A boundary remain draped overhead while a deep southerly flow ushered in plenty of moisture. Showers and thunderstorms resulted in heavy rainfall that led to instances of flooding and flash flooding.
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 remain draped overhead while a deep southerly flow ushered in plenty of moisture. Showers and thunderstorms resulted in heavy rainfall that led to instances of flooding and flash flooding.
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 16, 2:32 PM EST, 3 hours 28 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 332 PM EDT Mon Aug 16 2021 .SYNOPSIS... A warm front will slowly advance north across the region through Tuesday. The remnants of Fred will then cross the area Wednesday into early Thursday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Latest analysis depicts a stalled front beginning to lift north across central Virginia. A cool Canadian high pressure is centered over northern New England, while a warm, humid Bermuda high is off the Carolina coast. Tropical Storm Fred is approaching the Florida panhandle. Aloft, upper level ridge is co- located with the surface Bermuda high, with a broad trough over the mid and upper Mississippi Valley. A shortwave is passing northeastward over the upper Ohio Valley. Scattered showers continue across the area this afternoon, but are concentrated more in two zones. The first is across southeast Virginia in a bulge of higher dewpoints near the surface front. This activity will be lifting north toward the DC metro, but may tend to lose intensity over time due to decreasing instability with northward extent. Given the expectation of scattered and less intense rain rates, canceled the previous Flash Flood Watch early. The second focus is along the spine of the Appalachians closer to the shortwave energy and inverted surface trough. There has been a consistent high QPF signal in this area, and storm motions decrease along with potential for training along the terrain this evening. However, instability is somewhat limited, and with slightly lower precipitable water values, modeled rain rates are not excessive but could add up over a number of hours. This area has been very dry, so as long as the duration is more prolonged, the ground should be able to handle it. Evening shift will be monitoring trends. Tonight, the front will continue its slow march back north, and additional shortwave energy will move across the region. Elevated instability may work back to the north as well. Therefore, showers and some thunderstorms could continue, with possible emphasis across northern areas due to the position of the boundary and proximity to mid level forcing. Locally heavy rain may still be a threat due to the moist atmosphere, though signal for more intense rates begins to decrease after midnight. Clouds will lower and there could be some reduced visibility, especially on the ridges. Lows will be in the upper 60s to mid 70s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... The warm front should lift further north of the area on Tuesday, though some models indicate heavier rain lingering during the morning hours in northeast Maryland before it does so. Otherwise, the mid level ridge pushes westward and brings in a mid level dry slot. Overall, this should allow for lower rain chances, though a few showers and storms will remain possible about. Some filtered sun is possible, especially east of the Blue Ridge, which will help temperatures warm into the mid 80s and allow some slightly stronger instability to build. Therefore, if thunderstorms do develop, they would have a better chance of becoming strong with modest shear aloft, though poor lapse rates will likely be a limiting factor. Locally heavy rain and flooding potential will still be a possibility as well. Showers may be a bit more common closer to the Appalachians due to additional vorticity advection aloft, but there have been some decreases in rain potential there as well. Eye then turn to the remnants of Fred. Track and speed are somewhat divergent in model guidance still, though the general consensus is a path near or west of the Appalachians later Tuesday night and then advancing through Pennsylvania by Wednesday or Wednesday night. The speed of the system as well as how much rain falls over the next 24 hours will play a factor in the flood risk, though in general that threat increases with westward extent. A more eastward track could put the urban areas at risk too. There will also be a lot of wind shear associated with the system, so there could be a risk of severe thunderstorms and even tornadoes depending on how the systems evolves. Temperatures will likely be modulated by the amount of cloud cover, with highs in the lower to mid 80s and lows in the upper 60s/lower 70s. && .LONG TERM /THURSDAY THROUGH MONDAY/... Our region will be positioned between an upper level low over the upper midwest and an upper high along the east coast on Thursday. The positioning of these two systems will funnel the remnants of tropical Storm Fred northeastward toward New York and New England. A weak westerly flow at both the surface and at 850 will usher in a brief lull in widespread precipitation on Thursday. Afternoon temperatures will be mild in the mid 80s with overnight lows in the 60s and lower 70s. A shortwave is forecast to move through the flow bringing the return of precipitation to our region late Thursday night and into Friday. The upper level low off to the northwest is forecast to be absorbed into a trough building over the upper plains. Showers and isolated thunderstorms will continue to be a threat Friday through this weekend as the trough axis over the plains builds down over our region. The surface flow is expected to remain light and variable through this period which should prevent deep warm air advection and limit surface high temps to the mid to upper 80s. The main story through this weekend will be continued chances for showers along with an isolated threat for thunderstorms. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... A warm front will continue moving north across the region into Tuesday. Showers and scattered thunderstorms will result in brief vsby reductions but will be difficult to time more than an hour in advance. Highest chance for thunderstorms appears to be at DCA and CHO and perhaps MRB this evening, so only included a mention at these locations for now. MVFR ceilings will try to improve to VFR for a time this afternoon. However, clouds will likely lower again tonight, with fairly high probabilities of IFR affecting most terminals. Off and on showers and perhaps a thunderstorm will remain possible through the night. Conditions likely improve as the warm front pushes further north Tuesday into Wednesday, but reduced conditions again likely Wednesday into Wednesday night as Fred's remnants pass the area with potentially heavy rain. Winds should become light and variable behind the exiting Tropical Storm Fred. Showers from a nearby upper trough axis will be possible Thursday through this weekend bringing continued chances for subVFR conditions. && .MARINE... As a warm front lifts north tonight, southeast to southerly winds may come close to Small Craft Advisory criteria around southern Maryland, but confidence is too low for a headline at this time. The warm front will lift north Tuesday, leading to lighter winds, although there could be a gusty thunderstorm during the afternoon or evening. Tuesday night, southerly channeling looks likely to increase as the front clears the area, potentially resulting in SCA conditions for portions of the waters. Elevated winds may continue Wednesday and Wednesday night as the remnants of Fred pass near the area. Strong thunderstorms could also occur depending on the track. Winds are expected to become light and variable by the end of this week with subSCA conditions expected Thursday and Friday. && .TIDES/COASTAL FLOODING... Developing southeasterly easterly flow as a warm front pushes north across the region will result in increasing water levels. Sensitive locations like Annapolis and DC SW Waterfront may be very close to minor flood stage tonight, but confidence is low. Southerly flow associated with the remnants of Fred will further exacerbate water level rises. This may result in additional minor flooding at sensitive sites Wednesday night. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...ADS NEAR TERM...ADS SHORT TERM...ADS LONG TERM...JMG AVIATION...ADS/JMG MARINE...ADS/JMG TIDES/COASTAL FLOODING...ADS
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 1203 PM EDT Mon Aug 16 2021 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ052>057-171615- 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-Prince William/Manassas/Manassas Park-Fairfax- Arlington/Falls Church/Alexandria-Stafford-Spotsylvania- King George- 1203 PM EDT Mon Aug 16 2021 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...This Afternoon and Tonight Isolated instances of flooding are possible this afternoon and tonight. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional periods of heavy rain and flooding are possible from tropical moisture Tuesday through Thursday due in part to the remnants of Fred. Isolated severe thunderstorms are possible Wednesday and Wednesday night in association with Fred. .SPOTTER INFORMATION STATEMENT... Spotter activation may be necessary over the next several days. MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508- WVZ050>053-055-171615- 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-Hampshire-Morgan-Berkeley-Jefferson- Hardy- 1203 PM EDT Mon Aug 16 2021 This Hazardous Weather Outlook is for portions of eastern West Virginia, northern and central Virginia, and central and western Maryland. .DAY ONE...This Afternoon and Tonight Isolated instances of flooding are possible this afternoon and tonight. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional periods of heavy rain and flooding are possible from tropical moisture Tuesday through Thursday due in part to the remnants of Fred. Isolated severe thunderstorms are possible Wednesday and Wednesday night in association with Fred. .SPOTTER INFORMATION STATEMENT... Spotter activation may be necessary over the next several days. MDZ001-501-502-VAZ503-504-WVZ501>506-171615- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 1203 PM EDT Mon Aug 16 2021 This Hazardous Weather Outlook is for the Allegheny Front counties in western Maryland, eastern West Virginia, and Highland County Virginia. .DAY ONE...This Afternoon and Tonight Isolated instances of flooding are possible this afternoon and tonight. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional periods of heavy rain and flooding are possible from tropical moisture Tuesday through Thursday due in part to the remnants of Fred. Isolated severe thunderstorms are possible Wednesday and Wednesday night in association with Fred. .SPOTTER INFORMATION STATEMENT... Spotter activation may be necessary over the next several days.
The Sterling radar (KLWX), 43 km away, was scanning. The volume nearest the first event began at 22:59 UTC.
2 flash flood, 2 flood. Local standard time, as filed.
Water was estimated to be about two to three feet deep on King Street.
There were reports of high water around the 900 Block of North Liberty Street.
Taylorstown Road was closed both ways around between Loyalty Road and Downey Mill Road.
VA-689 Chesterbrook Road was closed at Little Pimmit Run.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2021Every state in 2021This day in weather historyWarnings in Virginia, August 2021
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: 980410, 980412, 980413, 980411.