NJ Flood Watch: Timeline and rainfall totals for Thursday’s stormy cooldown

The heat wave is over. Thursday is a cooldown day. And along with the big temperature change will come some big thunderstorms. Scattered storms will develop in the afternoon and evening hours.

UPDATES — Thursday, 12:20 p.m.... SPOTTY THUNDERSTORMS ARE TRYING TO FIRE UP... A little bit ahead of schedule. Don't be surprised to see the sky darken up and have a few raindrops spit at you.

While initial storms could produce severe weather — wind, hail, and/or an isolated tornado — the big concern is still for heavy rain and flash flooding. A Flood Watch has been issued for all 21 counties of New Jersey. Widespread 1 to 2 inches of rainfall is practically a sure bet, with localized areas of 4 to 6 inches possible. That is a lot of water, and could cause some big problems. Nasty storms will taper off late Thursday night. Friday will feature lingering showers, clouds, and much cooler temperatures. And then the payoff for this wretched week of weather comes over this weekend - it will be sunny and delightfully refreshing.

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Thursday NJ weather: Flash flooding a huge concern

July has been a crazy weather month, and we will close it out with one more active day.

Thursday Morning... The heat wave is over. It is still very humid Thursday morning, with temperatures in the 70s. But most of NJ will be halted in the 80s around midday, as clouds increase and thunderstorms roll in. The first half of the day looks fine — partly sunny, warm, and humid. A few isolated thunderstorms will creep through far northern New Jersey only.

Storm Timeline: Start... More widespread thunderstorms will blossom around the state starting around 2 p.m. Thursday afternoon.

Storm Timeline: Brunt... Through the rest of the afternoon and evening, strong thunderstorms with heavy rain will continue to develop. If I had to guess, the most widespread storm activity and the heaviest rain activity would unfortunately coincide with the bulk of the evening rush hour, around the 5 p.m. to 8 p.m. time frame.

Storm Timeline: End... By Midnight Thursday night, the worst storms should be exiting the southern coast. Rain will slowly taper with drier weather resuming through the overnight hours.

Totals... There is a scenario where "only " 1 to 2 inches of rain would fall statewide. That is still a lot of water, especially falling in a few hours. But we would avoid any widespread or long-term flooding issues. The problem comes from thunderstorms that produce 1 to 2 inches of rainfall per hour and/or from training thunderstorms, constantly forming and re-forming over one small area. That is where we trend toward the worst-case of areas of 4 to 6+ inches of rainfall.

Flood Watch... The National Weather Service issued a Flood Watch for all 21 counties of New Jersey from Thursday afternoon through Friday morning. It serves as a formal heads up that flash flooding may occur. I like that they blanketed the entire state with the watch, as I'm trying not to geographically pinpoint the flooding potential too specifically here. Practically everyone is prone to see downpours and flooding impacts. And some particularly vulnerable places flood even in light to moderate rain. If I had to guess, I would say the area most likely to see the big 4+ inch deluge area would be the NJ Turnpike corridor.

Severe Weather... The initial push of storms Thursday afternoon could have some teeth, fueled by the heat and humidity of the day. Gusty winds would be the biggest concern here, along with the chance for some hail and even an isolated tornado. Best chance for a strong storm cell would be along the western edge of the state. Once it rains in a given location, the atmosphere will become cooler and more stable. And then heavy rain and lightning would be the only threats going forward.

Action Steps... Please take the forecast and the flooding threat seriously. Consider your outdoor plans and travel plans carefully for Thursday. That includes the evening commute — if you can work from home, leave early, or consider alternate modes or routes that are flood-resistant. At the very least, keep a close eye on changing weather conditions as the day goes on. Never attempt to drive, walk, or swim through flooded areas — you never know how deep the water is, how fast it's moving, or what may be floating in it.

Friday NJ weather: Cloudy, showery, much cooler

Friday will be a much calmer weather day. And much cooler. Although things will be pretty "blah" through the afternoon.

Residual clouds and lingering showers are likely. Best chance of raindrops will be in the morning along the Jersey Shore, although I wouldn't rule out some patchy afternoon drizzle too. Nothing severe, and no risk of flooding this time around.

The temperature difference compared to earlier this week will be incredible. Highs on Friday will only reach about 70 to 75 degrees. It will be breezy. And humidity levels will drop to the "moderate" category, with dew points in the 60s. It might still feel a little sticky, but definitely better and more comfortable.

We should see some late-day clearing, hopefully with peeks of sun emerging by dinnertime.

Saturday NJ weather: Sunny and refreshing

The first weekend of August looks glorious. After a week of brutal heat and dramatic storms, we deserve this one. And even though we are talking about very low humidity and below-normal temperatures, I am not concerned at all that it will be "too cool."

Skies will turn mostly sunny on Saturday. The morning may begin with temperatures in the 50s. Highs will reach about 80 degrees, give or take, with a fresh northerly breeze. Delightfully refreshing.

Sunday NJ weather: Finally some beautiful weather

Sunday will be another great day. Sunny skies, dry air, dry weather, and highs in the lower 80s.

Honestly, this could be one of the best weekends of the entire summer. Perhaps the entire year.

Monday NJ weather: Can all of August stay like this?

The beautiful forecast rolls right into Monday and Tuesday. The only hiccup is an on-shore component to the wind kicking in Tuesday, potentially introducing some clouds and humidity to the mix. At least that ocean breeze will prevent temperatures from running away and getting too hot.

Next chance of rain and thunderstorms looks to be next Wednesday. Long-range forecasts show a return to hot temperatures by next weekend.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook for the latest forecast and realtime weather updates.