The combination of a strong upper-level high pressure over the central United States and moist southwest winds resulted in hot and humid conditions across the Mid-Atlantic that produced excessive heat conditions.
Every event with a place to put it; 11 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LWX wrote it up.
The combination of a strong upper-level high pressure over the central United States and moist southwest winds resulted in hot and humid conditions across the Mid-Atlantic that produced excessive heat conditions.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Baltimore/Washington wrote its last area forecast discussion before the first event at Jul 28, 9:02 AM EST, 2 hours 58 minutes earlier.
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</html>Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 839 AM EDT Fri Jul 28 2023 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ053>057-527-291000- Chesapeake Bay north of Pooles Island MD- Chesapeake Bay from Pooles Island to Sandy Point MD- Chesapeake Bay from Sandy Point to North Beach MD- Chesapeake Bay from North Beach to Drum Point MD- Chesapeake Bay from Drum Point MD to Smith Point VA- Tidal Potomac from Key Bridge to Indian Head MD- Tidal Potomac from Indian Head to Cobb Island MD- Tidal Potomac from Cobb Island MD to Smith Point VA- Patapsco River including Baltimore Harbor- Chester River to Queenstown MD-Eastern Bay- Choptank River to Cambridge MD and the Little Choptank River- Patuxent River to Broomes Island MD- Tangier Sound and the inland waters surrounding Bloodsworth Island-District of Columbia-Cecil-Southern Baltimore- Prince Georges-Anne Arundel-Charles-St. Marys-Calvert- Central and Southeast Montgomery-Central and Southeast Howard- Southeast Harford-Fairfax-Arlington/Falls Church/Alexandria- Stafford-Spotsylvania-King George- Central and Southeast Prince William/Manassas/Manassas Park- 839 AM EDT Fri Jul 28 2023 This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and I-95 corridor through central Maryland, northern Virginia, and District of Columbia. .DAY ONE...Today and Tonight Isolated severe thunderstorms producing damaging winds are possible this afternoon. An Excessive Heat Warning is in effect from 11 AM until 8 PM today. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Isolated to scattered severe thunderstorms are possible on Saturday, especially during the afternoon and evening hours. An Excessive Heat Warning is in effect for Baltimore and Washington metropolitan areas from Noon to 8 PM Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed Friday or Saturday afternoons. MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508- 526-WVZ050>053-055-291000- Washington-Frederick MD-Carroll-Northern Baltimore- Northwest Montgomery-Northwest Howard-Northwest Harford-Augusta- Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke-Nelson- Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper- Northern Fauquier-Southern Fauquier-Western Loudoun- Eastern Loudoun-Northern Virginia Blue Ridge- Central Virginia Blue Ridge-Northwest Prince William-Hampshire- Morgan-Berkeley-Jefferson-Hardy- 839 AM EDT Fri Jul 28 2023 This Hazardous Weather Outlook is for portions of eastern West Virginia, northern and central Virginia, and central and western Maryland. .DAY ONE...Today and Tonight Isolated severe thunderstorms producing damaging winds are possible this afternoon. A Heat Advisory is in effect from 11 AM until 8 PM today, with the exception of the Blue Ridge Mountains. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Isolated to scattered severe thunderstorms are possible on Saturday, especially during the afternoon and evening hours. A Heat Advisory is in effect for much of the area from Noon to 8 PM Saturday, with the exception of Augusta and Rockingham Counties and the Blue Ridge Mountains. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed Friday and Saturday afternoons. MDZ001-501-502-VAZ503-504-WVZ501>506-291000- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 839 AM EDT Fri Jul 28 2023 This Hazardous Weather Outlook is for the Allegheny Front counties in western Maryland, eastern West Virginia, and Highland County Virginia. .DAY ONE...Today and Tonight Isolated severe thunderstorms producing damaging winds are possible this afternoon. A Heat Advisory is in effect for eastern Allegany, eastern Mineral, and eastern Grant Counties from 11 AM until 8 PM today. .DAYS TWO THROUGH SEVEN...Saturday through Thursday A Heat Advisory is in effect from Noon to 8 PM Saturday for the lower elevations. Isolated to scattered severe storms are possible Saturday, especially during the afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed Saturday afternoon.
The national radar mosaic for the moment the first event began.
11 excessive heat. Local standard time, as filed.
The AWOS at Patuxent River NAS, KNHK, measured heat indices as high as 111F. Numerous other mesonets across St. Mary's County measured peak heat indices in excess of 110F.
A mesonet station in Columbia, Maryland, DW1546, measured heat indices as high as 113F. Several other mesonets across Central and Southeast Howard County measured peak heat indices in excess of 110F.
The RAWS station at Cedarville State Forest, CVLM2, measured heat indices as high as 114F. Numerous other mesonets across Prince George's County measured heat indices in excess of 110F.
A Maryland Department of Transportation mesonet, MD-001, located at the intersection of Interstate 270 and Interstate 370, measured heat indices as high as 111F. Several other mesonets across Central and Southeastern Montgomery County measured peak heat indices in excess of 110F.
Several mesonset stations across Cecil County measured heat indices above 110F for several hours.
The ASOS at Baltimore Inner Harbor, KDMH, measured peak heat indices as high as 112F. Several other mesonets across southern Baltimore County measured heat indices in excess of 110F.
The ASOS at Baltimore-Washington International Airport, KBWI, measured heat indices as high as 113F. Numerous other mesonets across Anne Arundel County measured heat indices in excess of 110F.
A Maryland Department of Transportation mesonet, MD-105, located at the intersection of Maryland Route 344 and Maryland Route 244 measured heat indices as high as 114F. Numerous other mesonets across Charles County measured peak heat indices in excess of 110F.
The RAWS station at Susquehanna State Park, SSQME, measured heat indices as high as 110F. Several other mesonets across Southeast Harford County measured peak heat indices at or in excess of 110F.
The ASOS at Hagerstown Regional Airport, KHGR, measured heat indices as high as 106F. Numerous other mesonets across Washington County measured heat indices in excess of 105F.
A Maryland Department of Transportation mesonet, MD-147, located at the intersection of Maryland Route 4 and Thomas Johnson Bridge, measured heat indices as high as 113F. Several other mesonets across Calvert County measured peak heat indices in excess of 110F.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2023Every state in 2023This day in weather historyWarnings in Maryland, July 2023
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 1121050, 1121053, 1121047, 1121052, 1121045, 1121046, 1121048, 1121049, 1121054, 1121055, 1121051.