A slow moving cold front moved into the area during the evening of the 12th into the overnight and early morning hours of the 13th. Moisture pooling ahead of the cold front caused instability to increase in addition to added atmospheric moisture.
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 slow moving cold front moved into the area during the evening of the 12th into the overnight and early morning hours of the 13th. Moisture pooling ahead of the cold front caused instability to increase in addition to added atmospheric moisture. Showers and thunderstorms developed, and some trained over the same areas resulting in instances of flooding and flash flooding. Central and northeastern Maryland were the areas hardest hit, where moisture and instability was highest.
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 Sep 12, 8:30 PM EST, 1 hour 30 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 930 PM EDT Tue Sep 12 2023 .SYNOPSIS... A boundary will remain nearby through this evening before moving to the east as a cool front later tonight. A stronger cold front and its associated upper-level trough will pass through the area later Wednesday into Wednesday night. Canadian high pressure will build overhead for late in the week into the weekend. && .NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/... Upper trough across the western Great Lks is expected to amplify across the northern Mid-Atlantic into the central Applachians next 24 to 36 hrs hours. As it does so, height falls will overspread the area tonight leading to large scale forcing and widespread showers and perhaps a few thunderstorms. This is already underway per KLWX radar trends and lightning data. Rainfall amounts are expected to be around a quarter of an inch, except in northeast MD where moisture convergence and instability will be maximized and HREF probabilities indicate possibility of intense rainfall rates and amounts up to 3 inches. In addition, this area has seen the most rain in the past 5 days or so and may be the most vulnerable to flooding. For this reason, a Flood Watch has been issued for Cecil and Harford Counties from 03Z till 15Z Wed. As far as severe weather is concerned, a low end threat for a brief spin-up tornado cannot be ruled as low-level flow continues to increase. The 01Z RAP objective analysis shows a bullseye in the Supercell Composite field across northeastern Maryland. && .SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Sfc cold front will be crossing the area after 12Z Wed, but 925 and 850 mb dewpoint fronts will be lagging behind as well as 500 mb trof axis. So, expect the risk of showers to persist through much of the day particularly east of the Blue Ridge Mountains. However, with the best moisture and instabillity axis shifting east of the Chesapeake Bay, expect any flooding or severe wx to remain well east of the Chesapeake Bay. Weak high pressure builds over the region for the second half of the week leading to cooler and fair weather conditions. && .LONG TERM /FRIDAY THROUGH TUESDAY/... High pressure is expected to remain overhead Friday through Sunday, yielding dry conditions with normal temperatures. By the weekend temperatures may gradually warm to near or just above normal with the high pressure and ample sunshine, though the further into the extended, the more dependent conditions will be on the track of Lee. As we continue to monitor Lee, stay up to date with the latest information on the tropics at nhc.noaa.gov. For now, dry conditions are expected to continue through the weekend with a possible weak frontal passage Sunday into the early part of the work week. Some precipitation is possible with this fropa, but will depend on how dry the air mass is. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... Showers and possible thunderstorms are expected tonight mainly through the overnight hours. The greatest chances have shifted northward given current radar trends. This places the main threat across the DC terminals initially, before shifting to KBWI and KMTN within the next couple hours. Some brief cig and/or vsby restrictions are possible. Scattered showers are still possible Wed, but most showers should be done by 15Z. As the upper trough passes overhead, a few showers may fire up during the afternoon, especially I-66 southward. VFR conditions are expected Friday and Saturday as high pressure sits overhead. Thanks to the tight pressure gradient with Lee offshore, winds both days will be 10-15kt out of the N/NW with gusts 15-20kts, though winds will likely be strongest Friday. && .MARINE... Widespread showers and isold/sct t-storms expected tonight through 18Z Wed. A few SMWs may be required. Gradient winds strengthen late Wed night and remain in SCA category into the weekend. SCAs are likely Friday and possible during the day Saturday as a tight pressure gradient from Lee passing offshore creates gusty NW winds over the waters. Winds gradually diminish by Saturday night. && .HYDROLOGY... A Flood Watch remains in effect across Harford and Cecil Counties from 11 PM this evening until 11 AM Wednesday. This area has seen the most rainfall within the past 5 days which would increase the risk for future flash flooding. Toward the D.C. and Baltimore metros, locally heavy rainfall could lead to isolated flooding across the typical more vulnerable locations. The latter threat essentially subsides through the overnight hours. && .TIDES/COASTAL FLOODING... With tidal anomalies slightly elevated, a couple of the more sensitive locations should push into Action stage during the next high tide. However, water levels should quickly drop off behind a strong cold front which pushes through midday Wednesday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Flood Watch through Wednesday morning for MDZ008-507-508. VA...None. WV...None. MARINE...None. && SYNOPSIS...LFR NEAR TERM...LFR/BRO SHORT TERM...LFR LONG TERM...CAS AVIATION...LFR/BRO/CAS MARINE...LFR/CAS HYDROLOGY... TIDES/COASTAL FLOODING...
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 1001 PM EDT Tue Sep 12 2023 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ053>057-527-140215- 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- 1001 PM EDT Tue Sep 12 2023 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 Flood Watch is in effect for Cecil and Harford Counties from 11 PM tonight through 11 AM Wednesday. A severe thunderstorm with damaging wind gusts along with isolated instances of flooding is possible tonight. .DAYS TWO THROUGH SEVEN...Wednesday through Monday The Flood Watch continues for Cecil and Harford Counties until 11 AM Wednesday. .SPOTTER INFORMATION STATEMENT... Please send any severe or flood reports to the National Weather Service in Sterling, Virginia. MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508- 526-WVZ050>053-055-140215- 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- 1001 PM EDT Tue Sep 12 2023 This Hazardous Weather Outlook is for portions of eastern West Virginia, northern and central Virginia, and central and western Maryland. .DAY ONE...Tonight A Flood Watch is in effect for Carroll and northern Baltimore Counties from 11 PM tonight through 11 AM Wednesday. A severe thunderstorm with damaging wind gusts along with isolated instances of flooding is possible tonight, especially near and east of the Blue Ridge and Catoctin Mountains. .DAYS TWO THROUGH SEVEN...Wednesday through Monday The Flood Watch continues for Carroll and northern Baltimore Counties until 11 AM Wednesday. .SPOTTER INFORMATION STATEMENT... Please send any severe or flood reports to the National Weather Service in Sterling, Virginia. MDZ001-501-502-VAZ503-504-WVZ501>506-140215- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 1001 PM EDT Tue Sep 12 2023 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...Wednesday through Monday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Sterling radar (KLWX), 82 km away, was scanning. The volume nearest the first event began at 03:00 UTC.
16 flash flood, 3 flood. Local standard time, as filed.
The fire department reported dozens of water rescues around the city of Baltimore along with Jones Falls flowing out of its banks.
The fire department reported dozens of water rescues around the city of Baltimore along with Jones Falls flowing out of its banks.
Old Hundred Road had water flowing over it in a couple spots.
Vehicles were stranded in high water along Wabash Avenue in northwest Baltimore City. Water was flowing at least wheel deep on the roads.
The water level rapidly rose above the flood stage of 13 feet along Gwynns Falls at Washington Boulevard. At 13 feet, Beach drive is flooded in several places and both the Riley Springs Trailbridge and Rapids Footbridge are completely covered by water.
The I-495 Inner Loop past exit 33 was partially closed due to high water.
Vehicles were stranded in high water in Arbutus due to flowing water.
Vehicles were stranded in flowing high water in Pikesville.
Occupied vehicles were in floodwater due to heavy rainfall.
There were occupied vehicles stranded in floodwater at Loch Raven Boulevard.
Cabin John Parkway northbound after Clara Barton Parkway was closed due to water flowing across the road. Vehicles were stranded in high water.
Flood waters entered businesses along Gladstone Avenue and Wyndhurst Avenue due to Stony Creek flowing out of its banks.
There were occupied vehicles in floodwater at the intersection of Oakleigh Road and Redwood Avenue.
US 29 was closed at Fairland Road due to high water.
Maple Avenue was closed between Kennebec Avenue and Sligo Creek Parkway due to water flowing across the roadway.
Roads were closed due to flowing water around Essex.
An occupied vehicle was stuck in flood water at Buckingham Road and Liberty Road.
The three left lanes of and the left shoulder of the I-495 Beltway Inner Loop were closed due to high standing water at exit 30A/US-29 Colesville Road.
The water level rapidly rose above flood stage of 11 feet along the Whitemarsh Run at White Marsh. At 11 feet, water covers the parking lots near the stream, particularly near the Town Center Court. The water fell below flood stage at 12:55 AM EST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2023Every state in 2023This day in weather historyWarnings in Maryland, September 2023
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: 1122459, 1122460, 1122457, 1122405, 1122408, 1122441, 1122409, 1122411, 1122412, 1122413, 1122415, 1122458, 1122418, 1122442, 1122420, 1122456, 1122421, 1122443, 1122427.