Severe Thunderstorm Watch, Wed 9/4

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

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.

Fizzled?

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.

There was a gorgeous supercell thunderstorm in Connecticut yesterday. 

WOW!!