A strong cold front slowly passed through the region during the morning and early afternoon hours of the 28th. A southerly flow ahead of the front caused deep moisture over the area. The deep moisture combined with a mid-level trough to produce moderate amounts of instability. The cold front combined with the instability to trigger showers and thunderstorms. Some thunderstorms were able to mix down strong winds from aloft.
Low level wind speed and direction changed rapidly with height causing tornadoes to develop in some of the stronger thunderstorms.

Thunderstorm Wind in MONTGOMERY, MARYLAND
From 28-APR-11 05:49:00 to 28-APR-11 05:49:00 (EST-5)
Location: BEALLSVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Reported by: Emergency Manager

Multiple trees were down in Beallsville.

Thunderstorm Wind in MONTGOMERY, MARYLAND
From 28-APR-11 05:49:00 to 28-APR-11 05:49:00 (EST-5)
Location: BEALLSVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Reported by: Emergency Manager

Trees were down along Big Woods Road.

Tornado in ALLEGANY, MARYLAND
From 28-APR-11 00:27:00 to 28-APR-11 00:28:00 (EST-5)
Location: TOWN CREEK
Tornado F-scale: EF0
Property damage: 10.00K
Reported by: NWS Storm Survey

Numerous trees were uprooted along a hillside near Pack Horse Road. A large tree that was three feet in diameter partially fell on a residence on Pack Horse Road. There was also damage to trees behind a residence along Maniford Road near the Green Ridge State Forest.

Tornado in MONTGOMERY, MARYLAND
From 28-APR-11 05:45:00 to 28-APR-11 05:47:00 (EST-5)
Location: POOLESVILLE
Tornado F-scale: EF0
Property damage: 2.00K
Reported by: NWS Storm Survey

Spotty tree damage was observed along a track on Beallsville Road, Elgin Road and Jerusalem Road. A trampoline was lofted and deposted atop a power pole with adjacent damage to a fence and a small tree.

Tornado in CARROLL, MARYLAND
From 28-APR-11 06:37:00 to 28-APR-11 06:38:00 (EST-5)
Location: CRANBERRY STATION
Tornado F-scale: EF0
Property damage: 5.00K
Reported by: NWS Storm Survey

A tornado tracked from near Old Westminster Pike across Ralph and Center Streets before lifting as it crossed Route 97. The tornado uprooted and snapped several trees and large branches.

Tornado in BALTIMORE, MARYLAND
From 28-APR-11 07:09:00 to 28-APR-11 07:11:00 (EST-5)
Location: TRENTON
Tornado F-scale: EF0
Property damage: 5.00K
Reported by: NWS Storm Survey

A tornado tracked along Mt. Carmel Road for 1.1 miles. The tornado snapped and uprooted several trees. Large branches were also down due to the tornado.

Tornado in ST. MARY'S, MARYLAND
From 28-APR-11 10:25:00 to 28-APR-11 10:29:00 (EST-5)
Location: ABELLS WHARF
Tornado F-scale: EF1
Property damage: 35.00K
Reported by: NWS Storm Survey

A tornado tracked across Breton Bay uprooting and snapping numerous large trees. Home roofing and siding damage also occurred. A cinder block wall was blown out from a storage shed. The tornado also passed over Camp Calvert.

Thunderstorm Wind in ANNE ARUNDEL, MARYLAND
From 28-APR-11 10:25:00 to 28-APR-11 10:25:00 (EST-5)
Location: BEVERLY BEACH
Magnitude: 52.00 EG
Property damage: 0.50K
Reported by: Public

A large hardwood limb was snapped near Rhode River.

Thunderstorm Wind in MONTGOMERY, MARYLAND
From 28-APR-11 05:49:00 to 28-APR-11 05:49:00 (EST-5)
Location: BARNESVILLE
Magnitude: 52.00 EG
Property damage: 2.00K
Reported by: Emergency Manager

Trees were down over Route 109.

Thunderstorm Wind in FREDERICK, MARYLAND
From 28-APR-11 04:17:00 to 28-APR-11 04:17:00 (EST-5)
Location: JEFFERSON
Magnitude: 56.00 EG
Property damage: 2.00K
Reported by: Emergency Manager

Trees were down near Poole Road and Holter Road.

Thunderstorm Wind in FREDERICK, MARYLAND
From 28-APR-11 06:20:00 to 28-APR-11 06:20:00 (EST-5)
Location: BARTHOLOW
Magnitude: 55.00 MG
Reported by: Trained Spotter

A wind gust of 63 mph was reported near New Market.

Tornado in CALVERT, MARYLAND
From 28-APR-11 10:41:00 to 28-APR-11 10:43:00 (EST-5)
Location: APPEAL
Tornado F-scale: EF0
Property damage: 7.00K
Reported by: NWS Storm Survey

A tornado touched down near the intersection of Hilltop Road and Coster Road. About a dozen trees were uprooted along with several large branches.

Thunderstorm Wind in ALLEGANY, MARYLAND
From 28-APR-11 00:22:00 to 28-APR-11 00:22:00 (EST-5)
Location: CORRIGANVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Reported by: Fire Department/Rescue

Several tree limbs were down near the Corriganville Fire Station.

Thunderstorm Wind in ALLEGANY, MARYLAND
From 28-APR-11 00:35:00 to 28-APR-11 00:35:00 (EST-5)
Location: GREEN RANGE STATION
Magnitude: 56.00 EG
Property damage: 1.00K
Reported by: NWS Storm Survey

A tree was down at the intersection of Mertens Road and Oldtown Orleans road.

Tornado in ALLEGANY, MARYLAND
From 28-APR-11 00:35:00 to 28-APR-11 00:36:00 (EST-5)
Location: GREEN RANGE STATION
Tornado F-scale: EF0
Property damage: 5.00K
Reported by: NWS Storm Survey

Numerous trees were uprooted and/or topped in a small area of Mertens Road. Tree canopies showed evidence of convergent flow near the damage track.

Tornado in BALTIMORE, MARYLAND
From 28-APR-11 08:54:00 to 28-APR-11 08:55:00 (EST-5)
Location: EVNA
Tornado F-scale: EF0
Property damage: 1.00K
Reported by: County Official

An aerial survey conducted by Baltimore county showed that a tornado touched down briefly just north of Evna Road in a heavily wooded area. The tornado snapped and uprooted about two dozen trees and down large branches.