Tornado watch issued for part of western Massachusetts as Boston weather forecast shows severe storm risk

A tornado watch is in effect for part of western Massachusetts Thursday. The WBZ Weather team has issued a NEXT Weather Alert for the chance of a few severe thunderstorms in the Boston forecast this afternoon and evening.

Currently, there is a tornado watch posted for Berkshire County, Vermont and much of New York state until 3 p.m.

The main question is, will that tornado threat be expanded eastward later on Thursday?

Tornado risk for Boston

The Storms Prediction Center has placed areas north and west of Boston and I-95 in a "2% tornado risk" for later Thursday. 

On the map below, the brown area which extends from southwestern New Hampshire through Vermont and the Berkshires is a "5% tornado risk."

This means that at any given point in the green or brown zones, there is either a 2% or 5% chance of a tornado forming within a 25-mile radius.

This may seem quite low, and it is, but we only receive a handful of days each year with this type of risk.

Let's be clear, this is not a day when all the atmospheric parameters are lining up perfectly for severe weather in southern New England. However, there is a decent amount of vertical wind shear present Thursday. Therefore, if any storms are able to form, they could quickly reach severe levels and perhaps even rotate.

The period of greatest risk in central and eastern Massachusetts would be from about 3 p.m. to 9 p.m. and mostly north and west of Boston, especially across New Hampshire, Vermont and Maine.

In additional to the small tornado risk, there is also a chance of damaging, straight-line winds, lightning and torrential downpours.

We will keep you updated all afternoon on WBZ-TV, CBS News Boston and on WBZ.com.