044
FXUS21 KWNC 081831
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 08 2026
SYNOPSIS: MID-LEVEL AND CORRESPONDING SURFACE HIGH PRESSURE FORECAST ACROSS THE
CENTRAL AND EASTERN CONTIGUOUS U.S. (CONUS) RESULTS IN AN INCREASED RISK OF
HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS AND
MIDDLE AND LOWER MISSISSIPPI VALLEY. SURFACE LOW PRESSURE OVER THE NORTHERN
ROCKIES AND NORTHERN PLAINS INCREASES RISKS FOR HIGH WINDS IN THE REGION.
MEANWHILE, ALONG THE WEST COAST, HIGH WINDS REMAIN POSSIBLE AS MID-LEVEL LOW
PRESSURE DEVELOPS.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE CENTRAL AND SOUTHERN
PLAINS, AND MIDDLE AND LOWER MISSISSIPPI VALLEY, SUN-WED, MAY 17-20
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF COASTAL CALIFORNIA AND OREGON,
SAT-TUE, MAY 16-19.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE NORTHERN ROCKIES AND NORTHERN
PLAINS, SAT-MON, MAY 16-18.
DETAILED SUMMARY
FOR MONDAY MAY 11 - FRIDAY MAY 15:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY MAY 16 - FRIDAY MAY 22: THE 0Z GEFS, ECENS, AND CMCE ALL DEPICT A
ROBUST MID-LEVEL RIDGE OVER THE CENTRAL AND EASTERN CONUS DURING WEEK-2.
MID-LEVEL TROUGHING IS FAVORED ALONG BOTH THE WEST COAST AND THE WESTERN
ATLANTIC BY MOST FORECAST GUIDANCE. THIS IS A FAIRLY STABLE PATTERN DURING THE
WEEK-2 PERIOD AFTER A MORE VARIABLE WEEK-1 PERIOD.
ANTICIPATED SURFACE HIGH PRESSURE FORECAST OVER THE SOUTHEASTERN CONUS DURING
WEEK-2 IS LIKELY TO BRING SOUTHERLY RETURN FLOW OVER THE SOUTHERN AND CENTRAL
PLAINS INTO THE LOWER AND MIDDLE MISSISSIPPI VALLEY. SHORTWAVE TROUGHS EJECTING
FROM THE LONG WAVE TROUGH OVER THE WESTERN U.S. MAY HELP TO FORCE MULTIPLE
ROUNDS OF PRECIPITATION ACROSS THE CENTRAL CONUS. UNCALIBRATED PRECIPITATION
GUIDANCE INDICATES WIDESPREAD 20 TO 40% CHANCES FOR 3 DAY PRECIPITATION AMOUNTS
OVER 1 INCH ACROSS THIS REGION DURING BOTH THE 8-10 AND 10-12 DAY PERIODS.
PROBABILISTIC EXTREMES TOOLS (PETS) FROM THE GEFS AND ECENS ALSO HIGHLIGHT AT
LEAST 20% CHANCES OF 3 DAY PRECIPITATION AMOUNTS EXCEEDING THE 85TH PERCENTILE
AND 1 INCH. THEREFORE, A SLIGHT RISK OF HEAVY PRECIPITATION IS FORECAST FOR
THESE AREAS MAY 17-20. WHILE SIGNALS RETREAT A LITTLE BY THE BACK HALF OF THE
PERIOD, THIS MAY BE THE RESULT OF INCREASED MODEL SPREAD AS MID-LEVEL HIGH
PRESSURE REMAINS ENTRENCHED ACROSS THE REGION. THIS PATTERN MAY RESULT IN A
LONGER DURATION OF THE ENHANCED RISK THAN IS FORECAST TODAY.
TROUGHING IS FAVORED TO DEVELOP NEAR THE WEST COAST. THIS SUPPORTS RELATIVELY
COOLER TEMPERATURES OVER THE SOUTHWEST COMPARED TO WEEK-1 ALONG WITH ELEVATED
CHANCES FOR COASTAL HIGH WINDS, FURTHER ENHANCED BY POTENTIAL THERMAL LOW
DEVELOPMENT OVER THE SOUTHWEST AND A TIGHTENING SURFACE PRESSURE GRADIENT ALONG
THE COAST. BOTH THE GEFS AND ECMWF PROBABILISTIC EXTREMES TOOLS (PETS) INDICATE
AT LEAST A 20 PERCENT CHANCE OF WIND SPEEDS EXCEEDING THE 85TH CLIMATOLOGICAL
PERCENTILE AND 25-MPH FOR MUCH OF THE COAST. THE SLIGHT RISK EXTENDS FROM
NORTHERN OREGON TO LOS ANGELES, AND IS NOW VALID THROUGH MAY 19 GIVEN ENHANCED
SIGNALS IN THE UNCALIBRATED GEFS AND ECMWF ENSEMBLES.
A SURFACE LOW PRESSURE SYSTEM IS FORECAST TO DEVELOP OVER THE NORTHERN AMERICAN
ROCKIES OR SOUTHERN CANADIAN ROCKIES LATE IN WEEK-1. THE PETS FROM THE GEFS AND
ECENS BOTH HIGHLIGHT ELEVATED CHANCES FOR WINDS TO EXCEED THE 85TH PERCENTILE
EARLY IN WEEK-2. UNCALIBRATED FORECAST GUIDANCE IS ALSO SUPPORTIVE OF ELEVATED
WIND GUSTS FROM THE NORTHERN ROCKIES INTO THE PLAINS DURING THIS PERIOD.
THEREFORE, A SLIGHT RISK OF HIGH WINDS IS POSTED FOR THIS REGION, MAY 16-18.
IN ALASKA, THE TYPICAL PEAK OF THE RIVER ICE BREAKUP SEASON IS APPROACHING, AND
ICE JAM FLOODING CAN OCCUR THIS TIME OF YEAR WITH LITTLE OR NO NOTICE AS
CONDITIONS ON FROZEN RIVERS CAN CHANGE QUICKLY. PLEASE CHECK WITH THE ALASKA
PACIFIC RIVER FORECAST CENTER FOR THE LATEST CONDITIONS AND ADVISORIES.
FORECASTER: RYAN BOLT
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