823
FXUS02 KWBC 201900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SUN JUL 20 2025
VALID 12Z WED JUL 23 2025 - 12Z SUN JUL 27 2025
...MAJOR HEAT WAVE BUILDING FROM THE SOUTHEAST INTO PARTS OF THE
CENTRAL U.S. NEXT WEEK AND BEYOND...
..OVERVIEW
A HOT UPPER RIDGE WILL CENTER OVER THE MISSISSIPPI VALLEY MIDWEEK
AND EXPAND/SPLIT TO THE EAST AND THE PLAINS LATER WEEK INTO NEXT
WEEKEND, WITH A MEAN TROUGHING OVER THE GREAT LAKES/NORTHEAST. AN
ACTIVE FLOW PATTERN ALOFT WILL CONTINUE ACROSS THE NORTHERN TIER
STATES AND SOUTHERN CANADA, WITH SEVERAL COLD FRONTAL PASSAGES.
ELSEWHERE, AN UPPER TROUGH WITH POTENTIAL CLOSED LOW IS LIKELY
NEAR NORTHERN CALIFORNIA WITH SOME MONSOONAL FLOW CHANNELED INTO
THE ROCKIES ON THE WESTERN PERIPHERY OF THE MAIN RIDGE. THERE WILL
ALSO BE A MOIST STATIONARY FRONT OVER THE NORTHERN GULF WITH A
SURFACE LOW SET TO WORK WESTWARD JUST OFFSHORE FROM THE EASTERN TO
CENTRAL GULF COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE SOLUTIONS REMAIN CLUSTERED MUCH BETTER THAN NORMAL VALID
IN A PATTERN WITH ABOVE NORMAL PREDICTABILITY. A FAVORED MODEL
COMPOSITE HAS GOOD ENSEMBLE SUPPORT AND PROVIDES A SOLID FORECAST
BASIS FOR MID-LATER THIS WEEK. SWITCHED TO A VERY REASONABLE
COMPOSITE OF COMPATIBLE MODELS AND ENSEMBLE MEANS ALONG WITH WPC
CONTINUITY BY NEXT WEEKEND AMID SLOWLY INCREASING FORECAST SPREAD.
..WEATHER/HAZARDS HIGHLIGHTS
A COLD FRONT IS PROGGED TO SLOWLY DROP SOUTHWARD ACROSS THE DAKOTAS
AND THE UPPER MIDWEST FOR THE MIDDLE OF THE WEEK, WITH A WEAK WAVE
OF LOW PRESSURE DEVELOPING ALONG IT. THIS BOUNDARY WILL BE
INTERSECTING A WARM AND VERY HUMID AIRMASS, AND THIS IS EXPECTED TO
FUEL THE DEVELOPMENT OF MULTIPLE THUNDERSTORM COMPLEXES FROM
NEBRASKA TO NEAR LAKE SUPERIOR WEDNESDAY INTO THURSDAY. A MARGINAL
RISK AREA IS VALID FOR BOTH DAY 4 AND DAY 5 ACROSS MUCH OF THIS
REGION SINCE SOME OF THE STORMS MAY HAVE CONVECTIVE TRAINING, AND
THUS INCREASING THE RISK OF LOCALIZED FLOODING WHERE THIS HAPPENS.
IMPROVING CONDITIONS RETURN TO THIS REGION BY FRIDAY INTO NEXT
WEEKEND AS A DRIER AIRMASS SETTLES IN.
ANOTHER AREA OF UNSETTLED WEATHER IS EXPECTED TO RESIDE ACROSS
NORTHERN FLORIDA AND EXTENDING WESTWARD TO THE CENTRAL GULF COAST
MID TO LATE WEEK. A SURFACE LOW IS LIKELY TO FORM ALONG A LINGERING
STATIONARY FRONT, AND THIS SHOULD GRADUALLY TRACK WEST THROUGH THE
END OF THE WEEK. THERE HAS BEEN A MODEST INCREASE IN QPF ASSOCIATED
WITH THIS COMPARED TO THE PREVIOUS FORECAST ISSUANCE, BUT STILL
WITHIN THE MARGINAL RISK CATEGORY FOR WEDNESDAY AND THURSDAY WITH
THE HEAVIEST RAINFALL STAYING OFFSHORE DURING THIS TIME. THE
RAINFALL POTENTIAL CONTINUES INTO FRIDAY AS WELL, AND THIS WILL
CONTINUE TO BE CLOSELY MONITORED IN THE DAYS AHEAD. THE POTENTIAL
EXISTS FOR SEVERAL INCHES OF RAINFALL IN LOCALIZED CASES FROM
SOUTHERN LOUISIANA TO THE FLORIDA PANHANDLE, AND A SLIGHT RISK MAY
EVENTUALLY BE NEEDED AS THE FORECAST GUIDANCE COMES INTO BETTER
FOCUS IN FUTURE MODEL RUNS.
ELSEWHERE ACROSS THE NATION, MOISTURE ASSOCIATED WITH THE SOUTHWEST
U.S. MONSOON WILL LIKELY BE REDUCED COMPARED TO RECENT DAYS, WITH
SOME LINGERING SHOWERS/STORMS ACROSS NEW MEXICO AND INTO SOUTHERN
COLORADO, AND AFFECTING LESS OF ARIZONA. HOWEVER, THERE MAY BE A
FEW CONVECTIVE CELLS THAT ARE SLOW MOVING ACROSS BURNSCAR AND OTHER
SENSITIVE AREAS, AND THEREFORE MARGINAL RISKS REMAIN PRUDENT IN THE
EXCESSIVE RAINFALL OUTLOOKS. ACROSS NEW ENGLAND, THERE WILL LIKELY
BE AN AXIS OF SHOWERS AND THUNDERSTORMS MOVING IN ON THURSDAY, BUT
IT CURRENTLY DOES NOT LOOK TO CAUSE MUCH IN THE WAY OF FLOODING
CONCERNS.
THE OTHER BIG STORY WILL BE THE BUILDING HEAT ACROSS A LARGE
PORTION OF THE EAST-CENTRAL U.S. FOR THE SECOND HALF OF THE WEEK
AND INTO NEXT WEEKEND, COURTESY OF A LARGE UPPER HIGH BECOMING
ANCHORED OVER THE MID-SOUTH. HEAT RISK IN THE MAJOR CATEGORY WILL
BE PREVALENT FROM THE DEEP SOUTH TO THE MIDWEST AND EXTENDING
EASTWARD TO INCLUDE TENNESSEE AND OHIO RIVER VALLEYS TO CLOSE OUT
THE WORK WEEK. SOME OF THIS HEAT WILL LIKELY REACH THE EAST COAST
BY FRIDAY AND NEXT WEEKEND FOLLOWING THE PLEASANT STRETCH OF
COOLER WEATHER FOR THE FIRST HALF OF THE WEEK. HIGHS WELL INTO THE
90S AND EVEN SOME LOW 100S WILL BE COMMONPLACE FROM THE CENTRAL
PLAINS TO THE EAST COAST, WITH THE HOTTEST READINGS ACROSS
OKLAHOMA, TEXAS, AND ARKANSAS. IT WILL ALSO BE UNCOMFORTABLY WARM
AND HUMID AT NIGHT, PROVIDING ONLY LIMITED RELIEF FROM THE HEAT.
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
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