SEVERE THUNDERSTORM WATCH in effect until 7 p.m. for Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Hunterdon, Mercer, Middlesex, Monmouth, Morris, Ocean, Salem, Somerset, Sussex and Warren counties

The past few days have featured a blast of summertime heat and building humidity across New Jersey. We hit 91 degrees at several weather stations on Wednesday. It was 94 degrees at Woodbine, Cape May County on Thursday. 95 at Sicklerville, Camden County on Friday. And some spots in South Jersey are already at 80 degrees early on this Saturday morning.

I sense that Saturday is going to be the hottest, most humid, and most oppressive day of the week. In addition, we all have to remain "weather aware" this afternoon, as a round of strong to severe thunderstorms appears likely statewide.

How Hot?

High temperatures Saturday will range from 85 (coast) to 95 (inland south). Of course, that does not tell the whole story, as humidity levels are high — dew points will push into the lower 70s. That puts the heat index, or "feels like" temperature, potentially above the 100-degree mark. Yup, that's hot! And right on the edge of dangerous heat. I hate to offer the same "Public Service Announcement" every single day, but you really have to take care of yourself — stay extra hydrated and take frequent breaks from the heat.

Air Quality Issues?

Anytime summertime heat surges, the concentration of ground-level pollution also rises. The NJ Department of Environmental Protection has posted an Air Quality Alert for 12 counties in two areas of the state: South Jersey (where it will be hottest), and the NYC metro area (where the air will be dirtiest). It's a Code Orange alert, which means the air will be unhealthy for sensitive groups, including the very young, the very old, and those with heart and lung ailments (including asthma). If you fall in that geography and in that group, you should spend as much time as possible in air-conditioned spaces Saturday.

The NJ DEP has issued a Code Orange Air Quality Alert for 12 counties in NJ on Saturday.
The NJ DEP has issued a Code Orange Air Quality Alert for 12 counties in NJ on Saturday.

When Will Storms Arrive?

While many New Jerseyans will be outside enjoying the heat, we will also have to watch the sky for a round of potent thunderstorms starting Saturday afternoon. Given the heat and humidity, any storms that pop are likely to reach strong or severe limits very quickly.

Forecast models are a little wishy-washy on when the storms will start popping. I believe there will be an isolated storm threat starting around 1 p.m., with scattered strong thunderstorms from about 4 p.m. to 8 p.m. Storms will be moving from northwest to southeast — so the closer you are to the Jersey Shore, the later the storms will arrive. Lingering showers and thunderstorms will be possible through about Midnight.

Note: It's not going to rain through the entire afternoon and evening. But everyone in New Jersey will likely see some rain at some point.

Greatest storm hazards?

The wicked lightning display alone will be enough to abruptly end your outdoor activities Saturday afternoon — by definition, lightning makes every thunderstorm potentially dangerous. Pockets of heavy rain could cause ponding on roadways and low-lying areas — although any downpours should be brief enough and the storms should move fast enough that we avoid major flash flooding problems. Gusty 60+ mph winds will be a significant concern. Small hail is possible. The tornado risk is low, but not zero.

Saturday's severe weather outlook from the Storm Prediction Center puts all of New Jersey in a "Slight Risk" of severe weather, level 2 of 5. (NOAA / SPC
Saturday's severe weather outlook from the Storm Prediction Center puts all of New Jersey in a "Slight Risk" of severe weather, level 2 of 5. (NOAA / SPC

What's Next?

Behind the storms will come a cold front. Behind the cold front will come slightly cooler and much drier air. So the heat wave ends on Sunday, as high temps scale back to the 80s — still a very warm day. It might still be sticky in the morning, but humidity levels will also lower throughout the day. There is indication that a secondary cold front Sunday afternoon could drive a quick line of showers through the Garden State.

Monday looks seasonably warm and quite pleasant. Our next widespread rain/thunderstorm chance will come on Tuesday. And then heat and humidity will start to build again through the middle of next week.

Clearly, there's a lot to be "weather aware" about on Saturday — the heat, the air quality, and the big thunderstorms. Be smart, stay safe, and enjoy your weekend!

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

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