383
FXUS02 KWBC 260707
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
307 AM EDT WED AUG 26 2026
VALID 12Z SAT AUG 29 2026 - 12Z WED SEP 02 2026
...HAZARDOUS HEAT FROM THE DESERT SOUTHWEST AND TEXAS TO
REPOSITION ACROSS THE SOUTH-CENTRAL U.S. AND MID-SOUTH...
..OVERVIEW
DANGEROUS LATE SUMMER HEAT CONTINUING ACROSS THE DESERT SOUTHWEST
AND TEXAS WILL SPREAD NORTHWARD ACROSS THE CENTRAL/SOUTHERN PLAINS
AND MID-SOUTH THIS WEEKEND INTO NEXT WEEK. SURGES OF MONSOONAL
MOISTURE WILL SUPPORT DAILY SHOWERS AND THUNDERSTORMS OVER PORTIONS
OF THE SOUTHWEST AND INTERMOUNTAIN WEST/ROCKIES WITH LOCALIZED
FLASH FLOODING POSSIBLE. MEANWHILE, SEVERAL LOWS/FRONTAL SYSTEMS
WILL PUSH ACROSS THE NORTHERN TIER OF THE CONUS AND DIG INTO THE
EAST-CENTRAL U.S. TO BRING MULTIPLE CHANCES FOR STRONG TO SEVERE
THUNDERSTORMS WITH LOCALLY HEAVY DOWNPOURS. LINGERING LEAD FRONTAL
BOUNDARIES ACROSS THE SOUTHERN MID-ATLANTIC AND SOUTHEAST WILL
OFFER LINGERING RISKS FOR STORMS WITH HEAVY RAIN/RUNOFF ISSUES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE REMAINS IN OVERALL GOOD AGREEMENT ON THE SYNOPTIC WEATHER
PATTERN, THOUGH UNCERTAINTY WITH THE TIMING OF SYSTEMS WORKING
THROUGH THE NORTHWEST TO THE U.S. NORTHERN TIER REMAINS. GIVEN
CONTINUED LARGER SCALE AGREEMENT, FAVOR A COMPOSITE MODEL TO ENSEMBLE
MEAN/MACHINE LEARNING GUIDANCE BLEND SOLUTION OVER TIME THAT SEEMS
TO PROVIDE A GOOD GENERAL FORECAST AND THREAT MESSAGING BASELINE
IN LINE WITH CONTINUITY. THE BLEND PROCESS TENDS TO MUTE/MITIGATE
EMBEDDED SMALLER SCALE SYSTEM DIFFERENCES AS CONSISTENT WITH
INDIVIDUAL PREDICTABILITY, BUT MAINTAINS MAIN FOCUSING FEATURES.
..WEATHER/HAZARDS HIGHLIGHTS
UNDER THE INFLUENCE OF THE UPPER HIGH/RIDGE THIS WEEK, DAILY
MAXIMUM TEMPERATURES ACROSS THE SOUTHERN PLAINS WILL CONTINUE TO
RISE INTO THE 90S AND 100S WITH OPPRESSIVE HEAT INDICES. RECORD-
BREAKING WARM OVERNIGHT TEMPERATURES ACROSS THE SOUTHERN TIER WILL
FURTHER LIMIT RECOVERY FROM THE HEAT, RESULTING IN WIDESPREAD MAJOR
TO EXTREME HEATRISK THAT MAY CAUSE HEAT RELATED ILLNESSES. AS THE
UPPER RIDGE FLATTENS INTO THIS WEEKEND AND SHIFTS EASTWARD INTO
EARLY-MID NEXT WEEK, HAZARDOUS HEAT WILL REFOCUS OVER THE SOUTHERN
PLAINS AND STEADILY EXPAND NORTH ACROSS THE SOUTH-CENTRAL U.S AND
MID-LOWER MISSISSIPPI VALLEY/MID-SOUTH WITH SOME TRIPLE DIGIT
MAXIMUM TEMPERATURES AND MORE WIDESPREAD RECORD HOT OVERNIGHT
VALUES. IN THIS UPPER PATTERN TRANSITION, EXPECT EXCESSIVE HEAT
THREAT MODERATION OVER THE DESERT SOUTHWEST THIS WEEKEND INTO NEXT
WEEK. PLEASE SEE WPC'S KEY MESSAGES FOR MORE EXTREME HEAT DETAILS.
MONSOONAL MOISTURE STREAMING NORTHWARD ON THE WESTERN TO NORTHERN
PERIPHERY OF THE UPPER RIDGE AND AHEAD OF LOCALLY SHOWERY NORTHWEST
U.S. UPPER TROUGHING WILL CONTINUE TO FUEL SCATTERED, DIURNALLY
DRIVEN CONVECTION FROM THE SOUTHWEST AND INTERMOUNTAIN WEST TO THE
ROCKIES. INDIVIDUAL CELLS MAY LEAD TO ISOLATED INSTANCES OF FLASH
FLOODING FOR SENSITIVE LOCATIONS SUCH AS BURN SCARS, FAVORED
TERRAIN LIKE SLOT CANYONS, AND URBAN AREAS. MARGINAL RISK AREAS
COVER PORTIONS OF THESE BROAD AREAS ON THE WPC DAY 4/SATURDAY AND
DAY 5/SUNDAY EXCESSIVE RAINFALL OUTLOOKS (EROS).
SHORTWAVES ROUNDING THE TOP OF THE RIDGE AND PIVOTING INTO THE
DOWNSTREAM MEAN UPPER TROUGH WHILE INTERACTING WITH WAVY FRONTAL
SYSTEMS WILL PERIODICALLY TRIGGER EPISODES OF HEAVY RAIN AND STRONG
TO SEVERE THUNDERSTORMS FROM THE PLAINS TO THE MIDWEST THEN
NORTHEAST THIS WEEKEND INTO NEXT WEEK. WEEKEND MARGINAL RISK ERO
AREAS SPOTLIGHT A FOCUS OVER THE UPPER MIDWEST. MEANWHILE
DOWNSTREAM, WEEKEND MARGINAL RISK ERO AREAS HIGHLIGHT A PROTRACTED
THREAT FOR REPEATED ROUNDS OF LOCALLY HEAVY RAINFALL FOR THE
SOUTHERN MID-ATLANTIC AND THE COASTAL SOUTHEAST/FLORIDA AS WAVY
FRONTAL BOUNDARIES APPROACH AND STALL OVER THESE MOIST REGIONS.
SCHICHTEL
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
ARE AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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