Following the passage of a coastal low, bands of moisture continued to pull northward across the same areas that had already experienced heavy rain. Heavy rainfall fell in some areas, especially in Baltimore and Carroll Counties, with widespread flooding and flash flooding throughout the period.
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.
Following the passage of a coastal low, bands of moisture continued to pull northward across the same areas that had already experienced heavy rain. Heavy rainfall fell in some areas, especially in Baltimore and Carroll Counties, with widespread flooding and flash flooding throughout the period.
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 23, 2:18 PM EST, 18 minutes earlier.
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
318 PM EDT Mon Jul 23 2018
.SYNOPSIS...
A broad and slow moving low pressure system over the Southeast
will influence the Mid Atlantic through the middle of the week.
A pair of cold fronts will move through the area during the
second half of the week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A deeply amplified trough axis remain across the Great Lakes and
Ohio Valley. A plume of rich moisture (precipitable water up to
2 inches)resides across the area. There has been a bit of a
lull in activity today, as a mid level jet exits. However, that
absence has allowed instability to develop, up to 2000 j/kg
SBCAPE. With ample shear, showers and thunderstorms have started
to develop. Recent HRRR-TL runs suggest an uptick in activity
during the second half of the afternoon, continuing through the
evening hours. Unidirectional wind flow throughout the column,
with deep warm cloud and low MBE vectors suggest training
echoes, supporting a flood/flash flood threat. Watch continues
across the area I-81 east.
CAMs and HRRR-TL runs suggest that the heaviest rainfall may be
decreasing overnight. However, did not dive into details in the
database due to the presence of a river of high atmospheric
moisture...leading to the potential of a shower/storm at just
about any time. The varying model qpf solutions support this
conclusion.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The axis of high precipitable water (2.0-2.5 inches) shifts west
Tuesday morning, with another mid level jet impulse streaming
across the area. Given practically the same synoptic scale
ingredients as past few days, anticipate the same results.
Database contains cat PoPs for repeated sounds of
showers/thunderstorms. Heavy rain the big concern. Given that
and saturated antecedent conditions, Flash Flood Watch has been
extended through Tuesday evening.
Deep moisture plume will start shifting a bit more east on Wed
with flooding threat diminishing somewhat for western areas but
remaining very high for eastern areas Wed. Mid-level drying will
start taking place late Wed night with convection and risk of
flooding likely decreasing substantially after midnight Wed
night.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
On Thursday, the upper level trough that has been sitting off to our
west will break down and shift eastward out of our region. The
region will see a brief drying out as Precipitable water values drop
below two inches with most areas being below a inch and half. The
decrease in moisture will lead to dry conditions on Thursday with
clearing skies to partly cloudy. Winds will be light out of the west
to southwest with temperatures reaching into the mid to upper 80s
range.
Friday through Sunday, a upper level 500mb trough will approach our
region from the north. A low pressure system to the east of the
trough and its corresponding cold front will approach from the
west. Thunderstorms and showers will be possible both Friday and
Saturday. It seems that storms will be limited in the their
intensity due to the lack of moisture with this system as the models
are forecasting precipitable water values around the inch and half
mark or lower. The cold front is expected to move through our region
during the early parts of this weekend and then linger to the
southeast of our region over southern Virginia and Northern North
Carolina. Some showers and storms will be possible on Sunday.
Temperatures are expected to warm up into the upper 80s to mid 90s
this weekend.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Anticipate uptick in showers/thunderstorms this afternoon into
this evening. Ceilings MVFR, but may briefly rise to VFR.
On the other hand, within any shower/storm anticipate a rapid
but brief drop aob IFR. Timing specifics difficult. Am carrying
a TEMPO for a few hours this afternoon. Since details can't be
pinpointed and don't want to carry restrictions for low
probability event...and running with 6SM vsbys at this time.
Will need to AMD as needed.
Pattern continues into Wed with training convection likely.
Several round of brief/local aob IFR anticipated.
On Thursday, skies will clear some leading to rising cloud levels
and breaking up of cloud cover. We expect a drying trend with no
precipitation expected on Thursday. Winds will be light out of the
southwest to west. VFR conditions are likely.
Friday, a cold front will approach from the west. Winds will remain
light but shift out of the south. Showers and thunderstorms will be
possible. SubVFR conditions will be possible.
&&
.MARINE...
Intervals of scattered-numerous showers/thunderstorms
anticipated into Wed. Special Marine Warnings may be required.
In addition to that, SCA conditions likely into Wed. Have
extended SCA into Tue night at this time.
Clearing skies and light winds out of the west to southwest is
expected on Thursday. The west to southwesterly flow will not allow
for much of fetch which likely means winds will remain light over the
bay.
Showers and storms will be possible. Winds will shift out of the
south which could lead to conditions that will be favorable for
winds to reach above 15 knots.
&&
.HYDROLOGY...
Repeated rounds of showers and thunderstorms through Wednesday
will lead to increasingly susceptible conditions for not only
flash flooding but eventually some river flooding. Solis already
saturated, so it won't take much to realize flood concerns.
Flash Flood Watches have been extended through Tuesday evening.
In addition, River Flood Watches in effect for several points
in the Potomac and Rappahannock basins, mainly in the east.
Warnings are also in effect for Frederick and Dawsonville.
Please refer to AHPS for details.
&&
.TIDES/COASTAL FLOODING...
Water levels continue to run well above normal (1.5 to 2 feet) due
to persistent onshore flow. Widespread minor flooding is anticipated
through tonight, with moderate flooding forecast at Annapolis. Water
levels may begin to (very) gradually decrease after tonight as winds
start to shift to more southerly and eventually southwesterly, but
the threat of flooding will exist around high tide through the
middle of the week.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Flash Flood Watch through late Tuesday night for DCZ001.
Coastal Flood Advisory until 9 AM EDT Tuesday for DCZ001.
MD...Flash Flood Watch through late Tuesday night for MDZ003>006-
011-013-014-016>018-503>508.
Coastal Flood Advisory from 10 PM this evening to 4 AM EDT
Tuesday for MDZ016-018.
Coastal Flood Advisory until 4 AM EDT Tuesday for MDZ017.
Coastal Flood Warning from 1 AM to 7 AM EDT Tuesday for MDZ014.
Coastal Flood Advisory until 1 AM EDT Tuesday for MDZ014.
Coastal Flood Advisory until 10 AM EDT Tuesday for MDZ011.
VA...Flash Flood Watch through late Tuesday night for VAZ025>031-
036>040-050>057-501-502-505>508.
Coastal Flood Advisory from 10 PM this evening to 4 AM EDT
Tuesday for VAZ057.
Coastal Flood Advisory until 9 AM EDT Tuesday for VAZ054.
WV...Flash Flood Watch through late Tuesday night for WVZ051>053.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ530>534-
537-539>543.
Small Craft Advisory until 8 PM EDT this evening for ANZ535-
536-538.
Small Craft Advisory from noon to 6 PM EDT Tuesday for ANZ535-
536-538.
&&
SYNOPSIS...
NEAR TERM...HTS
SHORT TERM...HTS/LFR
LONG TERM...JMG
AVIATION...HTS/JMG
MARINE...HTS/JMG
HYDROLOGY...HTS
TIDES/COASTAL FLOODING...DHHazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 320 PM EDT Mon Jul 23 2018 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-241930- 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- 320 PM EDT Mon Jul 23 2018 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...This Afternoon and Tonight A Flash Flood Watch is in effect through late tonight. Scattered showers and thunderstorms with gusty winds over the waters may require Special Marine Warnings. A Coastal Flood Warning goes into effect for Anne Arundel County at 1 AM. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday A Flash Flood Watch is in effect through Tuesday evening. The Coastal Flood Warning for Anne Arundel County remains in effect until 7 AM. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. Please report rainfall totals and any observed flooding to the National Weather Service. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-241930- 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- 320 PM EDT Mon Jul 23 2018 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...This Afternoon and Tonight A Flash Flood Watch is in effect for all areas along and east of the Interstate 81 corridor through late tonight. River flooding is likely on area mainstem rivers due to excessive runoff from heavy rain, mainly east of the Blue Ridge. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday A Flash Flood Watch is in effect for all areas along and east of the Interstate 81 corridor through Tuesday evening. River flooding is likely on area mainstem rivers due to excessive runoff from heavy rain, mainly east of the Blue Ridge through at least Wednesday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. Please report rainfall totals and any observed flooding to the National Weather Service. DHOF
The Sterling radar (KLWX), 82 km away, was scanning. The volume nearest the first event began at 19:33 UTC.
49 flood, 11 flash flood. Local standard time, as filed.
Battletown Road and Leiters Mill Road flooded and closed due to flooding from Antietam Creek.
The stream gage on the Patapsco River near Elkridge exceeded the 16 foot flood stage during the indicated period. The peak level of 18.45 feet occurred at 11:05am EST. Hammonds Ferry Road and Furnace Avenue were flooded.
Ramp from I-70 to I-695 flooded and closed.
The USGS stream gage on Gunpowder Falls near Hoffmanville exceeded the 6 foot flood stage during the indicated period. The peak level of 6.94 feet occurred at 11:45pm EST. River Valley Ranch reported some flooding in their area, with campers having to be moved inside due to floodwaters.
A bridge over Peggys Run collapsed on Mount Carmel Road.
Western Run Road flooded and closed at Western Run. The USGS stream gage on Western Run at this location exceeded the 8 foot flood stage during the indicated period. The peak level of 11.35 feet occurred at 2:00am EST.
Kern Road flooded and closed near Gunpowder Falls with a partial washout of the road reported.
The USGS stream gage on Gwynns Falls near Villa Nova exceeded the 11 foot flood stage during the indicated period. Queen Anne Road flooded. The peak level was 11.78 feet, which occurred at 2:45am EST.
Roller Road washed out near Lineboro.
A portion of Millers Station Road, where it crosses Grave Run, was completely undermined and washed out due to flooding.
The USGS stream gage on Gunpowder Falls near Glencoe exceeded the 7 foot flood stage throughout the indicated period. There were three distinct peaks during the long period above flood stage, the highest of which was 14.41 feet, which occurred at 7:30am EST on July 25th. Throughout the flood, portions of Upper Glencoe Road and Lower Glencoe Road were flooded. For most of the time, Sparks Road was also flooded. Water was in buildings off of Sparks Road for over 24 hours from the morning of the 24th until the afternoon of the 25th, ultimately reaching several feet inside those structures. The water receded during the evening of the 25th but rose again overnight, affecting those buildings a second time.
Flooding near the intersection of Gwynn Lake Drive and Gwynn Oak Avenue caused closure of both roads.
Greenspring Avenue flooded and closed near Jones Falls.
A school bus was reported stuck in slowly rising flood waters from the Gunpowder Falls near Glencoe. Two adults and one child were successfully rescued, uninjured.
Shaffer Mill Road flooded and closed near the intersection with Grave Run Road.
Medleys Neck Road flooded and closed at Moll Dyers Run near Abell Creek Lane.
Furnace Avenue closed between Race Road and the county line due to flooding.
Maryland Route 243 flooded and closed south of Route 5.
Baltimore Annapolis Boulevard flooded and closed near the Patapsco River.
Smith Avenue flooded at Jones Falls.
The USGS gage on Beaverdam Run near Cockeysville exceeded the 9 foot flood stage during the indicated period. The peak level of 9.26 feet occurred at 12:05pm EST. Beaver Run Lane was flooded.
Bradley Boulevard flooded and closed near Mercy Hollow Lane.
Road closure due to high water near Point Lookout Road and Maypole Road.
Road closed due to high water on Friendship School Road near Bishop Road.
Two women were reported to be stuck in a local business with rising waters surrounding the building. One self-evacuated, and the other was safely rescued.
Over half a dozen roads reported flooded and closed in Cumberland.
The USGS gage on Beaverdam Run near Cockeysville exceeded the 9 foot flood stage during the indicated period. The peak level of 11.17 feet occurred at 2:00am EST. Beaver Run Lane was flooded. York Road was also flooded with water approaching nearby businesses. Local media reported one vehicle drove around a road closed sign and got stuck in the floodwaters on York Road. The occupant was rescued.
The USGS stream gage on Western Run at this location exceeded the 8 foot flood stage during the indicated period. The peak level of 9.06 feet occurred at 2:00am EST. Western Run Road was flooded.
The USGS stream gage on Baisman Run near Broadmoor exceeded the 4 foot flood stage during the brief indicated period. An access road near the gage flooded, with water approaching a porch.
The USGS stream gage on Beetree Run near Bentley Springs, MD exceeded the 5.5 foot flood stage during the indicated period. The peak level of 6.70 feet occurred at 1:30am EST. Bentley Road floods at these levels.
The USGS stream gage on Little Falls near Blue Mount exceeded the 8.5 foot flood stage during the indicated period. The peak level of 10.16 feet occurred at 4:00am EST. Water approached a driveway off Wiseburg Road and exceeded the banks in that area. Water also covered Big Falls Road in the area.
Maryland Route 28 flooded and impassable in several spots near Beallsville.
Maryland Route 97 flooded and closed near the Carroll County Airport.
Nicodemus Road flooded and closed near Maryland Route 27 at Morgan Run.
The USGS stream gage on Cranberry Branch near Westminster rapidly exceeded the 5 foot flood stage. The peak level of 8.73 feet was the highest ever recorded at this location, and this was the first time this stream had reached flood stage since 1995. Widespread flooding was reported along the stream.
Swift water rescue required on Maryland Route 27 near Morgan Run and Nicodemus Road.
Six to 12 inches of water was flowing across Willard Road near Poolesville.
The ramp from eastbound Maryland Route 202 to Route 704 was flooded and closed.
Portions of Lineboro Road flooded and impassable between Hallie Avenue and Paul Circle.
Three lanes closed on the Inner Loop of the Capital Beltway near Colesville Road due to flooding.
The USGS stream gage on Sligo Creek near Takoma Park rapidly exceeded the 5.5 foot flood stage during the indicated period. The peak level of 6.75 feet occurred at 6:55pm EST, and Sligo Creek Parkway was flooded.
Swift water rescue on Sligo Creek Parkway near Brunett Avenue due to Sligo Creek being out of its banks.
Swift water rescue reported at Sundale Drive and East-West Highway.
The USGS stream gage on Gunpowder Falls near Hoffmanville exceeded the 6 foot flood stage during the indicated period. River Valley Ranch reported flooding in their area during this time, with campers moved to higher ground.
Sligo Creek rapidly rose, flowing over US 29 (Colesville Road) in the area.
Water rescue in the 700 block of Old Manchester Road due to overflow from Cranberry Branch.
Maryland Route 450 flooded and closed between Saint Stephens Church Road and Huntwood Drive.
Streams out of their banks near Hay Drive and Wentz Road. Rapidly rising water forced water over driveways with leftover debris blocking access.
Eight inches of water flowing over the roadway near the intersection of Priestford Road and Trappe Road.
More than ten roads flooded and closed throughout the city.
The USGS stream gage on Beetree Run at Bentley Springs briefly, but rapidly, exceeded the 5.5 foot flood stage during the indicated period. The peak level of 6.11 feet was observed at 8:37pm EST.
Blunt Road flooded and closed between Germantown Road and Brink Road.
Water rescue at Little Pipe Creek near the intersection of Old New Windsor Turnpike and Adams Mill Road.
A water rescue was reported in the 3400 block of Sams Creek Road.
The USGS stream gage on Beaver Run near Finksburg exceeded the 5 foot flood stage during the indicated period. The peak level of 6.03 feet occurred at 9:30pm EST. Hughes Road was flooded in the area.
The stream gage on the Patapsco River near Elkridge exceeded the 16 foot flood stage during the indicated period. The peak level of 19.69 feet occurred at 12:50pm EST. Hammonds Ferry Road and Furnace Avenue were flooded.
Overflow from Big Gunpowder Falls forced the closure of one southbound lane of US 1.
The USGS gage on Big Pipe Creek near Bruceville exceeded the 8 foot flood stage during the indicated period. The peak level of 8.58 feet occurred at 6:45am EST. Keysville-Bruceville Road was flooded.
Little Pipe Creek was out of its banks, flooding both Claybaugh Road and Simpsons Mill Road near the Johnsonville Bridge.
The stream gage on the Patapsco River near Elkridge exceeded the 16 foot flood stage during the indicated period. The peak level of 16.37 feet occurred at 9:25pm EST. Hammonds Ferry Road and Furnace Avenue were flooded.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2018Every state in 2018This day in weather historyWarnings in Maryland, July 2018
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: 774669, 781496, 774670, 781502, 774671, 774678, 774672, 781520, 774673, 774674, 781501, 774675, 774677, 774679, 774681, 774684, 774685, 774686, 774688, 774689, 781192, 774690, 774692, 774693, 774694, 774695, 781193, 781521, 780939, 780946, 780901, 774861, 774862, 774863, 781517, 774855, 774865, 774869, 774870, 774871, and more.