July 27: Thunderstorms Approaching

Discussion: An upper-level low is tracking from the Great Lakes into SE Canada. This upper-level low is part of a weakening trough but still has enough might to drag a cold front through our region overnight tonight. Perhaps cold front is said for lack of a better term. There will be little temperature influence (cooling) from this front. There will be a slight reduction in dew point temperatures however which should feel less humid.

Most of New Jersey has gotten used to dew points in the low-to-mid 70s this week. So dew points in the upper-60s/near-70, while still on the humid side, should feel just a hair more comfortable on Saturday and Sunday.

As far as the thunderstorms tonight go, all ingredients are on the table. We have a triggering cold front plowing through a very warm and soupy air mass. This at the very least should produce a line of heavy downpours given the precipitable moisture that’s getting hoisted up by the front. We’ve had sufficient sun hitting the ground today which checks the box for instability.

Convective Available Potential Energy (CAPE) is sufficient for frequent lightning in all areas in my opinion. There’s also sufficient shear along and just ahead of the cold front to keep these storms firing into dark hours and out over the ocean. Hopefully the shear does not produce too much wind damage potential.

I suspect this line of downpours and thunderstorms will move through New Jersey from W to E between about 8-11pm tonight. As we’ve already seen today, isolated-to-scattered showers and thunderstorms are possible just ahead of the cold front in the warm sector. So don’t be surprised if you see a severe-warned thunderstorm between now and the main event later tonight. Once this all pushes through we should be left with a nice Saturday and Sunday. Still warm but with a slightly better feel and low rain chance.

In English: There are already a few isolated thunderstorms floating around New Jersey with continued widespread elevated humidity. These conditions should persist until the main storm line pushes through between about 8-11pm this evening. In that time-frame expect heavy downpours of rain (capable of producing flash flooding), gusty winds (potentially damaging), moderate-to-frequent lightning and possibly hail. The low chance of a tornado is always possible in this kind of setup but irresponsible to suggest it as probable. We’re already in a severe thunderstorm watch and will likely see several severe thunderstorm warnings issued tonight. Skies should then clear by early Saturday AM (tomorrow morning) and set up a nice summery Saturday and Sunday for most, if not all, of New Jersey. For good measure I still cannot take SENJ off the hook for lingering humidity and a pop-up or two on either day. Everyone have a great weekend and please be safe! JC

Jonathan Carr

Jonathan Carr (JC) is the founder and sole operator of Weather NJ, New Jersey’s largest independent weather reporting agency. Since 2010, Jonathan has provided weather safety and forecasting services for New Jersey and immediate surrounding areas through the web and social media. Originally branded as Severe NJ Weather (before 2014), Weather NJ is proud to bring you accurate and responsible discussions ahead of high-stakes weather scenarios that impact the garden state. All Weather. All New Jersey.™