764
FXUS21 KWNC 011831
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 01 2024
SYNOPSIS: PRIOR TO WEEK-2, A COLD FRONT IS FORECAST TO BRING COOLER-THAN-NORMAL
TEMPERATURES TO THE NORTHERN GREAT PLAINS AND MIDWEST. UPSLOPE FLOW IS EXPECTED
TO RESULT IN THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL AND A FLASH FLOOD RISK
FOR THE COLORADO FRONT RANGE FROM AUGUST 9 TO 11. FARTHER TO THE SOUTH, A BROAD
AREA OF MID-LEVEL HIGH PRESSURE IS FORECAST TO PERSIST THROUGH MID-AUGUST,
WHICH RESULTS IN AN ELEVATED RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE
SOUTHERN GREAT PLAINS. LATER IN WEEK-2, THIS EXCESSIVE HEAT RISK MAY EXPAND
NORTHEAST TO THE MIDDLE MISSISSIPPI VALLEY. A TROPICAL CYCLONE (TC) MAY DEVELOP
NEAR THE FLORIDA PENINSULA OR OVER THE EASTERN GULF OF MEXICO BY EARLY NEXT
WEEK. UNCERTAINTY REMAINS HIGH ON ITS EVENTUAL STRENGTH, TRACK, AND IMPACTS.
HAZARDS
SLIGHT RISK OF EXCESSIVE HEAT FOR PARTS OF THE SOUTH-CENTRAL U.S., FRI-THU, AUG
9-15.
RAPID ONSET DROUGHT RISK FOR SOUTHWESTERN OKLAHOMA AND NORTHWESTERN TEXAS.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE COLORADO FRONT RANGE, FRI-SUN, AUG
9-11.
FLOODING POSSIBLE FOR THE COLORADO FRONT RANGE.
SLIGHT RISK OF HIGH WINDS FOR COASTAL AREAS OF THE SOUTHEAST, FRI-SAT, AUG 9-10.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHEAST, FRI-MON, AUG
9-12.
DETAILED SUMMARY
FOR SUNDAY AUGUST 04 - THURSDAY AUGUST 08:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY AUGUST 09 - THURSDAY AUGUST 15: A BROAD 500-HPA RIDGE OF MODERATE
STRENGTH FOR EARLY TO MID-AUGUST IS FORECAST ACROSS THE SOUTHERN GREAT PLAINS
THROUGH THE ENTIRETY OF WEEK-2. BASED ON ITS STRENGTH AND THE CALIBRATED HEAT
INDEX TOOL DEPICTING A 20 TO 40 PERCENT CHANCE OF HEAT INDEX VALUES TO EXCEED
THE 90TH PERCENTILE AND 105 DEGREES F, A SLIGHT RISK OF EXCESSIVE HEAT IS
POSTED FOR PARTS OF THE SOUTH-CENTRAL U.S. FROM AUG 9-15. THE ECMWF ENSEMBLE
MEAN FAVORS 500-HPA HEIGHTS INCREASING NORTHEASTWARD OVER THE MIDDLE
MISSISSIPPI VALLEY AND OHIO VALLEY LATER IN WEEK-2, BUT THE GEFS MAINTAINS NEAR
NORMAL 500-HPA HEIGHTS FOR THESE AREAS. IF MODEL AGREEMENT IMPROVES, A BROADER
SLIGHT RISK OF EXCESSIVE HEAT LATER IN WEEK-2 MAY BE WARRANTED.
A RAPID ONSET DROUGHT (ROD) RISK IS POSTED FOR SOUTHWESTERN OKLAHOMA AND
NORTHWESTERN TEXAS DUE TO: INCREASING 14 TO 30-DAY PRECIPITATION DEFICITS,
DECLINING SOIL MOISTURE, AND THE LIKELIHOOD FOR ABOVE-NORMAL TEMPERATURES WITH
HIGH EVAPOTRANSPIRATION RATES DURING THE NEXT TWO WEEKS OR MORE. THE WEEK-2
PRECIPITATION OUTLOOK ONLY SLIGHTLY FAVORS ABOVE-NORMAL PRECIPITATION AND THE
NEXT WEEK IS FORECAST TO BE COMPLETELY DRY. ALTHOUGH DROUGHT MAY DEVELOP ACROSS
PARTS OF THE CENTRAL TO NORTHERN GREAT PLAINS EARLY IN AUGUST, THE ROD RISK
FROM LAST WEEK WAS DISCONTINUED SINCE A 2-CATEGORY DEGRADATION IN THE U.S.
DROUGHT MONITOR IS NOT EXPECTED DUE TO THE PREDICTED COOLER, WETTER PATTERN
FORECAST DURING WEEK-2.
EARLY IN WEEK-2, A FRONT IS EXPECTED TO BECOME STATIONARY ACROSS THE CENTRAL
GREAT PLAINS AND MIDDLE MISSISSIPPI VALLEY. UPSLOPE FLOW COUPLED WITH ENHANCED
MONSOONAL MOISTURE IS EXPECTED TO PROMOTE DIURNAL CONVECTION WITH LOCALLY HEAVY
RAINFALL ACROSS THE COLORADO ROCKIES. BASED ON GOOD MODEL CONSISTENCY ON THIS
PATTERN SETUP AND CONCERN FOR FLASH FLOODING WITH ANY HEAVY RAINFALL ESPECIALLY
OVER BURN SCAR AREAS, A SLIGHT RISK OF HEAVY PRECIPITATION AND A POSSIBLE
FLOODING HAZARD ARE POSTED FOR PARTS OF COLORADO FRONT RANGE FROM AUG 9-11.
SINCE THE GEFS AND ECMWF ENSEMBLE MEANS DIFFER ON THE PLACEMENT OF WHERE THE
HEAVIEST PRECIPITATION OCCURS FARTHER TO THE EAST, NO PRECIPITATION HAZARD IS
POSTED ACROSS THE NORTH-CENTRAL U.S.
THE NATIONAL HURRICANE CENTER (NHC) IS MONITORING A WELL-DEFINED TROPICAL WAVE
OVER THE VIRGIN ISLANDS, PUERTO RICO, AND HISPANIOLA. NHC STATES THAT THERE IS
A 70 PERCENT CHANCE OF TROPICAL CYCLONE (TC) DEVELOPMENT NEAR THE FLORIDA
PENINSULA OR OVER THE EASTERN GULF OF MEXICO BY EARLY NEXT WEEK. THE LATEST
ECMWF ENSEMBLE MEMBERS HAVE SHIFTED THE MOST LIKELY TRACK FROM NEAR THE
SOUTHEAST COAST TO THE GULF OF MEXICO. THE GEFS AND ECMWF ENSEMBLE MEMBERS
CONTINUE TO OFFER A WIDE RANGE OF SOLUTIONS ON ITS TRACK, ANYWHERE FROM
LOUISIANA TO THE EASTERN CAROLINAS OR OFFSHORE OF THE EAST COAST. GIVEN THE
CONTINUED LARGE FORECAST UNCERTAINTY, A BROAD AREA IS HIGHLIGHTED WITH A SLIGHT
RISK OF HEAVY PRECIPITATION (AUG 9-12) AND HIGH WINDS (AUG 9-10) ACROSS THE
SOUTHEAST AND GULF COAST.
ANOMALOUS 500-HPA THROUGH OVER THE BERING SEA IS LIKELY TO PROMOTE ENHANCED,
ONSHORE FLOW WITH INCREASED ABOVE-NORMAL PRECIPITATION PROBABILITIES FOR
MAINLAND ALASKA. SINCE PRECIPITATION AMOUNTS ARE EXPECTED TO REMAIN BELOW
HAZARD THRESHOLDS, NO ASSOCIATED HEAVY PRECIPITATION HAZARD IS POSTED. NEAR
JUNEAU, LOCALIZED FLOODING MAY BE A CONCERN ASSOCIATED WITH THE GLACIAL
OUTBURST FLOOD FOR THE MENDENHALL RIVER.
FORECASTER: BRAD PUGH
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