293
FXUS02 KWBC 240519
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
119 AM EDT FRI JUL 24 2026
VALID 12Z MON JUL 27 2026 - 12Z FRI JUL 31 2026
...WEST-CENTRAL TO SOUTHERN U.S. HAZARDOUS HEAT THIS WEEKEND INTO
NEXT WEEK AS MONSOONAL RAINS FOCUS OVER THE FOUR CORNERS STATES...
..HEAVY CONVECTION/RAIN PATTERN FOCUS INTO THE EAST NEXT WEEK
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
A PERSISTENT UPPER-LEVEL RIDGE CENTERED OVER CENTRAL U.S. WILL
MAINTAIN DANGEROUS HEAT ACROSS MUCH OF THE CENTRAL-SOUTHERN U.S.
AND THE SOUTHEAST. MEANWHILE, TROUGHING OVER EASTERN U.S. WILL
SUPPORT A MORE ACTIVE PATTERN FROM THE GREAT LAKES AND OHIO VALLEY
TO THE MID-ATLANTIC AND EAST COAST, WITH REPEATED ROUNDS OF SHOWERS
AND THUNDERSTORMS. MONSOONAL MOISTURE WILL CONTINUE TO STREAM
NORTHWARD INTO THE FOUR CORNERS REGION, PROMOTING SCATTERED TO
NUMEROUS THUNDERSTORMS.
MODEL GUIDANCE CONTINUE TO SHOW GOOD AGREEMENT REGARDING THE
EVOLUTION AND PERSISTENCE OF THE LARGE-SCALE SYNOPTIC PATTERN
THROUGH THE PERIOD. MODELS BEGIN TO SHOW LARGER SPREAD TOWARDS MID-
WEEK IN REGARD TO TIMING AND AMPLITUDE OF INDIVIDUAL SHORTWAVES
EMBEDDED WITHIN THE FLOW, WHICH WILL IMPACT SENSIBLE WEATHER. A
BLENDED FORECAST EMPHASIZING THE DETERMINISTIC MODELS EARLY IN THE
PERIOD TRANSITIONS TO GREATER RELIANCE ON THE ENSEMBLE MEANS BY
MID-WEEK THROUGH THE REMAINDER OF THE PERIOD TO ACCOUNT FOR SOME OF
THE DIFFERENCES AMONGST THE MODELS.
..WEATHER/HAZARDS HIGHLIGHTS
THE DOMINATE SENSIBLE WEATHER STORY REMAINS THE PERSISTENCE OF
ABOVE-NORMAL TEMPERATURES ACROSS MUCH OF SOUTHERN AND CENTRAL U.S.
BENEATH THE UPPER-LEVEL RIDGE. AFTERNOON HIGHS ARE FORECAST TO
REACH THE UPPER 90S AND LOWER 100S ACROSS THE PLAINS, MISSISSIPPI
VALLEY, AND THE SOUTHEAST, WITH OVERNIGHT LOW REMAINING WELL ABOVE
CLIMATOLOGICAL NORMALS. COMBINED WITH HIGH HUMIDITY VALUES,
WIDESPREAD HEAT INDICES EXCEEDING 105 DEGREES APPEAR LIKELY, WITH
LOCALIZED VALUES APPROACHING 115, WHERE CLOUD COVER REMAINS
LIMITED. THIS WILL LEAD TO MAJOR TO EXTREME HEATRISK THREATS ACROSS
CENTRAL U.S. AND THE SOUTHEAST EARLY NEXT WEEK, AND GRADUALLY
ISOLATING TO SOUTH-CENTRAL U.S. AND THE SOUTHEAST THROUGH THE
REMAINDER OF THE WEEK.
OVER THE NORTHERN PERIPHERY OF THE RIDGE, MULTIPLE SHORTWAVE
DISTURBANCES WILL INTERACT WITH A FRONTAL BOUNDARY EXTENDING FROM
THE INTERMOUNTAIN WEST ACROSS THE DAKOTAS INTO THE GREAT LAKES,
SERVING AS A PRIMARY CORRIDOR FOR ORGANIZED CONVECTION. STRONG
INSTABILITY, ABUNDANT MOISTURE, AND DEEP-LAYER SHEAR MAY PROMOTE
REPEATED ROUNDS OF CONVECTION, WHICH MAY LEAD TO HEAVY RAINFALL
ACROSS THE GREAT LAKES/OHIO VALLEY ON MONDAY. THE FRONTAL BOUNDARY
GRADUALLY SHIFTS EASTWARD BY TUESDAY, BRINGING CHANCES FOR HEAVY
RAINFALL AND THUNDERSTORMS ACROSS PORTIONS OF THE MID-
ATLANTIC/OHIO VALLEY INTO THE NORTHEAST. THEREFORE, A MARGINAL
RISK OF EXCESSIVE RAINFALL HAVE BEEN PLACED FOR MONDAY ACROSS THE
GREAT LAKES/OHIO VALLEY, WITH THE RISK SHIFTING ACROSS MUCH OF THE
NORTHEAST ON TUESDAY.
ACROSS THE SOUTHWEST, AN ACTIVE MONSOON PATTERN PERSIST THROUGH
MUCH OF THE WEEK. DEEP TROPICAL MOISTURE CIRCULATING AROUND THE
WESTERN FLANK OF THE SUBTROPICAL RIDGE WILL CONTINUE TO SUPPORT
CONVECTION ACROSS THE FOUR CORNERS EARLY NEXT WEEK, AND GRADUALLY
EXPANDING INTO THE ROCKIES AND PLAINS BY MID-WEEK. THE POTENTIAL
FOR HEAVY RAINFALL RATES WILL LEAD TO LOCALIZED FLASH FLOODING
CONCERNS, ESPECIALLY OVER RECENT BURN SCARS, STEEP TERRAIN, AND
OTHER SENSITIVE AREAS SUSCEPTIBLE TO FLOODING. THEREFORE, A
MARGINAL RISK ARE IN PLACE FOR MONDAY AND TUESDAY FOR WPC EXCESSIVE
RAINFALL OUTLOOK (ERO).
TOWARDS MID-WEEK, THE FRONTAL BOUNDARY WILL DRAPE ACROSS THE
SOUTHEAST, BRINGING SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHEAST. WITH THE COMBINATION OF TROPICAL MOISTURE AND SLOW
MOVING STORMS, CHANCES FOR ISOLATED FLASH FLOODING REMAINS
POSSIBLE.
OUDIT
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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