6 things to know about Thursday’s thunderstorms
UPDATE at 4:20 p.m. Thursday…
The National Weather Service released a Severe thunderstorm watch for 18 of New Jersey’s 21 counties until midnight. (The only counties do not under surveillance are Atlantic, Cape May and Cumberland.)
A watch is a formal warning that dangerous and potentially damaging storms may occur. The biggest concern for Thursday night’s thunderstorms will be gusty winds. Heavy local rainfall can also lead to flooding. The risk of a fast tornado and/or hail is low, but not zero.
It is very important for all New Jersey residents to stay alert to changing weather conditions. If a warning is issued for your area, or if a nasty storm is heading your way, you should take shelter inside a sturdy building until it passes.
Stay smart and be safe out there.
UPDATE at 2:00 p.m. Thursday…
ORIGINAL POST from 7:33 a.m. Thursday…
1.) The main thing?
New Jersey returns to spring weather in a big way Thursday. Not only does this mean temperatures will be 20-30 degrees warmer than the past four days. But it also means showers, thunderstorms and bad weather are back.
The most important time of the day to “look at the sky” will be in the late afternoon and evening. Wind is the biggest concern, with heavy local showers also possible. The hail and tornado risks are low, but not zero.
2.) How hot?
As a warm front lifts into New Jersey on Thursday morning, temperatures are already rising. As of this writing (6:45 a.m.), we’re in the 40s in the northern half of the state and nearly 60 in the south.
High temperatures on Thursday are expected to reach around 65 to 70 degrees for the vast majority of the state. (Possible exceptions: NW NJ and the coast.) This is about 10 degrees above normal for the last day of March.
3.) When will it storm?
It looks like we will have three initial sets of rain affecting New Jersey throughout Thursday:
–Initial showers… Buoyed by this warm front, patchy to scattered rain showers will become likely beginning around 10 a.m. This initial rain should be light and not everyone will necessarily get wet. (At the very least, it will be mostly cloudy and windy.)
–More numerous, more stormy… After about 2 p.m. Thursday afternoon, the atmosphere will become warm and “juicy” enough to support thunderstorm development. Again, they will be scattered, so not everyone will see a storm at this point. But any storms crossing the Delaware River could quickly reach strong (over 40 mph) or severe (58+ mph) limits.
–Final line… The final big round of storms, after about 7 p.m. Thursday night, probably has the greatest potential for severe weather of the day. However, these storms “speed up the clock”, as the intensity plummets a bit after sunset.
At midnight, the threat of severe weather will end. We were able to see persistent showers through Friday morning, until a cold front swept in cooler and much drier air.
4.) Biggest concerns?
It’s a classic severe weather day – though I don’t think it really qualifies for “outbreak” status for NJ.
Jitter and helicity will be quite limited over New Jersey, but wind shear will be sufficient. Therefore, the following hazards will be at play, listed in descending order of concern:
–Destroying winds… As I explained above, afternoon and evening thunderstorms could bring strong gusts. 40+ mph seems like a safe bet at some point. And over 60 mph could knock down trees, damage the roof and turn loose objects into projectiles.
–Heavy showers… Thursday’s dew point increase will be impressive – we’re going from ridiculously dry air to “pretty humid” conditions. The threat of heavy rain is therefore present. More than an inch of rain in a short time could lead to flooding in low-lying, poorly drained areas.
–Hail / Tornado… Only the strongest thunderstorms with strong updrafts and sufficient wind shear can cause hail and tornadoes. The chance is there for New Jersey, but it’s weak. (For the record, the risk of a rapid spin-up will be greater in eastern Pennsylvania, given timing and forecast parameters.)
–Lightning… By definition, every thunderstorm contains potentially dangerous lightning. Don’t overlook the fact that you can be struck by an electric shock, even if a thunderstorm is miles away.
I think the wind and rain concern extends to most of the Garden State, away from the coast. It appears that the best chance for a stronger hailstorm or tornado is in the southwestern sector of NJ, generally along the I-295 corridor.
Note: Watch the sky and the thermometer today. If we get a substantial break from the sun and/or temperatures above 70 degrees, the atmosphere will really bake. This will lead to greater instability – more potential energy for late day storms.
5.) So what?
Standard storm safety rules apply. Keep an eye and an ear to the sky and be prepared to alter your plans accordingly as weather conditions change. When thunder rumbles, go inside. In case of flooding, turn around, don’t drown. And the safest place during a severe thunderstorm is on the lowest floor of a sturdy building.
6.) What’s next?
We cool again on Friday. But it won’t be another “Arctic explosion” – just a “correction to normal”. In fact, Friday’s highs will still be a little above normal near 60 degrees before receding in the afternoon. It will be a fairly windy day and I can’t rule out a few showers.
Saturday looks like a glorious early spring day. Mainly sunny, light winds, dry weather and seasonal high temperatures in the mid-50s.
A few rain showers could impact the first part of Sunday as a weak pulse passes through our atmosphere. And then Sunday afternoon and all of Monday looks good, with steady highs in the 50s.
Our next threat of a “bigger” storm system would be in the middle of next week – Tuesday and Wednesday. I could see a good inch of rain from that one, followed by another slight chill.
Note: The CMDZ weather blog will be on hiatus until next Tuesday, as I’m taking a well-deserved vacation. We will always post your latest 5-day forecast to the site daily. And you can always catch the latest weather update on the radio every 15 minutes 24 hours a day. Be safe out there today, and I’ll see you very soon.
Dan Zarrow is chief meteorologist for Townsquare Media New Jersey. Follow him on Facebook or Twitter for the latest real-time weather forecasts and updates.
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