793
FXUS21 KWNC 291807
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 29 2026
SYNOPSIS: EXTREME HEAT IS POSSIBLE DURING WEEK-2 ACROSS MANY AREAS OF THE
CONTIGUOUS U.S. (CONUS) ASSOCIATED WITH ANOMALOUS MID-LEVEL HIGH PRESSURE.
ANTICIPATED HIGH DEWPOINTS OVER THE CENTRAL AND EASTERN CONUS FAVOR ELEVATED
HEAT INDEX VALUES WITH WARM NIGHTS LIMITING OVERNIGHT RELIEF. AS THE MID-LEVEL
HIGH CONSOLIDATES OVER THE WESTERN AND CENTRAL CONUS, THERE MAY BE HEAT RELIEF
FOR SOME AREAS OF THE EASTERN CONUS, BUT WITH CHANCES FOR EXTREME HEAT
REMAINING POSSIBLE FOR THE WESTERN AND CENTRAL CONUS. SURFACE HIGH PRESSURE OFF
THE WEST COAST IN WEEK-2 INCREASES CHANCES FOR EPISODES OF HIGH WINDS ACROSS
THE PACIFIC NORTHWEST AND CALIFORNIA THROUGH MUCH OF THE PERIOD.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR THE GREAT LAKES, OHIO VALLEY, APPALACHIANS,
MID-ATLANTIC AND SOUTHEAST, TUES-WED, JUL 7-8.
SLIGHT RISK OF EXTREME HEAT ACROSS MUCH OF THE GREAT BASIN, ROCKIES, SOUTHWEST,
AND PLAINS, TUES-SAT, JUL 7-11.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR PORTIONS OF CALIFORNIA AND THE PACIFIC
NORTHWEST, TUE-MON, JUL 7-13.
DETAILED SUMMARY
FOR THURSDAY JULY 02 - MONDAY JULY 06:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JULY 07 - MONDAY JULY 13: A MAJOR HEAT WAVE DURING WEEK-1 MAY
LINGER INTO EARLY WEEK-2 ACROSS THE EASTERN CONUS. HOWEVER, THERE IS INCREASED
UNCERTAINTY REGARDING THE POTENTIAL IMPACTS IN THE WEEK-2 PERIOD. MID-LEVEL
RIDGING HAS LARGELY SHIFTED TOWARDS THE WESTERN AND CENTRAL CONUS BY THE START
OF WEEK-2. MID-LEVEL HEIGHTS MAY REMAIN SLIGHTLY ABOVE NORMAL ACROSS THE
EASTERN CONUS BUT A WEAKNESS IN THE MID-LEVEL HEIGHTS OVER THE EASTERN US
REDUCES CHANCES FOR EXTREME HEAT.
NEVERTHELESS, UNCALIBRATED TEMPERATURE ANOMALIES ARE FORECAST TO REMAIN NEAR TO
ABOVE NORMAL ACROSS MOST OF THE CONUS EARLY IN WEEK-2. THE ANOMALIES ARE
REDUCED FROM THE WEEK-1 PERIOD BUT REMAIN ELEVATED. PROBABILISTIC EXTREMES
TOOLS (PETS) FROM THE GEFS AND ECENS CONTINUE TO MAINTAIN 20 TO 40% CHANCES OF
MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE CLIMATOLOGICALLY ACROSS THE
EASTERN U.S. AND BENEATH THE MID-LEVEL RIDGE OVER THE CENTRAL AND WESTERN
CONUS. THE BIGGEST AREA OF DIVERGENCE FROM YESTERDAY IS ACROSS THE SOUTHERN
PLAINS INTO THE LOWER MISSISSIPPI VALLEY WHERE TOOLS FAVOR MORE NEAR NORMAL
CONDITIONS, AT LEAST EARLY IN THE PERIOD. SKILL WEIGHTED APPARENT TEMPERATURE
GUIDANCE ALSO CONTINUES TO FORECAST ELEVATED CHANCES FOR APPARENT TEMPERATURES
EXCEEDING THE 90TH PERCENTILE.
GIVEN THE AFOREMENTIONED TOOL GUIDANCE, A PAIR OF SLIGHT RISKS (20-40% CHANCES)
ARE FORECAST FOR EXTREME HEAT COVERING MUCH OF THE CONUS. THE FIRST RISK COVERS
PARTS OF THE GREAT LAKES, OHIO VALLEY, APPALACHIANS, MID-ATLANTIC AND SOUTHEAST
FOR JUL 7-8 FOR ANY HEAT THAT MAY PERSIST INTO WEEK-2 FOLLOWING THE ONGOING
HEATWAVE. A SECOND COVERS MUCH OF THE GREAT BASIN, ROCKIES, SOUTHWEST, AND
PLAINS, JUL 7-11. THIS REGION REMAINS UNDERNEATH POSITIVE MID-LEVEL HEIGHT
ANOMALIES AND MID-LEVEL RIDGE AXIS. WHILE THE SURFACE REFLECTION OF THE RIDGE
REMAINS SOMEWHAT UNDERWHELMING, THE TOOLS HAVE BEEN WARMING OVER THE PAST FEW
DAYS AND WARRANTS MONITORING. THE SLIGHT RISK BISECTS THE GREAT BASIN, ROUGHLY
INLINE WITH THE BEST AGREEMENT BETWEEN THE GEFS AND ECENS PETS. IN A NEW
DEVELOPMENT TODAY, THE GEFS PET INDICATES INCREASED CHANCES OF EXTREME HEAT ALL
THE WAY TO THE WEST COAST, WHICH WILL BE MONITORED OVER THE COMING DAYS FOR
POSSIBLE BETTER AGREEMENT AMONG THE FORECAST GUIDANCE.
SURFACE HIGH PRESSURE OFF THE WEST COAST AND MID-LEVEL LOW PRESSURE, ALONG WITH
THERMAL LOW PRESSURE OVER THE GREAT BASIN INCREASE CHANCES FOR EPISODES OF HIGH
WINDS DURING WEEK-2. THE GEFS AND ECMWF PETS INDICATE AT LEAST A 20 PERCENT
CHANCE OF WIND SPEEDS EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE AND 25-MPH.
THEREFORE, A SLIGHT RISK OF HIGH WINDS IS POSTED ACROSS THIS REGION, JUL 7-13.
ACROSS THE SOUTHWESTERN CONUS, THE RIDGE AXIS IS FORECAST TO MOVE TOWARDS A
MORE FAVORABLE POSITION FOR ENHANCED MONSOONAL MOISTURE ADVECTION AND INCREASED
PRECIPITATION OVER PARTS OF THE DESERT SOUTHWEST. 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 AREA WILL CONTINUE TO BE MONITORED WITH ENSEMBLE
GUIDANCE INDICATING PRECIPITABLE WATER INCREASING DURING THE WEEK-2 PERIOD.
ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY, SOME TOOLS ARE
BRINGING INCREASED PRECIPITATION CHANCES TO PARTS OF THESE AREAS. AT THIS TIME,
PRECIPITATION AMOUNTS DO NOT APPEAR TO BE REACHING HAZARDOUS CRITERIA AND THE
SOILS IN THIS AREA CAN LIKELY ABSORB MODERATE AMOUNTS OF PRECIPITATION AT THIS
TIME, PRECLUDING A PRECIPITATION HAZARD BUT WILL CONTINUE TO BE MONITORED.
TRANSIENT SHORTWAVES MOVING ACROSS ALASKA FAVOR PERIODS OF ENHANCED
PRECIPITATION ACROSS MUCH OF THE STATE, ALONG WITH A TILT TOWARD BELOW-AVERAGE
TEMPERATURES. HOWEVER, PRECIPITATION AND TEMPERATURE VALUES ARE EXPECTED TO
REMAIN BELOW HAZARDOUS THRESHOLDS.
FORECASTER: RYAN BOLT
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