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FXUS21 KWNC 121913
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 12 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 SOME PRECIPITATION ALTHOUGH 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, TUE-THU, AUG 20-22.
SLIGHT RISK OF EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHERN PLAINS, LOWER
MISSISSIPPI AND TENNESSEE VALLEYS AND SOUTHEAST, TUE-MON, AUG 20-26.
RAPID ONSET DROUGHT RISK FOR PORTIONS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR THURSDAY AUGUST 15 - MONDAY AUGUST 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY AUGUST 20 - MONDAY AUGUST 26: THERE IS 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 PROMOTING
ANOMALOUS WARMTH ACROSS THE INTERIOR WEST AND SOUTHEASTERN CONUS. A MODERATE
RISK OF EXCESSIVE HEAT IS DESIGNATED FOR PORTIONS OF THE SOUTHEAST, LOWER
MISSISSIPPI VALLEY, AND SOUTHERN PLAINS, AUG 20-22. THERE IS GREATEST AGREEMENT
AMONG THE GEFS AND ECENS PROBABILISTIC EXTREMES TOOLS (PET) AND HEAT TOOLS OVER
NEW MEXICO AND THE SOUTHERN PLAINS OF CHANCES BETWEEN 40-60% OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH PERCENTILE AND 100 DEG F WITH HIGHER HEAT
INDICES. THE NATIONAL BLEND OF MODELS (NBM) INDICATES THE POTENTIAL FOR NEAR
RECORD BREAKING TEMPERATURES DURING THE HIGHLIGHTED RISK PERIOD, WITH THE
POTENTIAL FOR SOME LOCATIONS ACROSS SOUTHERN TEXAS REACHING 108 DEG F. THE
MODERATE RISK OF EXCESSIVE HEAT IS SLIGHTLY DECREASED IN COVERAGE OVER THE
LOWER MISSISSIPPI VALLEY AND SOUTHEAST DUE TO DECREASING HEAT SIGNALS OVER THE
REGION, AND IS PRIMARILY BASED ON THE PROBABILITIES OF THE ECENS PET. MODELS
INDICATE GRADUAL WEAKENING OF THIS RIDGE BY THE END OF THE PERIOD, ALTHOUGH
THIS PATTERN RESEMBLES AN OMEGA BLOCK, WHICH COULD RESULT IN A STRONGER RIDGE
AND RESULTANT HEAT SIGNALS PERSISTING LONGER THAN IS CURRENTLY DEPICTED IN THE
MODELS. ADDITIONALLY, THE GEFS AND 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, ALTHOUGH THE ECENS IS LESS SUPPORTIVE.
THIS AREA WILL BE MONITORED FOR POSSIBLE DESIGNATION OF HEAT RISK IN THE
UPCOMING DAYS.
MID-LEVEL TROUGHING OVER THE EAST SUPPORTS A COLD FRONT OVER THE COAST FROM THE
END OF WEEK-1 INTO THE BEGINNING OF WEEK-2. THE MAJORITY OF HEAVY PRECIPITATION
IS ANTICIPATED TO OCCUR PRIOR TO WEEK-2, THUS NO ASSOCIATED PRECIPITATION
HAZARDS ARE DESIGNATED AT THIS TIME. THE POSSIBLE FLOODING HAZARD IS THUS ALSO
REMOVED IN TODAY’S OUTLOOK, ALTHOUGH LOCALIZED AREAS MAY CONTINUE TO EXPERIENCE
LINGERING FLOODING, EVEN WITH PRECIPITATION AMOUNTS NOT REACHING HAZARDOUS
THRESHOLDS GIVEN CURRENT ONGOING FLOODING AND PRECIPITATION DURING WEEK-1.
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. THE SPATIAL COVERAGE HAS
BEEN EXPANDED SLIGHTLY ACROSS TEXAS AND ARKANSAS DUE TO INCREASING DRYNESS IN
THE TOPSOIL. MEANWHILE, THE NORTHWARD EXTENT OF THE ROD RISK IS SLIGHTLY
DECREASED ACROSS SOUTHEASTERN OKLAHOMA WHERE HEAVY PRECIPITATION (GREATER THAN
ONE INCH) HAS OCCURRED IN THE LAST 24 HOURS.
MID-LEVEL TROUGHING IS PREDICTED DURING WEEK-2 OVER WESTERN ALASKA, 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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