW RISK IN PLACE UNTIL THE MIDDLE OF WEEK-2. NOT ALL
MODEL RUNS AGREE ON THIS SCENARIO, AS ALL THREE ENSEMBLE MEANS FORECAST
UNREMARKABLE AMOUNTS OF SNOW DURING THE FIRST HALF OF WEEK-2, BUT THE NUMBER OF
DETERMINISTIC RUNS FORECASTING HEAVY SNOW IS SUFFICIENT TO JUSTIFY THE SLIGHT
RISK. JUST EAST OF THIS REGION, DETERMINISTIC MODELS FORECAST STRONG AND GUSTY
WINDS IN THE HIGH PLAINS OF WESTERN MONTANA ON THE FIRST DAY OF WEEK-2. IN
ADDITION, PETS FROM BOTH THE GEFS AND THE EUROPEAN ENSEMBLE (ECENS) SHOW A 30
TO 50 PERCENT CHANCE THAT WINDS WILL REACH THE 85TH CLIMATOLOGICAL PERCENTILE,
AND AT LEAST A 40 PERCENT CHANCE THAT SUSTAINED WINDS WILL EXCEED 25 MPH.
THE ECENS, GEFS, AND CMCE REMAIN CONSISTENT AND IN GOOD AGREEMENT THAT A
500-HPA TROUGH AMPLIFIES OVER THE EAST DURING WEEK-1. THIS AMPLIFYING MID-LEVEL
TROUGH IS LIKELY TO SPAWN A STRENGTHENING LOW PRESSURE SYSTEM NEAR OR OFF THE
MID-ATLANTIC OR NORTHEASTERN CONUS COAST PRIOR TO THE START OF WEEK-2. THE
ENSEMBLE MEAN CONSENSUS FROM THE ECENS, GEFS, AND CANADIAN ENSEMBLE (CNENS)
FAVORS A NORTH TO NORTHEASTWARD TRACK NEAR OR OFFSHORE OF THE NORTHEAST, AT A
SLIGHTLY FASTER PACE THAN FORECAST YESTERDAY. BY THE OUTSET OF WEEK-2, ALL
ENSEMBLE MEANS HAVE MOVED THE LOW INTO EASTERN CANADA, TAKING THE HEAVY
PRECIPITATION WITH IT. AS A RESULT, ALL HEAVY PRECIPITATION HAZARDS IN THE EAST
HAVE BEEN DROPPED, ALTHOUGH SOME SMALL STREAM FLOODING MAY LINGER INTO WEEK-2.
IN THE WAKE OF THE LOW PRESSURE SYSTEM, A HIGH PRESSURE SYSTEM IS EXPECTED TO
MOVE INTO THE CENTRAL AND SOUTHEASTERN CONUS. THE POTENTIALLY TIGHT PRESSURE
GRADIENT MAY COVER PART OF THE NORTHEASTERN QUARTER OF THE CONUS, INTRODUCING A
SLIGHT RISK OF HIGH WINDS THERE EARLY WEEK-2. HOWEVER, LARGE ENSEMBLE SPREAD ON
THE INTENSITY OF THE SURFACE LOW PRECLUDES A MODERATE RISK OF HIGH WINDS.
TROPICAL STORM MELISSA IS CURRENTLY LOCATED TO THE SOUTHEAST OF JAMAICA. THE
NATIONAL HURRICANE CENTER (NHC) PREDICTS THAT MELISSA IS LIKELY TO RAPIDLY
INTENSIFY AND BECOME A MAJOR HURRICANE BY EARLY NEXT WEEK AS IT REMAINS OVER
THE CARIBBEAN SEA. PLEASE REFER TO NHC FOR THE LATEST STATEMENTS AND FORECASTS
ON MELISSA. THE INTERACTION BETWEEN THE AMPLIFYING MID-LEVEL TROUGH AND THE
RESULTING LOW PRESSURE SYSTEM NEAR THE EAST COAST AND TROPICAL CYCLONE MELISSA
REMAINS SOMEWHAT UNCERTAIN AT THIS TIME, BUT MODELS HAVE BEEN TRENDING TOWARD
MINIMIZING THE INTERACTION BETWEEN THESE TWO SYSTEMS, MOVING MELISSA TOWARD THE
CENTRAL NORTH ATLANTIC WELL EAST OF THE EAST COAST.
SURFACE HIGH PRESSURE, ACCOMPANIED BY COOLER-THAN-NORMAL TEMPERATURES, IS
FORECAST TO SETTLE SOUTHWARD INTO THE SOUTHEAST, FAVORING FAIR BUT UNUSUALLY
CHILLY NIGHTTIME LOWS FOR THIS REGION EARLY IN WEEK-2. FOR NOV 1-2, A SLIGHT
RISK OF MUCH BELOW-NORMAL TEMPERATURES IS POSTED WHERE THE GEFS AND ECENS
PROBABILISTIC EXTREMES TOOLS (PETS) DEPICT MORE THAN A 20 PERCENT CHANCE OF
MINIMUM TEMPERATURES FALLING BELOW THE 15TH PERCENTILE AND 40 DEG. F. THIS AREA
HAS BEEN EXTENDED A LITTLE FARTHER SOUTH AND EAST THAN YESTERDAY, CLOSER TO THE
GULF AND ATLANTIC COASTLINES, CONSISTENT WITH TODAY'S PETS. TEMPERATURES WILL
BE INCREASING AFTER THE FIRST TWO DAYS OF THE PERIOD, ESPECIALLY IN AREAS
FARTHER WEST CLOSER TO THE LOWER MISSISSIPPI VALLEY AND CENTRAL GULF COAST. THE
SLIGHT RISK IS ONLY DESIGNATED FOR AREAS WITHOUT A PRIOR FIRST FROST OF THE
FALL SEASON.
STRONG ONSHORE FLOW IS FORECAST ACROSS SOUTHEASTERN ALASKA TIED TO THE
AFOREMENTIONED TROUGHING WEST OF THE WEST COAST. BOTH THE ECENS AND GEFS PETS
SHOW SCATTERED AREAS WITH 20 TO 40 PERCENT CHANCES THAT BOTH SUSTAINED WINDS
AND 3-DAY PRECIPITATION AMOUNTS WILL EXCEED THE 85TH PERCENTILE. DETERMINISTIC
MODELS ARE CONSISTENT IN SHOWING AT LEAST A COUPLE OF SURFACE LOW PRESSURE
SYSTEMS TRACKING ACROSS OR NEAR SOUTHERN ALASKA DURING WEEK-2, BUT THERE IS
HIGH RUN-TO-RUN AND MODEL-TO-MODEL INCONSISTENCY REGARDING THE TIMING AND
LOCATION OF HIGH WINDS AND HEAVY PRECIPITATION. GIVEN THE UNCERTAINTIES, SLIGHT
RISKS OF HEAVY PRECIPITATION AND HIGH WINDS ARE POSTED FOR ALL OF WEEK-2 ACROSS
SOUTHERN AND SOUTHEASTERN ALASKA. THE SLIGHT RISK OF HEAVY SNOW IS REMOVED
SINCE IT SHOULD BE LIMITED TO THE SPARSELY-POPULATED HIGHER ELEVATIONS.
FORECASTER: RICH TINKER
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