351
FXUS02 KWBC 250714
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 AM EDT TUE AUG 25 2026
VALID 12Z FRI AUG 28 2026 - 12Z TUE SEP 01 2026
...HAZARDOUS HEAT FROM THE DESERT SOUTHWEST TO THE SOUTHERN PLAINS
TO REPOSITION FROM THE SOUTH-CENTRAL U.S. TO THE MID-SOUTH...
..OVERVIEW
THE RESILIENT UPPER LEVEL PATTERN WILL FEATURE TROUGHING IN THE
NORTHWEST AND EAST AND A STRONG RIDGE ANCHORED OVER THE SOUTHWEST
THIS WEEK. THE RIDGE WILL FLATTEN LATE THIS WEEK AS UPPER LEVEL
TROUGHING STRENGTHENS OVER THE NORTHWEST, BUT HAZARDOUS HEAT WILL
PERSIST FROM THE DESERT SOUTHWEST TO THE SOUTHERN PLAINS. THE
CLOSED HIGH/RIDGE WILL REPOSITION EASTWARD THIS WEEKEND, RESULTING
IN EXPANDING HEAT ESPECIALLY ACROSS THE SOUTH-CENTRAL U.S. AND MID-
SOUTH. MOISTURE ON THE WESTERN PERIPHERY OF THE RIDGE WILL SUPPORT
DAILY MONSOONAL CONVECTION OVER PORTIONS OF THE SOUTHWEST AND
INTERMOUNTAIN WEST/ROCKIES. MEANWHILE, SEVERAL FRONTAL SYSTEMS WILL
PUSH THROUGH THE UPPER TROUGHS, BRINGING SHOWERS AND THUNDERSTORMS
FROM THE NORTHERN/CENTRAL PLAINS FAR DOWN INTO THE EAST/SOUTHEAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE REMAINS IN OVERALL GOOD AGREEMENT ON THE SYNOPTIC WEATHER
PATTERN, ALBEIT WITH RENEWED UNCERTAINTY WITH THE TIMING OF
SYSTEMS WORKING THROUGH THE NORTHWEST TO THE U.S. NORTHERN TIER.
GIVEN CONTINUED LARGER SCALE AGREEMENT, FAVOR A COMPOSITE
MODEL/ENSEMBLE MEAN/MACHINE LEARNING GUIDANCE SOLUTION 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 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 ALONG WITH THE MAIN CLOSED
HIGH. FOR THE DESERT SOUTHWEST, DAILY MAX TEMPERATURES ARE FORECAST
TO SOAR INTO THE 110S, WHICH WILL CREATE HEAT CONCERNS THIS WEEK.
PLEASE SEE WPC'S KEY MESSAGES FOR MORE EXTREME HEAT DETAILS.
MONSOONAL MOISTURE STREAMING NORTHWARD ON THE WESTERN PERIPHERY OF
THE UPPER RIDGE AND AHEAD OF 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/FRIDAY AND DAY 5/SATURDAY EXCESSIVE
RAINFALL OUTLOOKS (EROS).
SHORTWAVES ROUNDING THE TOP OF THE RIDGE AND PIVIT INTO THE
DOWNSTREAM MEAN UPPER TROUGH WHILE INTERACTING WITH WAVY FRONTAL
SYSTEMS TO PERIODICALLY TRIGGER SHOWERS AND STRONG TO SEVERE
THUNDERSTORMS FROM THE PLAINS TO THE MIDWEST WHERE MARGINAL RISK
EROS HAVE BEEN INTRODUCED FOR FRIDAY AND SATURDAY. HEAVY RAINFALL
POTENTIAL MAY RENEW OVER THE NORTHERN PLAINS AND MIDWEST LATER
WEEKEND INTO NEXT WEEK WITH ORGANIZED LOW/FRONTAL SYSTEM APPROACH.
MEANWHILE DOWNSTREAM, ERO MARGINAL RISK AREAS HIGHLIGHT A
PROTRACTED THREAT FOR ESPECIALLY THE COASTAL SOUTHEAST THAT MAY
SEE REPEATED ROUNDS OF LOCALLY HEAVY PRECIPITATION AS WAVY FRONTAL
BOUNDARIES APPROACH AND ULTIMATELY 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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