245
FXUS21 KWNC 041949
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 04 2025
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FAVORED OVER THE EASTERN HALF OF THE
CONTIGUOUS U.S. (CONUS) THROUGHOUT WEEK-2, LEADING TO THE DEVELOPMENT OF
POTENTIALLY HAZARDOUS HEAT OVER PORTIONS OF THE MIDWEST, OHIO VALLEY, AND
MID-ATLANTIC. STRONG SURFACE HIGH PRESSURE OVER THE NORTH ATLANTIC FAVORS
ABUNDANT GULF MOISTURE TO MOVE OVER THE GREAT PLAINS, LEADING TO ELEVATED HEAT
INDICES AND ALSO FUELLING POTENTIALLY HEAVY RAINFALL ALONG THE GULF COAST AND
ALSO OVER PORTIONS OF THE GREAT PLAINS AND MISSISSIPPI VALLEY. MID-LEVEL LOW
PRESSURE OVER THE PACIFIC NORTHWEST AT THE OUTSET OF WEEK-2 HAS THE POTENTIAL
TO BRING PERIODS OF HIGH WINDS TO MUCH OF THE NORTHWESTERN CONUS THROUGH THE
MIDDLE OF THE FORECAST PERIOD.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR THE MIDDLE MISSISSIPPI AND OHIO VALLEYS AS WELL
AS PORTIONS OF THE GREAT LAKES AND CENTRAL PLAINS, AND UPPER MISSISSIPPI
VALLEY, SUN-WED, JUN 14-18.
SLIGHT RISK OF EXTREME HEAT FOR MUCH OF THE MID-ATLANTIC, SAT-MON, JUN 13-16.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR THE NORTHWESTERN CONUS, THU-MON, JUN
12-16.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE GULF COAST, MISSISSIPPI VALLEY, AND
EASTERN GREAT PLAINS, THU-SAT, JUN 12-14.
POSSIBLE FLOODING FOR MUCH OF THE MIDDLE MISSISSIPPI VALLEY AND EASTERN CENTRAL
AND SOUTHERN PLAINS.
DETAILED SUMMARY
FOR SATURDAY JUNE 07 - WEDNESDAY JUNE 11:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY JUNE 12 - WEDNESDAY JUNE 18: ENSEMBLE MEANS FROM THE GEFS, ECENS,
AND CMCE FOR 500-HPA HEIGHT ANOMALIES DEPICT AN AMPLIFIED TROUGH SITUATED OVER
THE WEST COAST DURING WEEK-2, ALTHOUGH THIS FEATURE IS FAVORED TO WEAKEN
THROUGHOUT THE FORECAST PERIOD. ASSOCIATED WITH THIS IS WEAK SURFACE LOW
PRESSURE OVER THE GREAT BASIN, WHICH ALONG WITH STRONG SURFACE HIGH PRESSURE
OVER THE NORTH PACIFIC SETS UP A TIGHT PRESSURE GRADIENT AND RESULTANT ENHANCED
SURFACE WINDS ACROSS THE NORTHWESTERN CONUS. THIS IS SUPPORTED BY THE
PROBABILISTIC EXTREMES TOOLS (PETS) FROM THE ECMWF, WHICH BROAD-BRUSHES AT
LEAST A 20% PROBABILITY OF 3-DAY MAXIMUM WIND SPEEDS EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE FOR ALL OF WEEK-2 FROM THE WEST COAST NORTH OF SAN
FRANCISCO EASTWARD INTO THE GREAT BASIN. THE GEFS AND CMCE PETS ARE LESS
BULLISH BUT STILL SHOW SOME SIGNAL OVER THESE AREAS FOR AT LEAST A PORTION OF
THE FORECAST PERIOD. SOLUTIONS FOR MEAN SEA LEVEL PRESSURE (MSLP) FROM THE
AFOREMENTIONED MODEL ENSEMBLES ARE QUITE CONSISTENT WITH REGARD TO THE POSITION
AND DURATION OF THE TIGHTEST PRESSURE GRADIENTS OVER THE REGION DESPITE THE
MIXED SIGNALS FROM THE PETS, WITH AGREEMENT REGARDING DECREASING LIKELIHOOD FOR
HIGH WINDS OVER THE WEEK. THEREFORE A SLIGHT RISK OF HIGH WINDS IS POSTED FOR
THE PACIFIC NORTHWEST, GREAT BASIN, AND NORTHERN CALIFORNIA FOR JUN 12-16.
A STRONG BERMUDA HIGH IS FAVORED BY THE ENSEMBLES THROUGHOUT WEEK-2, SETTING UP
MOIST SOUTHEASTERLY FLOW OFF THE GULF AND INTO THE CENTRAL CONUS. THE MODELS
ALSO INDICATE WEAK TROUGHING EAST OF THE ROCKIES WHICH IS ANTICIPATED TO PAIR
UP WITH THE GULF MOISTURE AND LEAD TO SIGNIFICANT DAYTIME HEATING AND
POTENTIALLY HEAVY PRECIPITATION FOR MUCH OF THE EASTERN GREAT PLAINS,
MISSISSIPPI VALLEY, AND GULF COAST. THIS ENHANCED RAINFALL SIGNAL IS
WELL-SUPPORTED BY THE ECMWF AND GEFS PETS, WHICH BOTH INDICATE AT LEAST A 20%
CHANCE OF 3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH PERCENTILE AND AT LEAST
1 INCH OF PRECIPITATION FOR AT LEAST PART OF WEEK-2. THE ECWMF IS ESPECIALLY
BULLISH, SUGGESTING THIS POTENTIAL THROUGHOUT THE FORECAST PERIOD, WHILE THE
GEFS ONLY REACHES THE ABOVE THRESHOLDS EARLY IN WEEK-2. GIVEN THIS, A SLIGHT
RISK OF HEAVY PRECIPITATION IS POSTED FOR THE EASTERN PLAINS, MISSISSIPPI
VALLEY, AND GULF COAST FOR JUN 12-14. ADDITIONALLY, THE MIDDLE MISSISSIPPI
VALLEY HAS BEEN PLAGUED BY SURPLUS PRECIPITATION AND SUBSEQUENT FLOODING DURING
THE SPRING AND THE GROUND HAS NOT HAD TIME TO DRAIN MUCH, SO NEW OR RENEWED
FLOODING IS A CONCERN, WARRANTING THE POSTING OF A POSSIBLE FLOOD HAZARD FOR
THE REGION.
MODEL ENSEMBLES ARE IN VERY GOOD AGREEMENT WITH REGARD TO A PERSISTENT
MID-LEVEL RIDGE OVER AREAS EAST OF THE ROCKIES , WITH WIDESPREAD 6-12 DM
POSITIVE 500-HPA HEIGHT ANOMALIES THROUGHOUT THE WEEK AND HEIGHTS AS MUCH AS
593 DM AT THE RIDGE AXIS. THIS FAVORS ANOMALOUSLY WARM TEMPERATURES WHICH, WHEN
COMBINED WITH HIGH HUMIDITIES DUE TO ADVECTION OF GULF MOISTURE, RESULTS IN
POTENTIALLY HAZARDOUS HEAT FOR MUCH OF THE MIDDLE OF THE CONUS. THE PETS
INDICATE AT LEAST A 20% CHANCE OF MAXIMUM TEMPERATURES THE 85TH PERCENTILE AND
AT LEAST 90 DEG F FOR MUCH OF THE CENTRAL PLAINS AND EASTWARD INTO THE MIDDLE
MISSISSIPPI AND OHIO VALLEYS BEGINNING ON JUN 14 AND EXTENDING THROUGH THE END
OF THE FORECAST PERIOD. SIMILAR THRESHOLDS ARE REACHED FOR MOST OF THE
MID-ATLANTIC FOR JUN 13-16, THEREFORE A SLIGHT RISK OF EXTREME HEAT IS POSTED
FOR THESE REGIONS FOR THE RESPECTIVE TIME PERIODS INDICATED. TEMPERATURES ARE
LIKELY TO BE QUITE HOT ACROSS THE SOUTHERN CONUS BUT HAZARD CRITERIA ARE NOT
LIKELY TO BE MET OUTSIDE THE REGIONS DISCUSSED ABOVE.
ICE-BOUND RIVERS ARE BEGINNING TO BREAK UP IN THE NORTH SLOPE OF ALASKA. THERE
IS NO ASSOCIATED HAZARD POSTED AT THIS TIME BUT THIS SITUATION WILL BE CLOSELY
MONITORED IN THE COMING DAYS AND WEEKS AS CONDITIONS CAN QUICKLY CHANGE,
LEADING TO THE POTENTIAL FOR ICE JAMS, AUFEIS, AND ASSOCIATED FLOODING.
FORECASTER: DANNY BARANDIARAN
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