169
FXUS21 KWNC 211804
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 21 2025
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FORECAST TO STRENGTHEN OVER THE WEST BY
THE END OF MAY LEADING TO ANOMALOUS WARMTH. THE MOST LIKELY AREA TO EXPERIENCE
EXTREME HEAT WOULD BE THE CENTRAL VALLEY OF CALIFORNIA FROM MAY 29 TO 31. A
STATIONARY FRONT MAY BECOME A FOCUS FOR HEAVY PRECIPITATION ACROSS CENTRAL TO
EASTERN TEXAS AND THE LOWER MISSISSIPPI VALLEY EARLY IN WEEK-2, WHILE THE RISK
OF HEAVY PRECIPITATION INCREASES FOR THE FLORIDA PENINSULA AT THE BEGINNING OF
JUNE.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR THE CENTRAL VALLEY OF CALIFORNIA, THU-SAT, MAY
29-31.
SLIGHT RISK OF HEAVY PRECIPITATION FOR CENTRAL TO EASTERN TEXAS AND THE LOWER
MISSISSIPPI VALLEY, THU-SAT, MAY 29-31.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE FLORIDA PENINSULA, MON-WED, JUNE 2-4.
DETAILED SUMMARY
FOR SATURDAY MAY 24 - WEDNESDAY MAY 28:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MAY 29 - WEDNESDAY JUNE 04: DOWNSTREAM OF A DEEP 500-HPA TROUGH
OVER ALASKA, THE ENSEMBLE MEAN SOLUTIONS CONTINUE TO DEPICT A BUILDING
MID-LEVEL RIDGE OVER THE WESTERN CONTIGUOUS U.S. (CONUS) EARLY IN WEEK-2.
HOWEVER, SIMILAR TO YESTERDAY, THERE ARE MODEL DIFFERENCES ON THE STRENGTH OF
THIS RIDGE WITH THE ECENS REMAINING THE MOST AMPLIFIED. FROM MAY 29 TO 31, THE
ECENS INCREASES 500-HPA HEIGHT ANOMALIES TO MORE THAN +120 METERS OVER THE
NORTHERN HALF OF CALIFORNIA AND THE GREAT BASIN WITH THE GEFS AND CMCE HAVING
THOSE ANOMALIES RANGING FROM +60 TO +120 METERS. ACCORDING TO THE NWS HEATRISK
TOOL, EXTREME HEAT THRESHOLDS ARE ROUGHLY MAXIMUM TEMPERATURES OF 100 AND 95
DEGREES F FOR THE CENTRAL VALLEY OF CALIFORNIA AND THE GREAT BASIN,
RESPECTIVELY. THE ECENS HAS MAXIMUM TEMPERATURES OF NEAR OR MORE THAN 100
DEGREES F ACROSS THE CENTRAL VALLEY FROM MAY 29 TO 31 AND ITS PROBABILISTIC
EXTREMES TOOL (PET) FEATURES A 20 TO 40 PERCENT CHANCE THAT MAXIMUM
TEMPERATURES EXCEED 100 DEGREES F ON THE 30TH AND 31ST. SINCE THE GEFS AND CMCE
HAVE A WEAKER 500-HPA RIDGE, THEIR PETS HAVE LESS THAN A 20 PERCENT CHANCE THAT
MAXIMUM TEMPERATURES REACH 100 DEGREES F FOR INTERIOR AREAS OF CALIFORNIA.
DESPITE THE LACK OF SUPPORT FROM THE GEFS AND CMCE, A SLIGHT RISK OF EXTREME
HEAT (MAY 29-31) IS POSTED FOR THE CENTRAL VALLEY OF CALIFORNIA DUE TO THE
BULLISH ECENS SIGNAL ON CONSECUTIVE DAYS. THE COMBINATION OF HIGH TEMPERATURES,
LOW RELATIVE HUMIDITY, AND DRYING VEGETATION MAY RESULT IN ELEVATED WILDFIRE
RISK FOR THAT PART OF CALIFORNIA. ALTHOUGH ABOVE-NORMAL TEMPERATURES ARE LIKELY
THROUGHOUT THE GREAT BASIN DURING WEEK-2, MAXIMUM TEMPERATURES ARE EXPECTED TO
REMAIN BELOW EXTREME HEAT THRESHOLDS.
PRIOR TO THE START OF WEEK-2, A COLD FRONT IS FORECAST TO PROGRESS NEAR OR EVEN
SOUTH OF THE GULF COAST. THE TAIL END OF THIS FRONT IS THEN EXPECTED TO BECOME
STATIONARY AND COULD BE THE FOCUS FOR LOCALLY HEAVY RAINFALL FOR CENTRAL TO
EASTERN TEXAS AND PARTS OF THE LOWER MISSISSIPPI VALLEY. THE DETERMINISTIC
MODEL RUNS CONTINUE TO FAVOR TROPICAL CYCLONE (TC) DEVELOPMENT ACROSS THE EAST
PACIFIC EARLY NEXT WEEK. IF THIS TC FORMS AND TRACKS MORE NORTHWARD, THEN
ENHANCED MID-LEVEL MOISTURE MAY OVERSPREAD THE SOUTH-CENTRAL CONUS. BASED ON
24-HOUR PRECIPITATION AMOUNTS FROM THE GEFS AND ECENS, A SLIGHT RISK OF HEAVY
PRECIPITATION IS DESIGNATED FOR THESE AREAS FROM MAY 29 TO 31. ANY HEAVY
RAINFALL COULD TRIGGER FLASH FLOODING ALONG WITH NEW AND RENEWED RIVER
FLOODING.
MULTI-MODEL ENSEMBLE MEANS ARE IN BETTER AGREEMENT TODAY AND ARE TRENDING
TOWARDS A SURGE OF TROPICAL MOISTURE NORTHWARD FROM THE WESTERN CARIBBEAN TO
THE FLORIDA PENINSULA DURING THE FIRST WEEK OF JUNE. THE GEFS AND ECENS PETS
HAVE A 20 TO 40 PERCENT CHANCE THAT 3-DAY PRECIPITATION AMOUNTS EXCEED THE 85TH
PERCENTILE ACROSS CENTRAL TO SOUTH FLORIDA FROM JUNE 2 TO 4 WHICH COINCIDES
WITH AN INCREASINGLY WET CLIMATOLOGY. IN ADDITION, THE ECENS HAS NEAR A 20
PERCENT CHANCE OF MORE THAN 2 INCHES OF PRECIPITATION AT THIS TIME RANGE. DUE
TO BETTER MODEL AGREEMENT, A SLIGHT RISK OF HEAVY PRECIPITATION (JUNE 2-4) WAS
ADDED TO THE FLORIDA PENINSULA. ACCORDING TO THE U.S. DROUGHT MONITOR, SEVERE
TO EXTREME DROUGHT COVERS SOUTH FLORIDA INCLUDING THE EVERGLADES. THE WETTER
PATTERN FORECAST TO START JUNE WOULD BE WELCOME DROUGHT RELIEF.
THE GEFS, ECENS, AND CMCE DEPICT A HIGHLY AMPLIFIED 500-HPA TROUGH OVER ALASKA
WHERE BELOW-NORMAL TEMPERATURES AND ABOVE-NORMAL PRECIPITATION ARE FAVORED FROM
MAY 29 TO JUNE 4. ALTHOUGH THE ECENS PET HAS A 20 TO 40 PERCENT CHANCE THAT
3-DAY PRECIPITATION AMOUNTS EXCEED THE 85TH PERCENTILE ACROSS SOUTHEASTERN
ALASKA THROUGH JUNE 2, HAZARDOUS PRECIPITATION IS NOT EXPECTED AT THIS TIME.
FORECASTER: BRAD PUGH
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