Thunderstorm Intensity in the NYC Metro Area

[larrye]

I think I grasp the concept that T-Storms, when they approach the coast, often encounter marine air and lose their intensity. We also know that T-Storms normally lose their intensity later in the evening when daytime heating is lost. 

But these concepts don't always hold true. Sometimes, T-Storms do not lose their intensity as they move from west to east closer to the Atlantic or Long Island Sound. And sometimes (albeit rarely), they do not lose their intensity diurnally. Can someone explain in both cases, why? What are the dynamics responsible for situations where T-Storms don't lose their intensity as they approach the coast or during the night?

Thanks in advance.

[so_whats_happening]

Unfortunately I dont follow closely what happens when storms come from my area west of philly to the NJ/NYC/LI region. If I had to take a guess at the situation you are pointing out wind direction I believe plays a large role for the marine layer along the coastline and how high up that layer reaches. If you get a low marine layer you can still potentially see storms as they have enough energy aloft to allow for the storm to continue versus a deeper marine layer or one higher up which would effectively stabilize a layer cutting off storm potential. Another factor for storms lasting past the diurnal swing could be CAPE aloft (ml and mu cape are some that can show potential while sb cape could be 0 or even negative (CIN)) as well as the intensity of the shortwave energy. There are probably more intricate ways of explaining this but without more knowledge of the region this is what im left with as conclusions, maybe a person closer to the coast would know better.

I know being out in Lancaster sometimes we get the marine layer influence from the Chesapeake bay that cuts off storm potential when we get a SE or SSE wind but I believe wind strength plays a large role in that situation since we are good 30-40 miles away from that source.