861
FXUS02 KWBC 281939
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
339 PM EDT TUE JUL 28 2026
VALID 12Z FRI JUL 31 2026 - 12Z TUE AUG 04 2026
***LONG DURATION HEAT WAVE EXPECTED FOR MUCH OF THE WESTERN U.S.
AND WESTERN HIGH PLAINS***
..PATTERN OVERVIEW
A STRONG UPPER HIGH, WITH HEIGHTS MAXIMIZED NEAR 600 DM, WILL
DOMINATE THE WESTERN U.S. THROUGH THE END OF THE WEEK AND INTO THE
BEGINNING OF THE MONTH OF AUGUST, SUPPORTING A WIDESPREAD HEAT WAVE
FROM THE DESERT SOUTHWEST TO THE WESTERN HIGH PLAINS. THE RIDGE
SHOULD BREAK DOWN A LITTLE GOING INTO EARLY NEXT WEEK AS A RATHER
STRONG COLD FRONT PASSES THROUGH THE PACIFIC NORTHWEST TO REACH
THE NORTHERN PLAINS EARLY NEXT WEEK. MEANWHILE, UPPER TROUGHS ARE
FORECAST TO PERIODICALLY DIP INTO AND AMPLIFY OVER THE EASTERN U.S.
FOR THE NEXT 7 DAYS AT LEAST, WITH THE MOST AMPLIFIED TROUGH
BEGINNING TO LIFT OUT OF THE EASTERN U.S. EARLY NEXT WEEK. A
TRANSITIONAL ZONAL FLOW PATTERN APPEARS TO TAKE SHAPE BY NEXT
TUESDAY WITH WARMER TEMPERATURES LIKELY FOR THE EAST COAST STATES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE MODEL GUIDANCE SUITE THIS MORNING FEATURES GOOD OVERALL
SYNOPTIC SCALE AGREEMENT ACROSS THE CONTINENTAL U.S. TO CLOSE OUT
THE WORK WEEK, WITH THE BEST AGREEMENT NOTED ON THE CLOSED 600 DM
UPPER HIGH CENTERED NEAR THE FOUR CORNERS THROUGH THE WEEKEND.
MEANWHILE, ENSEMBLE MEANS SHOW GOOD AGREEMENT THAT ONE OF THE MANY
TROUGHS DIPPING INTO THE EASTERN U.S. WILL BE MOST AMPLIFIED ON
SUNDAY, WITH THE POSSIBILITY OF IT CLOSING OFF OVER THE TN/OH
VALLEYS. THERE APPEARS TO BE A CONTINUED TREND FOR THIS UPPER
TROUGH TO CLOSE OFF FARTHER TO THE NORTH, WITH A STRONGER SURFACE
CYCLONE TO DEVELOP OVER THE MIDWEST ON SUNDAY. THERE ARE
INCREASINGLY PROMINENT SIGNALS TO SUPPORT HEAVY RAIN AHEAD OF THIS
CYCLONE AS IT EXITS THE NORTHERN PLAINS ON FRIDAY BEFORE MOVING
SOUTHEAST ACROSS THE MIDWEST THIS WEEKEND, REACHING INTO THE DEEP
SOUTH AND THE EASTERN GULF COAST BY EARLY NEXT WEEK. THE TIMING,
LOCATION AND AMOUNTS OF THE QPF ASSOCIATED WITH THIS SYSTEM ARE
SUBJECT TO ADJUSTMENTS AS MODELS HAVE NOT YET SETTLED INTO A STABLE
SOLUTION IN THIS EVOLVING PATTERN.
..WEATHER/HAZARDS HIGHLIGHTS
THE AREA WITH THE HEAVIEST RAINFALL TO CLOSE OUT THE WORK WEEK
WILL LIKELY BE ACROSS THE MIDWEST AS A SHORTWAVE DISTURBANCE ALOFT
PROMOTES THE DEVELOPMENT OF A SURFACE LOW WITH MESOSCALE
CONVECTIVE COMPLEXES THAT WILL LIKELY BRING MULTIPLE ROUNDS OF
HEAVY RAINFALL AND STRONG THUNDERSTORMS, WITH A SLIGHT RISK OF
EXCESSIVE RAINFALL EXTENDING FROM MINNEAPOLIS TO ST. LOUIS.
ADDITIONAL HEAVY RAINFALL IS LIKELY ACROSS PORTIONS OF THE DEEP
SOUTH AND GULF COAST REGION GOING INTO THE WEEKEND AS A SURFACE LOW
DEVELOPS ALONG A FRONTAL BOUNDARY THAT WILL BE DRAPED ACROSS THE
REGION, AND SHOWERS/STORMS BECOME MORE WIDESPREAD FOR THE EASTERN
U.S. BY SUNDAY. THIS SHOWERY/SCATTERED STORMY PATTERN APPEARS TO
BECOME A DAILY NORM ACROSS THE EASTERN U.S. GETTING INTO EARLY NEXT
WEEK.
WIDESPREAD HEAT WILL CONTINUE TO MAKE WEATHER HEADLINES ACROSS A
LARGE PORTION OF THE WESTERN AND CENTRAL U.S. AS A LARGE UPPER
RIDGE BECOMES PARKED OVER THE SOUTHWESTERN QUADRANT OF THE COUNTRY.
THE MOST EXTREME HEAT IS EXPECTED OVER THE LOWER ELEVATIONS OF THE
DESERT SOUTHWEST THROUGH MUCH OF THE FORECAST PERIOD, WITH HIGHS
WELL INTO THE 110S AND APPROACHING 120 DEGREES IN SOME INSTANCES,
AND READINGS NEAR 100 DEGREES EXTENDING NORTH INTO SOUTHERN IDAHO
AND WESTWARD TO INCLUDE THE CENTRAL VALLEY OF CALIFORNIA. ANOTHER
AREA OF EXCESSIVE HEAT IS LIKELY FROM MONTANA INTO WESTERN PORTIONS
OF THE DAKOTAS WITH HIGHS REACHING OR SURPASSING 100 DEGREES NEXT
WEEKEND BEFORE A COLD FRONT PASSES THROUGH EARLY NEXT WEEK. HOT AND
HUMID CONDITIONS WILL CONTINUE THROUGH THE END OF THE WEEK ACROSS
THE GULF COAST REGION, WITH HEAT INDICES ON THE ORDER OF 100-110
DEGREES WITH DEWPOINTS WELL INTO THE 70S SOUTH OF THE STALLED
FRONT. A SLIGHT ABATEMENT IN THE HEAT IS LIKELY BY THE WEEKEND WITH
MORE CLOUDS AND RAINFALL ACROSS THE REGION. MEANWHILE, DAILY
AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED FROM THE CENTRAL
ROCKIES TO THE DESERT SOUTHWEST THROUGH SATURDAY, WITH SLIGHTLY
LESS MONSOONAL MOISTURE EXPECTED INTO SUNDAY AND MONDAY.
KONG/HAMRICK
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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