074
FXUS21 KWNC 181131
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
312 PM EDT APRIL 17 2024
SYNOPSIS: ON APRIL 25 AND 26, A STATIONARY FRONT MAY EXTEND EAST
FROM THE LOWER MISSISSIPPI VALLEY TO THE SOUTHEAST. MID-LEVEL LOW
PRESSURE IS FORECAST TO REMAIN OVER THE WEST DURING THE FINAL WEEK
OF APRIL. THIS AREA OF MID-LEVEL LOW PRESSURE FAVORS LOW PRESSURE
DEVELOPMENT ACROSS THE HIGH PLAINS FROM APRIL 25 TO MAY 1. ALTHOUGH
THE EXACT TIMING IS UNCERTAIN ON THE STRONGEST WINDS, THERE IS AN
ELEVATED RISK OF HIGH WINDS FROM THE ROCKIES AND SOUTHWEST EAST TO
THE GREAT PLAINS THROUGHOUT WEEK-2. ALSO, THE PATTERN WOULD BE
FAVORABLE FOR THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL FOR MUCH OF
THE GREAT PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY, AND OHIO
VALLEY.
HAZARDS
SLIGHT RISK OF HIGH WINDS FOR PARTS OF THE SOUTHWEST, ROCKIES, AND
GREAT PLAINS, THU-WED, APR 25-MAY 1.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE GREAT PLAINS,
MIDDLE TO LOWER MISSISSIPPI VALLEY, AND LOWER OHIO VALLEY, THU-WED,
APR 25-MAY 1.
FLOODING POSSIBLE ACROSS EASTERN TEXAS AND THE LOWER MISSISSIPPI
VALLEY.
DETAILED SUMMARY
FOR SATURDAY APRIL 20 - WEDNESDAY APRIL 24:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY APRIL 25 - WEDNESDAY MAY 1: BY APRIL 25, A STATIONARY
FRONT IS FORECAST TO EXTEND EITHER ACROSS THE LOWER MISSISSIPPI
VALLEY OR NORTHERN GULF OF MEXICO. THE DETERMINISTIC 6Z GFS MODEL
DEPICTS A MORE NORTHERN PLACEMENT OF THIS FRONT WITH A WAVE OF LOW
PRESSURE TRACKING EAST ALONG IT. CONVERSELY, THE DETERMINISTIC 0Z
ECMWF MODEL FAVORS THE FRONT PROGRESSING SOUTHWARD INTO THE GULF OF
MEXICO AND QUICKLY DISSIPATING. IF THE DETERMINISTIC 6Z GFS MODEL
VERIFIES, THEN THERE WOULD BE AN INCREASED CHANCE OF HEAVY
PRECIPITATION FOR THE LOWER MISSISSIPPI VALLEY.
DURING THE FINAL WEEK OF APRIL AND THROUGH THE BEGINNING OF MAY, THE
GFS ENSEMBLE MEAN MAINTAINS A 500-HPA TROUGH OVER THE WEST. THIS
WOULD CONTINUE TO RESULT IN THE DEVELOPMENT OF SURFACE LOWS TO THE
LEE OF THE ROCKIES. SHORTWAVE TROUGHS AMPLIFYING OVER THE WEST AND
THE ASSOCIATED DEVELOPMENT OF SURFACE LOWS ACROSS THE HIGH PLAINS
SUPPORTS A BROAD SLIGHT RISK AREA OF HIGH WINDS FOR THE SOUTHWEST,
ROCKIES, AND MUCH OF THE GREAT PLAINS FROM APRIL 25 TO MAY1. IF THE
GFS AND ECMWF ENSEMBLE MEANS COME INTO BETTER AGREEMENT IN TIMING OF
SURFACE LOW DEVELOPMENT, THEN A MODERATE RISK OF HIGH WINDS MAY BE
WARRANTED. ALONG WITH THE OCCASIONAL GUSTY WINDS, THERE IS LIKELY TO
BE AN ELEVATED WILDFIRE RISK THROUGHOUT THE HIGH PLAINS.
AN UPSTREAM 500-HPA TROUGH, SURFACE LOW DEVELOPMENT ACROSS THE HIGH
PLAINS, AND ADEQUATE RETURN FLOW FROM THE GULF OF MEXICO ARE
FORECAST TO PROVIDE A FAVORABLE ENVIRONMENT FOR PERIODS OF
THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL FROM THE GREAT PLAINS TO
THE MISSISSIPPI VALLEY DURING WEEK-2. DUE TO TIMING UNCERTAINTY,
ONLY A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED AT THIS TIME.
MINOR TO MODERATE RIVER FLOODING IS ONGOING ACROSS EASTERN TEXAS AND
THE LOWER MISSISSIPPI VALLEY. SINCE ADDITIONAL RAINFALL (1 TO 3
INCHES) IS FORECAST PRIOR TO WEEK-2 AND THERE IS AN ELEVATED RISK OF
HEAVY RAINFALL DURING WEEK-2, A FLOODING POSSIBLE HAZARD IS
MAINTAINED FOR PARTS OF THESE AREAS.
THE GFS ENSEMBLE MEAN DEPICTS A PERSISTENT 500-HPA TROUGH OVER THE
ALEUTIANS AND WESTERN ALASKA THROUGH THE ENTIRETY OF WEEK-2.
ALTHOUGH THIS WOULD FAVOR ENHANCED ONSHORE FLOW INTO SOUTH-CENTRAL
AND SOUTHEASTERN ALASKA, PRECIPITATION AMOUNTS ARE EXPECTED TO
REMAIN BELOW HAZARDS THRESHOLDS.
FORECASTER: BRAD PUGH
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