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FXUS21 KWNC 011825
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 01 2024
SYNOPSIS: THERE IS GOOD AGREEMENT BETWEEN MULTIPLE MODEL ENSEMBLE MEANS
INDICATING AMPLIFIED MID-LEVEL HIGH PRESSURE ACROSS THE SOUTH-CENTRAL AND
SOUTHEASTERN CONTIGUOUS U.S. (CONUS) FROM THE BEGINNING TO MIDDLE OF WEEK-2
GRADUALLY WEAKENING BY THE END OF THE PERIOD. THIS PATTERN SUPPORTS INCREASED
RISK OF EXCESSIVE HEAT ACROSS PORTIONS OF THE GULF COAST STATES AND SOUTH
CAROLINA AT THE BEGINNING OF WEEK-2. MID-LEVEL LOW PRESSURE ACROSS THE INTERIOR
WEST MAY SUPPORT HIGH WINDS ACROSS PARTS OF THE SOUTHWESTERN QUADRANT OF THE
CONUS. AHEAD OF THIS MID-LEVEL LOW PRESSURE, A FAIRLY STATIONARY FRONT FAVORS
ENHANCED RISK OF PERIODS OF HEAVY PRECIPITATION ACROSS PARTS OF THE CENTRAL AND
SOUTHERN PLAINS, MIDDLE AND LOWER MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND
SOUTHERN APPALACHIANS WHICH COULD CONTINUE FLOOD RISK IN SOME OF THESE AREAS.
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT FOR PARTS OF THE GULF COAST STATES AND SOUTH
CAROLINA, THU-FRI, MAY 9-10.
SLIGHT RISK OF EXCESSIVE HEAT FOR PARTS OF THE GULF COAST STATES AND SOUTH
CAROLINA, THU-SAT, MAY 9-11.
SLIGHT RISK OF PERIODS OF HEAVY PRECIPITATION ACROSS PARTS OF THE CENTRAL AND
SOUTHERN PLAINS, MIDDLE AND LOWER MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND
SOUTHERN APPALACHIANS, THU-MON, MAY 9-13.
SLIGHT RISK OF EPISODES OF HIGH WINDS FOR PARTS OF THE SOUTHWESTERN QUADRANT OF
THE CONUS, THU-SAT, MAY 9-11.
POSSIBLE FLOODING OVER PARTS OF THE CENTRAL AND SOUTHERN PLAINS AND LOWER AND
MIDDLE MISSISSIPPI VALLEY.
RAPID ONSET DROUGHT RISK OVER PARTS OF THE FLORIDA PENINSULA.
DETAILED SUMMARY
FOR SATURDAY MAY 04 - WEDNESDAY MAY 08:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MAY 09 - WEDNESDAY MAY 15: THE 0Z GEFS AND ECENS ARE IN GOOD
AGREEMENT TODAY INDICATING AMPLIFIED MID-LEVEL RIDGING ACROSS THE SOUTH-CENTRAL
AND SOUTHEASTERN CONUS FROM THE BEGINNING TO MIDDLE OF WEEK-2. A SLIGHT RISK OF
EXCESSIVE HEAT CONTINUES TO BE HIGHLIGHTED ACROSS PARTS OF THE GULF COAST
STATES AND SOUTH CAROLINA, MAY 9 TO 11, WHERE THE GEFS AND ECENS PROBABILISTIC
EXTREMES TOOLS (PETS) SHOW AT LEAST A 20% CHANCE OF MAXIMUM TEMPERATURES
EXCEEDING THE 90TH PERCENTILE, CLIMATOLOGICALLY, AND 90 DEG F (100 DEG F ACROSS
SOUTHWESTERN TEXAS). AN EMBEDDED AREA IS DESIGNATED WITH A MODERATE RISK (40 TO
60% CHANCE), MAY 9-10, SUPPORTED BY BOTH DRY AIR TEMPERATURE AND HEAT INDEX
TOOLS. THE ECENS (GEFS) PET SHOWS AT LEAST A 50% (40%) CHANCE OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH PERCENTILE ACROSS MUCH OF THE MODERATE RISK
AREA. THE NATIONAL BLEND OF MODELS (NBM) SHOWS RELATIVELY WIDESPREAD POTENTIAL
FOR RECORD HIGH TEMPERATURES, MAY 9TH, IN THE LOW TO MID 90S ACROSS THE LOWER
MISSISSIPPI VALLEY AND FLORIDA, WITH TRIPLE DIGITS (DEG F) ACROSS SOUTHWESTERN
TEXAS.
THERE IS BETTER AGREEMENT TODAY COMPARED TO YESTERDAY BETWEEN THE GEFS AND
ECENS ENSEMBLE MEANS REGARDING AMPLIFIED MID-LEVEL TROUGHING ACROSS THE
NORTHWESTERN AND NORTH-CENTRAL CONUS CONTINUING FROM THE END OF WEEK-1 INTO THE
BEGINNING OF WEEK-2, GRADUALLY WEAKENING BY THE LATTER PORTION OF THE PERIOD.
AN INITIAL FRONT IS PREDICTED EXTENDING SOUTHWARD FROM THE GREAT LAKES FOLLOWED
BY A SURFACE LOW EJECTING EASTWARD FROM THE LEE OF THE ROCKIES AHEAD OF THE
MID-LEVEL TROUGH IN THE WEST. THESE DISTURBANCES SUPPORT A SLIGHT RISK FOR
PERIODS OF HEAVY PRECIPITATION ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS,
MIDDLE AND LOWER MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND SOUTHERN
APPALACHIANS, MAY 9 TO 13. THE GEFS AND ECENS PETS INDICATE AT LEAST A 20%
CHANCE OF 3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH PERCENTILE AND ONE INCH
ACROSS THE HIGHLIGHTED RISK AREA. RECENT DETERMINISTIC GFS RUNS SHOW ENHANCED
CONVECTIVE AVAILABLE POTENTIAL ENERGY (CAPE) THAT COULD BE CONDUCIVE FOR
THUNDERSTORMS IN THE HIGHLIGHTED RISK AREA.
SATURATED SOILS IN ADDITION TO EXPECTED ANTECEDENT HEAVY RAINFALL DURING WEEK-1
AND PREDICTED WEEK-2 HEAVY RAINFALL SUPPORTS INCREASED LIKELIHOOD FOR FLOODING
FOR PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS AND LOWER AND MIDDLE
MISSISSIPPI VALLEY. THIS HIGHLIGHTED FLOOD RISK AREA IS BASED ON WHERE THE
NATIONAL WATER CENTER’S EXPERIMENTAL FLOOD OUTLOOK SHOWS POSSIBLE FLOODING
DURING THE 4-7 DAY PERIOD AND WHERE THERE IS A SLIGHT RISK OF HEAVY
PRECIPITATION DURING WEEK-2.
A SERIES OF SURFACE LOWS ARE ANTICIPATED TO FORM OVER THE SOUTHWESTERN CONUS AT
THE BEGINNING OF WEEK-2. THESE DISTURBANCES COMBINED WITH ADJACENT SURFACE HIGH
PRESSURE OVER THE NORTH PACIFIC SUPPORTS AREAS OF TIGHT PRESSURE GRADIENTS AND
RESULTANT INCREASED CHANCES FOR HIGH WINDS ACROSS THE SOUTHWESTERN CONUS. A
SLIGHT RISK OF EPISODIC HIGH WINDS IS DESIGNATED ACROSS PARTS OF THE
SOUTHWESTERN QUADRANT OF THE CONUS, MAY 9-11 BASED ON WHERE BOTH THE GEFS AND
ECENS PETS SHOWS AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH
PERCENTILE AND 20 MPH ACROSS THE HIGHLIGHTED RISK AREA IN ADDITION TO WHERE
RECENT DETERMINISTIC MODEL RUNS INDICATE ENHANCED WIND SPEEDS AND SURFACE LOW
FORMATION. ANTICIPATED INCREASED POTENTIAL FOR HIGH WINDS COMBINED WITH DRY
SOILS AND ANTECEDENT AND EXPECTED DRY CONDITIONS SUPPORTS ENHANCED RISK FOR
WILDFIRES, ESPECIALLY ACROSS THE BIG BEND OF TEXAS, NEW MEXICO, AND ARIZONA,
WHERE THE NATIONAL INTERAGENCY FIRE CENTER (NIFC) SHOWS MODERATE RISK OF
SIGNIFICANT FIRE POTENTIAL BY THE END OF WEEK-1.
IN THE SOUTHEAST, ABOVE-NORMAL TEMPERATURES AND NEAR- TO BELOW-NORMAL
PRECIPITATION IS FORECAST DURING WEEKS 1 AND 2. IN PARTS OF THE CENTRAL FLORIDA
PENINSULA SOIL MOISTURE LEVELS ARE DECLINING DUE TO LIMITED PRECIPITATION IN
RECENT WEEKS AND MONTHS. RECENT WEEKS HAVE SEEN AREAS OF ABNORMAL DRYNESS (D0)
DEVELOPING AND EXPANDING. AS WE APPROACH THE MIDDLE OF MAY, INCREASING SUN
ANGLE AND TEMPERATURES IN THE 80-90 DEG F COULD LEAD TO FURTHER DRYING OF SOILS
AND POTENTIALLY LEAD TO DROUGHT CONDITIONS ACROSS THIS REGION. THEREFORE, AN
AREA OF RAPID ONSET DROUGHT (ROD) IS POSTED FOR PORTIONS OF CENTRAL FLORIDA.
IN ALASKA, AS WE MOVE INTO THE MIDDLE OF MAY SNOWMELT SEASON IS UNDERWAY AND
FROZEN RIVERS WILL BEGIN TO BREAK UP IN THE NEAR FUTURE. THIS LEADS TO THE
POTENTIAL FOR RIVER FLOODING RELATED TO ICE-JAMS. WE CONTINUE TO MONITOR THE
SITUATION BUT CURRENTLY THERE ARE NO INDICATIONS OF IMPENDING MAJOR RIVER
BREAK-UPS SO NO FLOODING-RELATED HAZARDS ARE POSTED AT THIS TIME.
FORECASTER: MELISSA OU
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