694
FXUS21 KWNC 131812
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 13 2024
SYNOPSIS: EXCESSIVE HEAT IS FORECAST TO CONTINUE INTO THE WEEK-2 PERIOD ACROSS
PORTIONS OF THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND SOUTHEAST
BENEATH MID-LEVEL HIGH PRESSURE CENTERED ACROSS THE CENTRAL CONTIGUOUS U.S.
(CONUS). MID-LEVEL LOW PRESSURE IS PREDICTED WEST AND EAST OF THE MID-LEVEL
HIGH PRESSURE, WHICH COULD SUPPORT ENHANCED PRECIPITATION IN SOME AREAS
ESPECIALLY ALONG THE EAST COAST, ALTHOUGH TOTALS ARE NOT ANTICIPATED TO REACH
HAZARDOUS CRITERIA AT THIS TIME.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHEAST, LOWER
MISSISSIPPI VALLEY, AND SOUTHERN PLAINS, WED-FRI, AUG 21-23.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHERN PLAINS, LOWER
MISSISSIPPI AND TENNESSEE VALLEYS AND SOUTHEAST, WED-TUE, AUG 21-27.
RAPID ONSET DROUGHT RISK FOR PORTIONS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR FRIDAY AUGUST 16 - TUESDAY AUGUST 20:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY AUGUST 21 - TUESDAY AUGUST 27: THERE CONTINUES TO BE GOOD
AGREEMENT AMONG MULTIPLE MODEL ENSEMBLE MEANS INDICATING MID-LEVEL RIDGING
BUILDING ACROSS THE CENTRAL CONUS FROM THE END OF WEEK-1 INTO AND THROUGH
WEEK-2 RESEMBLING AN OMEGA BLOCK. THIS PATTERN SUPPORTS INCREASED CHANCES FOR
ANOMALOUS WARMTH ACROSS THE INTERIOR WEST AND SOUTHEASTERN CONUS. MULTIPLE
MODELS INDICATE RIDGING PEAKING DURING THE END OF WEEK-1 AND GRADUALLY
BROADENING AND WEAKENING WITH TIME.
A MODERATE RISK OF EXCESSIVE HEAT IS CONTINUED FOR PORTIONS OF THE SOUTHEAST,
LOWER MISSISSIPPI VALLEY, AND SOUTHERN PLAINS, AUG 21-23. THE ECENS (GEFS)
PROBABILISTIC EXTREMES TOOL (PET) SHOWS A 60-70% (50-60%) CHANCE OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH PERCENTILE OVER NEW MEXICO AND TEXAS ON DAY 8
(AUG 21), WITH HEAT INDEX VALUES ANTICIPATED TO EXCEED TRIPLE DIGITS (DEG F).
THE NATIONAL BLEND OF MODELS (NBM) INDICATES THE POTENTIAL FOR NEAR RECORD
BREAKING TEMPERATURES ACROSS TEXAS AND COASTAL PORTIONS OF THE LOWER
MISSISSIPPI VALLEY DURING THE HIGHLIGHTED MODERATE RISK PERIOD, ESPECIALLY ON
AUG 21. SOME LOCATIONS ACROSS SOUTHERN TEXAS MAY REACH 108 DEG F. THE MODERATE
RISK OF EXCESSIVE HEAT IS SLIGHTLY DECREASED IN COVERAGE OVER ALABAMA DUE TO
DECREASING HEAT SIGNALS OVER THE REGION. BY DAY 9 (AUG 22) PROBABILITIES ARE
DECREASED COMPARED TO DAY 8 AND LIMITED TO TEXAS AND NEW MEXICO. A BROADER
SLIGHT RISK IS HIGHLIGHTED ACROSS THE SOUTHEAST, LOWER MISSISSIPPI VALLEY, AND
SOUTHERN PLAINS THROUGHOUT WEEK-2, WHERE TOOLS HAVE AT LEAST A 20% CHANCE OF
EXCEEDING HAZARDOUS CRITERIA. ADDITIONALLY, THE GEFS AND ECENS PETS SHOW AT
LEAST A 20% CHANCE OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE AND 95
DEG F ACROSS THE NORTHERN HIGH PLAINS AT THE BEGINNING OF WEEK-2, PRIMARILY ON
DAY 10 (AUG 23). DUE TO THE EXPECTATION OF HAZARDOUS HEAT BEING FAIRLY SHORT
LIVED AND RECENT MODEL RUN SOLUTIONS SHOWING WEAKER POSITIVE TEMPERATURE
ANOMALIES IN THE REGION, AN ASSOCIATED HEAT HAZARD IS NOT DESIGNATED AT THIS
TIME.
MID-LEVEL TROUGHING OVER THE EAST SUPPORTS THE POTENTIAL FOR A SERIES OF FRONTS
ACROSS THE COAST DURING THE PERIOD WHICH COULD BRING ENHANCED PRECIPITATION TO
SOME AREAS, ESPECIALLY THE NORTHEAST, CAROLINAS, AND SOUTHEAST. PRECIPITATION
AMOUNTS ARE NOT EXPECTED TO REACH HAZARDOUS THRESHOLDS BUT COULD CONTINUE
LOCALIZED FLOODING ACROSS THE CAROLINAS, COASTAL GEORGIA AND NORTHERN FLORIDA
WHERE THE NATIONAL WATER CENTER (NWC) HIGHLIGHTS CONSIDERABLE FLOOD IMPACTS FOR
THE 4-7 DAY PERIOD.
BELOW-NORMAL RAINFALL ANTICIPATED OVER MUCH OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY DURING WEEK-2, COMBINED WITH INCREASED LIKELIHOOD OF
EXCESSIVE HEAT AND BELOW-NORMAL 30-DAY ACCUMULATED PRECIPITATION, RESULTS IN AN
ELEVATED RISK OF RAPID ONSET DROUGHT (ROD) ACROSS PORTIONS OF THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY SUPPORTED BY DECLINING SOIL MOISTURE VALUES
AND DRY CONDITIONS FAVORED OVER THE NEXT TWO WEEKS.
MID-LEVEL TROUGHING IS PREDICTED TO SHIFT EASTWARD FROM THE WEST COAST TO
INTERIOR ALASKA DURING WEEK-2, SUPPORTING INCREASED CHANCES FOR ABOVE NORMAL
PRECIPITATION ACROSS MUCH OF THE STATE EXCLUDING THE SOUTHERN TIER. CONDITIONS
ARE NOT ANTICIPATED TO REACH HAZARDOUS CRITERIA DURING THE PERIOD.
FORECASTER: MELISSA OU
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