This is from latest BOX AFD:
2) Severe Weather: The main concern will revolve around the likelihood of scattered strong to severe thunderstorms; roughly between 1 and 8 PM on Tuesday. This a result of an approaching shortwave in westerly flow aloft. Given heat & humidity; the SPC SREF indicates modest probabilities of MLCapes exceeding 2000 J/KG across a good portion of the region. Guidance is also forecasting steep low level lapse rates with a ribbon of 30-40 knots of flow in the 850-700 mb layer. The one limiting factor is weaker winds in the 500-600 mb layer, which keeps effective shear values lower than we normally want to see for a severe weather event. That being said, high resolution CAM simulations are pretty aggressive with impressive 2-5 KM updraft helicity swaths depicted by the 3 KM NAM and even the 18z HRRR to some extent. The 4 hour max updraft product is lit up quite a bit on the HREF too across southern New England. So in a nutshell, scattered strong to severe thunderstorms are expected to sweep across the region from northwest to southeast between 1 and 8 pm Tuesday. Steep low level lapse rates along with modest DCape values > 800 J/KG suggest strong to damaging wind gusts are the main threat with this activity. While storms will be moving, PWATs near 2 inches also support brief torrential rain/localized street flooding particularly if activity moves across urban centers. Lastly, we can not rule out an isolated large hail report or two given even modest steep ML Lapse rates. We opted to included enhanced wording in the forecast.