A cluster of thunderstorms produced a waterspout over Tangier Sound.
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The episode as NWS LWX wrote it up.
A cluster of thunderstorms produced a waterspout over Tangier Sound.
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 21, 2:16 PM EST, 24 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 316 PM EDT Sat Aug 21 2021 .SYNOPSIS... An upper-level low will remain overhead through the weekend, while Henri tracks northward toward Long Island/New England. High pressure will build in for the first half of the week before a cold front approaches from the north during the second half of the week. && .NEAR TERM /THROUGH TONIGHT/... Isolated thunderstorms have formed across the area early this afternoon. With no flow to speak of below 500 hPa and no notable surface features on the synoptic scale, storms are forming in the vicinity of bay/river breezes and along the higher terrain. This is expected to remain the case through the remainder of the afternoon. MLCAPE values are generally around 1000-1500 J/kg, and DCAPE values range from around 600 J/kg in the DC Metro area to just north of 1000 J/kg across southwestern portions of the forecast area. As a result, neither updrafts or downdrafts with the storms are expected to be overly intense today. With greater moisture and lower DCAPE values (which will limit propagation due to outflow/cold pool development) in place to the east of the Blue Ridge, a few localized hydro issues may be possible over more sensitive urban areas. Thunderstorms should gradually weaken through the evening with loss of daytime heating. As we move into the overnight hours, attention will turn to our north, where an inverted surface trough is expected to develop over PA/NJ to the northwest of Henri/ahead of the upper low overhead. Model guidance indicates that a very heavy band of precipitation may form within this inverted trough, but thankfully CAM guidance has also been consistent run to run in keeping this heavier precipitation just to the north and east of our forecast area. However, this feature does bear watching as we move through the rest of the day into tonight, since it could potentially impact northeast MD if its location were to trend further southwest over time. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... The aforementioned upper low will continue to reside overhead during the day tomorrow. Meanwhile, Henri will continue to track toward the north, likely making landfall on Long Island some time tomorrow afternoon. Exactly how Henri interacts with the upper low will have a strong influence on our forecast for tomorrow, and an atypical amount of spread exists in the forecast for tomorrow afternoon into tomorrow night, especially across northeastern MD. Some members of the 12z HREF (most notably the HRRR and WRF-ARW members) draw Henri much further south than other model guidance, backing heavy rain into northeastern MD by tomorrow evening. If this type of scenario were to play out, some localized instances of flooding can't be ruled out. Thankfully, flash flood guidance is relatively high over northeastern MD outside of Baltimore, so we may avoid hydro issues as long as the heaviest rain stays out of Baltimore. These HRRR and WRF-ARW solutions are outliers at the moment, so it is very possible that the entire forecast area avoids heavier rain, with just some lighter rain across northern MD tomorrow afternoon into tomorrow night. Elsewhere, a stray shower or thunderstorm can't be ruled out tomorrow afternoon or evening, but areal coverage of storms isn't expected to be high and the storms aren't expected to be intense. Any precipitation associated with Henri should exit off to our north and east by daybreak Monday. The upper low will also depart off to our north and east during the day Monday, but a warm and humid airmass will still remain in place in its wake. As a result, a stray afternoon or evening thunderstorm can't be ruled out in response to daytime heating. With limited instability and weak flow, any storms that do form aren't expected to lead to any hazardous weather. Highs on Monday will return to near normal, with highs in the upper 80s for most. && .LONG TERM /TUESDAY THROUGH SATURDAY/... High pressure returns to the region for the bulk of the week, with hot and humid conditions and spotty afternoon thunderstorms. Hottest and driest day looks likely to be Tuesday in the wake of Henri with best compressional heating as the system moves away and high pressure builds in. This wanes Wednesday and Thursday as high pressure, initially just to our west, shifts east and we start to get a stronger flow of moist tropical air back northward across the region. By Friday into Saturday, we'll be watching a front approaching from the north, which may start to focus the storm development Friday, then may stall in the area Saturday. Still lots of uncertainty with this, but overall looks like a stormier and cooling trend as we head into next weekend. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Prevailing VFR conditions are expected through Monday. Thunderstorms will be possible each afternoon, but areal coverage of storms isn't expected to be high. A steadier period of rain associated with the outer fringe of Henri may potentially work into MTN or BWI tomorrow evening, but confidence in this occurring remains low. Winds will be light out of the east or north today through tonight, before becoming light out of the west to northwest tomorrow through Monday. Generally VFR Tuesday through Thursday under high pressure. Main concern is for patchy early morning fog and isolated to scattered afternoon/early evening thunderstorms. Best risk of both will be at MRB and CHO. The risk likely is lowest on Tuesday with a gradual increase in chances through Thursday. && .MARINE... Sub-SCA level winds are expected through Monday. Winds will be light out of either the east or north today, before becoming light out of the west to northwest tomorrow and Monday. An MWS may be needed this afternoon if a storm were to move over the waters. Light winds likely prevail over Tuesday thru Thursday under high pressure. Only concern would be for an isolated thunderstorm reaching the waters. The risk likely is lowest on Tuesday with a gradual increase in chances through Thursday. && .TIDES/COASTAL FLOODING... Latest guidance has continued to keep tidal anomalies lower. Most sites with the exception of DC Waterfront and Annapolis will remain below action stage over the next few days. Otherwise, not anticipating any minor tidal flooding issues over the next few days. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...KJP NEAR TERM...KJP SHORT TERM...KJP LONG TERM...RCM AVIATION...RCM/KJP MARINE...RCM/KJP TIDES/COASTAL FLOODING...BRO
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</html>The Dover AFB radar (KDOX), 104 km away, was scanning. The volume nearest the first event began at 19:39 UTC.
1 waterspout. Local standard time, as filed.
There were multiple reports of a waterspout just offshore of Crisfield between 3:40 and 3:50 PM EDT.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Atlantic Coastal Waters in 2021Every state in 2021This day in weather history
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: 967377.