A boundary triggered some thunderstorms and an unstable atmosphere caused a few to become severe.
Every event with a place to put it. 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.
A boundary triggered some thunderstorms and an unstable atmosphere caused a few to become severe.
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 Aug 19, 1:42 PM EST, 5 hours 58 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 242 PM EDT Sat Aug 19 2017 .SYNOPSIS... Weak high pressure will build in today...but an upper-level disturbance and reinforcing cold front will pass through the area this evening. High pressure will build overhead late tonight through Sunday before moving offshore Monday. High pressure will remain offshore Tuesday and a stronger cold front will pass through Wednesday. High pressure returns for the second half of the week. && .NEAR TERM /TONIGHT/... An upper level trough is crossing the Great Lakes this afternoon which is leading to a thick cu field across OH and W PA. Sfc high pressure will continue to move into the Mid-Atlantic region today and tonight. As the trough approaches, a cu field will begin to develop later today across the Mid-Atlantic region. Cooler temps in the mid-levels will lead to steepening lapse rates across OH/PA/W WV this afternoon. Showers and thunderstorms are expected to develop in this region where marginal instability and shear is coupled with the trough passage. There is a slight/marginal risk of severe thunderstorms just to the north of the forecast area today. This activity will approach the Appalachians late this afternoon into early evening and a few showers and an isolated thunderstorm may drop south into the Potomac Highlands. Some hi-res guidance has some showers making it as far east as I-95 tonight. The loss of daytime heating and weaker lapse rates will inhibit further downstream thunderstorm development. The trough axis will cross the Mid-Atlantic late tonight and clearing is expected tonight. Clear and calm conditions may lead to fog development in low-lying areas such as the Shenandoah Valley and central Foothills. High pressure will be across the region Sunday and dry weather is expected. Temps will be cooler Sunday with high temperatures reaching the mid to upper 80s. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... High pressure will move off the coast by Monday morning. Southerly flow will increase resulting in the return of warm and humid conditions. Westerly flow aloft will lead to the potential upper level disturbances to pass across the Mid-Atlantic region. A CU field will likely develop by afternoon and showers and thunderstorms are possible. At this time...disorganized activity is expected through the afternoon and early evening. Any convection will likely wane Monday night resulting in mild and dry conditions. && .LONG TERM /TUESDAY THROUGH SATURDAY/... A cold front is expected to move into the Ohio Valley Tuesday afternoon. This will present a chance of thunderstorms across teh northern part of our forecast area by mid/late afternoon, and across the entire region Tuesday night as the front moves into PA. The chance should persist through at least midday Wednesday. Ahead of the front east of the mountains highs Tuesday will reach the 90 degree mark, with lows in the lower to mid 70s. Wednesday highs should drop back into the 80s. High pressure will decend out of the upper Great Lakes and bring some very pleasant weather to the region for the second half of the week. Lows Thursday and Friday night will drop into the 50s west of the mountains, and lower 60s east. Highs Thursday through Saturday around 80. && .AVIATION /17Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected most of the time through Wednesday. An isolated shower or thunderstorm is possible late this afternoon and evening across the northern terminals...but most areas will be dry. Patchy fog cannot be ruled out early Sunday morning. Scattered thunderstorms are possible later Monday into Monday night as a southerly flow allow for more atmospheric moisture to return. A cold front is expected to move into PA Tuesday night...and cross the Bay midday Wednesday. Thunderstorms/sub-VFR weather will be possible during this time. VFR conditions to end the day Wednesday. && .MARINE... A reinforcing cold front will pass through the waters this evening. A pop up shower cannot be ruled out but most areas will be dry. High pressure will build overhead for Sunday before moving offshore Monday. A return southerly flow will develop Monday and persist through Tuesday night ahead of a cold front. A cold front is expected to push through the waters by midday Wednesday. Showers and thunderstorms will be possible beginning late Tuesday afternoon. Wind gusts may reach SCA levels Tuesday and Wednesday. && .TIDES/COASTAL FLOODING... Waters may rise to minor levels at Annapolis Monday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && .PRODUCTS...HSK/WOODY!
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 808 PM EDT Sat Aug 19 2017 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-201000- 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-Southern Baltimore-Prince Georges- Anne Arundel-Charles-St. Marys-Calvert-Southeast Harford- Prince William/Manassas/Manassas Park-Fairfax- Arlington/Falls Church/Alexandria-Stafford-Spotsylvania- King George- 808 PM EDT Sat Aug 19 2017 This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and adjacent counties in central Maryland and northern Virginia as well as the District of Columbia. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-201000- Washington-Frederick MD-Carroll-Northern Baltimore- Extreme Western Allegany-Central and Eastern Allegany- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke- Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper- Northern Fauquier-Southern Fauquier-Western Highland- Eastern Highland-Western Loudoun-Eastern Loudoun- Northern Virginia Blue Ridge-Central Virginia Blue Ridge- Hampshire-Morgan-Berkeley-Jefferson-Hardy-Western Grant- Eastern Grant-Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 808 PM EDT Sat Aug 19 2017 This Hazardous Weather Outlook is for eastern West Virginia, northern and central Virginia, and central and western Maryland with the exception of Garrett County. .DAY ONE...Tonight An isolated severe thunderstorm or two is possible over northern Virginia this evening. .DAYS TWO THROUGH SEVEN...Sunday through Friday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Sterling radar (KLWX), 53 km away, was scanning. The volume nearest the first event began at 00:38 UTC.
5 thunderstorm wind. Local standard time, as filed.
A tree was down on Crest Hill road at North Poes Road.
A tree was down on Ben Venue Road at Williams Orchard.
A tree was down Old Waterloo Road at Retreat.
A tree was down on Taylor Street at Falmouth Street.
A tree was down along Route 211 at Maddox Lane.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2017Every state in 2017This day in weather historyWarnings in Virginia, August 2017
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 2026-09-24. Each event’s entry at NCEI: 718046, 718047, 718048, 718049, 718050.