Following a round of moderate to heavy rain this morning in and around New York City is the potential for severe thunderstorms in the mid afternoon. With the next round of storms expected to impact the area comes the threat of hail, high winds, heavy rain, and lightning (not ruling out the potential for an isolated tornado or two). In order to stay safe, take appropriate action now if you live in the NYC Metro Area. Make sure that you have a flashlight, water, and a weather radio available in the event of an emergency.
An important factor in forecasting severe weather is the Convective Available Potential Energy or CAPE value. The CAPE is a measure related to the total energy available for convection and the maximum vertical updraft speed. It is important to note that the greater the CAPE, the more likely it is for severe thunderstorm development. It becomes much more common for severe thunderstorms to develop in and around the NYC area when the CAPE value is above 800, give or take a few, and as of now, the SREF ensemble computer models (run by the Storm Prediction Center)are suggesting a CAPE value of around 1,200. Along with this, more short range computer models such as the HRRR are suggesting a line of thunderstorms popping up around 4:00 PM EST today across the area. Remember to be on the look out for severe weather today and heed any and all advice distributed by the National Weather Service.