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FXUS21 KWNC 121811
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 12 2025
SYNOPSIS: AN AREA OF MID-LEVEL HIGH PRESSURE IS FORECAST TO REMAIN IN PLACE
ACROSS THE EASTERN CONTIGUOUS U.S. (CONUS) DURING THE WEEK-2 PERIOD. THIS
SUPPORTS A SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF THE CENTRAL CONUS AND
PARTS OF THE SOUTHEAST. ALONG THE NORTHERN PERIPHERY OF THE MID-LEVEL HIGH,
HEAVY PRECIPITATION IS POSSIBLE IN THE NORTHERN PLAINS, UPPER MISSISSIPPI
VALLEY AND GREAT LAKES. IN SOUTHERN TEXAS HEAVY PRECIPITATION IS ALSO POSSIBLE
ASSOCIATED WITH AN EASTERLY WAVE. EXTREME HEAT REMAINS POSSIBLE FOR PORTIONS OF
THE DESERT SOUTHWEST. MEANWHILE, WINDY CONDITIONS ARE SOMEWHAT FAVORABLE IN
PORTIONS OF THE SOUTHERN PLAINS AND ALONG PARTS OF THE COAST OF CALIFORNIA AND
OREGON.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF THE CENTRAL PLAINS, LOWER AND
MIDDLE MISSISSIPPI VALLEY AND SURROUNDING AREAS, FRI-SUN, JUN 20-22.
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF THE SOUTHEAST AND FLORIDA, FRI-SUN,
JUN 20-22
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF THE DESERT SOUTHWEST, FRI-SAT, JUN
20-21.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF SOUTHERN TEXAS, FRI-SAT, JUN
20-21.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE NORTHERN PLAINS, UPPER
MISSISSIPPI VALLEY, AND GREAT LAKES, FRI-MON, JUN 20-23.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE SOUTHERN PLAINS, FRI-TUE, JUN
20-24.
SLIGHT RISK OF HIGH WINDS FOR COASTAL REGIONS FROM CENTRAL OREGON SOUTH THROUGH
CENTRAL CALIFORNIA, FRI-MON, JUN 20-23.
DETAILED SUMMARY
FOR SUNDAY JUNE 15 - THURSDAY JUNE 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY JUNE 20 - THURSDAY JUNE 26: POSITIVE 500-HPA HEIGHT ANOMALIES ARE
FORECAST ACROSS MUCH OF THE CONUS EARLY IN THE WEEK-2 PERIOD, WITH THE
STRONGEST ANOMALIES OVER THE EASTERN CONUS. HOWEVER, THESE ANOMALIES ARE NOT
PARTICULARLY ROBUST AND NORMALIZED 500-HPA HEIGHT ANOMALIES ARE ONLY 1 TO 1.5
STANDARD DEVIATIONS ABOVE NORMAL. THE NORMALIZED ANOMALIES ARE STRONGEST FROM
THE GULF OF AMERICA NORTHWARD INTO THE CENTRAL CONUS. THE MID-LEVEL RIDGE AXIS
IS ALSO EXPECTED TO BE LOCATED OVER THIS REGION DURING MUCH OF WEEK-2.
AT THE SURFACE, DYNAMICAL MODEL GUIDANCE INDICATES A STRONG BERMUDA HIGH
PRESSURE AND RETURN FLOW OFF THE GULF HELPING TO ENHANCE LOW LEVEL MOISTURE AND
INDUCING A WARM AND STICKY AIRMASS ACROSS THE CENTRAL CONUS. A SKILL WEIGHTED
BIAS-CORRECTED HEAT INDEX FORECAST OF THE GEFS AND ECENS, INDICATES 30-40%
CHANCES OF THE HEAT INDEX EXCEEDING 105 DEG F ACROSS PARTS OF THE CENTRAL
PLAINS, MIDDLE AND LOWER MISSISSIPPI VALLEYS. THIS HEAT SIGNAL IS ALSO
SUPPORTED BY THE PROBABILISTIC EXTREMES TOOLS (PETS) FROM BOTH OF THOSE MODELS
AS WELL. ADDITIONALLY, DETERMINISTIC GUIDANCE SUPPORTS HEAT INDICES ABOVE 100
DEG F ACROSS THESE REGIONS. THEREFORE, A SLIGHT RISK OF EXTREME HEAT IS POSTED
FOR THE PREVIOUSLY DESCRIBED AREAS FOR FRI-SUN, JUN 20-22.
IN PARTS OF THE SOUTHEAST TODAY, DYNAMICAL GUIDANCE IS MORE SUPPORTIVE OF
TEMPERATURES APPROACHING HAZARDOUS CRITERIA BENEATH POSITIVE 500-HPA HEIGHT
ANOMALIES AND A PARTICULARLY MOIST AIRMASS. SOME OF THIS HEAT MAY ALREADY BE
UNDERWAY BY THE START OF WEEK-2 BUT ONGOING HEAT, WITH LITTLE RELIEF AT NIGHT,
MAY CAUSE ISSUES AT THE START OF THE PERIOD. THE NATIONAL BLEND OF MODELS (NBM)
IS FORECASTING MANY OVERNIGHT RECORD HIGH MINIMUM TEMPERATURES ACROSS MUCH OF
THE SOUTHEAST. THEREFORE, A SLIGHT RISK OF EXTREME HEAT IS POSTED FOR JUN 20-22
ACROSS PORTIONS OF THE CAROLINAS, GEORGIA, AND FLORIDA.
IN THE DESERT SOUTHWEST, DYNAMICAL GUIDANCE REMAINS SUPPORTIVE OF TEMPERATURES
APPROACHING HEAT CRITERIA. TEMPERATURES OF 105 TO 110 ARE SUPPORTED BY MANY
TOOLS AFTER A BRIEF RESPITE AT THE END OF WEEK-1. THEREFORE, A SLIGHT RISK OF
EXTREME HEAT IS POSTED FOR THE DESERT SOUTHWEST FOR JUN 20-21. FOLLOWING THIS
INITIAL HEAT, DYNAMICAL MODEL GUIDANCE FROM THE GEFS AND ECENS BEGINS TO SHOW
INCREASED CHANCES FOR PRECIPITATION TO MOVE INTO THE REGION ASSOCIATED WITH
INCREASED ATMOSPHERIC MOISTURE. CHANCES FOR HEAVY PRECIPITATION WILL BE WATCHED
IN THE COMING DAYS ACROSS THE SOUTHWEST.
IN THE NORTHERN PLAINS INTO THE GREAT LAKES, ALONG THE NORTHERN PERIPHERY OF
THE MID-LEVEL RIDGE, DYNAMICAL GUIDANCE IS INDICATING INCREASED CHANCES OF ONE
OR MORE MESOSCALE CONVECTIVE SYSTEMS (MCS) TO DEVELOP AND BRING CHANCES FOR
HEAVY PRECIPITATION TO THE REGION. THE ECENS REFORECAST AND PET SHOW INCREASED
CHANCES FOR ABOVE-NORMAL PRECIPITATION DURING WEEK-2 AND PRECIPITATION
EXCEEDING THE 85TH PERCENTILE IN THE FIRST 3 DAYS OF THE PERIOD, RESPECTIVELY.
SIMILARLY, THE STATISTICAL ANALOG TOOL HIGHLIGHTS INCREASED CHANCES FOR
ABOVE-NORMAL PRECIPITATION ACROSS THIS REGION AS WELL. THEREFORE, A SLIGHT RISK
OF HEAVY PRECIPITATION IS POSTED FOR JUN 20-23 IN THIS REGION.
IN SOUTHERN TEXAS, AN EASTERLY WAVE OFF THE BAY OF CAMPECHE, BRINGS INCREASED
CHANCES FOR HEAVY PRECIPITATION TO THE AREA. THE PETS FROM THE GEFS AND ECENS
INDICATED 20-40% CHANCES FOR 3 DAY PRECIPITATION AMOUNTS TO EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1 INCH. THIS COULD LEAD TO CHANCES OF FLASH
FLOODING DUE TO THE SHORT TIME IN WHICH PRECIPITATION IS FORECAST TO FALL AND
THE NATURE OF THE WATERSHEDS IN THE REGION. THEREFORE, A SLIGHT RISK OF HEAVY
PRECIPITATION IS FORECAST FOR JUN 20-21.
MODELS GENERALLY DEPICT FAIRLY STRONG WINDS AT THE SOUTHERN END OF THE GULF
MOISTURE INFLOW. WHILE THE PETS ARE RATHER MIXED, ENSEMBLE MEAN WIND SPEEDS
FROM THE ECMWF AND GEFS BOTH INDICATE PEAK DAILY WIND SPEEDS OF AT LEAST 20MPH
OVER WESTERN PORTIONS OF THE SOUTHERN PLAINS THROUGHOUT THE FORECAST PERIOD,
THEREFORE A SLIGHT RISK OF EPISODIC HIGH WINDS IS POSTED FOR THIS REGION FOR
THE FIRST HALF OF WEEK-2. FORECAST ENSEMBLE MEAN WIND SPEEDS ARE ALSO ELEVATED
ALONG THE WEST COAST DURING THE FIRST HALF OF WEEK-2 WITH WIND SPEEDS OF
25-30MPH ALONG THE IMMEDIATE COAST FROM MEDFORD, OR SOUTH TO POINT CONCEPTION
IN CALIFORNIA.
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: RYAN BOLT
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