EF0 tornado in Carroll County, Maryland

A supercell thunderstorm moved through northern Montgomery, northwestern Howard, and southeast Carroll Counties in Maryland during the evening hours of Wednesday March 11, 2026. The bow echo and associated downbursts/thunderstorm wind gusts caused sporadic tree damage from 60 to 80 mph gusts, and created both a brief EF-1 tornado near Cooksville in northwestern Howard County for which there is a previous report, and this EF-0 tornado in Prospect Hills MD, in southeastern Carroll County in the Patapsco Valley State Park. As the storm crossed into southeastern Carroll County, it produced a brief tornado in Patapsco Valley State Park, with an EF-0 touching down at 7:14 pm. In the park, just east of Marriottsville Rd, there were numerous trees uprooted and snapped. The most intense area of tree damage was right along the entrance drive in the McKeldin Area. Peak winds in this area were estimated to be 80 mph. Several trees were snapped down in multiple directions in a path up to 75 yards wide. Shortly after, the tornado lifted at 7:15 pm and no further tornadic damage was noted. However, sporadic wind damage in the direction of storm motion continued to occur with the winds from the severe thunderstorm. Special thanks to Montgomery and Carroll County Offices of Emergency Management for their assistance and damage assessments.

A powerful cold front spawned a narrow corridor of bowing line segments and line-embedded supercells, resulting in damaging straight-line wind gusts and tornadic damage.