541
FXUS21 KWNC 201800
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT APRIL 20 2026
SYNOPSIS: A STALLED FRONTAL BOUNDARY IS FAVORED TO INTERACT WITH MOIST
SOUTHERLY FLOW IN WEEK-2, INCREASING THE POTENTIAL OF HEAVY PRECIPITATION FOR
PORTIONS OF THE SOUTHERN PLAINS, THE TENNESSEE AND LOWER MISSISSIPPI VALLEYS,
AND SOUTHEAST U.S. EARLY IN THE FORECAST PERIOD.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHERN PLAINS, THE
TENNESSEE AND LOWER MISSISSIPPI VALLEYS, AND SOUTHEAST U.S., TUE-WED, APR 28-29.
DETAILED SUMMARY
FOR THURSDAY APRIL 23 - MONDAY APRIL 27:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY APRIL 28 - MONDAY MAY 04: ENSEMBLE SOLUTIONS FROM THE ECENS AND
GEFS FOR 500-HPA HEIGHT ANOMALIES DEPICT A SHORTWAVE TROUGH MOVING FROM THE
WESTERN CONTIGUOUS U.S. (CONUS) TO THE GREAT LAKES BY THE OUTSET OF THE WEEK-2
PERIOD, WITH ACCOMPANYING SURFACE LOW PRESSURE AND A TRAILING COLD FRONT.
MODELS FAVOR THIS FRONTAL BOUNDARY TO STALL OVER THE TENNESSEE VALLEY AND
WEAKEN OVER TIME. THESE FEATURES ARE NOT PARTICULARLY AMPLIFIED BUT FORM WHILE
MODERATE RETURN FLOW IS ESTABLISHED IN THE WAKE OF A SIMILAR SYSTEM ACTIVE
EARLIER IN WEEK-1. THIS RETURN FLOW INCREASES AVAILABLE MOISTURE TO THE
DEVELOPING SYSTEM AND IS FAVORED TO ENHANCE PRECIPITATION ACCUMULATIONS OVER
PORTIONS OF THE SOUTHEASTERN CONUS. UNCALIBRATED PROBABILITIES FROM THE ECENS
ARE FAIRLY BULLISH, WITH >40% PROBABILITIES OF 3-DAY PRECIPITATION
ACCUMULATIONS EXCEEDING 1” EARLY IN WEEK-2. THE PROBABILISTIC EXTREMES TOOLS
(PETS) FROM THE GEFS AND ECENS ALSO INDICATE A SIMILAR REGION HIGHLIGHTED WITH
>20% CHANCE OF 3-DAY PRECIPITATION ACCUMULATIONS TO EXCEED 1”. THEREFORE A
SLIGHT RISK OF HEAVY PRECIPITATION IS CONTINUED FOR PORTIONS OF THE SOUTHERN
PLAINS, THE TENNESSEE AND LOWER MISSISSIPPI VALLEYS, AND SOUTHEAST U.S., VALID
APR 28-29.
SURFACE WINDS ARE LIKELY TO BE ENHANCED BY THIS PASSING SYSTEM AS WELL,
ALTHOUGH GUIDANCE FROM THE GEFS AND ECENS PETS FOR MAXIMUM WIND SPEED SHOW NO
SIGNAL AT THE 25MPH THRESHOLD, WHICH PRECLUDES THE ISSUANCE OF A HIGH WIND
HAZARD. HOWEVER MUCH OF THE GREAT PLAINS, WHERE MODELS DO INDICATE A FAIRLY
STRONG SIGNAL AT THE 20MPH THRESHOLD, IS CURRENTLY IN DROUGHT AND WITH DRY AND
STRESSED VEGETATION. THESE CONDITIONS COMBINED REPRESENT A SIGNIFICANT RISK OF
WILDFIRE ACTIVITY, AND CARE SHOULD BE TAKEN TO MINIMIZE THE POTENTIAL OF
WILDFIRE INITIATION.
NO HAZARDS ARE ISSUED OVER ALASKA, BUT THE TYPICAL PEAK OF RIVER ICE BREAKUP IS
APPROACHING, AND FLOODING CAN OCCUR THIS TIME OF YEAR WITH LITTLE OR NO NOTICE
AS CONDITIONS ON FROZEN RIVERS CAN CHANGE QUICKLY. CHECK WITH THE ALASKA
PACIFIC RIVER FORECAST CENTER FOR THE LATEST CONDITIONS OR ADVISORIES.
FORECASTER: DANNY BARANDIARAN
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