613
FXUS21 KWNC 041751
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 04 2026
SYNOPSIS: MODEL ENSEMBLES CONTINUE TO FAVOR CHANCES OF ABOVE NORMAL
TEMPERATURES AND A CHANCE OF EXTREME HEAT INTO WEEK-2 TIED TO ANOMALOUS
MID-LEVEL HIGH PRESSURE ACROSS SOUTHERN AND CENTRAL CONTIGUOUS U.S. (CONUS). A
POTENTIAL SURGE OF MOISTURE FROM THE GULF OF CALIFORNIA MAY RESULT IN HEAVY
PRECIPITATION OVER PORTIONS OF THE DESERT SOUTHWEST AND GREAT BASIN. ANTECEDENT
DRYNESS, COMBINED WITH LITTLE PRECIPITATION FAVORED OVER THE NEXT TWO WEEKS
SUPPORTS A RAPID ONSET DROUGHT (ROD) RISK FOR PORTIONS OF THE CENTRAL AND
SOUTHERN PLAINS, LOWER AND MIDDLE MISSISSIPPI, OHIO AND TENNESSEE VALLEYS.
HAZARDS
SLIGHT RISK OF EXTREME HEAT ACROSS MUCH OF THE GREAT PLAINS, MIDDLE AND LOWER
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, SAT, SEP 12.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE DESERT SOUTHWEST AND
GREAT BASIN, SAT-MON, SEP 12-14.
RAPID ONSET DROUGHT (ROD) RISK FOR PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS
AND THE MIDDLE AND LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS.
DETAILED SUMMARY
FOR MONDAY SEPTEMBER 07 - FRIDAY SEPTEMBER 11:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY SEPTEMBER 12 - FRIDAY SEPTEMBER 18: DYNAMICAL MODEL GUIDANCE
REMAINS IN AGREEMENT REGARDING CHANCES FOR SUBTROPICAL RIDGING PERSISTING OVER
THE SOUTH-CENTRAL U.S. INTO WEEK-2, WITH THE 0Z ECMWF, GEFS, AND CANADIAN
ENSEMBLES DEPICTING POSITIVE 500-HPA HEIGHT ANOMALIES EARLY IN WEEK-2 ACROSS
THE CENTRAL AND EASTERN CONUS. THIS LENDS ITSELF TO CONTINUED ELEVATED CHANCES
FOR ABOVE NORMAL TEMPERATURES DURING MUCH OF THE WEEK-2 PERIOD. THE
PROBABILISTIC EXTREMES TOOLS (PETS) CONTINUE TO SHOW A GREATER THAN 20% CHANCE
FOR MAXIMUM TEMPERATURES TO EXCEED THE 95TH CLIMATOLOGICAL PERCENTILE FOR DAY 8
ACROSS MUCH OF THE CENTRAL CONUS. UNCALIBRATED APPARENT TEMPERATURES FORECAST
APPARENT TEMPERATURES SLOWLY DECLINING FROM WEEK-1 INTO WEEK-2 ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS. BY DAY 9, THESE CHANCES ARE SIGNIFICANTLY
REDUCED FOR EXTREME HEAT ACROSS THE SOUTH-CENTRAL AND SOUTHEASTERN CONUS.
THEREFORE, A SLIGHT RISK OF EXTREME HEAT REMAINS POSTED FOR ONLY SEP 12 FOR
THESE REGIONS.
MODEL ENSEMBLES INDICATE A MID-LEVEL TROUGH OFF THE WEST COAST EARLY IN WEEK-2.
THIS MAY COMBINE WITH ENHANCED MOISTURE FROM THE GULF OF CALIFORNIA DUE TO
TROPICAL ACTIVITY OVER THE EASTERN PACIFIC TO GENERATE HEAVY PRECIPITATION OVER
THE NORTH AMERICAN MONSOON REGION. UNCALIBRATED PROBABILITIES FROM THE GEFS AND
ECMWF BOTH INDICATE AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TO EXCEED HALF
AN INCH OVER THE REGION EARLY IN THE FORECAST PERIOD. DETERMINISTIC GUIDANCE IN
PARTICULAR CONTINUES TO SHOW CHANCES FOR HEAVY PRECIPITATION INTO THE
SOUTHWESTERN CONUS EARLY IN THE WEEK-2 PERIOD. THEREFORE, A SLIGHT RISK OF
HEAVY PRECIPITATION IS POSTED FOR SEP 12-14. THIS REGION IS PRONE TO FLASH
FLOODING AND CAUTION SHOULD BE EXERCISED NEAR CANYONS AND CREEK BEDS, AND
ADDITIONAL RAINFALL MAY HAMPER RECOVERY EFFORTS FROM RECENT FLOODING IN THE
GRAND CANYON.
A RAPID ONSET DROUGHT (ROD) RISK REMAINS DESIGNATED FOR PARTS OF THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY AND ADJACENT PORTIONS OF THE CENTRAL
PLAINS, OHIO, TENNESSEE AND MIDDLE MISSISSIPPI VALLEYS, AND SOUTHEAST U.S. AN
AREA OF WESTERN KENTUCKY AND TENNESSEE WAS ADDED TO THE RAPID ONSET DROUGHT
RISK TODAY; AS WITH OTHER AREAS OF THE ROD RISK, THIS AREA HAS SEEN 20% TO 40%
OF NORMAL PRECIPITATION AND DEFICITS OF 1 TO 2 INCHES OVER THE PAST 30 DAYS.
NEAR TO BELOW NORMAL PRECIPITATION AND ABOVE NORMAL TEMPERATURES REMAIN
FORECAST FOR THIS REGION OVER THE NEXT TWO WEEKS INCREASING EVAPOTRANSPIRATION
RATES INTO THE MIDDLE OF SEPTEMBER.
FORECASTER: RYAN BOLT
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