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FXUS21 KWNC 271811
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 27 2025
SYNOPSIS: THE MAJOR STORY LEADING UP TO THE WEEK-2 PERIOD IS THE EVENTUAL TRACK
OF TROPICAL DEPRESSION NINE AND ITS IMPACTS ACROSS THE SOUTHEAST AND
POTENTIALLY FURTHER INLAND. RECENT MODEL TRENDS ARE SUGGESTIVE OF A TRACK
OFFSHORE OR RIGHT ALONG THE COAST OF SOUTH CAROLINA, BUT THERE WILL LIKELY
CONTINUE TO BE CHANGES IN THE MODELS AS THE SYSTEM BECOMES BETTER DEFINED AND
ITS INTERACTION WITH HURRICANE HUMBERTO BECOMES MORE CLEAR. WHETHER OR NOT A
COHERENT SYSTEM REMAINS ALONG THE EAST COAST AT THE OUTSET OF WEEK-2 IS STILL
UNCERTAIN, BUT FRONTAL ACTIVITY STILL FAVORS ENHANCED PRECIPITATION AND HIGH
WINDS OVER PORTIONS OF THE COASTAL MID-ATLANTIC AND SOUTHEAST, INCLUDING
FLORIDA. LINGERING FLOODING REMAINS A CONCERN DURING WEEK-2 ACROSS PORTIONS OF
THE MID-ATLANTIC, SOUTHEAST, AND SOUTHERN APPALACHIANS, ALTHOUGH A MORE
OFFSHORE TRACK MAY HELP MITIGATE IMPACTS FARTHER INLAND. FOR THE REMAINDER OF
THE CONUS, WEEK-2 IS RATHER UNEVENTFUL, WITH BROAD MID-LEVEL HIGH PRESSURE
FAVORING ABOVE-NORMAL, BUT NOT HAZARDOUS TEMPERATURES.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE COASTAL MID-ATLANTIC
AND SOUTHEAST, AND FLORIDA, SUN-TUE, OCT 5-7.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE COASTAL MID-ATLANTIC AND
SOUTHEAST, THE NORTHERN FLORIDA PENINSULA, AND THE NORTHEASTERN GULF COAST,
SUN-TUE, OCT 5-7.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF COASTAL SOUTHEASTERN
ALASKA, SUN-MON, OCT 5-6.
FLOODING POSSIBLE ACROSS PORTIONS OF THE MID-ATLANTIC, SOUTHEAST, AND SOUTHERN
APPALACHIANS.
RAPID ONSET DROUGHT (ROD) POSSIBLE FOR PARTS OF TEXAS AND LOUISIANA.
DETAILED SUMMARY
FOR TUESDAY SEPTEMBER 30 - SATURDAY OCTOBER 04:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SUNDAY OCTOBER 05 - SATURDAY OCTOBER 11: THE WEATHER ACROSS THE SOUTHEAST
AND EAST COAST OF THE U.S. EARLY IN WEEK-2 IS LARGELY DEPENDENT ON THE
EVOLUTION OF TROPICAL DEPRESSION NINE, CURRENTLY LOCATED BETWEEN EASTERN CUBA
AND THE BAHAMAS. THERE HAS BEEN A SHIFT IN THE MODELING DURING THE PAST DAY,
WITH RECENT DETERMINISTIC RUNS OF THE GFS AND ECMWF FAVORING A TRACK OFFSHORE
OR CLOSE TO THE COAST OF SOUTH CAROLINA, BUT NOT MOVING INLAND AS IT BECOMES
INFLUENCED BY THE STRONGER CIRCULATION OF HURRICANE HUMBERTO TO THE EAST. THIS
IS REFLECTED IN THE CURRENT 5-DAY TRACK GUIDANCE FROM THE NATIONAL HURRICANE
CENTER (NHC). HOWEVER, THERE ARE STILL SEVERAL INDIVIDUAL ENSEMBLE MEMBERS FROM
THE GEFS AND ECENS THAT DEPICT A MORE INLAND TRACK, SO THIS SCENARIO CANNOT
COMPLETELY BE RULED OUT. HEAVY RAIN IS INCREASINGLY LIKELY OVER PORTIONS OF THE
COASTAL CAROLINAS WHERE WEEK-1 RAINFALL TOTALS EXCEEDING 4 INCHES ARE FORECAST
BY THE WEATHER PREDICTION CENTER (WPC). THIS WOULD RESULT IN SIGNIFICANT RIVER
AND FLASH FLOODING. FLOODING IMPACTS FURTHER INLAND ARE A BIT MORE UNCERTAIN
GIVEN THE TREND TOWARD A COASTAL OR OFFSHORE TRACK. ANY FLOODING MAY LINGER
INTO WEEK-2 AND THE FLOODING POSSIBLE HAZARD REMAINS UNCHANGED RELATIVE TO
YESTERDAY. IT INCLUDES PORTIONS OF THE MID-ATLANTIC, SOUTHEAST, AND SOUTHERN
APPALACHIANS, BUT MAY BE TRIMMED BACK CLOSER TO THE COAST IN TOMORROW’S UPDATE
IF MODELS CONTINUE TO DEPICT A MORE EASTERLY AND OFFSHORE TRACK OF TROPICAL
DEPRESSION NINE.
INTERESTS ACROSS THE MID-ATLANTIC AND SOUTHEAST, AND FURTHER INLAND ACROSS THE
SOUTHERN APPALACHIANS, SHOULD MONITOR UPDATES FROM NHC, WPC, AND THEIR LOCAL
WEATHER FORECAST OFFICES (WFOS) REGARDING THE CONTINUED EVOLUTION AND IMPACTS
FROM AL94 DURING THE NEXT WEEK.
IT IS UNCLEAR IF TROPICAL DEPRESSION NINE OR ITS REMNANT WILL BE A FACTOR BY
THE OUTSET OF WEEK-2. BOTH THE DETERMINISTIC 0Z GFS AND ECMWF EXIT THE SYSTEM
TO THE EAST PRIOR TO THE START OF THE PERIOD. THERE ARE STILL A FEW INDIVIDUAL
ENSEMBLE MEMBERS ALONG WITH THE 0Z EC-AIFS THAT BRING THE SYSTEM NORTHWARD UP
THE EAST COAST, BUT THIS APPEARS TO BE A LESS-LIKELY OUTCOME GIVEN SURFACE HIGH
PRESSURE PREDICTED ACROSS THE NORTHEAST. THE UNCALIBRATED 0Z GEFS AND ECENS
GENERALLY FAVOR BELOW-NORMAL PRECIPITATION ACROSS MANY AREAS OF THE EAST DURING
WEEK-2, WITH PROBABILITIES LESS THAN 20 PERCENT FOR PRECIPITATION EXCEEDING
1-INCH OVER MANY AREAS. THE STRONGEST SIGNALS FOR HIGHER PRECIPITATION AMOUNTS
ARE ALONG THE CAROLINA COAST EXTENDING BACK THROUGH FLORIDA TIED TO A
STATIONARY FRONT. THEREFORE, THE SLIGHT RISK OF HEAVY PRECIPITATION NOW
INCLUDES PORTIONS OF THE COASTAL MID-ATLANTIC AND SOUTHEAST, AND FLORIDA, OCT
5-7. WHILE THERE IS A STRONGER SIGNAL IN THE ECENS PROBABILISTIC EXTREMES TOOL
(PET) WITH 20 PERCENT CHANCES OF 3-DAY PRECIPITATION EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1-INCH EXTENDING MORE INLAND ACROSS THE SOUTHEAST
AND LOWER MISSISSIPPI VALLEY, THE DRIER UNCALIBRATED GUIDANCE AS WELL AS THE
LACK OF SIGNAL IN THE GEFS PET PRECLUDES AN EXPANSION OF THE SLIGHT RISK. THE
STRONG GRADIENT BETWEEN THE SURFACE HIGH TO THE NORTH AND RELATIVELY LOWER
PRESSURES OVER THE SOUTHEAST ALSO SUPPORTS A SLIGHT RISK OF HIGH WINDS ALONG
THE MID-ATLANTIC AND SOUTHEAST COASTS, THE NORTHERN FLORIDA PENINSULA, AND THE
NORTHEASTERN GULF COAST, OCT 5-7. THE ECENS PET DEPICTS A 20-30 PERCENT CHANCE
WIND SPEEDS EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE AND 25-MPH.
THE 0Z ECENS AND GEFS INDICATE BROADLY POSITIVE 500-HPA HEIGHT ANOMALIES OVER
MUCH OF THE CONUS DURING WEEK-2 TIED TO INITIAL RIDGING OVER EASTERN CANADA,
FOLLOWED BY ADDITIONAL RIDGING DEVELOPING ACROSS THE CENTRAL CONUS TOWARD THE
MIDDLE OF THE PERIOD. THIS PATTERN SUPPORTS ABOVE-NORMAL TEMPERATURES OVER MUCH
OF THE CONUS, WITH THE LARGEST POSITIVE TEMPERATURE ANOMALIES (EXCEEDING +10
DEG F) FAVORED ACROSS THE UPPER MIDWEST AND GREAT LAKES. WHILE THIS WOULD BE
CONSIDERED UNSEASONABLY WARM BY FALL STANDARDS, IT IS NOT HAZARDOUS WITH
TEMPERATURES GENERALLY IN THE 60S AND 70S DEG F. ALTHOUGH TEMPERATURES ARE
LIKELY TO BE WARMER FARTHER SOUTH ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY (80S TO LOW 90S DEG F), HEAT RISK GUIDANCE IS UNSUPPORTIVE
OF HEAT INDICES EXCEEDING HAZARD CRITERIA, PRECLUDING ANY TEMPERATURE RELATED
HAZARDS.
SURFACE LOW PRESSURE IS PROJECTED TO TRACK THROUGH THE BERING SEA INTO THE GULF
OF ALASKA DURING WEEK-2 LEADING TO ENHANCED ONSHORE FLOW AND POTENTIALLY HEAVY
PRECIPITATION AND GUSTY WINDS ACROSS SOUTHERN ALASKA EARLY IN THE PERIOD.
COMPARED TO YESTERDAY, THE PRECIPITATION SIGNAL HAS INCREASED IN THE 0Z ECENS
ALONG WITH THE PETS SUPPORTING REINTRODUCING THE SLIGHT RISK OF HEAVY
PRECIPITATION ACROSS SOUTHEASTERN ALASKA, OCT 5-6. ENHANCED PRECIPITATION AND
HIGHER ELEVATION SNOW ARE ALSO POSSIBLE ACROSS PORTIONS OF WESTERN MAINLAND
ALASKA, WITH AMOUNTS LIKELY REMAINING BELOW HAZARDS THRESHOLDS.
THE 0Z ECENS AND GEFS DEPICT MORE TROUGHING ACROSS THE WESTERN CONUS EARLY IN
WEEK-2 COMPARED TO YESTERDAY, WHICH MAY BRING RELATIVELY COOLER TEMPERATURES TO
PORTIONS OF THE NORTHWEST, AND ALSO ELEVATED WIND SPEEDS ACROSS THE GREAT
PLAINS AS DEPICTED IN THE ECENS PET. THESE TRENDS WILL CONTINUE TO BE
MONITORED, BUT CONDITIONS ARE NOT ANTICIPATED TO REACH HAZARDS THRESHOLDS AT
THIS TIME.
ACROSS PORTIONS OF TEXAS AND SOUTHWESTERN LOUISIANA, PRECIPITATION DEFICITS OF
SEVERAL INCHES HAVE ACCUMULATED DURING THE PAST 30-DAYS. PERCENT-OF-NORMAL
PRECIPITATION (PNP) FALLS WITHIN THE TWO LOWEST QUARTILES (1ST THROUGH 25TH
PERCENTILES AND 26TH THROUGH 50TH PERCENTILES) OF THE CLIMATOLOGICAL
DISTRIBUTION. ABOVE-NORMAL TEMPERATURES PREDICTED FOR THE NEXT TWO WEEKS, AND
GENERALLY LITTLE OR NO PRECIPITATION INCREASES THE POTENTIAL FOR RAPID ONSET
DROUGHT (ROD) ACROSS THIS REGION.
FORECASTER: THOMAS COLLOW
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