956
FXUS21 KWNC 061726
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 06 2026
SYNOPSIS: MODEL ENSEMBLES CONTINUE TO FAVOR ANOMALOUS MID-LEVEL HIGH PRESSURE
ACROSS THE SOUTHERN AND CENTRAL CONTIGUOUS U.S. (CONUS) AND ABOVE-NORMAL
TEMPERATURES ACROSS MOST OF THE LOWER 48, ALTHOUGH THE RISK OF EXTREME HEAT
APPEARS TO BE DIMINISHING AS WE MOVE INTO THE SECOND HALF OF SEPTEMBER. 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 HEAVY PRECIPITATION FOR PORTIONS OF THE DESERT SOUTHWEST AND
GREAT BASIN, MON-FRI, SEP 14-18.
FLOODING POSSIBLE FOR PORTIONS OF THE DESERT SOUTHWEST AND GREAT BASIN.
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 WEDNESDAY SEPTEMBER 09 - SUNDAY SEPTEMBER 13:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR MONDAY SEPTEMBER 14 - SUNDAY SEPTEMBER 20: DYNAMICAL MODEL GUIDANCE REMAINS
IN GOOD AGREEMENT REGARDING ELEVATED 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. HOWEVER, OVER
THE LAST SEVERAL DAYS MODEL CONSENSUS HAS BEEN GRADUALLY MOVING AWAY FROM
SUPPORT FOR EXTREME HEAT HAZARDS. THE PROBABILISTIC EXTREMES TOOLS (PETS) SHOW
VERY LITTLE POTENTIAL FOR MAXIMUM TEMPERATURES TO EXCEED THE 95TH
CLIMATOLOGICAL PERCENTILE (THE FAVORED THRESHOLD DURING SHOULDER SEASONS) AT
ANY POINT IN THE FORECAST PERIOD, AND DAILY ENSEMBLE CALCULATED HEAT INDICES NO
LONGER SHOW MUCH SIGNAL ABOVE 105F. THEREFORE THE SLIGHT RISK OF EXTREME HEAT
FROM PREVIOUS OUTLOOKS HAS BEEN DISCONTINUED. HOWEVER, TEMPERATURES ARE LIKELY
TO REMAIN WELL ABOVE-NORMAL FOR MUCH OF THE SOUTHEASTERN QUARTER OF THE CONUS,
AND THOSE SENSITIVE TO HEAT SHOULD CONTINUE TO EXERCISE CAUTION.
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 TOTALS TO
EXCEED HALF AN INCH OVER THE REGION THROUGH THE MIDDLE OF THE FORECAST PERIOD.
SIMILARLY, BOTH PETS INDICATE AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TO
EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE FOR MUCH OF WEEK-2. THEREFORE, A
SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED FOR SEP 14-18. ADDITIONALLY, GIVEN
THE CONTINUED AND INCREASING INDICATIONS OF POTENTIAL HEAVY PRECIPITATION, A
FLOODING POSSIBLE HAZARD IS POSTED FOR PORTIONS OF THE FOUR CORNERS REGION
DURING THE WEEK-2 PERIOD. 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. 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: DANNY BARANDIARAN
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