098
FXUS21 KWNC 061913
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 06 2025
SYNOPSIS: EARLY IN WEEK-2, A LOW PRESSURE SYSTEM IS FORECAST TO SLOWLY MOVE
AWAY FROM THE SOUTHEAST COAST, WHICH MAY BRING LOCALLY HEAVY AMOUNTS OF
PRECIPITATION TO PARTS OF THE LOWER EASTERN SEABOARD. AFTER A RELATIVELY BRIEF
PERIOD OF DRIER WEATHER ACROSS THE CENTRAL STATES, HEAVY RAIN AND THUNDERSTORMS
ARE PREDICTED TO RETURN TO THE REGION DURING THE MIDDLE AND LATTER PORTIONS OF
THE FORECAST PERIOD. MID-LEVEL HIGH PRESSURE FAVORS ABOVE-NORMAL TEMPERATURES
ACROSS THE NORTHERN AND CENTRAL GREAT PLAINS ALONG WITH THE CORN BELT EARLY IN
WEEK-2.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE CENTRAL AND SOUTHERN
PLAINS, AND THE MIDDLE MISSISSIPPI VALLEY, SAT-TUE, MAY 17-20.
DETAILED SUMMARY
FOR FRIDAY MAY 09 - TUESDAY MAY 13:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY MAY 14 - TUESDAY MAY 20: DURING WEEK-2, MULTI-MODEL ENSEMBLE
GUIDANCE PREDICTS A MID-LEVEL RIDGE AND POSITIVE HEIGHT ANOMALIES OVER THE
NORTHEASTERN QUARTER OF THE CONTIGUOUS U.S. (CONUS), AND MID-LEVEL TROUGHS
NEAR/OFF THE SOUTHEAST COAST AND OVER THE INTERIOR WEST. EARLY IN THE PERIOD, A
SLOW-MOVING LOW PRESSURE SYSTEM IS FORECAST TO MOVE AWAY FROM THE SOUTHEAST
COAST. PRECIPITATION IS LIKELY TO LINGER ACROSS PORTIONS OF THE MID-ATLANTIC,
THE CAROLINAS, GEORGIA, AND MUCH OF THE FLORIDA PENINSULA FOR THE FIRST FEW
DAYS OF THE PERIOD. ACCORDING TO UNCALIBRATED ECENS PRECIPITATION FORECASTS,
AND GEFS AND ECENS PRECIPITATION PROBABILISTIC EXTREMES TOOLS (PETS), SOME
AREAS MAY RECEIVE UP TO AN INCH OR MORE. PRECIPITATION DEFICITS OVER THE PAST
30 DAYS RANGE FROM 1-3 INCHES OVER MUCH OF THIS AREA, WITH THE HIGHER DEFICITS
OVER FLORIDA WHICH IS NEARING THE END OF ITS CLIMATOLOGICAL DRY SEASON.
THEREFORE, THIS RAIN IS CONSIDERED TO BE BENEFICIAL RATHER THAN HAZARDOUS.
A MID-LEVEL TROUGH MOVING ACROSS THE INTERIOR WEST IS PREDICTED TO SPREAD
PRECIPITATION ACROSS THE NORTHERN GREAT BASIN, NORTHERN ROCKIES, AND EVENTUALLY
THE NORTHERN HIGH PLAINS, AS THE MID-LEVEL TROUGH PROMOTES SURFACE CYCLOGENESIS
EAST OF THE NORTHERN ROCKIES. ABOUT 0.50-0.75 INCH OF PRECIPITATION IS EXPECTED
ACROSS THE REGION, WHICH FALLS SHORT OF HAZARDOUS THRESHOLDS. HEAVIER
PRECIPITATION (1-INCH OR GREATER IN A 3-DAY PERIOD, AND AMOUNTS GREATER THAN
THE 85TH CLIMATOLOGICAL PERCENTILE) IS FORECAST OVER PORTIONS OF THE CENTRAL
AND SOUTHERN PLAINS, AND THE MIDDLE MISSISSIPPI VALLEY, MAY 17-20, WHERE A
SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED. THIS IS ASSOCIATED WITH STORM
ACTIVITY IN ADVANCE OF THE WESTERN MID-LEVEL TROUGH AND INCREASED LOW-LEVEL
GULF MOISTURE. AFTER A BRIEF RESPITE FROM OCCASIONAL HEAVY RAIN, THUNDERSTORMS,
AND FLOODING, THIS AREA IS EXPECTED TO SEE A RENEWAL OF ENHANCED STORM
ACTIVITY. SLOW-MOVING OR TRAINING THUNDERSTORMS ARE CAPABLE OF PRODUCING
LOCALLY HEAVIER AMOUNTS OF RAIN, WITH AN ASSOCIATED FLASH FLOOD RISK.
A GRADUALLY WEAKENING 500-HPA RIDGE INITIALLY CENTERED OVER THE GREAT LAKES
REGION AND ADJACENT PORTIONS OF CANADA FAVORS ABOVE-NORMAL TEMPERATURES ACROSS
THE NORTH-CENTRAL CONUS. DETERMINISTIC RUNS OF THE 0Z ECMWF AND 06Z GFS PREDICT
HIGH TEMPERATURES MOSTLY IN THE 80’S TO AROUND 90 DEG F, THOUGH THE ECMWF
FORECASTS EVEN HIGHER TEMPERATURES OVER WESTERN SOUTH DAKOTA, IN THE 94-97 DEG
F RANGE. THIS LOCALIZED AREA OF ELEVATED WARMTH (RELATIVE TO ITS SURROUNDINGS)
PREDICTED BY THE ECMWF MODEL MAY BE DUE TO DOWNSLOPE WINDS OFF THE EASTERN
SLOPES OF THE BLACK HILLS. HAZARDS CRITERIA AT THIS TIME OF YEAR REQUIRE AIR
TEMPERATURES OF ABOUT 95 DEGREES AND HEAT INDEX VALUES NEAR 100 DEG F OVER A
FAIRLY BROAD AREA. FOR THE TIME BEING, NO TEMPERATURE HAZARDS ARE POSTED FOR
THE NORTH-CENTRAL CONUS. ANOTHER AREA BEING MONITORED FOR HIGH TEMPERATURES IS
CENTRAL TEXAS, WHERE THE DETERMINISTIC 0Z ECMWF, 06Z GFS, AND 12Z GFS ALL
PREDICT 95-100 DEG F FOR THIS AREA, THOUGH ON DIFFERENT DAYS. THIS IS JUST SHY
OF MEETING MINIMAL HAZARDOUS TEMPERATURE CRITERIA FOR THIS REGION, AND THIS
REGION WILL CONTINUE TO BE MONITORED IN UPCOMING OUTLOOKS.
THE GEFS, ECENS, AND CMCE FEATURE A 500-HPA TROUGH PERSISTING OVER THE BERING
SEA AND PORTIONS OF WESTERN ALASKA THROUGH MOST OF WEEK-2, AND A WEAK RIDGE
OVER EASTERN ALASKA. THE GEFS AND ECENS PRECIPITATION PETS PREDICT MAXIMUM
AMOUNTS OF 1.0-1.5 INCHES DURING THE PERIOD. THOUGH ONSHORE FLOW IS FAVORED
ACROSS SOUTHERN ALASKA, WITH SURFACE LOW PRESSURE NEAR THE ALEUTIANS, NO
HAZARDOUS PRECIPITATION IS POSTED. AS TEMPERATURES WARM THIS MONTH, RIVER ICE
BREAKUP WILL CONTINUE WHICH COULD LEAD TO ICE JAMS AND FLOODING.
FORECASTER: ANTHONY ARTUSA
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