811
FXUS02 KWBC 181851
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT FRI JUL 18 2025
VALID 12Z MON JUL 21 2025 - 12Z FRI JUL 25 2025
...MAJOR HEAT WAVE BUILDING FROM THE SOUTHEAST INTO PARTS OF THE
CENTRAL U.S. NEXT WEEK AND BEYOND...
..OVERVIEW
A GOOD GUIDANCE SIGNAL REMAINS THAT INDICATES THAT THE OVERALL
WEATHER PATTERN NEXT WEEK WILL BE DOMINATED BY A BUILDING UPPER
LEVEL RIDGE THAT WILL BE SITUATED OVER THE DEEP SOUTH AND EXTENDING
NORTH TO THE TENNESSEE AND OHIO RIVER VALLEYS. HEAT AND HUMIDITY
BUILD TO DANGEROUS LEVELS ACROSS MUCH OF THE CENTRAL U.S. AND
EXTENDING TO THE SOUTHEAST STATES. AN ACTIVE FLOW PATTERN WILL BE
IN PLACE TO THE NORTH OF THIS HIGH AS MULTIPLE SHORTWAVE IMPULSES
TRACK EASTWARD OVER THE NORTHERN TIER STATES AND THEN REACH NEW
ENGLAND. A COLD FRONT PROVIDES SOME RELIEF FROM THE RECENT HEAT AND
HUMIDITY FROM THE MID-ATLANTIC TO THE NORTHEAST TO BY THE START OF
NEXT WEEK. MEANWHILE, AN UPPER LEVEL TROUGH LIKELY DEVELOPS NEAR
THE WEST COAST GOING INTO EARLY NEXT WEEK, WITH SOME POTENTIAL FOR
AN UPPER LOW TO DEVELOP.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE SOLUTIONS ARE OVERALL CLUSTERED BETTER THAN NORMAL
VALID FOR EARLY-MID NEXT WEEK AND A FAVORED MODEL COMPOSITE HAS
GOOD ENSEMBLE SUPPORT. FAVOR A SWITCH TO A SEEMINGLY REASONABLE
COMPOSITE OF THE COMPATIBLE GEFS/ECMWF/CANADIAN ENSEMBLE MEANS
ALONG WITH THE BEST MATCHING ECMWF MODEL FOR SOME DETAIL AMID
SLOWLY INCREASING FORECAST SPREAD AND LOCAL UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
IT STILL REMAINS THE CASE THAT A CORRIDOR OF UNSETTLED WEATHER
WILL REMAIN IN PLACE FROM THE UPPER MIDWEST TO THE SOUTHEAST COAST
FOR THE BEGINNING OF THE WEEK. THUNDERSTORM COMPLEXES TRAVELING
AROUND THE NORTHERN PERIPHERY OF THE BIG UPPER HIGH WILL LIKELY
PRODUCE LOCALIZED AREAS OF HEAVY RAINFALL. THEREFORE, A BROAD
MARGINAL RISK AREA EXTENDS FROM THE EASTERN DAKOTAS AND UPPER
MIDWEST THROUGH THE OHIO VALLEY, AND TO NORTHERN FLORIDA AND THE
COASTAL CAROLINAS FOR BOTH DAYS 4 AND 5 (MONDAY AND TUESDAY). LOCAL
FOCUS REMAINS MORE RUN-RUN DEPENDENT, BUT LATEST TRENDS SHOW BEST
POTENTIAL HAS NOW SHIFTED FOR EARLY-MID NEXT WEEK TO THE UPPER
MIDWEST AS IMPULSES WORK OVER MOISTURE/INSTABILITY POOLING FRONTS.
THERE IS THEN ALSO A GROWING SIGNAL THAT IMPULSE ENERGY MAY REFIND
A TRACK AROUND AND UNDERNEATH THE MAIN UPPER RIDGE FROM THE
SOUTHEAST/FLORIDA BACK INTO THE NORTHERN GULF INTO LATER NEXT WEEK
TO MONITOR FOR DEVELOPMENT AND/OR LOCAL GULF COAST QPF ENHANCEMENT.
HEAT WILL ONCE AGAIN MAKE WEATHER HEADLINES FOR MUCH OF NEXT WEEK
ACROSS A LARGE PORTION OF THE SOUTHERN AND CENTRAL U.S. WITH A
LARGE UPPER HIGH BECOMING ANCHORED OVER THE MID-SOUTH. WIDESPREAD
MAJOR IMPACTS ON THE HEAT RISK SCALE ARE EXPECTED FROM THE CENTRAL
PLAINS TO THE SOUTHEAST STATES EARLY IN THE WEEK, AND THESE HIGHER
IMPACTS THEN REACH THE MIDWEST AND OHIO VALLEY BY MID TO LATE WEEK.
THIS WILL BE DUE TO WIDESPREAD HIGHS IN THE MIDDLE 90S TO LOW 100S
FOR MANY OF THESE AREAS, IN COMBINATION WITH DEWPOINTS WELL INTO
THE 70S, AND OVERNIGHT LOWS REMAINING UNCOMFORTABLY WARM. THIS WILL
LIKELY HAVE SOME STAYING POWER BEYOND THIS FORECAST PERIOD BASED
ON THE LATEST WEEK TWO OUTLOOK FROM THE CLIMATE PREDICTION CENTER
FROM THE CENTRAL PLAINS TO THE DEEP SOUTH.
ELSEWHERE ACROSS THE NATION, THERE SHOULD BE JUST ENOUGH MONSOONAL
MOISTURE IN PLACE ACROSS EASTERN ARIZONA AND MUCH OF NEW MEXICO,
AND PROBABLY EXTENDING INTO SOUTHERN PORTIONS OF COLORADO, AND
GIVEN THE POTENTIAL FOR SOME ISOLATED SLOW MOVING STORMS, A
MARGINAL RISK IS IN PLACE FOR BOTH MONDAY AND TUESDAY. ACROSS THE
EAST COAST REGION, A COLD FRONT IS FORECAST TO CLEAR THE NORTHEAST
AND THE MID-ATLANTIC REGION, AND BRINGING A HIGHER QUALITY AIRMASS
AFTER ALL OF THE HEAT AND OPPRESSIVE HUMIDITY LATELY AND LOWER RAIN
CHANCES. HOWEVER, THE HEAT WILL LIKELY RETURN TOWARDS THE END OF
THE WEEK AS THE CANADIAN SURFACE HIGH MOVES OFFSHORE AND A MORE
SOUTHERLY FLOW COMMENCES.
HAMRICK/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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page