F1 tornado, Frederick, Maryland, August 14, 1999

1. F040 to 72 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. F173 to 112 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. F2113 to 157 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. F3158 to 206 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. F4207 to 260 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. F5261 to 318 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

F1

Date

August 14, 1999

Touchdown

1:50 PM EDT (17:50 UTC)

Path length

3.0 miles (4.8 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Property damage

$800,000

County

Frederick County

Touchdown point

39.450, -77.470

Lift-off point

39.430, -77.420

Record number

630

An area of thunderstorms moved across much of Maryland from 1:15 PM to 5:45 PM EDT, producing damaging wind, frequent lightning, and brief heavy downpours. As the storms moved through Washington County trees were downed in Rohersville, a community 5 miles south of Boonesboro. The thunderstorm complex intensified rapidly as it moved into Frederick County around 1:45 PM EDT, and the northwest side of the city of Frederick took the brunt of the storm. As the storm reached the Abbington Farms area a tornado developed. The tornado was F1 strength with winds between 75 and 112 MPH and ranged from 50 to 200 yards wide as it travelled east for 3 miles. The twister did extensive damage to trees as it moved through the communities of Eastview, Walnut Springs, Shookstown, and Fort Detrick. Some trees fell onto cars and houses, and a few homes under construction were damaged. One home under construction in Walnut Ridge was torn to pieces by the tornado and the debris turned into airborne missles which heavily damaged two finished homes nearby. Two homes in the Eastview subdivision were condemned after trees fell onto the structures. A chimney was blown off a Willowdale Drive home. Yellow Springs Road had to be closed for several hours until power and telephone poles blocking the road could be cleared. A metal storage building on Rosemont Avenue was crumbled. Part of the roof of the Food Lion grocery store on Rosemont Avenue was torn off and thrown toward the gates of Fort Detrick. The store suffered water damage and the loss of frozen foods and perishables from the resulting power outage. Next, the storm moved across Fort Detrick, causing $260,000 in damage. The twister moved across Area B, then onto the main post where it uprooted trees, downed power lines, and blew off parts of buildings. The headquarters building and post chapel lost part of its roof. Nearly 30 cars along Rocky Springs Road and near post housing were damaged by downed trees and debris. In addition, the central portion of Frederick was hit by destructive straight line winds estimated between 60 and 70 MPH. Thirty Bradford pear trees were downed on Heather Ridge Drive. Sixteen city streets were closed by fallen trees. A one mile stretch of Route 40 west of the Golden Mile had to be closed for an hour to clear fallen trees. A glider valued at $11,000 was ripped from its mooring at the airport and totalled. The storm downed a total of 300 trees across Frederick, and resulted in outages for 8,000 power customers. High winds also downed trees in Brunswick, leaving 100 customers without power. As the area of thunderstorms moved across Montgomery County, large limbs were downed in Rockville and White Oak. A lightning strike also damaged a home in Poolesville. The bolt travelled through the electrical system of the home, shot flames out of an outlet and caught bedding on fire, resulting in $2500 in damage. When the storms moved across Prince Georges County, winds in excess of 55 MPH downed trees from College Park to Hyattsville. Tobacco crops in the southern half of the county were flattened. Nearly 8,000 customers lost power in Prince Georges and Montgomery Counties. High winds also crossed Baltimore County. Trees were downed from Cockeysville to Lutherville, and across the city of Baltimore. About 18,000 Baltimore city and 11,500 Baltimore County customers lost power as a direct result of the storm. Over 1.5 inches of rain fell in Baltimore and 2.0 inches fell in Cockeysville in less than one hour. Lightning knocked out phone service at the Cockeysville police precinct. A lightning strike in Harford County caused $5000 damage to a home. Another strike in Havre de Grace started a house fire which resulted in $80,000 in damage. Heavy downpours of rain between 4:30 PM and 6:00 PM EDT temporarily flooded the intersection of Route 24 and Jarrettsville Road in Forest Hill. Lightning was also blamed for 1000 power outages.Anne Arundel County reported 26,000 storm related power outages and over 80 downed trees after the storm crossed the northern part of the county. Winds gusted to 60 MPH in Crownsville around 5:00 PM EDT. Pea sized hail and 2 inches of rain also accompanied the storm. Winds estimated at 60 to 80 MPH blew through the northern side of Pasadena. Marble sized hail and 2.5 inches of rain also fell in the city. Several roads, including Bay Harbor and Bayview Vista in Cape St. Claire were closed by fallen trees. Heavy tree damage occurred through the communities of Willow Run, Green Haven, and Highpoint. The community of Silver Sands reported damage to roof trip, sheds, chimneys, and trees. The path of the most intense winds was roughly two miles long and a half mile wide along Catherine Avenue and Duval Highway including Outing Avenue and 201st through 215th Streets. Downed trees seriously damaged 5 homes and closed Duval Highway. A young boy inside one home near Catherine Avenue received minor cuts after an 80 year old tree fell onto the structure. The home was deemed a total loss by county officials and had to be torn down. A brief power outage caused 100 sewage stations to send untreated water in Marley Creek. Lightning strikes and power surges also damaged home appliances across the county and started a garage fire in Glen Burnie. A wind gust of 63 MPH was recorded in Rivera Beach, resulting in downed trees and power lines. A 16 year old girl was struck by lightning in Rivera Beach, and a home was also hit by the frequent cloud to ground strikes.

Moderate damage to buildings, trees downed onto homes and cars

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk. The outlook in force was issued at 16:32 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The live radar over the trackEvery 1999 tornado in MarylandEvery tornado in Maryland since 1950Warnings in force in Maryland nowThe forecast where you are

5 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.