A remnant outflow boundary triggered thunderstorms over the southwestern suburbs of DC (northern into east-central Virginia). A few of the thunderstorms became severe, including a significant severe thunderstorm near Fredericksburg/Massaponax, Virginia.
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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 remnant outflow boundary triggered thunderstorms over the southwestern suburbs of DC (northern into east-central Virginia). A few of the thunderstorms became severe, including a significant severe thunderstorm near Fredericksburg/Massaponax, Virginia.
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 24, 8:24 AM EST, 4 hours 21 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 924 AM EDT Mon Aug 24 2020 .SYNOPSIS... High pressure will persist over the western Atlantic today while a surface trough remains over the area during this time. A cold front will approach the area from the north Tuesday into Wednesday before lifting back north Thursday. High pressure strengthens over the Atlantic late in the week. && .NEAR TERM /THROUGH TONIGHT/... High pressure both at the surface and aloft will extend from the southeastern CONUS into the Atlantic through tonight. A west to southwest flow around the high will usher in hot and humid conditions today with max temps in the upper 80s and lower 90s for many locations. A shortwave trough ejecting from large scale height weaknesses in the Mississippi Valley will move eastward, but will likely arrive after peak heating. MLCAPE of 1000-1500 J/kg will develop, though mid level lapse rates will be modest. A relative jet max aloft will allow deep shear around 25-30 kt. Drying aloft and a downslope component to the flow may limit overall convective coverage, but it does appear scattered thunderstorms will develop over the terrain around midday, possibly strengthening some as they reach low level moisture/instability pooled in a lee surface trough around the I-95 corridor. The dry air aloft could allow for some strong downbursts if any updrafts can be sustained/overcome it. Therefore, there is a threat for locally damaging wind gusts this afternoon into early this evening. In general, the storms should have sufficient enough west to east movement to reduce the flood risk, though can't totally rule out an issue over the metro areas if there were a storm merger, for example. Both the more robust storms and greatest coverage should be east of the recently-wet areas of the central Shenandoah Valley. Should see any remaining convection exit rapidly to the east this evening. Patchy fog could develop in some of the usual spots. Lows will be in the mid 60s to lower 70s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... A greater... but conditional... severe weather risk will exist for Tuesday and Wednesday. Ridging will be building over the Plains during this time, while the Atlantic ridge is suppressed a bit, placing the area under faster west to northwest flow aloft. Surface high pressure will remain to the south. A cold front will drop down from the north late Tuesday, likely not reaching the area until after dark. The front will stall across the area Wednesday, before lifting back to the north Wednesday night. Westerly downsloping low level flow will likely keep a cap on convection well into Tuesday afternoon and allow temperatures to rise into the 90s. Shortwave energy will likely approach late in the afternoon or evening. Models still vary greatly on the amount of convective coverage. Some CAMs are indicating potential for a broken line of storms to drop southeast through the area, while other guidance focuses a higher threat farther to our northeast and west. From a consensus standpoint, the chance of storms will increase with northward extent across the area (as will supportive shear). Have limited PoPs to 40 or less until the picture becomes clearer. A Slight Risk for severe weather is in place, with the main threat being damaging winds. On Wednesday, the moisture/instability gradient associated with the front will be draped NW-SE across the area, parallel to the upper flow. The greatest shear will be on the stable side of the boundary, though there will be some overlap. Again, guidance varies greatly on the amount of storm development and coverage since the amount of moisture is questionable in the northwest flow aloft. However, fast moving clusters of storms posing a damaging wind threat could occur. There could even be some low level shear along the boundary, though am not confident in rotating storms at this juncture. Have chance PoPs southwest of the boundary with slight chance to the northeast, given uncertainties about how quickly it will lift back to the north. SPC has placed the entire area under a Slight Risk for severe, though to account for that possibility. Temperatures will be a little cooler Wednesday, especially northeast of the boundary (central Maryland). && .LONG TERM /THURSDAY THROUGH SUNDAY/... High pressure is expected to hold onto the region Thursday. A weak boundary will influence the possibility of a passing shower or rumble of thunder during the afternoon. Temperatures will be a little warmer reaching the lower 90s. The high pressure in place just across our southwestern zones and farther west is expected to weaken during the day Friday. A cold front will approach from the northwest later in the day. This front will bring an increased chance for showers and thunderstorms to much of the region late Friday into Friday night. Increasing moisture Friday night and Saturday, along with the possibility of the remnants of the Tropical Storm Laura arriving during the period, could lead to widespread shower activity and some gusty thunderstorms. Any additional heavy showers and thunderstorms, producing downpours, could lead to localized flooding in areas already hit hard during the past several weeks with repeated rounds of rainfall. The exact track and intensity of the remnants of Laura will play a big role as to whether we have widespread heavy rainfall or scattered showers and a few thunderstorms. The GFS and EURO deterministic models have similar agreement that the remnants will be moving north throughout the middle Mississippi River Valley before hanging a gradual right turn into the Ohio River Valley throughout the day Friday. We have time to prepare as Tropical Storm Laura is still in the northwest Caribbean Sea between eastern Cuba and Jamaica. The tropical system has to push northwest along the shores of Cuba and across the heart of the Gulf of Mexico. The National Hurricane Center is issuing advisories on both Tropical Storm Marco and Tropical Storm Laura. As for Saturday night through Sunday, drier air and slightly cooler temperatures with increasing sunshine should be the flavor during the period. Cool high pressure is expected to build in from the northwest. High temperatures on Sunday could be 10 to 15 degrees cooler than Friday, not to mention, much lower dewpoint temperatures as we transition from a tropical airmass to a more autumnal airmass. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... Scattered thunderstorms are expected this afternoon and early evening, progressing eastward generally between 18-00Z. Locally gusty winds and brief subVFR conditions are expected in any thunderstorms. Fog development seems a little less likely tonight. The thunderstorm forecast for both Tuesday and Wednesday remains quite uncertain as a boundary drops through the area then lifts back north, though strong storms are possible if they do develop. VFR conditions Thursday through Friday. A possible increase in shower and thunderstorm coverage Friday night could lead to MVFR or IFR conditions at CHO and MRB, and possibly IAD. Elsewhere, VFR conditions expected. && .MARINE... West to southwest winds have diminished some this morning, so the SCA has expired. Winds should remain below SCA criteria for most of the time today. However, scattered thunderstorms are expected generally between 3-11PM, and some Special Marine Warnings may be needed for gusty winds. Strong storms are possible again Tuesday and Wednesday, though coverage is uncertain. Otherwise, winds will remain generally light and westerly through late Tuesday. Northerly winds could approach SCA criteria Tuesday night as a front drops to the south. The front will lift back north late Wednesday, turning winds to the south. No marine hazards expected Thursday through Friday night. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...ADS NEAR TERM...BJL/ADS SHORT TERM...ADS LONG TERM...KLW AVIATION...BJL/ADS/KLW MARINE...BJL/ADS/KLW
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 755 AM EDT Mon Aug 24 2020 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-251000- 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- 755 AM EDT Mon Aug 24 2020 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...Today and Tonight A few thunderstorms will be capable of producing locally damaging wind gusts this afternoon and evening. There is also an isolated threat for flooding. Scattered thunderstorms may produce gusty winds over the waters this afternoon and evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Damaging wind gusts from isolated to scattered severe thunderstorms are possible Tuesday afternoon and evening, and again on Wednesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Please send any wind damage or flood reports to the National Weather Service. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-251000- 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- 755 AM EDT Mon Aug 24 2020 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...Today and Tonight There is an isolated threat for flooding this afternoon and early evening due to locally heavy rain from thunderstorms. A few thunderstorms will be capable of producing damaging wind gusts, especially east of the Blue Ridge mountains this afternoon and early evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Damaging wind gusts from isolated to scattered severe thunderstorms are possible Tuesday afternoon and evening, and again on Wednesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Please send any wind damage or flood reports to the National Weather Service.
The Sterling radar (KLWX), 43 km away, was scanning. The volume nearest the first event began at 17:44 UTC.
7 thunderstorm wind. Local standard time, as filed.
Trees were blown down near the intersection of Paul Spring Road and Rebecca Drive.
There were numerous reports of trees blown down near and just southwest of the City of Fredericksburg.
A tree was blown down near the intersection of Tignor Lane and Anderson Street. Trees were blown down near the 300 block of VA-638 Landsdowne Road.
Trees and power lines were blown down near the 3500 block of VA-636 Mine Road.
A tree was blown down in the 900 block of VA-296 Dahlgren Road.
Trees were blown down blocking part of US-1 Jefferson Davis Highway between VA-608 Massaponax Church Road and Old Telegraph Road.
Numerous trees and large branches were blown down in Massaponax. Nine houses in the Lees Park neighborhood sustained damage (including the partial collapse of a second floor exterior wall) when debris from a nearby home under construction was lofted by winds in the 5000 block of Holley Oak Lane.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2020Every state in 2020This day in weather historyWarnings in Virginia, August 2020
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: 905340, 905342, 905347, 905352, 905354, 905355, 905356.