A nearly stationary boundary set up near the Potomac River weak low pressure developed along the boundary. There was plenty of moisture in place from the Atlantic and Gulf of Mexico, and this combined with instability to produce very heavy rainfall rates in convection that developed.
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 nearly stationary boundary set up near the Potomac River weak low pressure developed along the boundary. There was plenty of moisture in place from the Atlantic and Gulf of Mexico, and this combined with instability to produce very heavy rainfall rates in convection that developed. Convection was maximized around the boundary across northern Virginia near the Potomac River, and this led to several instances of flooding and flash flooding.
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 8, 2:59 AM EST, 4 hours 43 minutes earlier.
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Mon Jul 8 2019
.SYNOPSIS...
A weak cold front will move to our south today. High pressure
will then build north of the area into the middle of the week.
Another front will approach by week's end.
&&
.NEAR TERM /THROUGH TONIGHT/...
The main surface front is along the Mason-Dixon region. Multiple
showers and a few embedded thunderstorms had developed overnight
and moved across much of central Maryland, eastern West Virginia
Panhandle and far northern Virginia, prompting flood and flash
flood warnings. Rain amounts averaged one to three inches in
many locations in parts of Washington County, Berkeley and
Jefferson Counties, and Loudoun County. Lesser amounts occur
elsewhere in western Maryland and parts of northeast Virginia.
Showers currently exist across a large portion of northeast
Maryland and the eastern West Virginia Panhandle, as well as
southern Maryland.
A Flash Flood Watch remains in effect for central and northern
zones, as well as much of the metro areas through 6 am this
morning. As we enter into the heart of this morning, much of
heavier showers and any thunderstorms should diminish and lead
to a stray shower or drizzle. Dry air finally advances enough to
end precipitation. Highs today near 80.
Canadian high pressure dominates tonight. This will provide a
relatively cooler and less humid period with less cloud cover.
Highs in the 80s and lows in the 60s. Could be patchy fog in the
early morning hours, but that's pretty much the only fly in the
ointment.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
High pressure will dominate dry conditions on Tuesday. Cooler
and less humid conditions should continue. Highs will be in the
80s and lows in the 60s Tuesday night. Some patchy fog is
possible early Tuesday.
We remain dry on Wednesday, as high pressure slides overhead,
and eventually offshore by Wednesday night. This thanks to an
approaching cold front from the west, associated with a surface
low tracking well to our north across the Great Lakes into the
northeast. Highs on Wednesday will be in the mid to upper 80s
once again.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A cold front will approach and move through our region some time
Thursday afternoon and into Friday. Ahead of the cold front a
southerly flow will lead to warm and moist air being advected into
our region. This will lead to CAPE values range from 1500 to 2500
along with 15 to 20 knots of shear. Showers and thunderstorms will
be a concern especially Thursday afternoon through early Friday. The
models disagreeing on the timing of the cold front the GFS being the
faster solution leading to Friday staying mainly dry while the Euro
keeps precipitation in place through Friday afternoon. This will be
a day to watch for potential severe weather especially pulse style
storms. Daytime temps during this period are expected to hover in
the mid to upper 80s.
Behind the frontal passage, a high pressure system will build into
our region from the south through the weekend. Temperatures are
forecast to hover in the mid 80s to low 80s with light winds out of
the west. Scattered showers and thunderstorms could be potential
Sunday afternoon due to upper level shortwave lift but models don't
have a strong signal on a widespread threat.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Showers and a possible rumble of thunder over MRB and near IAD
through daybreak, plus a few showers near BWI and MTN terminals.
Otherwise, a cold front will push south and undercut warm moist
air will likely lead to IFR cigs, which may linger much of today
before breaking up late. Conditions will then become VFR by
tonight. Patchy fog possibly a concern late Monday night/early
Tuesday, but otherwise VFR for Tuesday.
VFR conditions expected Wednesday, as high pressure keeps
things dry. Not expecting any wind issues either, with light
winds expected both days.
A cold front on Thursday will bring showers and storms to the
region, which may lead to flight restrictions. However, am
expecting conditions to be primarily VFR outside of
thunderstorms.
&&
.MARINE...
Thunderstorm wind gusts are the main concern overnight.
Northerly flow behind slow moving cold front and ahead of
building high pressure likely leads to SCA gusts on much of the
waters today and this evening, so SCA has been raised. Winds
relax Tuesday as gradient relaxes while high builds in.
Winds remain below SCA criteria for at least Wednesday and
Thursday, as high pressure builds over the region on Wednesday,
before sliding offshore by Thursday. Winds on Thursday, while
slightly stronger out of the SW, should remain below SCA
criteria. However, could see some stronger gusts in any
thunderstorms over the waters.
&&
.HYDROLOGY...
A Flash Flood Watch remains in effect until 6 am this morning
for central and northeast Maryland, part of southern Maryland,
eastern West Virginia and northeast Virginia. One Flash Flood
Warning and two Flood Warnings are in effect through early this
morning.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Flash Flood Watch until 6 AM EDT early this morning for DCZ001.
MD...Flash Flood Watch until 6 AM EDT early this morning for
MDZ003>006-011-013-014-016-501>506.
VA...Flash Flood Watch until 6 AM EDT early this morning for VAZ028-
030-031-052>055-501-502-505-506.
WV...Flash Flood Watch until 6 AM EDT early this morning for
WVZ050>053-503-504.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ532-
533-540-541.
Small Craft Advisory until midnight EDT tonight for ANZ534-537-
542-543.
Small Craft Advisory until 2 PM EDT this afternoon for ANZ530-
531-538-539.
&&
SYNOPSIS...KLW
NEAR TERM...KLW
SHORT TERM...KLW
LONG TERM...JMG
AVIATION...KLW/JMG
MARINE...KLW/JMG
HYDROLOGY...KLWHazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 622 AM EDT Mon Jul 8 2019 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-091030- 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- 622 AM EDT Mon Jul 8 2019 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 A Flash Flood Watch remains in effect through 10am this morning for the Washington and Baltimore Metropolitan areas. Scattered incidents of flooding are possible due to slow moving showers and thunderstorms. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are asked to report any severe weather or flooding to the National Weather Service via normal procedures. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-091030- 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- 622 AM EDT Mon Jul 8 2019 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 A Flash Flood Watch remains in effect through 10am this morning for portions of northern Virginia, eastern West Virginia, and central and western Maryland. Scattered incidents of flooding are possible due to slow moving showers and thunderstorms. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotters are asked to report any flooding to the National Weather Service via normal procedures.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
731 AM EDT MON JUL 08 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0713 AM FLASH FLOOD FREDERICK 39.43N 77.42W
07/08/2019 FREDERICK MD LAW ENFORCEMENT
NUMEROUS ROADS FLOODED AND IMPASSIBLE IN THE CITY OF
FREDERICK.
&&
EVENT NUMBER LWX1905076
JEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
809 AM EDT MON JUL 08 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0752 AM FLASH FLOOD 1 ESE BARNESVILLE 39.22N 77.36W
07/08/2019 MONTGOMERY MD FIRE DEPT/RESCUE
WATER STUCK IN HIGH WATER NEAR INTERSECTION OF PEACH
TREE RD. AND BARNESVILLE RD.
&&
EVENT NUMBER LWX1905077
CJLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
819 AM EDT MON JUL 08 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0751 AM FLASH FLOOD 2 SSE BOYDS 39.16N 77.30W
07/08/2019 MONTGOMERY MD FIRE DEPT/RESCUE
VEHICLE STUCK IN HIGH WATER AT INTERSECTION OF
CORNFLOWER RD. AND KINGS CROSSING BLVD.
&&
EVENT NUMBER LWX1905078
CJLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
821 AM EDT MON JUL 08 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0748 AM FLASH FLOOD 1 E BARNESVILLE 39.22N 77.37W
07/08/2019 MONTGOMERY MD FIRE DEPT/RESCUE
VEHICLE STUCK IN HIGH WATER AT INTERSECTION OF W OLD
BALTIMORE RD. AND BARNESVILLE RD.
&&
EVENT NUMBER LWX1905079
CJLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
824 AM EDT MON JUL 08 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0809 AM FLASH FLOOD 2 W NORTH POTOMAC 39.09N 77.28W
07/08/2019 MONTGOMERY MD FIRE DEPT/RESCUE
VEHICLE STUCK IN HIGH WATER AT INTERSECTION OF TURKEY
FOOT RD. AND FALLING LEAF DR.
&&
EVENT NUMBER LWX1905080
CJLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
826 AM EDT MON JUL 08 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0809 AM FLASH FLOOD NORTH POTOMAC 39.10N 77.25W
07/08/2019 MONTGOMERY MD FIRE DEPT/RESCUE
VEHICLE STUCK IN HIGH WATER AT THE INTERSECTION OF
WONDER VIEW WAY AND QUINCE ORCHARD RD.
&&
EVENT NUMBER LWX1905081
CJLThe Sterling radar (KLWX), 16 km away, was scanning. The volume nearest the first event began at 12:42 UTC.
28 flash flood, 4 flood. Local standard time, as filed.
Hunter Mill Road was closed due to flooding under the Dulles Toll Road.
The water level at Four Mile Run rapidly rose above flood stage of 12 feet at 8:16 AM EST and it crested at 15.30 feet at 8:45 AM EST. Water flooded the north bank into grassy areas and parking lots. Water also approached Arlington Mill road on the south side of the stream and water approached structures on the north side of the stream.
The water level at Cameron Run rapidly rose above flood stage of 11 feet. The water level crested at 15.7 feet at 9:40 AM EST. Most of Lower Holes Run Trail along Cameron Run was flooded, and backwater flooded areas along Backlick Run upstream of Cameron Run.
At least three feet of standing water was in the Wiehle Reston Parking Lot adjacent to the Washington and Old Dominion Railroad Regional Park.
The water level at the New Alexandria stormwater pump station rapidly rose above flood stage of 5.5 feet, cresting at 7.51 feet at 9:15 AM EST, July 8th. This caused widespread street and yard flooding below the pump station, and at least a couple structures were impacted below I Street.
The water level rapidly passed flood stage of 6 feet, chresting at 9.03 feet on July 8th at 9:27 AM EST.
Sugarland Run was out of its banks with flooding near the Stuart Woods Apartments.
A steel and concrete pedestrian bridge was washed away along Four Mile Run in Bluemont Park.
Accotink Creek rapidly rose above flood stage of 9.5 feet. Woodburn Road and Prosperity Avenue were flooded at Accotink Creek. Water reached the outbuilding near Braddock Road and it covered ballfields at Wakefield Park.
The southbound Lane of Richmond Highway was closed due to flooding.
Paul Spring Road was closed due to flooding near the intersection with Fort Hunt Road. .
Woodburn Road was closed due to flooding near the intersection with Robey Avenue.
Prosperity Road was closed due to flooding near the intersection with Morningside Drive.
Holmes Run road was closed due to flooding near the intersection with Cedarwood Drive.
Waples Mill Road was closed due to flooding near the intersection with Oakton Road.
Hilltop Road was closed due to flooding between Willomere Drive and Old Lee Highway.
Shreve Road was closed due to flooding between Wieland Place and Buckelew Drive.
Lawyers Road was closed due to flooding near the intersection with Helmwood Court and it was also closed between Hunters Mill Road and Lydia Place.
Dempsey Street was closed due to flooding near the intersection with Old Chesterbrook Road.
Old Courthouse Road was closed due to flooding near the intersection with Besley Road.
Meadowlark Road was closed due to flooding near the intersection with Brookside Lane.
Hunter Mill Road was closed due to flooding between Cedar Pond Drive and Hunter Station Road.
Browns Mill Road was closed due to flooding between Windstone Drive and Rosewood Hill Drive.
Sunset Hills Road was closed due to flooding near the intersection with Metro Center Drive.
One lane of Georgetown Pike was closed due to flooding near the intersection with Potomac River Road.
Colvin Run Road was closed due to flooding at Leesburg Pike.
Walker Road was closed due to flooding between Sunnybrook Drive and Manning Street.
Springvale Road was closed due to flooding between Brevity Drive and Springvale Court.
Route 7 was closed near the intersection with Faulkner Drive.
The gauge at Difficult Run rapidly rose above flood stage of 11 feet at 10:37 AM EST. Leigh Mill Road was flooded as a result.
The gauge at Difficult Run crested at 12.59 feet at 12:45 PM EST and remained above flood stage of 11 feet until 2:40 PM EST. Leigh Mill Road was flooded as a result.
Accotink Creek crested at 12.61 feet at 12:30 PM EST. Woodburn Road and Prosperity Avenue were flooded at Accotink Creek. Water reached the outbuilding near Braddock Road and it covered ballfields at Wakefield Park.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2019Every state in 2019This day in weather historyWarnings in Virginia, July 2019
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: 842880, 840762, 840780, 840777, 843228, 843232, 842881, 840788, 840793, 840795, 840796, 840797, 840799, 840800, 840805, 842852, 842853, 842854, 842857, 842859, 842860, 842861, 842862, 842863, 842864, 842865, 842867, 842869, 843235, 840752, 840753, 840794.