A potential, rare mid-April snowstorm is brewing for the Berkshires from Thursday night through Friday, prompting government forecasters to post a winter storm watch following a soaking rainfall beginning before dawn Thursday. Heavy, wet snow is possible, especially for higher elevations of western Massachusetts and southern Vermont, according to the National Weather Service. The winter storm watch is in effect from 8 p.m. Thursday until 2 a.m. Saturday. A few inches of snow could fall in the hill towns above 1,500 feet, making travel difficult, the forecasters stated. Depending on the track of a coastal storm expected to develop off southern New Jersey and Delaware, a substantial rainfall on Thursday may transition into an overnight snowfall, impacting the Friday morning commute.