A hot, humid, and very unstable airmass resulted in scattered pulse thunderstorms that produced several instances of damaging downbursts. A couple instances of wind damage were significant just east of Washington, DC.
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 hot, humid, and very unstable airmass resulted in scattered pulse thunderstorms that produced several instances of damaging downbursts. A couple instances of wind damage were significant just east of Washington, DC.
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 31, 1:50 PM EST, 2 hours 37 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 250 PM EDT Wed Jul 31 2024 .SYNOPSIS... A warm front passes by to the west late Thursday night before a cold front approaches from the Ohio River Valley over the weekend. This system crosses through the area on Sunday before high pressure settles nearby into early next week. && .NEAR TERM /THROUGH TONIGHT/... On the back side of a broad longwave trough, very isolated showers have begun to fire up mainly along and east of U.S. 15. Surface conditions are plenty ripe for updraft development with current temperatures in the low 90s and dew points ranging from the upper 60s to mid 70s. This pool of higher moisture content has generally focused east of U.S. 15 where current mixed-layer CAPE sits in the 1,500 to 2,000 J/kg range. While most pulse- type showers have been brief in nature, one such updraft has been longer lived just south of D.C. This particular feature has been the only to produce sporadic lightning strikes. Otherwise, GOES-16 visible satellite imagery shows an area of towering cumulus arcing from the D.C. metro up through the Baltimore metro and to the Mason-Dixon Line. Have maintained a swath of isolated thunderstorm chances along and east of I-95 through dark. Given paltry vertical shear profiles, any severe threat appears to be rather minimal. As mentioned, today's temperatures have crossed the 90 degree mark with eventual highs pushing to near 95 degrees. This carries maximum heat indices to around 98 to 103 degrees. Moving into the night, seasonably mild conditions persist with forecast lows mainly in the low/mid 70s. West of I-81, readings in the mid/upper 60s are more likely. Depending on how an upstream mesoscale convection system tracks, some residual thunderstorm chances may reach the Allegheny Front overnight. With that said, a Marginal Risk for severe thunderstorms have been advertised by the Storm Prediction Center for such a threat. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... The heat and humidity further pick up with daily high temperatures rising into the mid/upper 90s each day. Both are candidates for Heat Advisories given heat indices which push toward advisory thresholds. A westerly component to the wind on Thursday could help slightly lower dew points over the area. This ultimately keeps heat indices in the 100 to 105 degree range. However, a shift to southerly flow on Friday should allow a return to low/mid 70s dew points over a large chunk of the area. Thus, Heat Advisories become more likely to finish out the work week as heat indices push into the 100 to 110 degree range. As usual, little relief can be anticipated at night with forecast lows around 5 to 10 degrees above early August climatology. On the convective side of things, Marginal Risks are in place for the entire forecast area on both Thursday and Friday. Between the two days, Friday certainly has much better forcing as a slow moving shortwave tracks from the Midwest toward the Ohio River Valley. There will certainly be plenty of heat to work with each afternoon, likely contributing to ample instability levels. Forecast surface progressions do indicate a semi-permanent north/south oriented trough across the area. This will likely provide a focus for convective initiation along with any typical mesoscale boundaries. Given the uncertainties around convective development and longevity this time of year, details will certainly be fuzzy at this juncture. For now, prepare for ample heat, humidity, and daily thunderstorm chances (some accompanying severe threat). && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A mid-level disturbance will move slowly across our region Saturday through Sunday. Increasing heat and humidity will help to fuel showers and thunderstorms across a large portion of our area. Some of the thunderstorms could produce gusty winds and heavy downpours Saturday afternoon into Saturday evening. High temperatures both days will reach near or lower 90s. A lingering front Monday and Tuesday could pose for a starting point of additional showers and thunderstorms each day. For now, we have a slight chance of showers and thunderstorms. Highs will be in the lower 90s each day. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... With isolated convection firing up early this afternoon, all terminals outside of KMRB have a VCSH group attached to them through the late afternoon hours. Only the most robust activity has been causing lightning (i.e., KDCA and KBWI as of 18-19Z). Otherwise, mainly southwest to westerly winds are noted although local bay and river breezes are causing a southeasterly wind around KMTN and KDCA, respectively. Shower chances diminish overnight as the boundary layer stabilizes. For Thursday, winds initially meander between northwest and westerly. Any westerly component to the winds could hinder some future convective development. However, there is an expectation of a shift to southwesterly during the afternoon/evening hours. Some threat for mid/late afternoon convection is evident which supported a VCTS inclusion into the 30-hour TAF sites (KIAD, KDCA, and KBWI). Heading into Friday, a better shot for thunderstorms loom which will support some periods of afternoon/evening restrictions. However, both days will largely feature VFR conditions outside of bouts of convection. MVFR to perhaps IFR conditions possible in any heavy showers and gusty thunderstorms on Saturday. Otherwise, VFR conditions Sunday and Sunday night. Winds southwest 5 to 10 knots through much of the period. Winds late Sunday into Sunday night could become northwest 5 to 10 knots with a front to the southeast. && .MARINE... Given relatively weak gradients, any threat for Small Craft Advisories would appear to be driven by the mesoscale. With that said, through Thursday, there are no obvious periods with winds reaching advisory caliber. By Friday, a more prolonged southerly flow ensues which may support some localized channeling effects. Daily chances for afternoon/evening convection will certainly pose a hazard to those out on the waters the next few days. In fact, Special Marine Warnings are in effect for the upper and lower tidal Potomac for a pair of more robust cells. However, the more impactful period ahead would be on Thursday and Friday with the waters in a Marginal Risk for severe thunderstorms each day. Given that threat, Special Marine Warnings may be required at times. No marine hazards expected Saturday through Sunday night. Winds southwest around 10 knots generally through the period. && .TIDES/COASTAL FLOODING... South to southwest flow will keep water levels elevated through the end of the week. This may result in near minor flooding of vulnerable shoreline, though confidence in exceeding minor thresholds is low given the generally light west-of-south flow. Somewhat stronger winds on Friday could raise water levels a bit more, with minor flooding perhaps more of a possibility then. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...BRO NEAR TERM...BRO SHORT TERM...BRO LONG TERM...KLW AVIATION...BRO/KLW MARINE...BRO/KLW TIDES/COASTAL FLOODING...LWX
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 333 PM EDT Wed Jul 31 2024 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ053>057-527-011945- 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-Fairfax-Arlington/Falls Church/Alexandria- Stafford-Spotsylvania-King George- Central and Southeast Prince William/Manassas/Manassas Park- 333 PM EDT Wed Jul 31 2024 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 A severe thunderstorm is possible along the Western Shore this afternoon, with damaging wind gusts as the primary threat. Special Marine Warnings may be required for isolated thunderstorms over the waters this afternoon to early evening. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday A Heat Advisory is in effect Thursday from 12 PM to 8 PM for the entire area. Hot and humid conditions are expected Friday, that bring heat index values to around 105 to 110. Strong to severe thunderstorms may be possible on Friday and Saturday during the afternoon and evening hours. The primary threat will be damaging wind gusts. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508- 526-WVZ050>053-055-011945- 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-Northwest Prince William-Hampshire- Morgan-Berkeley-Jefferson-Hardy- 333 PM EDT Wed Jul 31 2024 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 No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Outside the Blue Ridge Mountains, hot and humid conditions are expected which will bring heat index values to around 100 to 105 degrees on Thursday and Friday. Heat indices up to 110 degrees are possible east of the Blue Ridge Mountains during this time. Strong to severe thunderstorms may be possible on Friday and Saturday during the afternoon and evening hours. The primary threat will be damaging wind gusts. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ001-501-502-VAZ503-504-WVZ501>506-011945- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 333 PM EDT Wed Jul 31 2024 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 No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Hot and humid conditions are expected which will bring heat index values to around 100 to 105 degrees, mainly over the lower elevations, on Thursday and Friday. Strong to severe thunderstorms may be possible on Friday and Saturday during the afternoon and evening hours. The primary threat will be damaging wind gusts. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Preliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
415 PM EDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0401 PM Marine Tstm Wind 1 E Eastport 38.97N 76.46W
07/31/2024 M45 mph ANZ532 MD Buoy
39 knots measured at Greenbury Point Buoy.
&&
Event Number LWX2403600
KJPPreliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
432 PM EDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0410 PM Marine Tstm Wind 1 E Bay Ridge 38.94N 76.44W
07/31/2024 M51 mph ANZ532 MD Buoy
Measured gust to 44 knots at Tolly Point Buoy.
&&
Event Number LWX2403601
KJPPreliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
436 PM EDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0424 PM Marine Tstm Wind 5 ESE Bay Ridge 38.92N 76.36W
07/31/2024 E39 mph ANZ532 MD Buoy
&&
Event Number LWX2403602
KJPPreliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
448 PM EDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0443 PM Marine Tstm Wind 10 E Bay Ridge 38.92N 76.27W
07/31/2024 M49 mph ANZ540 MD Mesonet
&&
Event Number LWX2403603
KJPPreliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
502 PM EDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0445 PM Marine Tstm Wind 14 E Bay Ridge 38.92N 76.21W
07/31/2024 E39 mph ANZ540 MD Mesonet
&&
Event Number LWX2403604
KJPPreliminary Local Storm Report
National Weather Service Baltimore MD/Washington DC
507 PM EDT Wed Jul 31 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0440 PM Marine Tstm Wind 14 E Bay Ridge 38.90N 76.21W
07/31/2024 E39 mph ANZ540 MD Buoy
&&
Event Number LWX2403605
KJPThe Sterling radar (KLWX), 25 km away, was scanning. The volume nearest the first event began at 21:27 UTC.
3 thunderstorm wind. Local standard time, as filed.
There were a couple of reports of trees blown down near Merrifield and Annandale. A tree blew down near the intersection of US-50 Arlington Boulevard and Prosperity Drive. A tree blew down on Woodburn Road.
Trees and power lines blew down near the intersection of Oronoco Street and North Payne Street.
Tree damage was reported in Hybla Valley, including on Karl Road and Bayberry Drive.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2024Every state in 2024This day in weather historyWarnings in Virginia, July 2024
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: 1207466, 1207467, 1207468.