April 19: Rain and Storms Approaching!

A strong low pressure system will spin up into the Great Lakes between now and Tuesday. This should bring widespread rain, gusty winds, and possibly thunderstorms to the region Monday morning through Tuesday morning. Let’s break it down…

This should be one of the rainiest systems we’ve seen so far this year. As you can see here on the GFS total expected precipitation model image, between 1″ and 3″ of rainfall is possible depending on where the heaviest downpours set up:

As far as thunderstorms go, the National Weather Service Storm Prediction Center (NWS SPC) has almost all of SNJ in the SLGT (slight) risk zone for severe weather. NNJ is mostly in the marginal threat zone which simply means a lesser risk. With that said, the I-95 corridor through DC, Baltimore, and Philly have a decent chance for thunderstorms. As usual (9 times out of 10) these storms fizzle before reaching the coast but that’s what now-casting is for. Whenever widespread rainfall is expected, thunderstorms are often of an embedded nature instead of towering cumulonimbus cells. We’ll have to keep an eye on any diurnal surface heating that occurs ahead of the rain. This should be minimal given cloud coverage. Wind shear is likely the biggest culprit of severe weather tomorrow.

For severe thunderstorms to be triggered, they must meet specific criteria: wind gusts in excess of 58mph and/or hail 1″ or larger in diameter. I’ll be watching for either-or tomorrow and the NWS will sound severe thunderstorm warnings as soon as such criteria is met. For the most part though, tomorrow’s headline should be heavy widespread rain.

In English: Expect cloud coverage to increase heading into this evening and overnight hours. Expect 1-3″ of rain between tomorrow morning and Tuesday morning with gusty winds and possibly embedded thunderstorms. Flash flooding is possible under heavy downpours, especially in areas of poor drainage. I’ll have the fully detailed Monday-Friday Outlook posted tomorrow morning but will also be now-casting via radar observations.

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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.™