923
FXUS21 KWNC 121853
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 12 2026
SYNOPSIS: PERSISTENT MID-LEVEL HIGH PRESSURE OVER THE FOUR CORNERS OCCURRING
NEAR THE PEAK OF SUMMER BRINGS THE RISK OF EXTREME HEAT FOR MUCH OF THE
WESTERN, CENTRAL, AND SOUTHEASTERN CONTIGUOUS U.S. (CONUS) THROUGHOUT WEEK-2.
MID-LEVEL LOW PRESSURE OVER THE NORTHEAST U.S. MAY RESULT IN HEAVY
PRECIPITATION FOR PORTIONS OF THE SOUTHERN MID-ATLANTIC REGION EARLY IN THE
FORECAST PERIOD. INCREASING INFLOW OF TROPICAL MOISTURE IS FAVORED TO ENHANCE
MONSOON RAINS OVER THE DESERT SOUTHWEST THROUGH THE MIDDLE OF WEEK-2.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR MUCH OF THE WESTERN AND CENTRAL CONUS, AS WELL
AS THE GULF COAST, AND MUCH OF THE SOUTHEAST U.S., MON-SUN, JUL 20-26.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF VIRGINIA AND THE CAROLINAS, AND
FOR ADJACENT PORTIONS OF GEORGIA, MON-WED, JUL 20-22.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE DESERT SOUTHWEST AND
SOUTHERN GREAT BASIN, MON-FRI, JUL 20-24.
RAPID ONSET DROUGHT (ROD) POSSIBLE FOR PORTIONS OF THE DAKOTAS.
DETAILED SUMMARY
FOR WEDNESDAY JULY 15 - SUNDAY JULY 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR MONDAY JULY 20 - SUNDAY JULY 26: MULTIPLE MODEL ENSEMBLES DEPICT ANOMALOUS
MID-LEVEL RIDGING PERSISTING OVER THE WESTERN CONUS THROUGHOUT WEEK-2, WITH A
CLOSED 594-DM CONTOUR EMERGING OVER THE FOUR CORNERS BY THE MIDDLE OF THE
FORECAST PERIOD. THIS PATTERN IS HIGHLY FAVORABLE FOR ABOVE-NORMAL TEMPERATURES
ACROSS MUCH OF THE LOWER 48, AND WHEN OCCURRING NEAR THE PEAK OF SUMMER BRINGS
A WIDESPREAD RISK OF EXTREME HEAT, PARTICULARLY FOR THE WESTERN CONUS.
GENERALLY SOUTHERLY FLOW OFF THE GULF OF AMERICA IS FAVORED TO BOOST DEWPOINTS
EAST OF THE ROCKIES, RESULTING IN POTENTIALLY HAZARDOUS HEAT INDEX VALUES FOR
MUCH OF THE GREAT PLAINS AND ALONG THE GULF COAST.
THE POTENTIAL FOR EXTREME HEAT CONTINUES TO BE SUPPORTED BY A VARIETY OF
FORECAST TOOLS, ALTHOUGH A DOWNWARD TREND IN SIGNAL STRENGTH HAS BEEN NOTED
OVER THE PAST FEW DAYS. THE PROBABILISTIC EXTREMES TOOL (PET) FROM THE GEFS
INDICATES WIDESPREAD 20% CHANCES OF MAXIMUM TEMPERATURES TO EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE FOR ALL BUT THE NORTHEASTERN PORTION OF THE CONUS
THROUGHOUT THE FORECAST PERIOD. THE ECMWF PET IS MUCH MORE CIRCUMSPECT,
EXCEEDING THE ABOVE PERCENTILE THRESHOLD ONLY OVER PORTIONS OF THE PACIFIC
NORTHWEST AND SOUTHEAST U.S. THE GEFS-ECWMF COMBINED EXTREME HEAT TOOL SHOWS
WIDESPREAD 20% OR GREATER CHANCES (AS HIGH AS 50% FOR PORTIONS OF THE WEST) OF
EITHER MAXIMUM TEMPERATURES OR HEAT INDEX VALUES TO EXCEED THE 90TH PERCENTILE
AT SOME POINT DURING THE WEEK-2 PERIOD FOR MOST OF THE CONUS EXCEPT THE
NORTHEAST AND DESERT SOUTHWEST. AS WITH THE PETS, WHEN CONSIDERED INDIVIDUALLY
THE TWO MODELS DISAGREE WIDELY WITH RESPECT TO REGIONS AFFECTED AND SIGNAL
STRENGTH. GIVEN THE LARGE SPREAD IN MODEL SOLUTIONS, MODERATE EXTREME HEAT
HAZARDS FOR FLORIDA AND PORTIONS OF THE NORTH-CENTRAL CONUS HAS BEEN
DISCONTINUED, HOWEVER A SLIGHT RISK OF EXTREME HEAT REMAINS POSTED FOR MUCH OF
THE WESTERN AND CENTRAL CONUS, AND THE SOUTHERN TIER OF THE CONUS (EXCLUDING
THE LOWER FOUR CORNERS AND SOUTHERN HIGH PLAINS), VALID FOR ALL OF WEEK-2. THE
COMBINATION OF ANOMALOUS WARMTH, NEAR TO BELOW NORMAL PRECIPITATION FAVORED
DURING WEEK-2, AND ANTECEDENT DRYNESS SUPPORTS AN ENHANCED RISK OF ROD ACROSS
PORTIONS OF THE NORTHERN PLAINS.
MODEL ENSEMBLES ARE SHOWING INCREASED SIGNAL OF ENHANCED PRECIPITATION STEMMING
FROM THE SOUTHWESTERN MONSOON. DYNAMICAL MODELS ARE DEPICTING A POTENTIAL
ENHANCEMENT OF MONSOON CONVECTION THROUGH THE MIDDLE OF WEEK-2, WITH
UNCALIBRATED PROBABILITIES FROM THE ECWMF AND GEFS INDICATING WIDESPREAD 50%
CHANCES OF 3-DAY PRECIPITATION TOTALS TO EXCEED HALF AN INCH, WITH SOME
LOCATIONS SEEING 20% CHANCES OF 1 INCH ACCUMULATIONS. GIVEN THIS, A SLIGHT RISK
OF HEAVY PRECIPITATION IS POSTED FOR MUCH OF THE DESERT SOUTHWEST AND SOUTHERN
GREAT BASIN, VALID JUL 20-24. THIS REGION IS PRONE TO FLASH FLOODING WITH
RELATIVELY SMALL PRECIPITATION ACCUMULATIONS ESPECIALLY ALONG DRY CREEK BEDS
AND IN CANYONS AND EXTREME CAUTION SHOULD BE EXERCISED IN SUCH AREAS SHOULD
THUNDERSTORM ACTIVITY INITIATE NEARBY. MONSOONAL THUNDERSTORMS CAN ALSO PRODUCE
DRY LIGHTNING, RESULTING IN INCREASED WILDFIRE RISK.
TIED TO THE TROUGHING FAVORED OVER THE EASTERN U.S. EARLY IN WEEK-2, ENSEMBLES
CONTINUE TO POINT TO SURFACE LOW DEVELOPMENT ALONG THE EASTERN SEABOARD.
RELATIVE TO YESTERDAY, MODELS PLACE THE HEAVIEST PRECIPITATION FURTHER EASTWARD
WITH THE BULK OF POTENTIALLY HAZARDOUS ACCUMULATION TOTALS REMAINING OFFSHORE.
HOWEVER, BOTH THE RAW GEFS AND ECMWF PROBABILITY OF EXCEEDANCE TOOLS REMAIN
SUPPORTIVE OF A HEAVY PRECIPITATION RISK, DEPICTING 20-40% CHANCES OF 3-DAY
AMOUNTS EXCEEDING AN INCH OVER SOUTHERN VIRGINIA AND THE CAROLINAS. THEREFORE,
A CORRESPONDING SLIGHT RISK AREA REMAINS POSTED IN THE OUTLOOK (JUL 20-22) AND
IS ADJUSTED ACCORDINGLY.
FORECASTER: DANNY BARANDIARAN
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