652
FXUS21 KWNC 221800
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 22 2025
SYNOPSIS: AT THE OUTSET OF WEEK-2 SURFACE LOW PRESSURE IS FORECAST TO BE
DEPARTING ACROSS THE GREAT LAKES AND SOUTHEASTERN CANADA, WITH A TRAILING COLD
FRONT EXTENDING ACROSS THE CENTRAL AND EAST-CENTRAL CONTIGUOUS U.S. (CONUS).
THIS FAVORS ENHANCED CHANCES OF HEAVY PRECIPITATION AND THUNDERSTORMS
CONTINUING INTO THE EARLY PART OF WEEK-2 ACROSS THE CENTRAL AND SOUTHERN PLAINS
AND MIDDLE AND LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS. BROAD MID-LEVEL
HIGH PRESSURE IS FORECAST TO DEVELOP ACROSS THE CONUS LATER IN WEEK-2, FAVORING
INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES OVER MANY AREAS.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE CENTRAL AND SOUTHERN
PLAINS AND THE MIDDLE AND LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS, WED,
APR 30.
POSSIBLE FLOODING FOR THE LOWER MISSISSIPPI RIVER.
DETAILED SUMMARY
FOR FRIDAY APRIL 25 - TUESDAY APRIL 29:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY APRIL 30 - TUESDAY MAY 06: LATE IN WEEK-1, SURFACE LOW PRESSURE
IS FORECAST TO TRACK ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. AS THIS
SYSTEM DEPARTS, A TRAILING COLD FRONT IS PREDICTED TO REMAIN ACROSS PARTS OF
THE GREAT PLAINS AND MISSISSIPPI VALLEY EARLY IN WEEK-2 SERVING AS A FOCUS FOR
CONTINUED INCREASED CHANCES OF HEAVY PRECIPITATION AND THUNDERSTORMS. THE
UNCALIBRATED 0Z ECENS CONTINUES TO DEPICT A SWATH OF HEAVY PRECIPITATION
STRETCHING FROM NORTHEASTERN TEXAS INTO THE TENNESSEE VALLEY ON DAY-8 (APR 30),
WITH THE 0Z GEFS ALSO SHOWING A WETTER SOLUTION OVER THESE AREAS COMPARED TO
YESTERDAY. THE ECENS AND GEFS PROBABILISTIC EXTREMES TOOLS (PETS) DEPICT THESE
AREAS HAVING AT LEAST A 20 PERCENT CHANCE PRECIPITATION TOTALS EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1-INCH. AS A RESULT, A SLIGHT RISK OF HEAVY
PRECIPITATION IS POSTED ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS AND
THE MIDDLE AND LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS, APR 30.
THEREAFTER, ENHANCED PRECIPITATION CHANCES ARE FORECAST TO SHIFT INTO TEXAS AND
ALONG THE GULF COAST. HOWEVER, DAILY PRECIPITATION TOTALS ARE GENERALLY LOW IN
THE GEFS AND ECENS ENSEMBLES (LESS THAN 0.5 INCHES), AND THE ISOLATED,
CONVECTIVE NATURE OF THE PRECIPITATION PRECLUDES EXTENDING THE HAZARD.
THE CONVECTIVE AND SPORADIC NATURE OF THE PRECIPITATION DURING WEEK-2 LEADS TO
LESS CONFIDENCE IN DETERMINING EXACT AREAS MOST AT RISK OF ADDITIONAL FLOODING,
ALTHOUGH LOCALIZED FLOODING IS A CONCERN OVER PORTIONS OF THE CENTRAL AND
SOUTHERN PLAINS THAT DO RECEIVE HEAVY RAINFALL. A POSSIBLE FLOODING HAZARD
REMAINS POSTED ACROSS THE LOWER MISSISSIPPI RIVER GIVEN THE POTENTIAL FOR NEW
AND RENEWED RISES IN WATER LEVELS DURING WEEK-2 TIED TO ANY ADDITIONAL RAINFALL
OVER THE REGION AS WELL AS RUNOFF FROM RAINFALL UPSTREAM. MAIN CHANNELS ARE
ALREADY VERY HIGH, AND THUS ARE UNLIKELY TO HAVE LARGE RESPONSES TO ADDITIONAL
PRECIPITATION. REGARDLESS, TRIBUTARIES AND STREAMS WILL CONTINUE TO BE
SUSCEPTIBLE TO RENEWED FLOODING OR FLASH FLOODING IF ADDITIONAL RAINFALL
OCCURS.
AS THE AFOREMENTIONED SURFACE LOW AND ASSOCIATED MID-LEVEL TROUGH EXIT THE
REGION EARLY IN WEEK-2, THERE IS SOME POTENTIAL FOR ELEVATED WIND SPEEDS ACROSS
THE NORTHERN CONUS. HOWEVER, THE SIGNAL IN THE PETS HAS DIMINISHED COMPARED TO
YESTERDAY, WITH MUCH OF THE ENHANCED THREAT OVER THE NORTHERN PLAINS TIMING
OFF. PROBABILITIES IN THE GEFS AND ECENS UNCALIBRATED GUIDANCE FOR WIND SPEEDS
EXCEEDING 20-MPH ARE GENERALLY WEAK (LESS THAN 20 PERCENT) AND CONFINED TO THE
GREAT LAKES AND ADJACENT AREAS ON DAY-8 (APR 30). AS A RESULT, A SLIGHT RISK
FOR HIGH WINDS IS NO LONGER INDICATED, BUT SOME HIGHER WIND GUSTS STILL CANNOT
BE RULED OUT, PARTICULARLY ACROSS THE GREAT LAKES IN THE WAKE OF THE FRONTAL
PASSAGE.
ANOMALOUS RIDGING IS FORECAST ACROSS THE EASTERN CONUS AT THE BEGINNING OF THE
PERIOD. THIS FAVORS A PERIOD OF UNSEASONABLY WARM TEMPERATURES OVER MUCH OF THE
EAST DURING THE FIRST HALF OF WEEK-2, WITH MODELS TRENDING WARMER ACROSS THE
REGION COMPARED TO YESTERDAY. THE ECENS PET DEPICTS PARTS OF THE MID-ATLANTIC
AND NORTHEAST HAVING AT LEAST A 40 PERCENT CHANCE MAXIMUM TEMPERATURES EXCEED
THE 95TH CLIMATOLOGICAL PERCENTILE ON DAY-8 (APR 30), WITH DAILY RECORDS A
POSSIBILITY BASED ON THE NATIONAL BLEND OF MODELS (NBM). THIS TRANSLATES INTO
ACTUAL TEMPERATURES POTENTIALLY WELL INTO THE 80S DEG F OVER PARTS OF THE
MID-ATLANTIC, WITH RELATIVELY COOLER TEMPERATURES (70S DEG F) FAVORED ACROSS
THE NORTHEAST AND OHIO VALLEY. WHILE THESE TEMPERATURES ARE NOTEWORTHY BY
LATE-APRIL AND EARLY-MAY STANDARDS, AND FOR SOME AREAS COULD BE THE WARMEST
TEMPERATURES OF THE YEAR THUS FAR, NO HEAT RELATED HAZARDS ARE ISSUED DUE TO
THE TIME OF YEAR AND LACK OF ADVERSE IMPACTS. A GENERAL TREND TOWARD MORE BROAD
RIDGING AND A PATTERN TYPICAL OF LATE-SPRING IS FORECAST TO EMERGE OVER MUCH OF
THE CONUS LATER IN WEEK-2.
TROUGHING FORECAST ACROSS ALASKA FAVORS INCREASED CHANCES FOR ABOVE-NORMAL
PRECIPITATION OVER THE SOUTHEASTERN PART OF THE STATE, WITH ACTUAL
PRECIPITATION AMOUNTS NOT EXPECTED TO REACH HAZARDS THRESHOLDS. BELOW-NORMAL
TEMPERATURES FORECAST OVER MANY AREAS FAVOR A DELAY IN SEASONAL RIVER ICE
BREAKUP. HOWEVER, AS TEMPERATURES CONTINUE TO WARM, THE EVENTUAL RIVER ICE
BREAKUP MAY LEAD TO ICE JAMS AND ASSOCIATED FLOODING IN THE COMING WEEKS.
FORECASTER: THOMAS COLLOW
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