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FXUS21 KWNC 081947
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 08 2025
SYNOPSIS: FAVORED DEVELOPMENT OF STRONG MID-LEVEL HIGH PRESSURE ACROSS CENTRAL
NORTH AMERICA NEXT WEEK IS ANTICIPATED TO RESULT IN A PATTERN CHANGE FROM
WEEK-1, WITH 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
EARLY IN THE PERIOD FAVORS INCREASED CHANCES FOR EPISODES OF HIGH WINDS OVER
THE WEST COAST AND PARTS OF THE INTERIOR WEST. A STALLED FRONTAL BOUNDARY
REMAINS FORECAST ACROSS THE SOUTHEASTERN U.S. BRINGING AN INCREASED LIKELIHOOD
FOR ENHANCED PRECIPITATION AND HIGH WINDS 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
SOUTHERN AND SOUTHEASTERN COASTAL ALASKA.
HAZARDS
SLIGHT RISK OF HIGH WINDS OVER THE WEST COAST STATES AND INTO THE SOUTHWESTERN
U.S., TUE-THU, SEP 16-18.
SLIGHT RISK OF HEAVY PRECIPITATION OVER THE SOUTHWEST, TUE-THU, SEP 16-18.
SLIGHT RISK OF EXTREME HEAT ACROSS EASTERN PARTS OF KANSAS AND OKLAHOMA, THE
MIDDLE AND LOWER MISSISSIPPI VALLEY, OHIO AND TENNESSEE VALLEYS, AND MUCH OF
ALABAMA, TUE-FRI, SEP 16-19.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS THE FLORIDA PENINSULA AND COASTAL
SOUTHEAST, TUE-SAT, SEP 16-20.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS SOUTH-CENTRAL AND SOUTHEAST ALASKA,
TUE-SAT, SEP 16-20.
SLIGHT RISK OF HIGH WINDS FROM THE WEST-CENTRAL GULF COAST EASTWARD ACROSS
FLORIDA AND SOUTHERN GEORGIA, CONTINUING NORTHEAST ACROSS THE SOUTHEAST COAST,
TUE-SAT, SEP 16-20.
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 THURSDAY SEPTEMBER 11 - MONDAY SEPTEMBER 15:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY SEPTEMBER 16 - MONDAY SEPTEMBER 22: MEAN 500-HPA HEIGHT ANOMALY
FORECASTS FROM THE 0Z GEFS AND ECMWF ENSEMBLES SHOW THE WEEK-2 PERIOD STARTING
OFF WITH AN AMPLIFIED RIDGE CENTER OVER CENTRAL CANADA WHICH EXTENDS SOUTHWARD
OVER THE MIDWEST, BOOKENDED BY A PAIR OF TROUGHS OVER WESTERN ALASKA AND THE
CANADIAN MARITIMES. THE LATTER FEATURE IS PREDICTED TO EXTEND SOUTHWESTWARD
NEAR AND ALONG THE U.S. ATLANTIC SEABOARD. WEAK TROUGHING IS ALSO INDICATED
OVER THE WESTERN CONUS DURING THE FIRST FEW DAYS OF THE PERIOD. FAVORED WARM
TEMPERATURES ARE FORECAST FOR MUCH OF THE CONUS HEADING TOWARDS THE AUTUMNAL
EQUINOX. FURTHER NORTH THOUGH, STRONGER MEAN TROUGHING PREDICTED IN THE
DYNAMICAL MODELS OVER THE EASTERN BERING SEA AND WESTERN ALASKA WOULD FAVOR
MORE UNSETTLED WEATHER OVER THE SOUTHERN PORTION OF ALASKA DURING WEEK-2.
IN RESPONSE TO THE MID-LEVEL RIDGE AXIS EXTENDING FROM CENTRAL CANADA INTO THE
MIDWEST LATE NEXT WEEK, BOTH RAW AND CALIBRATED TEMPERATURE TOOLS CONTINUE TO
HIGHLIGHT ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES FOCUSED OVER THE
MIDDLE MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS AT THE START OF WEEK-2,
EXPANDING EASTWARD AND A BIT SOUTHWARD WITH TIME. PROBABILISTIC EXTREME TOOLS
(PETS) FROM THE GEFS AND ECWMF DEPICT AT LEAST 20% CHANCES FOR DAYTIME
TEMPERATURES EXCEEDING THE 90TH PERCENTILE AND 90 DEGREES F, SUPPORTING THE
CONTINUATION OF A SLIGHT RISK OF EXTREME HEAT, REMAINING VALID THROUGH SEP 19.
THE GEFS FAVORS THE CORE OF THE HEAT SIGNAL TO BE LOCATED OVER THE MID-SOUTH
(I.E. WITHIN ABOUT 500 MILES OF MEMPHIS, TN), WHILE THE ECENS FAVORS THIS HEAT
SIGNAL TO BE CENTERED A BIT FARTHER SOUTH NEAR/ALONG THE CENTRAL GULF COAST.
FOR MANY AREAS WITHIN THE HIGHLIGHTED REGION, THIS WOULD MARK A SWIFT RETURN OF
SUMMER-LIKE TEMPERATURES FOLLOWING A FALL-LIKE COOLDOWN FAVORED DURING WEEK-1.
THE COMBINATION OF LONGER-TERM PRECIPITATION DEFICITS, ABOVE-NORMAL
TEMPERATURES AND BELOW-NORMAL PRECIPITATION FORECAST DURING THE NEXT TWO WEEKS
ALSO 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.
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 16-20. THIS IS RELATED TO A PREDICTED
STALLED FRONTAL BOUNDARY OVER THIS REGION, AND A WEAK MID-LEVEL TROUGH. THE
ECENS AND GEFS PROBABILISTIC EXTREMES TOOLS (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 16-18, WHERE MOISTURE MAY STREAM ACROSS THIS REGION FROM THE
GULF OF CALIFORNIA, IN RELATION TO A PASSING TROPICAL CYCLONE OVER THE EASTERN
PACIFIC. THREE QUARTERS OF AN INCH OF PRECIPITATION IS CONSIDERED REASONABLE,
ESSENTIALLY SPLITTING THE DIFFERENCE BETWEEN A WETTER ECENS PET AND DRIER GEFS
PET. THE THIRD AREA OF FAVORED HEAVY PRECIPITATION IS ALONG THE SOUTHERN COAST
OF ALASKA, FROM ABOUT THE EASTERN KENAI PENINSULA EASTWARD TO KETCHIKAN,
THEREBY INCLUDING ALL OF SOUTHEAST ALASKA. WITH A MID-LEVEL TROUGH PREDICTED
UPSTREAM OVER THE EASTERN BERING SEA AND WESTERN ALASKA, AND SURFACE LOW
PRESSURE OVER THE FAR NORTHWESTERN PART OF THE GULF OF ALASKA, SOUTHERLY
ONSHORE FLOW IS EXPECTED TO PREVAIL ACROSS THE AFOREMENTIONED PORTION OF THE
ALASKA COAST, SEP 16-20. THE GEFS AND ECENS PETS SUPPORT PRECIPITATION AMOUNTS
EXCEEDING THE 85TH HISTORICAL PERCENTILE, AND AT LEAST 2 INCHES.
THERE IS A SLIGHT RISK OF HIGH WINDS (WIND SPEEDS IN EXCESS OF THE 85TH
CLIMATOLOGICAL PERCENTILE AND 20-25 MPH) FOR TWO REGIONS IN THE CONUS. ONE IS
FROM THE WEST COAST STATES INTO THE SOUTHWEST CONUS, SEP 16-18, AND IS
ASSOCIATED WITH A MID-LEVEL TROUGH PASSING THROUGH THE AREA. THE OTHER REGION
IS FROM THE WEST-CENTRAL GULF COAST EASTWARD TO SOUTHERN GEORGIA AND FLORIDA,
CONTINUING NORTHEASTWARD OVER THE SOUTHEAST COAST, SEP 16-20. THIS SLIGHT RISK
IS ASSOCIATED WITH A SLOWLY MEANDERING BAROCLINIC ZONE PREDICTED ACROSS THE
SOUTHEAST, IN ADDITION TO A WEAK MID-LEVEL TROUGH CLOSE TO THE SOUTHEAST COAST.
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
16-22) 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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