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FXUS21 KWNC 251805
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 25 2026
SYNOPSIS: LEADING UP TO AND THROUGH THE JULY 4TH HOLIDAY WEEKEND, EXTREME HEAT
REMAINS THE PRIMARY HAZARDS CONCERN FOR MANY AREAS OF THE CONTIGUOUS U.S.
(CONUS) EAST OF THE ROCKIES ASSOCIATED WITH VERY STRONG MID-LEVEL HIGH PRESSURE
FORECAST. ANTICIPATED HIGH DEWPOINTS WOULD PROMOTE HEAT INDEX VALUES EXCEEDING
100 TO 105 DEG F IN MANY AREAS WITH WARM NIGHTS IN THE 70S-80S LIKELY LIMITING
OVERNIGHT RELIEF. AS THE MID-LEVEL HIGH PRESSURE SHIFTS WESTWARD INTO THE
CENTRAL CONUS LATER IN THE PERIOD, THERE IS AN INCREASED LIKELIHOOD OF EXTREME
HEAT DEVELOPING OVER MANY PARTS OF THE UPPER MIDWEST. ACROSS THE WESTERN CONUS,
MID-LEVEL LOW PRESSURE FAVORED EARLY IN WEEK-2 INCREASES CHANCES FOR EPISODES
OF HIGH WINDS OVER THE WEST COAST AND NORTHERN INTERMOUNTAIN REGION.
HAZARDS
HIGH RISK OF EXTREME HEAT FOR PORTIONS OF THE MIDDLE AND LOWER MISSISSIPPI,
OHIO, AND TENNESSEE VALLEYS, GREAT LAKES, APPALACHIANS, MID-ATLANTIC, AND
SOUTHEAST, FRI, JUL 3.
MODERATE RISK OF EXTREME HEAT FOR MUCH OF THE CENTRAL AND EASTERN CONUS,
FRI-SAT, JUL 3-4.
SLIGHT RISK OF EXTREME HEAT FOR MUCH OF THE CENTRAL AND EASTERN CONUS, FRI-MON,
JUL 3-6.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF CALIFORNIA, PACIFIC NORTHWEST,
NORTHERN INTERMOUNTAIN, AND NORTHERN GREAT BASIN, FRI-SAT, JUL 3-4.
DETAILED SUMMARY
FOR SUNDAY JUNE 28 - THURSDAY JULY 02:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY JULY 03 - THURSDAY JULY 09: LEADING INTO THE 4TH OF JULY HOLIDAY
WEEKEND, THERE CONTINUES TO BE GOOD AGREEMENT AMONG THE DYNAMICAL MODELS
FEATURING ANOMALOUS TROUGHING OVER THE NORTHWESTERN CONUS WITH HIGHLY AMPLIFIED
RIDGING DOWNSTREAM OVER THE CENTRAL AND EASTERN CONUS. AT THE START OF WEEK-2
(JUL 3), BOTH THE 0Z GEFS AND ECMWF ENSEMBLES FAVOR A FAIRLY STRONGER 500-HPA
RIDGE CENTER COMPARED TO YESTERDAY, CONSISTING OF A LARGER COVERAGE OF 594 DM
HEIGHTS CENTERED OVER THE OHIO AND TENNESSEE VALLEYS WITH 6Z GEFS FEATURING 597
DM HEIGHTS. THIS NOW TRANSLATES TO GREATER THAN 2 STANDARD DEVIATIONS IN
NORMALIZED ANOMALY HEIGHT SPACE, INCREASING CONFIDENCE FOR WELL ABOVE-NORMAL,
AND POSSIBLY RECORD BREAKING SUMMERTIME TEMPERATURES ALONG WITH ELEVATED RISKS
OF EXTREME HEAT FOR MANY AREAS IN THE MIDWEST AND EASTERN U.S PERSISTING FROM
WEEK-1 INTO EARLY WEEK-2. CONSISTENT WITH PREVIOUS ENSEMBLE MEAN GUIDANCE, MUCH
OF THE AMPLIFIED RIDGING IS FAVORED TO RETROGRADE, ALLOWING FOR MORE TROUGHING
TO DEVELOP OVER THE NORTHEASTERN CONUS TOWARDS THE MIDDLE OF WEEK-2. WHILE THIS
IS EXPECTED TO BRING SOME EVENTUAL RELIEF TO THE ANOMALOUS WARMTH OVER THE
EASTERN U.S., THE RISK FOR EXTREME HEAT ACCOMPANYING THE AMPLIFIED RIDGE CENTER
LOOKS TO EXPAND WESTWARD INTO PORTIONS OF THE PLAINS, MISSISSIPPI VALLEY, AND
INTO THE INTERIOR WEST LATER IN THE PERIOD. THE FAVORED RIDGING OVER THE
WESTERN CONUS DURING THE LATTER PART OF WEEK-2 IS NOTEWORTHY AS MODELS CONTINUE
TO MAINTAIN THE DEVELOPMENT OF LONGWAVE TROUGHING OVER THE NORTHEASTERN PACIFIC
AT THIS LEAD. COUPLED WITH A MEAN TROUGH FAVORED OVER EASTERN NORTH AMERICA,
THIS RESULTS IN A STABLE, OMEGA LIKE PATTERN TAKING SHAPE. SUCH A PATTERN
TRANSITION IMPLIES THE POTENTIAL FOR PERSISTENCE, AND POSSIBLY BRINGING WEATHER
RELATED HAZARD IMPACTS THAT COULD BE OF LONG DURATION LATER IN JULY.
TIED TO THE MORE AMPLIFIED 500-HPA RIDGING FAVORED IN THE GEFS, ECMWF, AND
CANADIAN ENSEMBLES, BOTH RAW AND CALIBRATED TEMPERATURE TOOLS SHOW A STRONGER
TEMPERATURE RESPONSE LATE NEXT WEEK RELATIVE TO YESTERDAY'S GUIDANCE. BOTH THE
GEFS AND ECMWF DEPICT A SUBSTANTIAL INCREASE IN THE PROBABILITIES FOR DOUBLE
DIGIT POSITIVE TEMPERATURE DEPARTURES ACROSS THE EASTERN CONUS AND THE MIDWEST,
WITH THE HIGHEST CHANCES (>80%) FOCUSED OVER THE EASTERN OHIO AND TENNESSEE
VALLEYS EASTWARD TO THE MID-ATLANTIC AND ADJACENT PARTS OF THE SOUTHEAST.
CORRESPONDING TEMPERATURE INCREASES ARE EVIDENT IN THE PROBABILISTIC EXTREME
TOOLS (PETS), WHERE THE GEFS AND ECMWF INDICATE AT LEAST 60% AND 80% CHANCES,
RESPECTIVELY, OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH CLIMATOLOGICAL
PERCENTILE, WITH STRONGER WARM SIGNALS FEATURED FARTHER NORTH ACROSS THE UPPER
MIDWEST, GREAT LAKES, AND NORTHEAST EARLY IN WEEK-2. OVER THE PAST FEW DAYS,
THE NATIONAL BLEND OF MODELS (NBM) ALSO CONTINUES TO SHOW A GROWING NUMBER OF
SITES WHERE BOTH MAXIMUM AND MINIMUM TEMPERATURES ARE FORECAST TO APPROACH
AND/OR BREAK DAILY RECORDS. THERE IS A NOTED UPTICK OVER THE APPALACHIANS
(HIGHS REACHING THE MID-90S DEG F) WITH THE BULK OF THESE SITES LOCATED
UNDERNEATH THE AMPLIFIED RIDGE CENTER.
BASED ON THESE DEVELOPMENTS SINCE YESTERDAY, THE PAIR OF HIGH RISK AREAS FOR
EXTREME HEAT ARE CONSOLIDATED INTO A SINGLE HIGH RISK AREA, AND EXPANDED TO
INCLUDE PORTIONS OF THE MISSISSIPPI VALLEY, APPALACHIANS, GREAT LAKES, AND THE
NORTHERN MID-ATLANTIC, NOW VALID FOR JUL 3 BEFORE MORE NORTHWESTERLY MID-LEVEL
FLOW BEGINS TO BUILD IN. WITHIN THE HIGH RISK AREA, BOTH DETERMINISTIC NBM AND
ECMWF INDICATE DAYTIME APPARENT TEMPERATURES BETWEEN 100 AND 110 DEG F (UPPER
90S ACROSS THE NORTHERN PERIPHERY OF AREA), AND CALIBRATED HEAT TOOLS ALSO SHOW
ELEVATED CHANCES FOR HEAT INDEX VALUES EXCEEDING HEAT HAZARD CRITERIA. A
BROADER MODERATE RISK AREA REMAINS ISSUED, VALID FOR JUL 3-4, AND IS LIKEWISE
EXPANDED TO INCLUDE PORTIONS OF THE SOUTHEAST, UPPER MIDWEST, AND THE NORTHEAST
BASED ON INCREASED SUPPORT IN THE PETS AND CALIBRATED HEAT TOOLS. TO CAPTURE
THE RETROGRADING RIDGE, AN EVEN BROADER SLIGHT RISK AREA REMAINS POSTED AND
EXPANDED TO INCLUDE THE ENTIRE CENTRAL AND NORTHERN PLAINS IN PROXIMITY TO THE
STRONGEST MID-LEVEL HEIGHT DEPARTURES FAVORED OVER THIS PART OF THE COUNTRY,
AND EXTENDED THROUGH JUL 6. FOR BOTH THE UPDATED MODERATE AND SLIGHT RISK
AREAS, COVERAGE HAS BEEN REMOVED OVER PORTIONS OF THE SOUTHERN PLAINS BASED ON
COOLER TEMPERATURES FAVORED IN THE RAW TOOLS. CONSIDERATION WAS GIVEN FOR THE
ADDITION OF A SEPARATE SLIGHT RISK AREA OF EXTREME HEAT OVER PARTS OF THE
WESTERN CONUS BASED ON WARMING TRENDS IN THE TOOLS LATE IN THE PERIOD, HOWEVER
PETS ARE NOT QUITE SUPPORTIVE AND THERE REMAINS UNCERTAINTY AS TO WHETHER
TEMPERATURES WILL EXCEED HAZARD THRESHOLDS AT THIS LEAD. WITH THIS ELEVATED
RISK FOR EXTREME HEAT EARLY IN WEEK-2, IT IS IMPORTANT TO NOTE THAT ANOMALIES
ARE GENERALLY STRONGER IN THE MINIMUM TEMPERATURE FORECASTS, WHICH WOULD LIMIT
OVERNIGHT RELIEF TO HEAT BEING FELT DURING THE DAY. ANOTHER KEY CONSIDERATION
IS THE NATION'S 250TH ANNIVERSARY THIS JULY 4TH, WITH NUMEROUS OUTDOOR
ACTIVITIES PLANNED. STAYING HYDRATED AND LIMITING EXPOSURE TO VERY HOT, HUMID
WEATHER IS VERY IMPORTANT, ESPECIALLY VULNERABLE POPULATIONS INCLUDING OLDER
ADULTS.
AT THE BASE AND HEAD OF THE ANOMALOUS TROUGHING FAVORED EARLY IN WEEK-2 ACROSS
THE WESTERN CONUS, A SLIGHT RISK OF HIGH WINDS REMAINS POSTED FOR JUL 3-4. THIS
RISK AREA IS EXPANDED TO COVER MORE OF THE WEST COAST AND MORE OF THE NORTHERN
INTERMOUNTAIN AND NORTHERN GREAT BASIN WHERE TROUGHING IS FORECAST TO LIFT OUT,
AND THE ECMWF PET DEPICTS INCREASED CHANCES FOR WIND SPEEDS EXCEEDING THE 85TH
PERCENTILE. ACROSS THE SOUTHWESTERN CONUS, THERE CONTINUES TO BE GOOD AGREEMENT
BETWEEN THE GEFS AND ECMWF, PLACING A 594 500-HPA HEIGHT CENTER OVER THE
EASTERN FOUR CORNERS, RESULTING IN A MORE FAVORABLE CIRCULATION FOR MONSOONAL
MOISTURE ADVECTION AND INCREASED PRECIPITATION OVER PARTS OF THE DESERT
SOUTHWEST. ALTHOUGH PETS SHOW INCREASED CHANCES OF 3-DAY AMOUNTS EXCEEDING THE
85TH PERCENTILE OVER THE DESERT SOUTHWEST AND INTO THE CENTRAL ROCKIES
ASSOCIATED WITH THIS CIRCULATION DURING THE LATER HALF OF WEEK-2, BOTH RAW AND
CALIBRATED PRECIPITATION AMOUNTS IN THE ENSEMBLE MEANS REMAIN FAIRLY LOW,
PRECLUDING A CORRESPONDING PRECIPITATION HAZARD AT THIS TIME. LOCALIZED
THUNDERSTORMS ARE STILL POSSIBLE AND THIS REGION WILL CONTINUE TO BE MONITORED
IN THE UPCOMING OUTLOOKS.
FORECASTER: NICK NOVELLA
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