183
FXUS21 KWNC 101855
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 10 2025
SYNOPSIS: FAVORED DEVELOPMENT OF STRONG MID-LEVEL HIGH PRESSURE ACROSS CENTRAL
NORTH AMERICA LATER NEXT WEEK IS ANTICIPATED TO RESULT IN WIDESPREAD
ABOVE-NORMAL TEMPERATURES AND POSSIBLE EXTREME HEAT CONDITIONS EMERGING FOR A
LARGE FRACTION OF THE EAST-CENTRAL CONTIGUOUS U.S. (CONUS) DURING WEEK-2. THE
ABNORMALLY WARM TEMPERATURES, COMBINED WITH ANTECEDENT DRYNESS AND BELOW NORMAL
PRECIPITATION FAVORED DURING THE NEXT TWO WEEKS SUPPORT A RAPID ONSET DROUGHT
(ROD) RISK OVER PARTS OF THE EAST. LINGERING MID-LEVEL LOW PRESSURE FORECAST
OVER THE WESTERN THIRD OF THE CONUS FROM THE END OF WEEK-1 INTO THE BEGINNING
OF WEEK-2 FAVORS INCREASED CHANCES FOR EPISODES OF HIGH WINDS OVER CENTRAL
PARTS OF THE WEST COAST. A STALLED FRONTAL BOUNDARY REMAINS FORECAST ACROSS THE
SOUTHEASTERN U.S. BRINGING AN INCREASED LIKELIHOOD FOR ENHANCED PRECIPITATION
TO THE REGION. EARLY IN WEEK-2, TROPICAL MOISTURE ASSOCIATED WITH AN EASTERN
PACIFIC TROPICAL CYCLONE ENHANCES THE RISK FOR HEAVY PRECIPITATION ACROSS
PORTIONS OF THE SOUTHWEST. SURFACE LOW PRESSURE IS FORECAST TO BRING INCREASED
CHANCES OF HEAVY PRECIPITATION TO COASTAL PORTIONS OF SOUTHEASTERN ALASKA.
HAZARDS
SLIGHT RISK OF HIGH WINDS OVER PARTS OF COASTAL PORTIONS OF NORTHERN CALIFORNIA
AND SOUTHERN OREGON, THU-FRI, SEP 18-19.
SLIGHT RISK OF EXTREME HEAT ACROSS EASTERN PARTS OF THE SOUTHERN PLAINS, LOWER
HALF OF THE MISSISSIPPI VALLEY, TENNESSEE, ALABAMA, AND NORTHWESTERN GEORGIA,
THU-SAT, SEP 18-20.
SLIGHT RISK OF HEAVY PRECIPITATION OVER THE SOUTHWEST, THU-MON, SEP 18-22.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS MOST OF FLORIDA AND THE COASTAL
SOUTHEAST, THU-MON, SEP 18-22.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS COASTAL PORTIONS OF THE KENAI
PENINSULA AND THE NORTHERN PORTION OF SOUTHEAST ALASKA, THU-MON, SEP 18-22.
RAPID ONSET DROUGHT (ROD) RISK ACROSS INTERIOR PORTIONS OF THE DEEP SOUTH,
LOWER AND MIDDLE MISSISSIPPI VALLEY, WESTERN TENNESSEE AND MUCH OF THE OHIO
VALLEY, WEST VIRGINIA, AND SMALL PARTS OF ADJACENT STATES.
DETAILED SUMMARY
FOR SATURDAY SEPTEMBER 13 - WEDNESDAY SEPTEMBER 17:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY SEPTEMBER 18 - WEDNESDAY SEPTEMBER 24: MEAN 500-HPA HEIGHT ANOMALY
FORECASTS FROM THE 0Z GEFS, ECENS, AND CMCE ENSEMBLES SHOW THE WEEK-2 PERIOD
STARTING OFF WITH AN AMPLIFIED RIDGE CENTER OVER CENTRAL CANADA WHICH EXTENDS
SOUTHEASTWARD OVER THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGION, AND A
WEAKER RIDGE APPROACHING SOUTHEAST ALASKA. A SIGNIFICANT MID-LEVEL TROUGH
CONTINUES TO BE PREDICTED BY THE ENSEMBLE MEANS OVER THE EASTERN BERING SEA AND
WESTERN ALASKA, WITH SEVERAL SHALLOW, SHORTWAVE TROUGHS OVER THE NORTHWESTERN
AND NORTH-CENTRAL CONUS, AND OFF THE EAST COAST.
IN RESPONSE TO THE MID-LEVEL RIDGE AXIS EXTENDING FROM CENTRAL CANADA INTO THE
UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGION LATE NEXT WEEK, BOTH RAW AND
CALIBRATED TEMPERATURE TOOLS CONTINUE TO HIGHLIGHT ELEVATED CHANCES FOR
WIDESPREAD COVERAGE OF ABOVE-NORMAL TEMPERATURES OVER MOST OF THE CENTRAL AND
EASTERN CONUS. A SLIGHT RISK OF EXTREME HEAT IS POSTED OVER FAR EASTERN PARTS
OF THE SOUTHERN PLAINS, MOST OF THE LOWER HALF OF THE MISSISSIPPI VALLEY, MOST
OF TENNESSEE AND ALABAMA, AND NORTHWESTERN GEORGIA, SEP 18-20. DAYTIME HIGH
TEMPERATURES ARE PREDICTED TO REACH THE MIDDLE AND UPPER 90’S WITHIN MUCH OF
THIS REGION, WITH THE GREATEST DEW POINT TEMPERATURES (AT LEAST 70 DEG F)
CONFINED TO NEAR THE GULF COAST, WHICH WOULD SUPPORT HIGHER HEAT INDEX VALUES.
THIS IS BASED ON UNCALIBRATED GEFS/ECENS GUIDANCE AND ON THE GEFS/ECENS
PROBABILISTIC EXTREME TOOLS (PETS). LITTLE HAS CHANGED DURING THE PAST SEVERAL
DAYS REGARDING THE PREDICTED LOCATION OF THE CORE HEAT SIGNAL; WITH THE GEFS
FAVORING THE MORE NORTHERLY SOLUTION WITH THE HEAT SIGNAL CENTERED OVER THE
EASTERN CORN BELT, WHILE THE ECENS FAVORS THE CORE SIGNAL FARTHER SOUTH, OVER
THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS, AND THE CENTRAL GULF COAST STATES.
THE COMBINATION OF LONGER-TERM PRECIPITATION DEFICITS, ABOVE-NORMAL
TEMPERATURES AND BELOW-NORMAL PRECIPITATION FORECAST DURING THE NEXT TWO WEEKS
SUPPORTS A RAPID ONSET DROUGHT (ROD) RISK POSTED IN AN ARC THAT EXTENDS FROM
THE INTERIOR DEEP SOUTH NORTHWARD INTO THE MIDDLE MISSISSIPPI VALLEY, THEN
EASTWARD ACROSS MUCH OF THE OHIO VALLEY AND CENTRAL APPALACHIANS. DRY
VEGETATIVE FUELS IN THIS AREA TYPICALLY MEANS INCREASED RISK OF WILDFIRES.
THERE ARE ENHANCED CHANCES FOR HEAVY PRECIPITATION OVER THREE AREAS OF THE
UNITED STATES DURING THIS HAZARDS PERIOD. THE FIRST AREA IS ALONG THE SOUTHEAST
COAST INCLUDING MOST OF FLORIDA, SEP 18-22. THIS IS RELATED TO A PREDICTED
STALLED FRONTAL BOUNDARY OVER THIS REGION, AND A WEAK MID-LEVEL TROUGH. THE
ECENS AND GEFS PETS INDICATE INCREASED CHANCES OF PRECIPITATION AMOUNTS IN
EXCESS OF THE 85TH HISTORICAL PERCENTILE AND ALSO IN EXCESS OF 1-INCH. THE
SECOND AREA OF FAVORED HEAVY PRECIPITATION IS OVER THE SOUTHWEST, SEP 18-22,
WHERE TROPICAL MOISTURE MAY STREAM INTO THIS REGION FROM THE GULF OF
CALIFORNIA, IN RELATION TO A PASSING TROPICAL CYCLONE OVER THE EASTERN PACIFIC.
3-DAY PRECIPITATION AMOUNTS OF 0.75-1.00 INCH ARE CONSIDERED REASONABLE,
ESSENTIALLY SPLITTING THE DIFFERENCE BETWEEN A WETTER ECENS PET AND DRIER GEFS
PET. WHILE LOW-LEVEL FLOW AND MOISTURE INPUT LOOKS FAVORABLE FOR HEAVY
RAINFALL, THE MID-LEVEL FLOW IS SUPPORTIVE OF A DRIER PATTERN, WHICH RESULTS IN
ONLY A SLIGHT RISK BEING POSTED TODAY. THE INFLUX OF TROPICAL MOISTURE FROM
PASSING TROPICAL CYCLONES OVER THE EASTERN PACIFIC ALONG WITH TRIGGERED GULF
SURGES, ARE COMMONLY ACCOMPANIED BY FLASH AND/OR URBAN FLOODING, AND THIS
POSSIBILITY SHOULD BE MONITORED CLOSELY. THE THIRD AREA OF FAVORED HEAVY
PRECIPITATION IS ALONG THE SOUTHERN COAST OF ALASKA, FROM ABOUT THE EASTERN
KENAI PENINSULA EASTWARD TO INCLUDE APPROXIMATELY THE NORTHERN HALF OF THE
ALASKA PANHANDLE, SEP 18-22. WITH A MID-LEVEL TROUGH PREDICTED UPSTREAM OVER
THE EASTERN BERING SEA AND WESTERN ALASKA, AND SURFACE LOW PRESSURE NEAR THE
ALASKA PENINSULA, SOUTHERLY ONSHORE FLOW IS EXPECTED TO PREVAIL ACROSS THE
AFOREMENTIONED PORTION OF THE ALASKA COAST. THE GEFS AND ECENS PETS SUPPORT
3-DAY PRECIPITATION AMOUNTS EXCEEDING THE 85TH HISTORICAL PERCENTILE, AND AT
LEAST 2 INCHES (3 INCHES LOCALLY).
THERE IS A SLIGHT RISK OF HIGH WINDS (WIND SPEEDS IN EXCESS OF THE 85TH
CLIMATOLOGICAL PERCENTILE AND 20-25 MPH) ALONG THE PACIFIC COAST OF OREGON AND
NORTHERN CALIFORNIA, SEP 18-19, ASSOCIATED WITH A MID-LEVEL TROUGH PASSING
THROUGH THE AREA AND AN ENHANCED SURFACE PRESSURE GRADIENT BETWEEN HIGH
PRESSURE OVER THE EASTERN PACIFIC AND LOW PRESSURE OVER THE INTERIOR OF THE
WEST COAST STATES. THE WIND HAZARD THAT WAS POSTED NEAR THE CENTRAL AND EASTERN
GULF COAST THE PAST TWO DAYS HAS NOW BEEN REMOVED, BASED ON MODEL GUIDANCE OF
10-METER WIND SPEEDS FROM THE GEFS, ECENS, AND ECENS-AI MODEL RUNS.
AT THIS TIME, NO TROPICAL CYCLONE ACTIVITY IS FORESEEN FOR THE GULF COAST OR
EAST COAST STATES FOR THE NEXT TWO WEEKS. HOWEVER, THIS OUTLOOK PERIOD (SEP
18-24) FALLS JUST PAST THE PEAK OF THE ATLANTIC HURRICANE SEASON (SEP 10), AND
HURRICANE SEASON IS FAR FROM OVER.
FORECASTER: ANTHONY ARTUSA
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