018
FXUS21 KWNC 311821
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 31 2026
SYNOPSIS: A BROAD AREA OF MID-LEVEL HIGH PRESSURE IS ANTICIPATED TO SHIFT FROM
THE WESTERN TO THE CENTRAL CONTIGUOUS U.S. (CONUS) THROUGHOUT WEEK-2. THIS
PATTERN FAVORS ABOVE-NORMAL TEMPERATURES FOR THE WEEK-2 MEAN, WITH INCREASED
CHANCES FOR EXTREME HEAT SHIFTING EASTWARD AS WELL OVER TIME. THE COMBINATION
OF ANOMALOUSLY WARM AND DRIER THAN NORMAL CONDITIONS IS EXPECTED TO ENHANCE THE
RISK FOR WILDFIRE ACTIVITY WHERE NUMEROUS WILDFIRE INCIDENTS HAVE BEEN REPORTED
WITHIN HIGHLIGHTED HEAT RISK AREAS. ANTECEDENT DRYNESS ALONG WITH THE
LIKELIHOOD OF ABOVE-NORMAL TEMPERATURES AND BELOW-NORMAL PRECIPITATION DURING
THE NEXT TWO WEEKS SUPPORTS AN INCREASED RISK FOR THE RAPID ONSET OF DROUGHT
OVER PARTS OF THE CENTRAL AND SOUTHERN PLAINS, AND MIDDLE AND LOWER MISSISSIPPI
VALLEY. A FAVORABLE MONSOONAL CIRCULATION SUPPORTS AN INCREASED AND POTENTIALLY
PROLONGED RISK OF HEAVY PRECIPITATION ACROSS THE DESERT SOUTHWEST AND LOWER
FOUR CORNERS.
HAZARDS
MODERATE RISK OF EXTREME HEAT FOR PORTIONS OF THE WEST, CENTRAL AND SOUTHERN
PLAINS, MIDDLE AND LOWER MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND
SOUTHEAST, SAT-SUN, AUG 8-9.
SLIGHT RISK OF EXTREME HEAT FOR MOST OF THE CONUS EXCLUDING THE GREAT LAKES
REGION, NORTHEAST, AND APPALACHIANS, SAT-FRI, AUG 8-14.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE DESERT SOUTHWEST AND
ADJACENT REGIONS, SAT-FRI, AUG 8-14.
RAPID ONSET DROUGHT (ROD) POSSIBLE FOR PARTS OF THE CENTRAL AND SOUTHERN
PLAINS, AND MIDDLE AND LOWER MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR MONDAY AUGUST 03 - FRIDAY AUGUST 07:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY AUGUST 08 - FRIDAY AUGUST 14: MULTIPLE ENSEMBLES INDICATE
AMPLIFIED MID-LEVEL RIDGING ACROSS MUCH OF THE CONUS PEAKING AT THE END OF
WEEK-1, SHIFTING FROM THE WESTERN TO EAST-CENTRAL CONUS THROUGHOUT WEEK-2.
THERE ARE SIGNIFICANT DIFFERENCES ACROSS MODEL ENSEMBLE MEANS REGARDING THE
SPECIFICS OF THE MAGNITUDE AND LOCATION OF THE RIDGE, WITH THE ECENS
MAINTAINING MORE AMPLIFIED RIDGING WITH THE GREATEST 500-HPA HEIGHTS REACHING
596 DM ACROSS THE SOUTHWEST AT THE START OF WEEK-2 (GEFS WITH 594 DM). THE
ECENS INDICATES MORE AMPLIFIED HEIGHTS LINGERING ACROSS THE WEST UNTIL MID
WEEK-2 BEFORE WEAKENING AND SHIFTING TO THE CENTRAL AND EAST-CENTRAL CONUS,
WHEREAS THE GEFS SIGNIFICANTLY DECREASES HEIGHTS ON DAYS 9-10 (AUG 9-10) AND
RE-STRENGTHENS THEM TOWARDS THE END OF THE PERIOD ACROSS THE CENTRAL AND
EAST-CENTRAL CONUS. THESE MODEL DIFFERENCES REGARDING THE MID-LEVEL PATTERN
TRANSLATES TO INCREASED UNCERTAINTY REGARDING THE EVOLUTION OF THE EXTREME HEAT
RISK. THE GEFS FAVORS MORE OF THE HEAT REMAINING ACROSS THE WEST AND CENTRAL
CONUS FOR A LONGER DURATION IN WEEK-2, WHEREAS THE ECENS SHIFTS MOST OF THE
HEAT TO THE EASTERN HALF OF THE CONUS BY THE LATTER PART OF THE PERIOD.
BROAD AREAS ARE HIGHLIGHTED WITH SLIGHT AND MODERATE RISKS OF EXTREME HEAT WITH
THE EXPECTATION THAT THE HEAT WILL SHIFT EASTWARD WITH TIME. A MODERATE RISK
(40-60% CHANCE) IS POSTED FOR PORTIONS OF THE WEST, CENTRAL AND SOUTHERN
PLAINS, MIDDLE AND LOWER MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND
SOUTHEAST, AUG 8-9. TODAY’S OUTLOOK HAS TRIMMED SOME AREAS FOR THE MODERATE
RISK OF EXTREME HEAT WITH DECREASED COVERAGE ACROSS THE NORTHERN AND
SOUTHWESTERN PERIPHERY COMPARED TO YESTERDAY, WITH A SLIGHT EXTENSION FARTHER
EAST INTO MORE PARTS OF THE TENNESSEE AND LOWER MISSISSIPPI VALLEYS BASED ON
VARIOUS TEMPERATURE TOOLS INCLUDING THE WPC EXPERIMENTAL PROBABILISTIC HEATRISK
TOOL INDICATING MAJOR OR HIGHER RISK IN ADDITION TO THE PATTERN EVOLUTION. A
BROADER AREA OF SLIGHT RISK (20-40% CHANCE) IS HIGHLIGHTED ACROSS MOST OF THE
CONUS EXCLUDING THE GREAT LAKES REGION, NORTHEAST, AND APPALACHIANS THROUGHOUT
WEEK-2 WITH NO CHANGES TO THE SPATIAL COVERAGE. ENHANCED DEWPOINTS EAST OF THE
ROCKIES MAY SUPPORT HIGHER HEAT INDEX VALUES. DRY AIR TEMPERATURES OR HEAT
INDEX VALUES MAY EXCEED 110 DEG F ACROSS PARTS OF THE DESERT SOUTHWEST AND
CENTRAL CONUS, AND 100 DEG F IN MANY OTHER OF THE HIGHLIGHTED HEAT RISK AREAS.
THE NATIONAL BLEND OF MODELS (NBM) FORECASTS TEMPERATURES IN SOME LOCATIONS
ACROSS THE SOUTHERN TIER TO APPROACH AND/OR BREAK RECORDS FOR NIGHTTIME
MINIMUMS, IMPLYING LITTLE OVERNIGHT RELIEF TO THE HEAT. THE COMBINATION OF
ANOMALOUSLY WARM AND DRIER THAN NORMAL CONDITIONS IS EXPECTED TO BE FAVORABLE
FOR WILDFIRE ACTIVITY WHERE NUMEROUS WILDFIRE INCIDENTS (BOTH CONTAINED AND
ONGOING) HAVE BEEN REPORTED WITHIN THESE ELEVATED HEAT RISK AREAS.
A RAPID ONSET DROUGHT (ROD) RISK IS DESIGNATED FOR PARTS OF THE CENTRAL AND
SOUTHERN PLAINS, AND MIDDLE AND LOWER MISSISSIPPI VALLEY WHERE 30-DAY
PRECIPITATION DEFICITS ARE GREATER THAN 2 INCHES AND CONTINUED DRYNESS AND HEAT
ARE FORECAST THROUGH EARLY AUGUST.
ACROSS THE SOUTHWEST, DETERMINISTIC AND ENSEMBLE BASED ECMWF SOLUTIONS CONTINUE
TO POINT TO INCREASED DEWPOINTS AND TOTAL PRECIPITABLE WATER CONTENT
OVERSPREADING THE SONORAN DESERT, CONSISTENT WITH A GULF OF CALIFORNIA MOISTURE
SURGE EVENT BY LATE NEXT WEEK. GIVEN THAT TROPICAL CYCLONE ACTIVITY IN THE
EASTERN PACIFIC IS FAVORED TO CALM DOWN IN THE WAKE OF GENEVIEVE, ANY GULF
SURGE POTENTIAL IS MOST LIKELY TIED TO THE PRECURSOR PAIRING OF A STRONG
THERMAL LOW ESTABLISHED OVER ARIZONA AND EASTERLY WAVE ACTIVITY MOVING OFF OF
THE SINALOA HIGHLANDS OF WESTERN MEXICO TO INITIATE A MOISTURE EVENT. BASED ON
RAW AND CALIBRATED PRECIPITATION TOOLS, A SLIGHT RISK OF HEAVY PRECIPITATION
REMAINS POSTED AND CONTINUES TO BE VALID FOR ALL OF WEEK-2 DUE TO THE
PERSISTENCE OF WET SIGNALS IN THE ECMWF PET ASSOCIATED WITH A FAVORABLE
MONSOONAL CIRCULATION WHERE ADDITIONAL GULF SURGE EVENTS ARE POSSIBLE LATER IN
THE PERIOD.
FORECASTER: MELISSA OU
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