As New Yorkers hunkered down for a severe thunderstorm Thursday afternoon, many took pictures of the swirling storm and posted their shots to Facebook.

The National Weather Service sent out a warning that multiple states might get destructive weather throughout the evening.

New Yorkers were told to prepare for a "derecho," according to the Huffington Post, which the Storm Prediction Center described as "widespread, long-lived windstorm that is associated with a band of rapidly moving showers or thunderstorms ... By definition, if the wind damage swath extends more than 240 miles and includes wind gusts of at least 58 mph then the event may be classified as a derecho."

The Huffington Post reported a possible tornado touchdown near a mall and country club in Elmira, N.Y.

Tornado sightings were also reported near Brookville and Barnett, Pa., according to local officials.

The National Weather Service issuing tornado warnings for parts of Pennsylvania and sent out an alert at 4 p.m. EDT: "Seek shelter now inside a sturdy structure and stay away from windows!"

To survive a tornado The National Weather Service offered the following advice:

"The safest place to be during a tornado is in a basement. Get under a workbench of other piece of sturdy furniture. If no basement is available... seek shelter on the lowest floor of the building in an interior hallway or room such as a closet. Use blankets or pillows to cover your body and always stay away from windows. If in mobile homes of vehicles... evacuate them and get inside a substantial shelter. If no shelter is available... lie flat in the nearest ditch or other low spot and cover your head with your hands."

Severe thunderstorms this summer have been part of an extreme weather pattern along with extreme heat and drought.

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