A weak pressure trough/surface front ignited a cluster of strong to severe thunderstorms. The storms began over eastern West Virginia during the early afternoon, then progressed eastward through central Maryland and northern Virginia, producing scattered damaging downburst wind gusts and some hail.
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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 weak pressure trough/surface front ignited a cluster of strong to severe thunderstorms. The storms began over eastern West Virginia during the early afternoon, then progressed eastward through central Maryland and northern Virginia, producing scattered damaging downburst wind gusts and some hail.
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 Jun 22, 8:41 AM EST, 4 hours 1 minute earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 941 AM EDT Mon Jun 22 2020 .SYNOPSIS... High pressure will build over the Atlantic Ocean into the southeastern states through Tuesday, though a couple upper disturbances will cross during this time. A weak cold front will push through the area Wednesday. The front will attempt to move offshore late in the week. Another front may follow later next weekend. && .NEAR TERM /THROUGH TONIGHT/... Shortwave trough/MCV currently over the Ohio Valley will be the main player for the weather today. While the vorticity center will lift northwest of the area this afternoon, there will be plenty of forcing trailing it which will enter our forecast area during peak heating. Deep layer S/SW flow will bring heat and humidity (highs upper 80s/lower 90s, dew points upper 60s/lower 70s)...leading to MLCAPE values 1500 J/kg or greater by this afternoon. Thus expecting numerous showers and thunderstorms to develop and work SW to NE across the area. There's one fly in the ointment for the Baltimore area, and that is potential for some storms to fire along bay breeze boundaries. If this were to occur and stabilize the atmosphere, it could cause the western storms to fizzle as they push east of the Blue Ridge late this afternoon/early evening. Deep layer shear will be weak; however, due to the instability and ample downdraft CAPE, some severe storms are possible with the main threat of damaging winds. This will likely mean storms will be cold pool dominant and progressive, though with nearly unidirectional winds, there could be brief training. That could lead to localized flooding if it were to occur in a spot that has recently seen heavy rain. The best chance for storms will be between 2 pm and 10 pm this afternoon and evening, although if the sea breeze boundary causes convection to initiate, it could be closer to noon around the Baltimore Metro area/western shore of the Bay. The trough axis won't push east of the area until later tonight, so there could be some lingering showers and storms through this evening. Otherwise, it will be a muggy night with patchy fog in some spots. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... On Tuesday, a shortwave/MCV from current convection in the Plains will lift northeastward as upper level low pressure pivots over the Great Lakes. A surface boundary will also push toward the area but likely not reach us until at least Tuesday night. The environment will be a bit different Tuesday, with poorer lapse rates and lower instability, but perhaps with a bit more shear. Still some uncertainty with how things will unfold, but scattered to numerous showers and thunderstorms again look like a good bet. Threats may flip flop a bit due less robust downdraft parameter, with a lower severe weather threat, but perhaps a higher heavy rain threat as precipitable water values will be 1.75+ inches and nearly unidirectional flow could promote training. Will have to monitor this period, especially depending on how much rain falls today. It will be similarly hot and humid. Have some PoPs lingering into Tuesday night since it's uncertain where the forcing mechanisms will be by that time, and some lingering showers could arrive from upstream. Even though the longwave trough will still be positioned to our west Wednesday, 00Z guidance has the low level boundary passing through, reaching southeastern areas during the afternoon. Abundant dry air aloft will be behind the boundary with limited forcing and westerly winds. Therefore have cut PoPs back, but have not gone completely dry since guidance has been wavering during this time period. Temperatures/humidity may be a touch lower. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Energy will move into the region from the Lower Great Lakes Thursday. The cold front will gradually move east and offshore Thursday afternoon, but not before we see another round of showers and thunderstorms Thursday morning and early afternoon. Temperatures will not be as warm with highs in the middle to upper 80s. By Thursday night and continuing through Saturday, weak high pressure will gain control of the region and bring slightly cooler and drier conditions. Highs will be in the lower to middle 80s each day. A chance of showers and thunderstorms return Sunday with the next front sagging into the region. The front could stall on Monday and allow or additional development of showers and thunderstorms. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... Main issue for this afternoon and evening will be showers and thunderstorms (lowest risk at CHO and MTN). Have timed a 3 hour window for VCTS based on latest guidance, though it's possible it could be earlier at the metro terminals if bay breeze storms fire early and then stabilize the atmosphere. There will be a strong wind threat with the storms. Low end risk of fog tonight, mainly in the typical (CHO/MRB) locations. Another round of showers and storms will be possible Tuesday afternoon and evening. At this time, Wednesday is looking drier behind a weak front. VFR conditions are primarily expected Thursday and Thursday night. A chance of showers and thunderstorms could pose MVFR conditions at a few of the terminals. VFR conditions Friday and Friday night. && .MARINE... Light south winds continue. Showers and thunderstorms appear increasingly likely today and Tuesday (mainly during the afternoon and evening hours). Special Marine Warnings will likely be required. Southerly winds will also increase a bit this afternoon through Tuesday. While there could be some periods of marginal Small Craft Advisory (SCA) conditions, confidence is low at this time, especially Monday afternoon and evening. There may be a better chance of SCA conditions late Tuesday afternoon and evening as the low level wind field increases. Winds will become westerly on Wednesday with a lower risk of storms. Small craft conditions possible Thursday through Friday night. && .TIDES/COASTAL FLOODING... Southerly flow will continue through the middle of the week. Winds should be relatively light (generally less than 15 MPH). So while minor flooding can't be ruled out, it seems unlikely despite elevated tides, which will reach caution stage in spots at the astronomically higher high tides. && .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 TIDES/COASTAL FLOODING...ADS
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 514 AM EDT Mon Jun 22 2020 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-230915- 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- 514 AM EDT Mon Jun 22 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 Showers and thunderstorms are likely this afternoon and evening. Some storms may be severe. The primary threat is damaging wind gusts, though isolated hail and flooding can't be ruled out. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional showers and thunderstorms are likely Tuesday afternoon and evening, and these storms may also pose an isolated risk of damaging winds and flooding. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening, and again Tuesday afternoon and evening. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-230915- 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- 514 AM EDT Mon Jun 22 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 Showers and thunderstorms are likely this afternoon and evening. Some storms may be severe. The primary threat is damaging wind gusts, though isolated hail and flooding can't be ruled out. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Additional showers and thunderstorms are likely Tuesday afternoon and evening, and these storms may also pose an isolated risk of damaging winds and flooding. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening, and again Tuesday afternoon and evening.
The Sterling radar (KLWX), 118 km away, was scanning. The volume nearest the first event began at 17:41 UTC.
20 thunderstorm wind, 1 hail. Local standard time, as filed.
Several trees were blown down near Spring Gap.
A tree was blown down on MD-80 Fingerboard Road near Singleton Drive. Several other trees and large branches were blown down in a half mile radius.
Several trees were blown down in the vicinity of Pipe Creek Road and Stern Road.
A tree was blown down on Creek Road near Hancock.
Multiple trees were blown down in the Gaithersburg area.
There were reports of trees blown down on MD-80 Fingerboard Road near Park Mills Road.
Multiple trees were blown down along US-301 Crain Highway in southern Charles County.
A tree blew down onto MD-109 Old Hundred Road near Peach Tree Road.
Numerous trees were blown down in the Kensington/Bethesda area, including along and near I-495 Capital Beltway. A tree fell on a car causing an accident on the Outer Loop of I-495 Capital Beltway near the Bethesda Trolley Trail, but there were no injuries.
Multiple trees were blown down along Budds Creek Road in Clements.
Several trees were blown down in Huntingtown.
Several trees were blown down in Saint Leonard.
A tree was blown down onto US-40 Baltimore National Pike near Turf Valley Road.
Quarter size hail was reported in West Laurel.
A tree was blown down on US-29 Columbia Pike at MD-216 Lime Kiln Road.
A tree was blown down on westbound I-70 at US-29 Columbia Pike.
A tree blew down onto I-695 Baltimore Beltway Outer Loop near MD-122 Security Boulevard.
A tree was blown down on northbound I-83 Baltimore-Harrisburg Expressway prior to Exit 17/West Padonia Road.
A tree was reported down on MD-88 Black Rock Road near Benson Mill Road.
Numerous (dozens) of trees were blown down in and near Ellicott City. One tree fell on and destroyed a house.
A tree was blown down on I-695 Baltimore Beltway near Cromwell Bridge Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2020Every state in 2020This day in weather historyWarnings in Maryland, June 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: 900175, 900178, 900182, 900180, 900186, 900190, 900184, 900189, 900193, 900191, 900194, 900195, 900197, 900201, 900202, 900198, 900204, 900199, 900200, 900205, 900210.