The number of tornadoes spawned by Friday’s storms has risen to as many as 13, with the addition of two twisters to the list.

The National Weather Service, which has been surveying areas where the twisters had been reported, said Tuesday that it had found one new tornado site in Allegany County, Md., and confirmed one in Northampton County, Va.

In Allegany, about 100 miles northwest of Washington, a tornado in the Bellegrove area left many trees snapped and uprooted, the Weather Service said.

In Northampton County, at the southern tip of the Eastern Shore of the Chesapeake Bay, the twister touched down in Savage Neck state park, north of Cape Charles, the Weather Service said. The site is about 125 miles southeast of Washington.

With a maximum wind speed estimated at 75 mph, the tornado, the third confirmed in Virginia, tossed kayaks around and sheared off treetops, the Weather Service’s Wakefield, Va., office said.

The listing of 13 tornadoes includes 12 that were described as confirmed by Weather Service survey teams.

Another tornado has been listed by the Weather Service as “very brief” and was confirmed by video. That one occurred about 2:30 p.m. in the Countryside area of Montgomery County.

The Weather Service said it had confirmed two other tornadoes in Montgomery and one in Prince George’s County.