126
FXUS21 KWNC 021801
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 02 2026
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS FORECAST TO STRENGTHEN OVER THE SOUTHERN
TO CENTRAL GREAT PLAINS AND LOWER TO MIDDLE MISSISSIPPI VALLEY DURING
MID-AUGUST WHICH WOULD INCREASE THE CHANCE OF EXTREME HEAT. ANTECEDENT DRYNESS
ALONG WITH THE LIKELIHOOD OF ABOVE-NORMAL TEMPERATURES AND BELOW-NORMAL
PRECIPITATION DURING THE NEXT TWO WEEKS SUPPORTS AN ENHANCED RISK FOR THE RAPID
ONSET OF DROUGHT TO PARTS OF THE CENTRAL TO SOUTHERN GREAT PLAINS AND OZARKS
REGION. AN ENHANCED MONSOON IS FORECAST BY AUGUST 10 WITH AN INCREASED CHANCE
OF LOCALLY HEAVY PRECIPITATION AND FLASH FLOODING FROM THE DESERT SOUTHWEST
NORTH TO THE CENTRAL ROCKIES.
HAZARDS
MODERATE RISK OF EXTREME HEAT FOR PARTS OF THE GREAT BASIN, CENTRAL ROCKIES,
AND CENTRAL TO SOUTHERN HIGH PLAINS, MON-TUE, AUG 10-11.
MODERATE RISK OF EXTREME HEAT FOR MUCH OF THE CENTRAL TO SOUTHERN GREAT PLAINS
AND MIDDLE TO LOWER MISSISSIPPI VALLEY, MON-SUN, AUG 10-16.
SLIGHT RISK OF EXTREME HEAT FOR MOST OF THE CONUS EXCLUDING THE GREAT LAKES
REGION, NORTHEAST, APPALACHIANS, AND DESERT SOUTHWEST, MON-SUN, AUG 10-16.
MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWEST, MON-FRI, AUG
10-14.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE DESERT SOUTHWEST AND FOUR CORNERS
REGION, MON-SUN, AUG 10-16.
FLASH FLOODING POSSIBLE FOR PARTS OF THE SOUTHWEST.
INCREASED RISK FOR RAPID ONSET DROUGHT (ROD) ACROSS PARTS OF THE CENTRAL TO
SOUTHERN GREAT PLAINS AND OZARKS REGION.
DETAILED SUMMARY
FOR WEDNESDAY AUGUST 05 - SUNDAY AUGUST 09:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR MONDAY AUGUST 10 - SUNDAY AUGUST 16: THE GEFS AND ECENS REMAIN CONSISTENT
AND IN GOOD AGREEMENT THAT A BROAD AND MODERATELY STRONG 500-HPA RIDGE PERSISTS
OVER THE SOUTHERN TWO-THIRDS OF THE CONTIGUOUS U.S. (CONUS) THROUGH MID-AUGUST.
COMPARED TO THE BEGINNING OF THE MONTH, THESE ENSEMBLE MEANS DEPICT A SLIGHTLY
WEAKER RIDGE (500-HPA HEIGHTS BELOW 597 DM) BUT THERE REMAINS EITHER A SLIGHT
OR MODERATE RISK OF EXTREME HEAT FOR MUCH OF THE LOWER 48 STATES FROM AUG 10 TO
16. THE 500-HPA RIDGE IS FORECAST TO WEAKEN (STRENGTHEN) OVER THE WESTERN
(CENTRAL AND SOUTHEASTERN) CONUS FROM EARLY TO MID-AUGUST. A MODERATE RISK OF
EXTREME HEAT, VALID AUG 10 AND 11, IS POSTED FOR PARTS OF THE GREAT BASIN,
CENTRAL ROCKIES, AND CENTRAL TO SOUTHERN HIGH PLAINS WHERE THE NWS HEATRISK
TOOL INDICATES MORE THAN A 40 PERCENT CHANCE OF REACHING THE MAJOR HEATRISK
CATEGORY. ALSO, A CONSENSUS OF THE GEFS AND ECENS PROBABILISTIC EXTREMES TOOLS
(PETS) GENERALLY DEPICT THAT MAXIMUM TEMPERATURES HAVE AT LEAST A 40 PERCENT
CHANCE OF EXCEEDING THE 85TH PERCENTILE. MAXIMUM TEMPERATURES ARE EXPECTED TO
REACH 100 DEG F IN THE LOWER ELEVATIONS OF THE GREAT BASIN. THE STRENGTHENING
RIDGE ALOFT, WITH 500-HPA HEIGHTS INCREASING TO NEAR OR EXCEEDING 594 DM,
SUPPORTS A MODERATE RISK OF EXTREME HEAT FROM THE CENTRAL AND SOUTHERN GREAT
PLAINS EAST TO THE MIDDLE AND LOWER MISSISSIPPI VALLEY FOR THE ENTIRE WEEK-2
PERIOD. ENSEMBLE MEANS INDICATE TEMPERATURE ANOMALIES OF 5-10+ DEG F ABOVE
NORMAL IN THE OUTLINED MODERATE RISK AREA ACROSS THE SOUTH-CENTRAL CONUS.
MAXIMUM HEAT INDEX VALUES ARE FORECAST TO RANGE FROM 100-105 DEG F IN THE
CENTRAL GREAT PLAINS TO 105-110 DEG F IN THE SOUTHERN GREAT PLAINS AND LOWER
MISSISSIPPI VALLEY. THE GEFS WOULD ALSO SUPPORT A MODERATE RISK OF EXTREME HEAT
FOR THE COASTAL PLAIN OF THE SOUTHEAST. HOWEVER, THE ECENS AND CMCE ARE COOLER
MODEL SOLUTIONS AND WITH AN AMPLIFIED 500-HPA TROUGH NEARBY OVER THE NORTHEAST,
FORECAST CONFIDENCE IS NOT HIGH ENOUGH TO DESIGNATE A MODERATE RISK FOR THE
SOUTHEAST AT THIS TIME. THE PERSISTENCE OF THE ANOMALOUS 500-HPA RIDGE SUPPORTS
A SLIGHT RISK OF EXTREME HEAT FOR A MAJORITY OF THE CONUS THROUGH THE END OF
WEEK-2, AUG 16. DUE TO THE LIKELIHOOD OF A ROBUST MONSOON BY AUG 10, THE DESERT
SOUTHWEST WAS REMOVED FROM THE SLIGHT RISK TODAY. ANOMALOUSLY WARM TEMPERATURES
AND DRIER-THAN-NORMAL CONDITIONS ARE EXPECTED TO MAINTAIN AN ELEVATED WILDFIRE
DANGER ACROSS THE NORTHERN INTERMOUNTAIN WEST THROUGH MID-AUGUST.
THE ENSEMBLE MEAN SOLUTIONS REMAIN CONSISTENT THAT THE 500-HPA RIDGE AXIS
BECOMES CENTERED OVER THE FOUR CORNERS REGION HEADING INTO WEEK-2, FAVORING A
ROBUST MONSOON. IN ADDITION, A WEAKENING RIDGE ALOFT SHOULD ALLOW FOR MORE
WIDESPREAD CONVECTION. THE PREDICTED 500-HPA HEIGHT PATTERN ALONG WITH 1 TO
3-DAY PRECIPITATION AMOUNTS FROM THE GEFS AND ECENS SUPPORT A MODERATE RISK OF
HEAVY PRECIPITATION FROM ARIZONA NORTHEASTWARD INTO SOUTHWESTERN COLORADO FROM
AUGUST 10 TO 14. ANY LOCALLY HEAVY RAINFALL COULD TRIGGER FLASH FLOODING,
ESPECIALLY IN BURN SCAR AREAS, AND A FLASH FLOODING POSSIBLE HAZARD COINCIDES
WITH THE MODERATE RISK OF HEAVY PRECIPITATION. BASED ON THE GEFS AND ECENS PETS
(> 20% CHANCE OF 3-DAY AMOUNTS EXCEEDING THE 85TH PERCENTILE), A SLIGHT RISK OF
HEAVY PRECIPITATION EXTENDS FROM THE DESERT SOUTHWEST NORTHEAST TO THE CENTRAL
ROCKIES AND GOES THROUGH AUG 16.
MULTI-MODEL ENSEMBLE MEANS AGREE THAT A 500-HPA TROUGH SHIFTS EAST NEAR THE
GREAT LAKES AT THE BEGINNING OF WEEK-2, WHICH COULD RESULT IN MESOSCALE
CONVECTIVE SYSTEMS (MCS) TRACKING SOUTHEASTWARD ACROSS THE MIDWEST. GIVEN THE
VERY HUMID AIRMASS, ANY MCS WILL BE CAPABLE OF PRODUCING FLASH FLOODING.
PATTERN RECOGNITION AND 1 TO 3-DAY PRECIPITATION AMOUNTS FROM THE GEFS AND
ECENS WERE USED AS GUIDES TO DEFINE THE SLIGHT RISK OF HEAVY PRECIPITATION,
VALID FROM AUGUST 10 TO 12.
A RAPID ONSET DROUGHT (ROD) RISK IS DESIGNATED FOR PARTS OF THE CENTRAL AND
SOUTHERN PLAINS ALONG WITH THE OZARKS REGION WHERE 30-DAY PRECIPITATION
DEFICITS ARE GREATER THAN 2 INCHES AND CONTINUED DRYNESS AND HEAT ARE FORECAST
THROUGH EARLY TO MID-AUGUST.
FORECASTER: BRAD PUGH
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