143
FXUS21 KWNC 231831
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 23 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 EAST-CENTRAL CONTIGUOUS U.S. (CONUS) AND THE
SOUTHERN PLAINS. THIS FRONT IS FORECAST TO BECOME STATIONARY, WHICH FAVORS
ENHANCED CHANCES OF HEAVY PRECIPITATION AND THUNDERSTORMS ACROSS PORTIONS OF
THIS REGION CONTINUING INTO THE FIRST FEW DAYS OF WEEK-2. 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 TEXAS, THE LOWER MISSISSIPPI
VALLEY, TENNESSEE, AND ALABAMA, THU-SAT, MAY 1-3.
POSSIBLE FLOODING FOR THE LOWER MISSISSIPPI RIVER.
DETAILED SUMMARY
FOR SATURDAY APRIL 26 - WEDNESDAY APRIL 30:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MAY 01 - WEDNESDAY MAY 07: LATE IN WEEK-1, SURFACE LOW PRESSURE IS
FORECAST TO TRACK ACROSS THE GREAT LAKES AND SOUTHERN ONTARIO, WITH AN
ASSOCIATED TRAILING COLD FRONT DRAPED ACROSS THE EAST-CENTRAL CONUS, SERVING AS
A FOCUS FOR CONTINUED INCREASED CHANCES OF HEAVY PRECIPITATION AND
THUNDERSTORMS. BACK-TO-BACK SHORT WAVE TROUGHS OVER THE CENTRAL AND EASTERN
CONUS FAVOR AN EXTENDED PERIOD OF UNSETTLED WEATHER AND INCREASED PRECIPITATION
CHANCES OVER THE EAST. DURING THE FIRST FEW DAYS OF WEEK-2 THE FRONT IS
EXPECTED TO STALL, WITH THE HEAVIER PRECIPITATION FAVORED ACROSS TEXAS, THE
LOWER MISSISSIPPI VALLEY, TENNESSEE, AND ALABAMA, WHERE A SLIGHT RISK OF HEAVY
PRECIPITATION IS POSTED FOR MAY 1-3. THIS MEANS THERE IS AT LEAST A 20 PERCENT
CHANCE OF RAINFALL AMOUNTS EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE AND
1-INCH. THIS SLIGHT RISK AREA IS SUPPORTED BY THE PROBABILISTIC EXTREMES TOOL
(PET) PRECIPITATION GUIDANCE FROM THE GEFS AND ECENS SOLUTIONS, AND BY
UNCALIBRATED 0Z ECENS PRECIPITATION FORECASTS. COMPARED TO YESTERDAY, THERE IS
A SLIGHT SOUTHWARD DISPLACEMENT OF THE HEAVY RAINFALL AREA.
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 ASSOCIATED WITH THE STATIONARY
FRONT, 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 ACROSS THIS REGION
(INCLUDING THE SOUTHERN PLAINS) WILL CONTINUE TO BE SUSCEPTIBLE TO RENEWED
FLOODING OR FLASH FLOODING IF ADDITIONAL RAINFALL OCCURS.
THOUGH NO WIND HAZARDS ARE POSTED TODAY, ONE AREA OF CONCERN IS THE SOUTHWEST,
IN ADVANCE OF A MID-LEVEL, SOUTHERN STREAM TROUGH. TYPICALLY DURING THE SPRING,
AS THE DESERTS HEAT UP, STRONGER WINDS ROUNDING THE BASE OF APPROACHING
MID-LEVEL TROUGHS ARE MIXED DOWN TO THE SURFACE RESULTING IN VERY GUSTY WINDS
THAT OCCASIONALLY PRODUCE SIGNIFICANT DAMAGE. THE ECENS AND GEFS PETS DEPICT
WIND SPEEDS OF AT LEAST 20 MPH IN PARTS OF THE SOUTHWEST, WHICH MAY BE
UNDERDONE GIVEN THE INHERENT NATURE OF ENSEMBLE SMOOTHING.
ANOMALOUS RIDGING FAVORS UNSEASONABLY WARM TEMPERATURES ACROSS THE EAST COAST
STATES LATE IN WEEK-1 AND EARLY IN WEEK-2. YESTERDAY’S ECENS PET DEPICTED PARTS
OF THE MID-ATLANTIC AND NORTHEAST HAVING AT LEAST A 40 PERCENT CHANCE MAXIMUM
TEMPERATURES WOULD EXCEED THE 95TH CLIMATOLOGICAL PERCENTILE ON 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. WHILE NOT QUITE AS IMPRESSIVE TODAY, THE ECENS PET
STILL DEPICTS PARTS OF THE SOUTHERN MID-ATLANTIC AND SOUTHEAST TO HAVE AT LEAST
A 40 PERCENT CHANCE MAXIMUM TEMPERATURES WOULD EXCEED THE 85TH PERCENTILE ON
MAY 1, AND TODAY’S NBM DOES NOT SHOW NEAR-RECORD OR RECORD TEMPERATURES OVER
THE EAST. THIS IS LIKELY DUE TO THE GRADUAL DISPLACEMENT OF ANOMALOUSLY WARM
AIR (BY THE PASSAGE OF SUCCESSIVE SHORTWAVES) OFF THE ATLANTIC COAST. WHILE
THESE TEMPERATURES ARE NOTEWORTHY BY LATE-APRIL AND EARLY-MAY STANDARDS, 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 INCREASED ONSHORE
FLOW AND ABOVE-NORMAL PRECIPITATION OVER THE SOUTHEASTERN PART OF THE STATE,
THOUGH FORECASTED PRECIPITATION AMOUNTS OF 1-2 INCHES FALL SHORT OF HAZARDS
THRESHOLDS. BELOW-NORMAL TEMPERATURES FORECAST OVER MANY AREAS MAY FAVOR A
SLIGHT DELAY IN SEASONAL RIVER ICE BREAKUP. HOWEVER, AS TEMPERATURES CONTINUE
TO WARM, THE EVENTUAL RIVER ICE BREAKUP MAY LEAD TO ICE JAMS AND ASSOCIATED
UPSTREAM FLOODING IN THE COMING WEEKS.
FORECASTER: ANTHONY ARTUSA
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