Severe T-Storm Watch for NJ until 9pm: Heavy rain and wind

Why?

A Severe Thunderstorm Watch, issued by the National Weather Service and Storm Prediction Center, serves as a formal heads-up that strong thunderstorms may pose a danger to life and property. It means all the ingredients — instability, moisture, shear, and lift — are in place for storms to form and grow.

Potential severe weather hazards include damaging winds (60+ mph), hail (1" diameter or larger), and/or tornadoes. Flooding due to heavy rain and frequent lightning can also occur — although not technically covered by a Severe T-Storm Watch.)

When?

This watch is in effect until 9 p.m. Friday. Scattered showers and thunderstorms are already starting to push into western New Jersey this afternoon. They will continue driving south and east through late evening. Intensity may pulse up significantly at times, due to our hot and very humid atmosphere.

Thunderstorms may not fizzle out and/or exit the Garden State completely until after Midnight.

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Where?

13 of New Jersey's 21 counties fall under this watch: Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Hunterdon, Mercer, Middlesex, Monmouth, Ocean, Salem, and Somerset.

Northern New Jersey experienced a few storms earlier Friday, which helped to zap some of the available instability in the atmosphere. While storms and heavy rain are possible there, the most intense storms are expected farther south.

Storms are expected to be the nastiest as the initial cells arrive, to the north and west. Once sunset passes (around 8 p.m.), storm intensity should dial back. Especially as they approach the (slightly cooler and more stable) Jersey Shore.

What?

The biggest concern from Friday evening's storms is rain and flooding. Not just for the watch area, but for the entire state. As you surely noticed, New Jersey's air is incredibly "juicy" right now — hot and humid. With plentiful moisture flowing into the atmosphere, these storms will have plenty of fuel to produce torrential downpours. Forecast models paint localized areas picking up 1 to 2+ inches of rainfall in a short period of time Friday evening.

Second, damaging winds are possible. Downed branches and trees may cause power outages. Driving may be difficult due to crosswind gusts, debris, and/or horizontal rain.

The chance of other severe weather hazards occurring — hail and tornadoes — is low this time around. But not zero.

So What?

A watch does not mean a storm is imminent.

Nor does it mean everyone in the watch area will definitely see a storm.

All it does is force your ears to prick up and pay attention to the weather — consider your outdoor plans very carefully this evening, be flexible, and keep an eye on changing weather conditions.

If a "warning" is issued for your area, that means a dangerous storm is imminent or already occurring. (It may be a Severe Thunderstorm Warning, a Tornado Warning, a Flash Flood Warning, etc.) That is when it is time to seek shelter in a sturdy building, until the storm passes.

What's Next?

Following Friday night's stormy weather, we have another steamy day ahead to begin the first weekend of August. High temperatures on Saturday will likely reach about 90 degrees, with a heat index ("feels like" or "apparent" temperature) close to 100.

In addition, another round of thunderstorms is likely late-day Saturday. Almost identical timing to Friday's storms, from mid-afternoon through late evening. Once again, severe weather is a possibility. I would not be surprised at all to see NWS/SPC issue another round of watches.

Sunday will also be an unsettled weather day. Although the threat for damaging winds will diminish, occasional downpours remain possible.

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