Is "Severe" and official category for thunderstorms? Do they have to reach certain thresholds of wind, for instance?
The NWS defines "severe" thunderstorm as: A severe thunderstorm by definition is a thunderstorm that produces one inch hail or larger in diameter and/or winds equal or exceed 58 miles an hour.
We have a lot of thunderstorms that are not severe, and the likelihood of this afternoon producing thunderstorms of any size is only 50% or so. The likelihood of a severe storm this afternoon is .officially slight, although we are right on the edge of marginal (that's a lower probability category).
These forecasts come out of NOAA's Storm Prediction Center in Norman, Oklahoma: https://www.spc.noaa.gov/
The severe weather definitions are here: https://www.weather.gov/bgm/severedefinitions
Below is a graphic of the severe outlook risk categories that the SPC uses in their reports.
No there were several of the cutest little storms. They were very compact but a couple of them were quite exciting, especially the one that popped up just east of here and went along the south shore of Long Island.
As hard as it may be to imagine on this lovely afternoon, the NWS has put the whole area under a severe thunderstorm watch. Instability ahead of an oncoming front could cause the rapid build up of. showers and storms this afternoon, especially after 3:00 pm