669
FXUS21 KWNC 171822
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 17 2024
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FORECAST ACROSS THE SOUTHERN TIER OF THE
CONTIGUOUS U.S. (CONUS) DURING WEEK-2. THIS FAVORS INCREASED CHANCES FOR
ANOMALOUSLY WARM TEMPERATURES, AND EXCESSIVE HEAT CONDITIONS POSSIBLY AFFECTING
PARTS OF THE SOUTHERN PLAINS AND THE FLORIDA PENINSULA. MID-LEVEL LOW PRESSURE
PREDICTED ACROSS THE NORTHWESTERN AND NORTH-CENTRAL CONUS EARLY IN THE PERIOD
COULD LEAD TO A DISTURBANCE TRAVERSING THE CONUS. THIS SUPPORTS AN INCREASED
LIKELIHOOD FOR HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL AND
EAST-CENTRAL CONUS, ALONG WITH ELEVATED WIND SPEEDS ACROSS THE FOUR CORNERS AND
HIGH PLAINS AS THIS POTENTIAL SYSTEM EJECTS OUT OF THE ROCKIES EARLY IN WEEK-2.
HAZARDS
MODERATE RISK FOR EXCESSIVE HEAT ACROSS SOUTHERN TEXAS SAT-MON, MAY 25-27.
SLIGHT RISK FOR EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHERN PLAINS, SAT-WED,
MAY 25-29.
SLIGHT RISK FOR EXCESSIVE HEAT ACROSS PORTIONS OF THE FLORIDA PENINSULA,
SAT-TUE, MAY 25-28.
SLIGHT RISK FOR HEAVY PRECIPITATION ACROSS PORTIONS OF THE PLAINS, MISSISSIPPI,
TENNESSEE, AND OHIO VALLEYS, GREAT LAKES, AND SOUTHEAST, SAT-MON, MAY 25-27.
SLIGHT RISK FOR HIGH WINDS ACROSS PARTS OF THE FOUR CORNERS AND CENTRAL AND
SOUTHERN HIGH PLAINS, SAT-MON, MAY 25-27.
RAPID ONSET DROUGHT RISK ACROSS THE SOUTHERN FLORIDA PENINSULA AND SOUTHERN
TEXAS.
DETAILED SUMMARY
FOR MONDAY MAY 20 - FRIDAY MAY 24:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY MAY 25 - FRIDAY MAY 31: SUBTROPICAL RIDGING IS FORECAST ACROSS
PORTIONS OF THE SOUTH-CENTRAL CONUS DURING THE WEEK-2 PERIOD. THIS FAVORS
INCREASING CHANCES FOR ANOMALOUSLY WARM TEMPERATURES STRETCHING FROM THE
CENTRAL AND SOUTHERN PLAINS EASTWARD TO THE SOUTHERN MID-ATLANTIC AND SOUTHEAST
COASTS. GIVEN THE TIME OF YEAR, MANY AREAS AWAY FROM THE GULF COAST ARE NOT
EXPECTED TO HAVE TEMPERATURES REACH EXCESSIVE HEAT CRITERIA. STRONGER SIGNALS
FOR EXCESSIVE HEAT ARE ACROSS PORTIONS OF TEXAS WHERE THE GEFS PROBABILISTIC
EXTREMES TOOL (PETS) DEPICTS AT LEAST A 20 PERCENT CHANCE OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE AND 95 DEG F FOR MUCH
OF THE SOUTHERN HALF OF TEXAS. THE STRONGEST PROBABILITIES OF 40 TO 60% ARE
FOUND IN THE RIO GRANDE VALLEY OF SOUTHERN TEXAS. IN THIS REGION, RAW ENSEMBLE
MEANS FROM THE GEFS AND ECENS SHOW DAILY MAXIMUM TEMPERATURES NEAR AND ABOVE
105 DEG F. SUCH TEMPERATURES WOULD NEARLY REACH RECORD HIGHS AT MANY OF THESE
LOCATIONS, WHICH IS ALSO SUPPORTED BY THE NATIONAL BLEND OF MODELS (NBM)
ANALYSIS. BASED ON THIS, AND THE CALIBRATED GEFS HEAT RISK GUIDANCE, WHICH
INDICATES AT LEAST A 30 PERCENT CHANCE OF HEAT INDICES EXCEEDING THE 95TH
CLIMATOLOGICAL PERCENTILE OR 110 DEG F ACROSS PARTS OF SOUTHERN TEXAS, THE
MODERATE RISK FOR EXCESSIVE HEAT IS MAINTAINED FOR MAY 25-27. A BROADER SLIGHT
RISK (20 TO 40% CHANCE) CONTINUES ACROSS MUCH OF THE SOUTHERN HALF OF TEXAS FOR
DAYS 8-12 (MAY 25-29). FOR THE WESTERN SIDE OF THE SLIGHT RISK AREA, EXCESSIVE
HEAT IS LIKELY TO BE TEMPERATURE DRIVEN, BUT HIGHER DEW POINTS FAVORED ACROSS
SOUTHEASTERN TEXAS MAY PUSH HEAT INDICES ABOVE 110 DEG F DESPITE THE RELATIVELY
LOWER TEMPERATURES COMPARED TO THOSE FURTHER WEST.
WITH ABOVE-NORMAL TEMPERATURES STRONGLY FAVORED IN SOUTHERN TEXAS,
PRECIPITATION IS ALSO FORECAST TO BE BELOW-NORMAL DURING WEEK-1 AND 2 ACROSS
PORTIONS OF THE REGION. THERE HAVE BEEN NOTABLE DECLINES IN SOIL MOISTURE
ACROSS SOUTHERN TEXAS IN RECENT WEEKS AND ABNORMALLY DRY CONDITIONS HAVE
EXPANDED OVER THE PAST FEW WEEKS. WITH CONTINUED EXPECTATIONS FOR WARM AND DRY
CONDITIONS, A RAPID ONSET DROUGHT (ROD) RISK IS MAINTAINED FOR THE REGION.
IN FLORIDA, THE GEFS PET IS TRENDING COOLER WITH TEMPERATURES TODAY, CONSISTING
OF PROBABILITIES BETWEEN 20 AND 40% ACROSS MUCH OF THE FLORIDA PENINSULA FOR
TEMPERATURES EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE. RAW ENSEMBLE MEANS
FROM THE GEFS AND ECENS GENERALLY SHOW HIGH TEMPERATURES IN THE MID-90’S DEG F
FOR MUCH OF THE WEEK-2 PERIOD. HOWEVER, THE MID-LEVEL 500-HPA HEIGHTS ARE
GENERALLY REDUCED RELATIVE TO PRIOR DAYS AND ABOVE-NORMAL HEIGHTS RETROGRADE
OVER THE GULF OF MEXICO BY THE MIDDLE OF THE PERIOD. THE NBM IS ALSO LESS
ROBUST IN BOTH IN FORECAST DAILY RECORD HIGH MAXIMUM AND MINIMUM TEMPERATURES
RELATIVE TO PRIOR FORECASTS. THEREFORE, THE MODERATE RISK OF EXCESSIVE HEAT IS
NO LONGER POSTED FOR FLORIDA BUT A SLIGHT RISK OF EXCESSIVE HEAT REMAINS FOR
MAY 25-28 ACROSS THE SOUTHERN HALF OF THE FLORIDA PENINSULA. DECREASING SOIL
MOISTURE AND A WARM DRY PATTERN PREDICTED IN WEEK-1 AND 2 SUPPORT A ROD HAZARD
ACROSS PARTS OF SOUTH FLORIDA.
TROUGHING FORECAST ACROSS THE NORTHWESTERN AND NORTH-CENTRAL CONUS FAVORS
BELOW-NORMAL TEMPERATURES ACROSS MUCH OF THE WEST, EXTENDING INTO PARTS OF THE
NORTHERN AND CENTRAL PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEY, AND GREAT
LAKES. THE ECENS AND GEFS DEPICT A SHORTWAVE DISTURBANCE MOVING ACROSS THE
CONUS EARLY IN WEEK-2. GIVEN THE POTENTIAL FOR A STORM SYSTEM TO EJECT OUT OF
THE ROCKIES, A SLIGHT RISK OF HIGH WINDS IS POSTED ACROSS PARTS OF THE FOUR
CORNERS AND CENTRAL AND SOUTHERN HIGH PLAINS FOR MAY 25-27. DETERMINISTIC RUNS
FROM THE 0Z GFS AND ECMWF DEPICTING WIND SPEEDS EXCEEDING 25-MPH OVER THESE
AREAS COMBINED WITH THE ANOMALOUSLY DRY CONDITIONS COULD ENHANCE THE WILDFIRE
RISK OVER THE REGION.
ACROSS THE EASTERN CONTIGUOUS U.S. (CONUS), THE ECENS PET AND UNCALIBRATED
ENSEMBLE INDICATE AT LEAST A 20 PERCENT CHANCE OF 3-DAY PRECIPITATION TOTALS
EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE AND 1-INCH ACROSS A BROAD AREA OF
THE CENTRAL AND EAST-CENTRAL CONUS. IN PREVIOUS GUIDANCE, THE GEFS PET HAS BEEN
SOMEWHAT LESS SUPPORTIVE OF THE WETTER SOLUTION PROVIDED BY THE ECENS PET. THE
RAW ENSEMBLE PRECIPITATION GUIDANCE FROM THE GEFS AND ECENS SUPPORTS A SLIGHT
RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE MISSISSIPPI, OHIO, TENNESSEE
VALLEYS, AND SOUTHEAST FOR MAY 25-27. THIS RISK AREA IS SOMEWHAT SMALLER THAN
YESTERDAY DUE TO SLIGHTLY LESS SUPPORT FROM THE RAW PRECIPITATION GUIDANCE
ACROSS THE UPPER MISSISSIPPI VALLEY AND MID-ATLANTIC. THE ECENS MAINTAINS A
MORE ROBUST SCENARIO BRINGING MORE PRECIPITATION FURTHER EAST INTO THE
MID-ATLANTIC AND NORTHEAST. HOWEVER, NO HAZARD IS POSTED FOR THESE REGIONS AT
THIS TIME GIVEN TO REDUCED AGREEMENT FROM THE GEFS.
NO HAZARDS ARE ISSUED FOR ALASKA, WITH NEAR- TO BELOW-NORMAL TEMPERATURE
PROBABILITIES FAVORED FOR MOST OF THE STATE SOUTH OF THE BROOKS RANGE. SNOWMELT
SEASON IS UNDERWAY AND FROZEN RIVERS ARE BEGINNING TO BREAK UP, LEADING TO THE
POTENTIAL FOR RIVER FLOODING RELATED TO ICE-JAMS. HOWEVER, THERE ARE NO
INDICATIONS OF IMPENDING MAJOR RIVER BREAK-UPS OR SERIOUS THREAT OF ICE-JAMMING
SO NO FLOODING-RELATED HAZARDS ARE POSTED AT THIS TIME. CAUTION SHOULD CONTINUE
TO BE EXERCISED AS RIVER BREAK-UP CAN BE UNPREDICTABLE AND LOCAL CONDITIONS CAN
CHANGE QUICKLY. ANOMALOUS RIDGING OVER THE NORTH-CENTRAL PACIFIC FAVORS AN
ENHANCED STORM TRACK INTO WESTERN MAINLAND ALASKA, ALTHOUGH PRECIPITATION
AMOUNTS ARE EXPECTED TO REMAIN LOW AND NOT REACH HAZARDOUS THRESHOLDS.
FORECASTER: RYAN BOLT
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