891
FXUS21 KWNC 261841
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 26 2026
SYNOPSIS: EXTREME HEAT IS LIKELY TO CONTINUE FROM WEEK-1 INTO THE JULY 4
HOLIDAY ACROSS MANY AREAS OF THE CENTRAL AND EASTERN CONTIGUOUS U.S. (CONUS)
ASSOCIATED WITH ANOMALOUS MID-LEVEL HIGH PRESSURE. ANTICIPATED HIGH DEWPOINTS
FAVOR HEAT INDEX VALUES EXCEEDING 100 TO 105 DEG F OVER MANY AREAS WITH WARM
NIGHTS LIKELY LIMITING OVERNIGHT RELIEF. AS THE MID-LEVEL HIGH SHIFTS WESTWARD,
SOME HEAT RELIEF IS FORECAST ACROSS THE EASTERN SEABOARD, BUT WITH EXTREME HEAT
POTENTIAL INCREASING ACROSS PARTS OF THE INTERIOR WESTERN CONUS. THIS
TRANSITION MAY ALSO FAVOR FRONTAL ACTIVITY AND ROUNDS OF HEAVY PRECIPITATION
ACROSS PORTIONS OF THE NORTHEAST AND MID-ATLANTIC EARLY IN THE PERIOD.
MID-LEVEL LOW PRESSURE OFF THE WEST COAST EARLY IN WEEK-2 INCREASES CHANCES FOR
EPISODES OF HIGH WINDS ACROSS THE PACIFIC NORTHWEST AND CALIFORNIA.
HAZARDS
HIGH RISK OF EXTREME HEAT ACROSS PORTIONS OF THE EASTERN GREAT PLAINS,
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, APPALACHIANS, SOUTHEAST, AND
MID-ATLANTIC, SAT, JUL 4.
MODERATE RISK OF EXTREME HEAT FROM THE GREAT PLAINS TO THE EASTERN SEABOARD
(EXCLUDING PORTIONS OF THE GREAT LAKES, NORTHEAST, AND GULF COAST), SAT-SUN,
JUL 4-5.
SLIGHT RISK OF EXTREME HEAT ACROSS MUCH OF THE GREAT BASIN, ROCKIES, GREAT
PLAINS, AND THE EASTERN CONUS, SAT-TUE, JUL 4-7.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHEAST, OHIO
VALLEY, AND MID-ATLANTIC, SAT-MON, JUL 4-6.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF CALIFORNIA AND THE PACIFIC NORTHWEST,
SAT-TUE, JUL 4-7.
DETAILED SUMMARY
FOR MONDAY JUNE 29 - FRIDAY JULY 03:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JULY 04 - FRIDAY JULY 10: A MAJOR HEAT WAVE IS FORECAST TO BE
ONGOING ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS AT THE START OF WEEK-2.
FOR THE EASTERN SEABOARD, THE PEAK OF THE HEAT IS LIKELY TO OCCUR DURING THE
LATE WEEK-1 TIMEFRAME, WITH RIDGING RETROGRADING FARTHER TO THE WEST AT THE
BEGINNING OF WEEK-2. DESPITE THESE TRENDS, THE ECMWF PROBABILISTIC EXTREME TOOL
(PET) CONTINUES TO INDICATE GREATER THAN A 60 PERCENT CHANCE MAXIMUM
TEMPERATURES EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE ON DAY-8 (JULY 4).
ADDITIONALLY, THE UNCALIBRATED 0Z DETERMINISTIC ECMWF DEPICTS HEAT INDEX VALUES
GREATER THAN 105 DEG F ACROSS THE MID-ATLANTIC. WHILE THE GEFS IS ARGUABLY LESS
ROBUST WITH THE MOST EXTREME HEAT INTO THE 4TH OF JULY, IT STILL DEPICTS ACTUAL
TEMPERATURES IN THE 90S DEG F EXTENDING THROUGH THE NORTHERN MID-ATLANTIC AND
POSSIBLY NEAR TO ABOVE 100 DEG F ACROSS PARTS OF THE CAROLINAS. GIVEN SOME OF
THE RELATIVELY COOLER SIGNALS EMERGING OVER MORE NORTHERN AREAS, THE RISKS OF
EXTREME HEAT HAVE BEEN ADJUSTED SLIGHTLY SOUTHWARD COMPARED TO YESTERDAY ACROSS
THE EAST. HOWEVER, A HIGH RISK (GREATER THAN 60 PERCENT CHANCE) FOR EXTREME
HEAT REMAINS VALID FOR JULY 4 OVER THE CENTRAL AND SOUTHERN PORTIONS OF THE
MID-ATLANTIC INTO THE SOUTHEAST GIVEN THE BEST TOOL AGREEMENT AND CONTINUED
INDICATION FOR RECORD HIGH TEMPERATURES IN THE NATIONAL BLEND OF MODELS (NBM).
THE HIGH RISK EXTENDS WESTWARD THROUGH PARTS OF THE TENNESSEE VALLEY, MIDWEST,
MISSISSIPPI VALLEY AND EASTERN PLAINS UNDERNEATH THE RIDGE AXIS AND CONSISTENT
WITH A VERY HUMID AIR MASS IN PLACE, WITH SKILL WEIGHTED HEAT RISK TOOLS
INDICATING AT LEAST A 60 PERCENT CHANCE OF HEAT INDEX VALUES EXCEEDING 100
(105) DEG F INTO PARTS OF THE NORTHERN (CENTRAL) PLAINS. THE NBM ALSO DEPICTS
WIDESPREAD RECORD HIGH MINIMUM TEMPERATURES THROUGHOUT MUCH OF THE EASTERN U.S.
(POTENTIALLY ONLY DROPPING INTO THE MID- TO UPPER 70S DEG F), RESULTING IN
LITTLE OVERNIGHT RELIEF FROM THE HEAT. ANOTHER KEY CONSIDERATION IS THE
NATION'S 250TH ANNIVERSARY ON JULY 4, WITH NUMEROUS OUTDOOR ACTIVITIES PLANNED.
STAYING HYDRATED AND LIMITING EXPOSURE TO VERY HOT, HUMID WEATHER IS VERY
IMPORTANT, ESPECIALLY VULNERABLE POPULATIONS INCLUDING OLDER ADULTS.
A MODERATE RISK (40-60 PERCENT CHANCE) OF EXTREME HEAT IS POSTED FROM THE GREAT
PLAINS TO THE EASTERN SEABOARD FOR JULY 4-5. AS PREVIOUSLY DISCUSSED, THERE IS
MORE UNCERTAINTY IN REGARDS TO HOW LONG THE HEAT WILL PERSIST ACROSS THE EAST,
ESPECIALLY ACROSS THE NORTHERN MID-ATLANTIC WHERE SIGNALS ARE MORE MIXED. THERE
IS HIGHER CONFIDENCE REGARDING THE CORE OF THE HEAT POTENTIAL BECOMING FOCUSED
ACROSS THE GREAT PLAINS, WHERE TRIPLE DIGIT TEMPERATURES ARE POSSIBLE. BY
DAY-10, THE 0Z ECMWF, GEFS, AND CANADIAN ENSEMBLES ALL DEPICT A 595-596 DM
RIDGE ACROSS THE FOUR CORNERS, WHICH WOULD RESULT IN EXTREME HEAT CONDITIONS
EMERGING ACROSS PORTIONS OF THE INTERIOR WEST. THEREFORE, A BROADER SLIGHT RISK
(20-40 PERCENT CHANCE) OF EXTREME HEAT IS VALID JULY 4-7, ENCOMPASSING THE
MODERATE RISK, AND ALSO INCLUDING PORTIONS OF THE ROCKIES AND GREAT BASIN.
EXTREME HEAT IS FAVORED TO PERSIST ACROSS THE WEST THROUGHOUT ALL OF WEEK-2,
AND PERHAPS CONTINUE TO EXPAND INTO THE DESERT SOUTHWEST AND CALIFORNIA CENTRAL
VALLEY. HOWEVER, MODELS INDICATE WEAK TROUGHING AND ENHANCED NORTHWESTERLY
MID-LEVEL FLOW DEVELOPING DOWNSTREAM OF THE RIDGE WHICH WOULD LEAD TO
DIMINISHING HEAT RISK ACROSS THE EASTERN U.S. LATER IN THE PERIOD. BECAUSE THE
SLIGHT AND MODERATE RISKS COVER LARGE AREAS, THEIR VALID TIME PERIODS GENERALLY
CAPTURE THE HEAT RISK OVER ALL LOCATIONS INCLUDED. HOWEVER, THE TRANSIENT
NATURE OF THE RIDGE MAKES IT DIFFICULT TO ACCURATELY DEPICT THE HEAT
PROGRESSION, AND IT IS LIKELY THAT ADDITIONAL EXTENSIONS IN TIME WILL BE NEEDED
IN FUTURE UPDATES TO THE WESTERN PORTIONS OF THE MODERATE AND SLIGHT RISKS AS
THE HEAT DIMINISHES IN THE EAST.
TIED TO WESTWARD SHIFTING RIDGING, AND THE POTENTIAL PROGRESSION OF FRONTAL
ACTIVITY, ENHANCED PRECIPITATION AND POTENTIAL THUNDERSTORMS ARE POSSIBLE
ACROSS PARTS OF THE OHIO VALLEY, LOWER NORTHEAST, AND MID-ATLANTIC. WHILE
SIGNALS ARE WEAK, CONSIDERATION IS GIVEN TO THE OVERALL SYNOPTIC PATTERN AND
INCREASED IMPACTS ON JULY 4. BOTH THE GEFS AND ECMWF PETS INDICATE AT LEAST A
20 PERCENT CHANCE OF 3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE ACROSS PARTS OF THE REGION. UNCALIBRATED TOOLS ARE
MARGINALLY SUPPORTIVE AS WELL WITH ENHANCED CHANCES OF PRECIPITATION TOTALS
REACHING 1-INCH, AND LOCALLY HIGHER AMOUNTS POSSIBLE IN THUNDERSTORMS.
THEREFORE, A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED FOR THE
AFOREMENTIONED AREAS, JULY 4-6.
AT THE BASE OF ANOMALOUS TROUGHING FAVORED EARLY IN WEEK-2 ACROSS THE WEST
COAST OF THE CONUS AND NORTHEAST PACIFIC, A SLIGHT RISK OF HIGH WINDS REMAINS
POSTED FOR JULY 4-7. THIS RISK AREA IS SHIFTED FARTHER SOUTH INTO CALIFORNIA
COMPARED TO YESTERDAY, CONSISTENT WITH THE GEFS AND ECMWF PETS INDICATING AT
LEAST A 20 PERCENT CHANCE OF WIND SPEEDS EXCEEDING THE 85TH CLIMATOLOGICAL
PERCENTILE AND 25-MPH. ACROSS THE SOUTHWESTERN CONUS, THE RIDGE AXIS IS
FORECAST TO MOVE INTO A MORE FAVORABLE POSITION FOR ENHANCED MONSOONAL MOISTURE
ADVECTION AND INCREASED PRECIPITATION OVER PARTS OF THE DESERT SOUTHWEST.
ALTHOUGH PETS SHOW INCREASED CHANCES OF 3-DAY PRECIPITATION EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE OVER THE DESERT SOUTHWEST AND INTO THE CENTRAL
ROCKIES DURING THE SECOND 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.
TRANSIENT SHORTWAVES MOVING ACROSS ALASKA FAVOR PERIODS OF ENHANCED
PRECIPITATION ACROSS MUCH OF THE STATE, ALONG WITH A TILT TOWARD BELOW-AVERAGE
TEMPERATURES. HOWEVER, NO AREAS OF HAZARDOUS WEATHER ARE EXPECTED.
FORECASTER: THOMAS COLLOW
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