Scattered thunderstorms produced instances of flooding in northeastern Maryland.
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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.
Scattered thunderstorms produced instances of flooding in northeastern Maryland.
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 Jul 12, 2:06 PM EST, 5 hours 9 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 306 PM EDT Mon Jul 12 2021 .SYNOPSIS... Bermuda high pressure system will build across the region through mid-week before weakening thereafter. A weakening cold front will fizzle to our north Wednesday, with another cold front poised to drop southward into the area this weekend. && .NEAR TERM /THROUGH TONIGHT/... The early to mid morning low clouds burned off quickly as the boundary layer began to heat up. As the day has progressed, ample diabatic heating coupled with moist southerly winds has bolstered temperatures into the upper 80s/low 90s with dew points in the low/mid 70s. This combination has raised area-wide heat indices into the 97 to 103 degree range. There is some marginal potential to reach 105 degrees, but any instance of this should be on the order of an hour. Thus, have opted to not issue a Heat Advisory for this afternoon. However, the more sensitive populations and those with extended exposure to the elements may see an increased risk for heat exhaustion. Over the past couple of hours, towering cumulus fields across the Blue Ridge and west of I-81 have evolved into a series of pulse thunderstorms. Thus far, heavy downpours have dropped around 1 to 1.25 inches of rain via personal weather stations. Given the slow eastward motion of these cells, localized ponding of roads may occur in conjunction with frequent lightning. As the day progresses, the mentioned activity will progress downstream into a very moist and unstable thermodynamic environment. For areas south of I-66 and Highway 50, stronger convection should be more difficult to sustain with mid/upper ridging taking shape overhead. This leads to weaker mid-level lapse rates, generally in the 5.5 to 6 C/km range. Farther north, especially near the Mason-Dixon Line, the environment is more conducive to severe convection with closer to 3,000 J/kg of mixed-layer CAPE. Additionally, this region is slightly removed from the sprawling ridge. Expect afternoon/evening strong to severe thunderstorms across the Slight risk area from central to northeastern Maryland. The most intense updrafts will bring a damaging wind potential. There is some inherent flooding potential as well given the near 2 inch precipitable water values, high freezing levels, and 5 knot Corfidi vectors. Elsewhere, the sub-severe convection could still bring heavy downpours and frequent lightning. While some showers may linger toward midnight, a vast majority of the activity will shut off before then. Warm and humid conditions continue into the night with mid 70s in the forecast for areas along and east of I-95. Some upper 70s are even possible in DC and locations near the Tidal Potomac. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Not a whole lot changes into the Tuesday-Wednesday timeframe with the continuation of heat/humidity, along with chances for showers and thunderstorms. The western flank of a 594-dm upper ridge maintains its presence across areas east of I-95. Thus, convective chances should be somewhat shunted on Tuesday across these regions. Otherwise, expect another day of high temperatures into the low/mid 90s with dew points in the low/mid 70s. Consequently, heat indices approach the 100 to 105 degree range, locally higher. If these end up on the higher end of the range, heat headlines may be considered. The best chances for organized convection should be across the higher terrain and locations closer to the Mason-Dixon Line. There is some localized severe convection potential. Overnight lows may be a degree or two cooler than the previous night, but it should prove to be another very muggy night. Wednesday will likely bring a more widespread convective event as an upstream trough approaches from the west. The combination of this forcing mechanism with the moist and unstable environment should prove instrumental to such showers and thunderstorm generation. The Storm Prediction Center outlook currently highlights a vast majority of the region in a Marginal risk through the night. This will likely change in future updates with additional guidance and convective evolutions. The increase in cloud cover should decrease temperatures a tad with heat indices nearing the century mark. Rain-cooled air may be enough to cool off nighttime temperatures into the upper 60s to low 70s in the warmer spots. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Hot and humid conditions continue Thursday and Friday as upper level ridging and an associated Bermuda high holds strong. As a result, expecting temperatures to continue range in the low to mid 90s for many across the region with dew points in the 70s. This will lead to increased chances late afternoon/early evening showers and thunderstorms each day. However H5 heights will decrease Saturday as an upper level trough and associated cold front approach from the west. This will lead to greater chances for showers and thunderstorms developing across the region. Thereafter, spread amongst guidance increases in regards to where the front settled for Sunday and Monday. The ECMWF indicates high pressure sinking southward from the Great Lakes while the GFS increases the Bermuda High offshore which would cause the front to linger over our region. Confidence remains low in regards to any particular outcome, thus will have to continue to monitor trends over the next several days. In any case, cooler weather looks likely by the end of the weekend into early next week. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... Hot and humid conditions continue across the terminals through the middle of the week. While conditions are expected to be generally VFR during this time, chances for showers and thunderstorms will persist which can lead to instances of reduced CIG/VSBYs briefly. In addition, chances for early morning fog/low clouds will also continue, especially for areas mainly along and west of the Blue Ridge. Mainly VFR conditions are also expected both Thursday and Friday. outside of any scattered shower/thunderstorm activity during the late afternoon/evening, which could briefly reduce CIG/VSBYs. Winds will remain southerly during this time. && .MARINE... Southerly channeling continues across lower portions of the Tidal Potomac and Chesapeake Bay. This will remain an issue through at least Tuesday morning where a Small Craft Advisory is currently in effect. Given little change in the pattern, this may be extended into more of Tuesday. Otherwise, with daily chances for convection, gusty showers over the waters may warrant the issuance of SMWs each day. Southerly winds both Thursday and Friday will lead to sub-SCA conditions, outside of any instances of gusty showers/thunderstorms that may develop over the waters, which may prompt the issuance of SMWs. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ534-537-543. && SYNOPSIS...LFR/BRO NEAR TERM...BRO SHORT TERM...BRO LONG TERM...MSS AVIATION...MSS MARINE...MSS/BRO
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 742 PM EDT Mon Jul 12 2021 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ052>057-132345- 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- 742 PM EDT Mon Jul 12 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...Tonight A Severe Thunderstorm Watch remains in effect until 11 PM this evening for Harford and Cecil counties in northeast Maryland. Damaging wind gusts are the primary hazard. This may also require Special Marine Warnings across the middle to upper Chesapeake Bay waters. Heavy rainfall in training thunderstorms could lead to isolated instances of flooding or flash flooding through this evening across northern and northeast Maryland. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Isolated severe thunderstorms with damaging wind gusts are possible Wednesday and Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible this afternoon and evening. MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508- WVZ050>053-055-132345- 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- 742 PM EDT Mon Jul 12 2021 This Hazardous Weather Outlook is for portions of eastern West Virginia, northern and central Virginia, and central and western Maryland. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Isolated severe thunderstorms with damaging wind gusts are possible Wednesday and Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ001-501-502-VAZ503-504-WVZ501>506-132345- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 742 PM EDT Mon Jul 12 2021 This Hazardous Weather Outlook is for the Allegheny Front counties in western Maryland, eastern West Virginia, and Highland County Virginia. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Isolated severe thunderstorms with damaging wind gusts are possible Wednesday and Saturday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. CJL
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
427 PM EDT MON JUL 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0347 PM TSTM WND DMG 1 S MIDDLEWAY 39.29N 77.98W
07/12/2021 JEFFERSON WV 911 CALL CENTER
LARGE TREE FELL ON A CAR NEAR THE INTERSECTION OF
LEETOWN RD AND DAVID LEIGHT LN (NO INJURIES)
0407 PM TSTM WND DMG 2 NE RANSON 39.32N 77.84W
07/12/2021 JEFFERSON WV 911 CALL CENTER
LARGE TREE LIMB DOWN BLOCKING FLOWING SPRINGS RD NEAR
FLOWING ACRES RD
&&
EVENT NUMBER LWX2104752
EVENT NUMBER LWX2104753
SMZPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
445 PM EDT MON JUL 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0310 PM TSTM WND DMG FAIRPLAY 39.54N 77.75W
07/12/2021 WASHINGTON MD FIRE DEPT/RESCUE
TREE DOWN ON WIRES AND BLOCKING ROADWAY IN THE 17000
BLOCK OF SPIELMAN RD
&&
EVENT NUMBER LWX2104754
SMZPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
556 PM EDT MON JUL 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0302 PM TSTM WND DMG 3 NE CHARLES TOWN 39.31N 77.82W
07/12/2021 JEFFERSON WV NWS EMPLOYEE
TREE FELL DOWN ON NIGHTINGALE LN.
&&
EVENT NUMBER LWX2104755
CJLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
641 PM EDT MON JUL 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0439 PM TSTM WND DMG 3 E ROCK ENON SPRINGS 39.21N 78.33W
07/12/2021 FREDERICK VA 911 CALL CENTER
POWER LINE DOWN ON GRAYWOLF TRAIL IN WINCHESTER.
&&
EVENT NUMBER LWX2104756
CJLThe national radar mosaic for the moment the first event began.
5 flood. Local standard time, as filed.
Multiple vehicles were disabled in high water near North Philadelphia Boulevard and Beards Hill Road.
A bridge near Old Robinhood Road and Paradise Road was submerged in at least a foot of water near the Aberdeen Swim Club.
Two vehicles were stuck in high water along Aldino Road east of West Chapel Road. The roadway was closed.
Hopewell Road was closed at Route 155 due to flooding.
The stream gauge on Big Pipe Creek at Bruceville exceeded minor flood stage, cresting at 8.4 feet at 12:45 AM EST. At 8 feet, Keysville-Bruceville Road begins to flood.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2021Every state in 2021This day in weather historyWarnings in Maryland, July 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: 972506, 972509, 972513, 972514, 972517.