Forecasting severe thunderstorms makes forecasting a snowstorm look easy. There can be tremendous potential in the atmosphere for a “big day” but the lack of some subtle, poorly resolved feature can cause the whole forecast to bust.
Today it looks like we’ll have plenty of instability and shear… but will we trigger severe thunderstorms? I’m not so sure.
In general the atmosphere will be featuring “sinking” air today which is not what you want for storm initiation. Generally “lift” in the atmosphere can help remove a cap and start the process to get storms to grow. That said even though there isn’t a large scale lifting mechanism IF we get some storms to develop (I don’t think they’ll be widespread) they could be quite strong given the amount of instability/shear present.
As for Sunday this is a very difficult forecast. Like a winter storm our severe potential depends a lot on the track of a low pressure system. If the low pressure tracks to the north of CT (say over the Mass Pike or Albany) we could be looking at a substantial severe weather threat. If, however, the low tracks over or south of us the severe weather threat is virtually nil.
Where will it go? Hard to say! The 6z NAM tracks the low over New York City and Long Island… the end result is a cloudy, rainy and cool day. The 6z GFS, however, tracks the low north of us near Albany which results in a very substantial severe weather risk for southern New England (supercells, tornadoes, etc.). We’ll have to keep an eye on model trends today and see which solution is more likely.
At this point I’m forecasting an “elevated” risk for severe thunderstorms today and tomorrow. Both are subject to revision as the threat becomes more clear one way or another.