318
FXUS21 KWNC 221815
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 22 2024
SYNOPSIS: A COLD FRONT IS FORECAST TO PROGRESS SOUTHWARD ACROSS THE CENTRAL AND
EASTERN CONTIGUOUS U.S. (CONUS) NEXT WEEK WHICH IS LIKELY TO BRING HEAT RELIEF
INITIALLY TO TEXAS AND THEN FLORIDA. FROM MAY 30 TO JUNE 1, SOUTHEASTERLY FLOW
AND A WARM FRONT SHIFTING NORTHWARD IS EXPECTED TO PROMOTE THUNDERSTORMS WITH
LOCALLY HEAVY RAINFALL ACROSS THE SOUTH-CENTRAL GREAT PLAINS. BEYOND JUNE 1, A
MORE ZONAL FLOW PATTERN IS FORECAST THROUGHOUT THE CONUS WHICH DECREASES
FORECAST CONFIDENCE WITH NO HAZARDS POSTED LATER IN WEEK-2. A DEEP MID-LEVEL
LOW FAVORS ABOVE-NORMAL PRECIPITATION ACROSS ALASKA.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT FOR THE SOUTHEASTERN FLORIDA PENINSULA, THU,
MAY 30.
SLIGHT RISK OF EXCESSIVE HEAT FOR THE CENTRAL AND SOUTHERN FLORIDA PENINSULA,
THU-SAT, MAY 30-JUN 1.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE CENTRAL AND SOUTHERN GREAT
PLAINS, THU-SAT, MAY 30-JUN 1.
RAPID ONSET DROUGHT RISK ACROSS THE SOUTHERN FLORIDA PENINSULA AND SOUTHERN
TEXAS.
DETAILED SUMMARY
FOR SATURDAY MAY 25 - WEDNESDAY MAY 29:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MAY 30 - WEDNESDAY JUNE 05: MODEL GUIDANCE REMAINS CONSISTENT AND
IN GOOD AGREEMENT THAT A RELATIVELY STRONG COLD FRONT FOR LATE MAY SHIFTS SOUTH
OF THE RIO GRANDE VALLEY AND INTO THE GULF OF MEXICO PRIOR TO THE START OF
WEEK-2, MAY 30TH. THIS COLD FRONT IS LIKELY TO END THE EARLY SEASON HEAT WAVE
ACROSS THE SOUTH-CENTRAL CONUS. ANY MODERATION IN TEMPERATURES ACROSS THE
FLORIDA PENINSULA IS EXPECTED TO BE SLOWER AND THE UNCALIBRATED GEFS ENSEMBLE
MEAN ON MAY 30 DEPICTS MAXIMUM TEMPERATURES OF NEAR 95 DEGREES F FOR SOUTH
FLORIDA. THE NATIONAL BLEND OF MODELS IS SHOWING NEAR OR RECORD HIGHS FOR MIAMI
ON THAT DAY AS WELL. THEREFORE, A MODERATE RISK OF EXCESSIVE HEAT IS MAINTAINED
THROUGH MAY 30TH. BASED ON THE GEFS PROBABILISTIC EXTREMES TOOL (PET) AND ITS
FORECAST OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE, A SLIGHT RISK
OF EXCESSIVE HEAT IS POSTED FOR THE SOUTHERN HALF OF THE FLORIDA PENINSULA
THROUGH JUNE 1. BEYOND THAT TIME, SLIGHTLY COOLER TEMPERATURES ARE EXPECTED DUE
TO LOWER 500-HPA HEIGHTS AND AN EXPECTED INCREASE IN SEA BREEZE CONVECTION.
ALTHOUGH ABOVE-NORMAL TEMPERATURES ARE FORECAST FOR THE INTERIOR WEST
THROUGHOUT WEEK-2, EXCESSIVE HEAT IS NOT ANTICIPATED AT THIS TIME WITH THE GEFS
AND ECMWF ENSEMBLE MEANS GENERALLY SHOW MAXIMUM TEMPERATURES RANGING FROM THE
80S (GREAT BASIN) TO 100-105 DEGREES F (DESERT SOUTHWEST). LATER IN WEEK-2,
THERE ARE SIGNS THAT THE MID-LEVEL RIDGE STRENGTHENS AGAIN OVER THE
SOUTH-CENTRAL CONUS. IF ENSEMBLE MEANS REMAIN CONSISTENT, THEN AN EXCESSIVE
HEAT HAZARD MAY BE WARRANTED FOR THIS REGION IN SUBSEQUENT OUTLOOKS.
THE COLD FRONT, WHICH BRINGS HEAT RELIEF, IS EXPECTED TO RETREAT BACK TO THE
NORTH AND MAY BECOME A STATIONARY FRONT CENTERED OVER THE SOUTHERN OR CENTRAL
GREAT PLAINS. THIS STATIONARY FRONT ALONG WITH SOUTHEASTERLY SURFACE LOW FAVORS
THE INITIATION OF THUNDERSTORMS ACROSS THE HIGH PLAINS. GIVEN THE TIME OF YEAR
AND NORTHWEST FLOW ALOFT, THESE THUNDERSTORMS COULD EVOLVE INTO A MESOSCALE
CONVECTIVE SYSTEM (MCS) SPREADING EASTWARD THROUGH KANSAS, OKLAHOMA, AND
NORTHERN TEXAS. THE UNCALIBRATED ECMWF ENSEMBLE MEAN REMAINS CONSISTENT WITH
PROBABILITIES OF 20 TO 50 PERCENT FOR MORE THAN 1 INCH IN THE DESIGNATED AREA
FOR A SLIGHT RISK OF HEAVY PRECIPITATION. BASED ON 24-HOUR PRECIPITATION
AMOUNTS FROM THE GEFS AND ECMWF ENSEMBLE MEANS, THE VALID PERIOD IS FROM MAY 30
TO JUNE 1. GIVEN THE TIME OF YEAR AND WET ANTECEDENT CONDITIONS FOR PARTS OF
THE REGION, THERE IS A FLASH FLOODING RISK WITH ANY LOCALLY HEAVY RAINFALL.
ALTHOUGH THE PREDICTED LONGWAVE PATTERN WOULD NOT SUPPORT ANY WIDESPREAD HIGH
WIND EVENTS FOR THE SOUTHWEST AND SOUTHERN HIGH PLAINS, THESE AREAS WILL BE
CLOSELY MONITORED FOR A HIGH WIND POTENTIAL AS WILDFIRE DANGER IS EXPECTED TO
REMAIN ELEVATED HEADING INTO WEEK-2.
THE GREATEST RISK FOR RAPID ONSET DROUGHT (ROD) DURING THE REMAINDER OF MAY
INTO EARLY JUNE EXISTS FOR SOUTHERN PARTS OF FLORIDA AND TEXAS. THE ROD HAZARDS
ARE BASED ON 30 TO 60-DAY PRECIPITATION DEFICITS, LOW SOIL MOISTURE, AND
CONTINUED DRYNESS AND ABOVE-NORMAL TEMPERATURES INTO THE BEGINNING OF JUNE.
THESE ROD AREAS WILL BE REASSESSED ON THURSDAY, MAY 23.
MULTI-MODEL ENSEMBLE MEANS ARE IN EXCELLENT AGREEMENT THAT A DEEP 500-HPA
CLOSED LOW DEVELOPS OVER THE ALEUTIANS AND SOUTHWESTERN ALASKA BY THE BEGINNING
OF JUNE. THIS ANOMALOUS MID-LEVEL TROUGH IS LIKELY TO ENHANCE ONSHORE FLOW TO
SOUTHERN ALASKA WHERE ABOVE-NORMAL PRECIPITATION IS FAVORED. SINCE THE GEFS AND
ECMWF PETS DEPICT PROBABILITIES OF LESS THAN 20 PERCENT FOR 3-DAY PRECIPITATION
AMOUNTS TO EXCEED 2 INCHES, A HEAVY PRECIPITATION HAZARD IS NOT POSTED.
FORECASTER: BRAD PUGH
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