181
FXUS21 KWNC 101907
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 10 2026
SYNOPSIS: MID-LEVEL LOW PRESSURE MOVING OUT OF THE NORTHEAST FAVORS COLD
SURFACE HIGH PRESSURE OVER THE EASTERN CONTIGUOUS U.S. (CONUS) EARLY WEEK-2,
SUPPORTING INCREASED CHANCES FOR MUCH BELOW NORMAL TEMPERATURES AND THE FIRST
FALL FROSTS AND/OR FREEZES OVER COASTAL AND SOUTHERN NEW ENGLAND, THE NORTHERN
MID-ATLANTIC, MUCH OF THE CENTRAL AND NORTHERN APPALACHIANS, AND THE EASTERN
GREAT LAKES. THIS SYSTEM MOVES OFF THE EAST COAST BY MIDWEEK, USHERING IN
WARMER AIR. FARTHER WEST, RAINFALL ENHANCED BY LOW-LEVEL SOUTHERLY FLOW COULD
APPROACH HAZARDS THRESHOLDS ACROSS THE CENTRAL GULF COAST TOWARD MID-WEEK, BUT
TIMING AND INTENSITY ARE HIGHLY UNCERTAIN, SO NO RELATED HAZARD IS POSTED. OVER
ALASKA, MID-LEVEL TROUGHING AND CYCLONIC FLOW OVER THE GULF OF ALASKA SUPPORTS
PERIODS OF ABOVE-NORMAL PRECIPITATION AND HIGH WINDS FROM THE SOUTH-CENTRAL
MAINLAND THROUGH SOUTHEAST ALASKA, BUT CONDITIONS ARE EXPECTED TO REMAIN BELOW
HAZARD THRESHOLDS.
HAZARDS
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR SOUTHERN AND COASTAL NEW
ENGLAND AND PARTS OF THE EASTERN GREAT LAKES, NORTHERN AND CENTRAL
APPALACHIANS, AND NORTHERN MID-ATLANTIC, SUN-MON, OCT 18-19.
DETAILED SUMMARY
FOR TUESDAY OCTOBER 13 - SATURDAY OCTOBER 17:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SUNDAY OCTOBER 18 - SATURDAY OCTOBER 24: THE HAZARDS PERSPECTIVE LARGELY
REMAINS ON TRACK SINCE YESTERDAY. THE LATEST 0Z GUIDANCE FROM THE EUROPEAN
ENSEMBLE (ECENS) AND GEFS FEATURE A MODERATELY-AMPLIFIED 500-HPA TROUGH MOVING
OUT OF THE NORTHEAST EARLY IN THE PERIOD, WITH A MODERATELY-AMPLIFIED MID-LEVEL
RIDGE UPSTREAM EXTENDING FROM THE WESTERN AND CENTRAL CONUS INTO SOUTHERN
CANADA. AT THE SURFACE, A SURFACE LOW PRESSURE SYSTEM AND ASSOCIATED COLD
FRONT IS EXPECTED TO SWEEP ACROSS MUCH OF THE EASTERN TWO THIRDS OF THE CONUS
NEAR THE END OF WEEK-1, FOLLOWED BY A FAIRLY STRONG AND COLD SURFACE HIGH
PRESSURE MOVING IN FROM CANADA BY THE START OF WEEK-2. PROBABILISTIC GUIDANCE
FROM THE ECENS, GEFS, AND CANADIAN ENSEMBLES (CMCE) SHOWS ENHANCED CHANCES THAT
THIS MAY RESULT IN THE FIRST FROST OR FREEZE OF AUTUMN IN SOME OF THE HIGHER
LATITUDES IN THE EASTERN CONUS EARLY IN THE PERIOD. A SLIGHT RISK FOR MUCH
BELOW NORMAL TEMPERATURES IS POSTED IN THESE REGIONS FOR DAYS 8-9 (OCT 18-19),
AVOIDING PARTS OF UPSTATE NEW YORK AND INTERIOR NEW ENGLAND WHERE NEAR- TO
BELOW-FREEZING TEMPERATURES HAVE ALREADY OCCURRED. ON DAY 8 (OCT 18), THE ECENS
PROBABILISTIC EXTREMES TOOL (PET) SHOWS CHANCES FOR MINIMUM TEMPERATURES BELOW
THE 15TH CLIMATOLOGICAL PERCENTILE RANGE FROM 30 PERCENT IN EASTERN OHIO TO
MORE THAN 60 PERCENT ACROSS MAINE. THE GEFS PET IS MORE MUTED, SHOWING A 30 TO
40 PERCENT CHANCE THROUGHOUT THE AREA OF ENHANCED RISK. ON DAY 9 (OCT 19), THE
ECENS IS FASTER TO PUSH OUT THE COLD AIR THAN THE GEFS. THE GEFS PET KEEPS THE
ODDS FOR MUCH BELOW NORMAL TEMPERATURES BETWEEN 20 AND 30 PERCENT ACROSS THE
REGION WHILE THE ECENS PET SHOWS SIMILAR PROBABILITIES RESTRICTED TO NEW
ENGLAND AND A SMALL PART OF ADJACENT UPSTATE NEW YORK. GIVEN THE UNCERTAINTY IN
THE TIMING OF MODERATING TEMPERATURES, THE TIME FRAME FOR THE MUCH BELOW
TEMPERATURE THREAT REMAINS THE SAME AS YESTERDAY, OCT 18-19. BUT NO MATTER HOW
QUICKLY THE COLD AIR RETREATS EASTWARD, THE DYNAMICAL MODELS AND ENSEMBLES ALL
SHOW THE SURFACE HIGH PRESSURE MOVING OFF THE EAST COAST BEFORE MIDWEEK,
RESULTING IN LOW-LEVEL WARM AIR ADVECTION THROUGHOUT THE EASTERN CONUS THAT
ENDS THE MUCH BELOW NORMAL TEMPERATURE THREAT.
FARTHER WEST, THIS LOW-LEVEL SOUTHERLY FLOW IS EXPECTED TO BRING AN ANOMALOUS
PUSH OF TROPICAL MOISTURE NORTHWARD ACROSS THE GULF AND INTO THE CENTRAL GULF
COAST STATES. THE ECENS AND GEFS PETS BOTH SHOW MARGINALLY ENHANCED CHANCES
(JUST OVER 20 PERCENT) FOR 3-DAY RAINFALL TOTALS TO EXCEED THE 15TH
CLIMATOLOGICAL PERCENTILE AND 1 INCH ALONG AND NEAR THE GULF COAST FROM EASTERN
TEXAS TO SOUTHERN ALABAMA OR THE WESTERN FLORIDA PANHANDLE BEGINNING ON OR
AFTER OCT 19. THE DYNAMICAL EUROPEAN MODEL (ECMWF) AND THE EUROPEAN ARTIFICIAL
INTELLIGENCE FORECAST SYSTEM MODELS (ECMWF-AIFS) BOTH SHOW 3-DAY TOTALS OF 2 TO
LOCALLY 4 INCHES OF RAIN FALLING ON PARTS OF THE LOWER MISSISSIPPI VALLEY AND
ADJACENT GULF COAST AROUND MID-WEEK, BUT THE ECENS, GEFS, AND CMCE MEANS, ALONG
WITH THE GFS-AI DYNAMICAL MODEL, ARE MUCH DRIER. GIVEN THE UNCERTAINTY, NO
HAZARD IS POSTED AT THIS TIME, BUT THE SITUATION WILL NEED TO BE MONITORED.
OVER ALASKA, MID-LEVEL TROUGHING REMAINS FAVORED LATE WEEK-1 CENTERED OVER THE
GULF OF ALASKA. DEAMPLIFICATION IS FAVORED EARLY WEEK-2, BUT THE ENSEMBLE MEANS
TODAY SHOW THE POTENTIAL FOR A WEAKENED 500-HPA TROUGH TO RELOAD AND
EFFECTIVELY REMAIN IN PLACE THROUGHOUT THE PERIOD. THIS MAINTAINS FAIRLY WEAK
CYCLONIC MID-LEVEL FLOW OVER THE GULF OF ALASKA, WHICH FAVORS UNSETTLED WEATHER
FROM THE SOUTH-CENTRAL MAINLAND THROUGH SOUTHEAST ALASKA. GIVEN HOW HIGH
PRECIPITATION NORMALS ARE IN THIS REGION DURING OCTOBER, IT SEEMS UNLIKELY THAT
AMOUNTS WILL REACH HAZARDS THRESHOLDS, AND THE WEAK NATURE OF THIS SYSTEM DOES
NOT FAVOR HIGH WINDS REACHING HAZARDS THRESHOLDS EITHER. BUT THERE IS THE
POTENTIAL FOR ANY TROPICAL CYCLONE ACTIVITY IN THE WESTERN PACIFIC TO RECURVE
NORTHWARD AND BECOME INCORPORATED INTO THE EXTRATROPICAL WESTERLIES, RESULTING
IN A MORE AMPLIFIED MID-LEVEL PATTERN WITH AN INCURSION OF TROPICAL MOISTURE.
SO ALTHOUGH NO HAZARDS ARE POSTED AT THIS TIME, THE MID-LEVEL PATTERN OVER THE
NORTHERN PACIFIC WILL CONTINUE TO BE MONITORED.
FORECASTER: RICH TINKER
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