Aug 16: Watching PM Thunderstorms

Jonathan Carr
By Jonathan Carr August 16, 2016 11:38

Aug 16: Watching PM Thunderstorms

Today is another hot and humid day but storms tonight could pave the way for relief starting tomorrow.

A warm front has moved through most of New Jersey overnight from S/SW to N/NE. We’re now in the warm sector of the mature stage of a Norwegian cyclone model . The cold front will not be through until tomorrow and therefore the only lifting mechanisms that could break the capping inversion are either a pre-frontal trough (PFT) or sea breeze front (SBF). While a sea breeze front could certainly move in, the ocean is getting pretty warm. Therefore it would not be as reactive as a month ago when 60-62F marine degree air was involved. With the overall warm and muggy air mass of the warm sector, any marine easterly component should be quickly equalized.

That pretty much leaves the PFT to provide enough lift to trigger storms. The latest guidance passes the PFT through NJ later this evening for NWNJ and overnight for SENJ. Model soundings show a very unstable environment with even MLCAPE values of 3,000-4,000 j/kg. Lifted Index (LI) values are close to double-digits in the negative and very little convective inhibition exists. Effective wind shear is about 30kts which is marginally sufficient to assist thunderstorm development. The PFT has a lot to work with and the capping inversion is less depicted than yesterday’s soundings as seen here on the 4k NAM for later in SWNJ:


Here’s a 4k NAM sounding for later in NNJ:


Therefore, I expect sunny, hot and muggy conditions for most of the day today with rain and thunderstorm action possible along the PFT later this evening and overnight. NWNJ has the best dynamics and should see action first, possibly during early evening hours. Any rain or storms should then push through the rest of NJ overnight and finish last at the SNJ coast early tomorrow morning. Tomorrow we’ll then deal with the cold frontal passage out of the W/NW which will eventually take us out of the warm sector and give us some, not total, relief heading into the weekend. As of right now, a stronger cold front is modeled  to push through between Sunday-Monday which should bring substantial relief with a very pleasant air mass to start next week.

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In English: Expect another hazy, hot and humid day today. Rain and thunderstorms are possible. NWNJ should see action first before midnight tonight (as early as sunset) and SWNJ should see it last overnight into tomorrow morning. Let’s allow a small chance of pop-ups this afternoon since we’re in the warm sector all day but most activity should hold off until later this evening. Thunderstorms should be of an isolated-to-scattered nature with severe criteria possible (moreso for NWNJ than SENJ). Therefore, not everyone will get hit and you know how the coast usually pans out. For those who do get hit, you can expect gusty winds, heavy downpours and frequent lightning. Conditions will begin to improve tomorrow with less humidity and lower temperatures. I’ll be providing radar analysis later tonight if/when storms arrive.

I took the top image a few weeks ago from Surf City Bay Park. Be safe! JC



Jonathan Carr
By Jonathan Carr August 16, 2016 11:38

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