614
FXUS21 KWNC 021850
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 02 2024
SYNOPSIS: A BROAD MID-LEVEL RIDGE IS PREDICTED TO EXTEND FROM THE NORTH-CENTRAL
CONTIGUOUS U.S. (CONUS) TO THE SOUTHWESTERN STATES, AND FAVORS EXCESSIVE HEAT
OVER THE NORTHERN ROCKIES AND THE NORTHERN GREAT PLAINS DURING THE FIRST FEW
DAYS OF THE FORECAST PERIOD. HEAVY PRECIPITATION IS FAVORED ALONG AND NEAR THE
GULF AND SOUTHERN ATLANTIC COASTS DURING THE FIRST HALF OF WEEK-2. THERE IS
SIGNIFICANT UNCERTAINTY AS TO THE DEVELOPMENT AND FUTURE TRACKS OF TROPICAL
SYSTEMS DURING THIS FORECAST PERIOD. DESPITE THE UNCERTAINTY, IT WOULD BE
PRUDENT FOR INTERESTS ALONG THE GULF COAST TO KEEP UPDATED WITH THE LATEST
TROPICAL WEATHER CONDITIONS AS WE MOVE PAST THE CLIMATOLOGICAL PEAK OF THE
ATLANTIC HURRICANE SEASON.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT FOR THE NORTHERN HIGH PLAINS, TUE-THU, SEP
10-12.
SLIGHT RISK FOR THE NORTHERN ROCKIES AND THE NORTHERN PLAINS, TUE-FRI, SEP
10-13.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE GULF AND SOUTHERN ATLANTIC COASTS,
TUE-FRI, SEP 10-13.
SLIGHT RISK OF HIGH WINDS OVER THE NORTHERN AND CENTRAL HIGH PLAINS, TUE-FRI,
SEP 10-13.
RISK FOR RAPID ONSET DROUGHT FOR PORTIONS OF THE OHIO AND MIDDLE MISSISSIPPI
VALLEY.
DETAILED SUMMARY
FOR THURSDAY SEPTEMBER 05 - MONDAY SEPTEMBER 09:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY SEPTEMBER 10 - MONDAY SEPTEMBER 16: AN ANOMALOUS MID-LEVEL RIDGE IS
PREDICTED TO EXTEND FROM HUDSON BAY, CANADA, ACROSS THE NORTH-CENTRAL CONUS,
AND INTO THE SOUTHWEST. MAXIMUM 500-HPA HEIGHTS ACROSS THE UNITED STATES RANGE
FROM 60-90 METERS ABOVE NORMAL OVER THE NORTHERN PLAINS, WITH HIGHER HEIGHTS
NORTH OF THE CANADIAN BORDER. ANOTHER ANOMALOUS RIDGE IS FORECASTED SOUTH OF
THE ALEUTIANS, WITH MAXIMUM HEIGHTS GREATER THAN 120 METERS ABOVE NORMAL. WEAK
MID-LEVEL TROUGHS ARE PREDICTED FROM WESTERN ALASKA SOUTHEASTWARD ACROSS THE
GULF OF ALASKA AND FAR EASTERN PACIFIC, AND OVER THE EASTERN CONUS.
A MODERATE RISK (40-60%) OF EXCESSIVE HEAT IS DEPICTED OVER THE NORTHERN HIGH
PLAINS, SEP 10-12. THIS IS ASSOCIATED WITH THE PROXIMITY OF A MODERATELY STRONG
ANOMALOUS RIDGE AND POSITIVE HEIGHT DEPARTURES IN THAT REGION, AND ANTICIPATED
DOWNSLOPE FLOW. A SLIGHT RISK (20-40%) OF EXCESSIVE HEAT IS FAVORED FOR THE
NORTHERN ROCKIES AND NORTHERN PLAINS, SEP 10-13, RELATED TO THE MID-LEVEL RIDGE
AND POSITIVE HEIGHT ANOMALIES PREDICTED OVER THAT AREA. WITHIN THE MODERATE
RISK AREA OF EXCESSIVE HEAT NOTED ABOVE, 2-METER TEMPERATURES ARE PREDICTED BY
THE ECENS AND GEFS MODELS TO RANGE FROM 15-20 DEGREES F ABOVE NORMAL, WITH AT
LEAST A 20% CHANCE THAT DAYTIME HIGH TEMPERATURES WILL EXCEED 95F. THE MAIN
DIFFERENCE BETWEEN THE ECENS AND GEFS IS THE APPROXIMATE TIME FRAME WHEN THE
FAVORED TEMPERATURE ANOMALIES ARE MOST LIKELY TO OCCUR, WITH THE GEFS EXTENDING
THIS PERIOD AT LEAST ANOTHER DAY OR TWO BEYOND WHAT THE ECENS IS PREDICTING,
AND FORECASTING AN EASTWARD SHIFT OF THE RELATIVE WARMTH INTO EASTERN PORTIONS
OF THE NORTHERN AND CENTRAL PLAINS AND ADJACENT MISSISSIPPI VALLEY.
A SLIGHT RISK OF HEAVY PRECIPITATION HAS BEEN POSTED ALONG/NEAR THE GULF AND
SOUTHERN ATLANTIC COASTS FROM SEP 10-13, ASSOCIATED WITH A QUASI-STATIONARY,
WEAKENING BAROCLINIC ZONE. THREE-DAY PRECIPITATION AMOUNTS ARE FAVORED TO
EXCEED THE 85TH PERCENTILE OF THE HISTORICAL DISTRIBUTION, AND REACH AT LEAST 1
INCH. MANY ENSEMBLE MEMBERS FORECAST A TROPICAL DISTURBANCE TO EMERGE FROM THE
WESTERN CARIBBEAN MOVING INTO THE GULF OF MEXICO AT THE BEGINNING OF THE WEEK-2
PERIOD. UNFORTUNATELY, THERE IS LITTLE TO NO CLUSTERING OF ENSEMBLE MEMBERS OF
BOTH THE ECENS AND GEFS, AND THERE IS LARGE SPREAD IN THE FORECAST TRACK OF
THESE POTENTIAL TROPICAL DISTURBANCES. AT THIS TIME, IT IS UNCLEAR AS TO WHICH
OF THESE SURFACE LOW PRESSURE CENTERS (IF ANY) MAY DEVELOP INTO A TROPICAL
STORM OR HURRICANE, AND WHICH AREA(S) ALONG THE GULF COAST ARE MOST VULNERABLE.
THERE IS A SLIGHT RISK OF HIGH WINDS (>85TH PERCENTILE AND >20 MPH) OVER
PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS, SEP 10-13. THIS IS ASSOCIATED
WITH EXPECTED DOWNSLOPE FLOW AND POSSIBLE LEE CYCLOGENESIS OVER THIS REGION.
THESE WIND SPEEDS, COUPLED WITH LOW DEW POINTS AND THE EXCESSIVE HEAT NOTED
EARLIER LEAD TO AN INCREASED RISK OF WILDFIRES DURING THIS PERIOD.
THE POTENTIAL FOR RAPID ONSET DROUGHT CONTINUES OVER PARTS OF THE OHIO AND
MIDDLE MISSISSIPPI VALLEY. SOIL MOISTURE VALUES IN THIS REGION ARE WITHIN THE
LOWEST QUARTILE (AND IN SOME CASES, DECILE) OF THE HISTORICAL DISTRIBUTION.
PRECIPITATION DEFICITS WITHIN THE LAST 90 DAYS HAVE MOUNTED FROM ONE TO AS MUCH
AS SIX INCHES.
IN ALASKA, THE SOUTHERN COAST IS FAVORED TO GET ABOVE NORMAL PRECIPITATION
DURING THE WEEK-2 PERIOD, WITH UP TO 2 INCHES PREDICTED BY THE ENSEMBLE MEANS.
HOWEVER, THIS FALLS SOMEWHAT SHORT OF THE HAZARDOUS PRECIPITATION CRITERION FOR
THIS AREA (NEAR 3 INCHES), AND THEREFORE NO HAZARD IS POSTED.
FORECASTER: ANTHONY ARTUSA
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