UPDATE from Saturday 2 p.m. …
A Watch for severe thunderstorms issued for ALL 21 New Jersey boroughs through 11pm Saturday. That’s a long time to worry about damage from wind, hail, a tornado, and possible flooding.
The bottom line of my original article (below) remains the same: when the sky darkens or you hear thunder, it’s time to go inside for a while. (Read on for more information on the timeline and the effects of the storm.)
ORIGINAL POST from 8:18 a.m. Saturday …
The bottom line
Welcome to the weekend! This mid-July weekend is on average the hottest of the calendar year in New Jersey. We sure got through some intense, prolonged heat and Humidity in the last few weeks.
Our next major transition will be this weekend as a slow moving cold front sweeps over us. At first it gets steamy, with persistently high humidity and hot temperatures. Then it gets stormy with the resurgence of serious flash flood concerns.
Despite the justifiably dramatic headlines, there is also good news in the forecast. At the beginning of next week, both the temperatures and the dew points will adjust to more reasonable, more seasonal and more pleasant values.
With tons of summer outdoor activities going on this weekend – and these plans may be at risk – I wanted to create a detailed schedule of how the weather is going to change and what to look out for.
Saturday morning to noon: Steamy
Saturday will be the sixth and final consecutive day of the ’90s in New Jersey.
I’m not sure you’ve been outside, but the humidity is just gross. The dew points across the country are fixed in the 1970s and make the air soupy and stuffy.
A Heat advice Covers most of the state by 8 p.m. Saturday, calling for potentially dangerous conditions leading to heat exhaustion and heat stroke. You know the exercise by now: Dress appropriately, take cool breaks and stay super hydrated.
Yes, you will find some relief on the Jersey Shore as long as the sea breeze machine kicks in. But it’s still a sticky, steamy, summer day. Also remember to a Moderate risk of rip currents is booked for the coast on this certainly busy beach day.
Saturday afternoon: Occasional strong storms
In the lush air, prefrontal thunderstorms are expected to approach over New Jersey 14 o’clock Saturday (give or take). These storm cells will develop and grow very quickly. You will be able to generate local downpours, frequent lightning and gusty winds. Hail and an occasional tornado are also possible.
The first storms in the afternoon are hit or missed. At least part (if not most) of New Jersey will remain storm and rain free.
If a thunderstorm approaches you, it will put a quick end to all outdoor activities. Keep your eyes and ears on the sky. (And Weather radar too.) And be ready to take cover when the sky darkens. When the thunder pounds, go inside.
Saturday evening: Heavy rain, flood worries
The “main event” with the most widespread rain will not take place until Saturday evening. I don’t see that these constant, heavy rains really ramp up afterwards 19 o’clock Saturday. And the worst should only evacuate the coast after midnight Lingering showers are possible through 5 am Sunday.
I think everyone in New Jersey gets wet, if not drenched, here. The average rainfall is about an inch.
However, some models pump out 3 to 6 inches of rain for part of North Jersey by Sunday morning. This is incredibly worrying given the impending flash floods.
We use a product called Flash Flood Guidance to estimate the minimum amount of rainfall that would cause a flood situation. For New Jersey on Saturday, that number ranges from about an inch and a half in water-saturated NE NJ to 4 inches in South Jersey. Needless to say, the forecast falls precisely within this zone.
A Flash flood monitoring was issued for almost all of the state except Inland Atlantic, Cape May, and Cumberland counties. The clock runs from 2:00 p.m. on Saturday to 2:00 a.m. on Sunday. (Covering a few thunderstorms in the afternoon, in addition to the large evening thrust.)
While not every New Jerseyan will experience a flood on Saturday, it is a pretty serious situation. Please remain vigilant as weather conditions change and heed any warnings that may be issued. Never try to drive, walk, or swim through floodplain areas – not only is it dangerous, but flooding is also pretty disgusting.
Sunday: Just Spotty Showers, not that hot
The prognosis for the second half of the week has developed increasingly better, as the already mentioned creeping cold front crosses the state cleanly.
The overnight rain should subside by Sunday sunrise. However, there could be some spotty shower activity on the back of the gravure system to the northeast. The best chance for raindrops on Sundays is 1.) in the morning and 2.) in North Jersey.
The cloud cover can also be a little thicker than you’d like, especially in the first half of Sunday.
As dew points drop back from the 70s to the 60s, the air will finally feel less tropical. Still sticky and still warm – but not so stuffy and thick.
The high temperatures on Sunday will be limited to the mid-80s at the most. Near (or just below) normal in mid-July.
Next week: better
On Monday, Tuesday and Wednesday there may be occasional showers or thunderstorms every day. There might be some scattered 90s, especially Tuesday and the end of the week.
But as long as the dew points stay in the 60s and we have some low temperatures overnight in the 60s, the weather will be pretty manageable. Especially after another cold frontal passage on Wednesday, I am happy to say that our weather in general looks bright and appropriate.
The next heavy rain is expected at the end of next week.
Dan Zarrow is a senior meteorologist at Townsquare Media New Jersey. Follow him on Facebook or Twitter for the latest forecasts and real-time weather updates.