512
FXUS21 KWNC 221845
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 22 2025
SYNOPSIS: MID-LEVEL LOW PRESSURE IS FORECAST TO MOVE CLOSER TO THE WEST COAST
OF THE CONTIGUOUS U.S. EARLY IN WEEK-2 BRINGING RENEWED CHANCES OF HEAVY
PRECIPITATION AND HIGH ELEVATION SNOW TO THE PACIFIC NORTHWEST. A COMPLEX
FORECAST REMAINS ACROSS THE EASTERN U.S. WITH FRONTAL PASSAGE AND POTENTIAL
SURFACE LOW FORMATION ACROSS THE EAST COAST TOWARD THE END OF OCTOBER. THERE IS
ALSO THE POSSIBILITY THAT MOISTURE FROM TROPICAL STORM MELISSA, CURRENTLY OVER
THE CARIBBEAN, GETS PULLED INTO THE SYSTEM, BUT THIS SCENARIO REMAINS UNCERTAIN
GIVEN MODEL DIFFERENCES REGARDING THE STORM TRACK.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHEAST AND
NORTHERN MID-ATLANTIC, THU-FRI, OCT 30-31.
MODERATE RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST,
FRI-SAT, OCT 31-NOV 1.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE OHIO VALLEY,
APPALACHIANS, NORTHEAST, AND MID-ATLANTIC, THU-SAT, OCT 30-NOV 1.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS NORTHERN CALIFORNIA AND THE PACIFIC
NORTHWEST, THU-MON, OCT 30-NOV 3.
MODERATE RISK OF HEAVY SNOW ACROSS PORTIONS OF THE CASCADES, FRI-SAT, OCT
31-NOV 1.
SLIGHT RISK OF HEAVY SNOW ACROSS THE CASCADES, THU-MON, OCT 30-NOV 3.
SLIGHT RISK OF HEAVY SNOW ACROSS HIGH ELEVATIONS OF THE NORTHERN AND CENTRAL
ROCKIES AND GREAT BASIN, THU-MON, OCT 30-NOV 3.
MODERATE RISK OF HIGH WINDS ACROSS PORTIONS OF THE PACIFIC NORTHWEST, FRI-SAT,
OCT 31-NOV 1.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE PACIFIC NORTHWEST, THU-MON,
OCT 30-NOV 3.
SLIGHT RISK OF HIGH WINDS ACROSS MUCH OF THE GREAT PLAINS EXTENDING INTO THE
NORTHEASTERN CONUS AND MID-ATLANTIC, THU-SAT, OCT 30-NOV 1.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS SOUTHEAST ALASKA, THU-SAT, OCT 30-NOV
1.
SLIGHT RISK OF HIGH WINDS ACROSS COASTAL SOUTHEASTERN ALASKA, THU-SAT, OCT
30-NOV 1.
SLIGHT RISK OF HEAVY SNOW ACROSS HIGH ELEVATIONS OF SOUTHEAST ALASKA, THE
ALASKA RANGE, KENAI MOUNTAINS, AND THE WRANGELL MOUNTAINS, THU-SAT, OCT 30-NOV
1.
DETAILED SUMMARY
FOR SATURDAY OCTOBER 25 - WEDNESDAY OCTOBER 29:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY OCTOBER 30 - WEDNESDAY NOVEMBER 05: WHILE A BREAK IN ATMOSPHERIC
RIVER (AR) ACTIVITY IS FORECAST ACROSS THE WEST COAST OF THE CONUS LATE IN
WEEK-1 INTO THE OUTSET OF WEEK-2, LONGWAVE TROUGHING INITIALLY ACROSS
SOUTHWESTERN ALASKA IS FORECAST TO SHIFT CLOSER TO THE WEST COAST BY DAY-9 (OCT
31). THERE IS A STRONG MID-LEVEL PRESSURE GRADIENT IN THE 0Z ECENS, GEFS, AND
CMCE MODELS, AND CORRESPONDING INTEGRATED VAPOR TRANSPORT TOOL (IVT) TOOLS
DERIVED FROM THE ECENS AND GEFS DEPICT IVT VALUES APPROACHING 500 KG/M/S ACROSS
THE PACIFIC NORTHWEST. ADDITIONALLY THE UNCALIBRATED 0Z ECENS DEPICTS 24-HOUR
PRECIPITATION TOTALS OF 1-2 INCHES OVER THE REGION ON OCT 31, AND THE ECENS AND
GEFS PROBABILISTIC EXTREME TOOLS (PETS) HAVE ALSO INCREASED THE SIGNAL FOR
HEAVY PRECIPITATION COMPARED TO YESTERDAY. AS A RESULT OF THESE FACTORS, A
MODERATE RISK OF HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS PORTIONS OF THE
PACIFIC NORTHWEST, OCT 31-NOV 1, WITH A CORRESPONDING MODERATE RISK FOR HEAVY
SNOW ACROSS THE NORTHERN CASCADES WHERE PROBABILITIES ARE ABOVE 40 PERCENT FOR
SNOWFALL EXCEEDING 12-INCHES EARLY IN THE PERIOD OVER PARTS OF THE REGION BASED
ON THE ECENS. ADDITIONALLY A MODERATE RISK OF HIGH WINDS IS POSTED ACROSS
PORTIONS OF WESTERN WASHINGTON AND OREGON WHERE THE ECENS PET DEPICTS AT LEAST
A 40 PERCENT CHANCE OF WIND SPEED EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE
AND 25-MPH. A SLIGHT RISK FOR HEAVY PRECIPITATION REMAINS POSTED ACROSS THE
PACIFIC NORTHWEST INTO NORTHERN CALIFORNIA, OCT 30-NOV 3, ALONG WITH A SLIGHT
RISK FOR HEAVY SNOW ACROSS THE CASCADES, AND A SLIGHT RISK OF HIGH WINDS ALONG
THE WEST COAST TO THE CALIFORNIA AND OREGON BORDER. THE INCREASE IN ONSHORE
FLOW ALSO SUPPORTS THE ADDITION OF A SLIGHT RISK OF HEAVY SNOW FURTHER INLAND
ACROSS HIGH ELEVATIONS OF THE GREAT BASIN AND NORTHERN AND CENTRAL ROCKIES, OCT
30-NOV 3.
A POTENT SHORTWAVE TROUGH IS FORECAST TO TRACK ACROSS THE CENTRAL AND EASTERN
CONUS DURING THE FIRST HALF OF WEEK-2. WHILE PRECIPITATION IS FORECAST TO EXIT
BY THE START OF THE PERIOD, AN ENHANCED SURFACE PRESSURE GRADIENT IS
ANTICIPATED TO DEVELOP ACROSS THE GREAT PLAINS ON THE BACKSIDE OF THE TROUGH
AND TO THE EAST OF SURFACE HIGH PRESSURE OVER THE ROCKIES. THIS GRADIENT IS
MORE RELAXED COMPARED TO YESTERDAY AS THE TROUGH CONTINUES TO MOVE FURTHER
EAST, BUT THE ECENS PET CONTINUES TO INDICATE AN ENHANCED SIGNAL FOR WIND
SPEEDS EXCEEDING 20-MPH ACROSS THE PLAINS SUPPORTING THE CONTINUATION OF THE
SLIGHT RISK OF HIGH WINDS THROUGH NOV 1.
AS THE TROUGHING MOVES FURTHER EAST, FRONTAL ACTIVITY AND POSSIBLE SURFACE LOW
PRESSURE ARE PREDICTED TO BRING INCREASED PRECIPITATION CHANCES TO THE EAST.
THE FORECAST IS FURTHER COMPLICATED BY THE EVOLUTION OF TROPICAL STORM MELISSA,
CURRENTLY OVER THE CARIBBEAN. INDIVIDUAL ENSEMBLE MEMBERS FROM THE GEFS AND
ECENS VARY GREATLY WITH MELISSA, WITH A MORE WEST-BASED TRACK CURRENTLY MORE
FAVORED IN THE ECENS. SLOWER SOLUTIONS ARE CONCERNING GIVEN THE POSSIBILITY FOR
MORE FRONTAL INTERACTION WITH THE UPSTREAM TROUGH. TODAY'S ECENS AND
DETERMINISTIC ECMWF SOLUTIONS HAVE TRENDED MORE TO THE EAST COMPARED TO
YESTERDAY SHOWING ENHANCED PRECIPITATION ACROSS THE NORTHERN MID-ATLANTIC INTO
NEW ENGLAND. WHILE THE UNCALIBRATED ECENS INDICATES AT LEAST A 40 PERCENT
CHANCE OF DAY 8-10 (OCT 30-NOV 1) PRECIPITATION TOTALS EXCEEDING 1-INCH OVER
THESE AREAS, THE GEFS GENERALLY KEEPS CHANCES CLOSER TO 20 PERCENT. WHILE
UNCERTAINTY REMAINS HIGH IN REGARDS TO THE EXACT EVOLUTION, ESPECIALLY IN
REGARDS TO ANY TROPICAL CYCLONE INTERACTION, A MODERATE RISK FOR HEAVY
PRECIPITATION REMAINS HIGHLIGHTED ACROSS PORTIONS OF THE NORTHERN MID-ATLANTIC
AND NORTHEAST, OCT 30-31 CONSIDERING THE TIMING INCLUDES HALLOWEEN AND
POTENTIAL FOR ADVERSE IMPACTS TO OUTDOOR EVENTS. A SLIGHT RISK OF HEAVY
PRECIPITATION CONTINUES THROUGH NOV 1, WITH THE SLIGHT RISK OF HIGH WINDS
EXTENDING ACROSS THE GREAT LAKES, NORTHEAST, AND MID-ATLANTIC THROUGH NOV 1.
RELATIVELY COLDER AIR MAY BUILD INTO PORTIONS OF THE TENNESSEE VALLEY AND THE
SOUTHEAST ON THE BACKSIDE OF THIS SYSTEM. THE GEFS IS A BIT COOLER COMPARED TO
THE ECENS DUE TO ITS QUICKER EXIT OF PRECIPITATION AND DEVELOPING SURFACE HIGH
PRESSURE. MINIMUM TEMPERATURES FROM THE UNCALIBRATED 0Z ECENS AND GEFS ARE
GENERALLY IN THE LOW TO MID-40S DEG F IN LOW ELEVATION AREAS, WITH THE PETS
DEPICTING A STRONGER SIGNAL FOR TEMPERATURES POTENTIALLY DROPPING BELOW 40 DEG
F. GIVEN THAT THESE TEMPERATURES ARE MARGINAL FOR ANY AGRICULTURAL HAZARDS, A
RELATED HAZARD IS NOT POSTED TODAY, BUT WILL BE RE-ASSESSED TOMORROW IF MODEL
AGREEMENT IMPROVES.
ACROSS ALASKA, STRONG ONSHORE FLOW IS FORECAST ACROSS THE SOUTHERN AND EASTERN
PORTIONS OF THE STATE TIED TO THE AFOREMENTIONED TROUGHING OVER THE NORTHEAST
PACIFIC. THE ECENS PET CONTINUES TO SUPPORT A SLIGHT RISK FOR HIGH WINDS WITH
ELEVATED SIGNALS FOR WIND SPEEDS EXCEEDING 40-MPH ALONG THE COAST, OCT 30-NOV
1. A SLIGHT RISK OF HEAVY PRECIPITATION IS ADDED ACROSS SOUTHEAST ALASKA, OCT
30-NOV 1, WHERE THE GEFS AND ECENS PETS DEPICT AT LEAST A 20 PERCENT CHANCE
3-DAY PRECIPITATION TOTALS EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE AND
2-INCHES, WITH THE STRONGEST SIGNALS FOCUSED MORE TO THE SOUTH. MOUNTAIN SNOW
IS LIKELY ACROSS THE HIGH ELEVATION AREAS OF SOUTHERN MAINLAND ALASKA AND
SOUTHEAST ALASKA, SUPPORTING A SLIGHT RISK FOR HEAVY SNOW FOR THE SAME TIME
PERIOD.
FORECASTER: THOMAS COLLOW
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