Severe Thunderstorm Watch Until 9 p.m. for Most of NJ

6:15 update:




A severe thunderstorm watch has been issued until 9:00 p.m. for the following counties:

In New Jersey: Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, Salem, Ocean, Monmouth, Mercer, and Middlesex.


A severe thunderstorm watch means conditions are favorable for the development of severe weather including large hail and damaging winds. Severe thunderstorms can sometimes produce tornadoes with little or no warning.


The current surface analysis currently shows CAPE values of 1,000 j/g to 1,500 j/kg across much of Central and Southern New Jersey. Low-level lapse rates are around 8 c/km right now which is pretty steep. The lifted index values currently are in a range of -3 to -5. The supercell composite is suggesting values of 0.50 to 2 region wide. The significant hail composite is showing values of 0.50 to 1.50 across Southwestern New Jersey which the Derecho Composite showing values of 1 to 4.

What this all basically means is that there appears to be sufficient instability for thunderstorms to turn rapidly turn severe should there be any forcing mechanism to initiate them. What I think could do the trick is an area of thunderstorms that is beginning to redevelop over Maryland and Virginia. This could cause some very late afternoon and especially early evening scattered thunderstorms to form. These thunderstorms have the potential to form as line segments and supercells.

Most of the region has warmed well beyond the model guidance this afternoon with high temperatures so far in the 82 to 84 degree range. A localized sea breeze front may cool things down in portions of the coastal counties, but elsewhere it should remain quite warm and unstable until the sun begins to set this evening. The sea breeze front itself may serve as a focus for thunderstorm initiation if it begins to interact with the convection that should develop and transpire to our southwest.

Severe Thunderstorms Early This Evening Possible

The Storm Prediction Center has been and will continue to monitor New Jersey and SW for a possible weather watch issuance within the next hour or two for severe thunderstorms.

The current surface analysis currently shows CAPE values of 1,000 j/g to 1,500 j/kg across much of Central and Southern New Jersey. Low-level lapse rates are around 8 c/km right now which is pretty steep. The lifted index values currently are in a range of -3 to -5. The supercell composite is suggesting values of 0.50 to 2 region wide. The significant hail composite is showing values of 0.50 to 1.50 across Southwestern New Jersey which the Derecho Composite showing values of 1 to 4.

What this all basically means is that there appears to be sufficient instability for thunderstorms to turn rapidly turn severe should there be any forcing mechanism to initiate them. What I think could do the trick is an area of thunderstorms that is beginning to redevelop over Maryland and Virginia. This could cause some very late afternoon and especially early evening scattered thunderstorms to form. These thunderstorms have the potential to form as line segments and supercells.

Most of the region has warmed well beyond the model guidance this afternoon with high temperatures so far in the 82 to 84 degree range. A localized sea breeze front may cool things down in portions of the coastal counties, but elsewhere it should remain quite warm and unstable until the sun begins to set this evening. The sea breeze front itself may serve as a focus for thunderstorm initiation if it begins to interact with the convection that should develop and transpire to our southwest.

Slight Risk for Severe Thunderstorms Today

A slight risk of severe thunderstorms continues for today by the Storm Prediction Center. A cold front will put on the brakes as it approaches the region while we will be in the warm sector of the front. Waves of low pressure will move along the boundary causing areas of thunderstorms to develop today and move along and south of the boundary.

With sunshine expected after morning clouds and showers, the atmosphere should see instability rapidly increase. Steep lapse rates and sufficient shear will pose a risk for damaging wind gusts and large hail. There is a 2% chance of an isolated tornado due to the shear.

A Few T-storms the Rest of Today, Slight Risk of Severe Wx on Sunday

The morning rain is now exiting the coastline. Overcast skies may eventually give way to mostly cloudy skies this afternoon, resulting in some peaks of sunshine. The sunshine would quickly destabilize the atmosphere and with some moisture left in place combined with good bulk shear, some widely scattered thunderstorms may develop, especially out of the current shower cluster exiting West Virginia. Even if it is cloudy, thunderstorms that initiate may move into the overcast areas. The Storm Prediction Center maintains a “see text” or 5% risk of severe weather for today. There is a 5% risk for damaging winds and a 5% risk for large hail. There is some thinning noted in Central Pennsylvania and Central Maryland before that next batch of organized showers and eventual thunderstorms moves our way from West Virginia and this will probably bring the greatest potential for pop-up showers and thunderstorms as there isn’t a whole lot of forcing out there. But even given this area on the radar…the cluster of showers and thunderstorms may affect areas mainly south of Trenton.

Several rounds of thunderstorms are a possibility on Sunday. While instability will be modest with expected cloud cover, enough of it will combine with bulk shear and more organized trigger mechanisms to warrant a probability of strong to severe thunderstorms. The Storm Prediction Center has placed the region under a slight risk of severe thunderstorms for Sunday, with a 15% probability of severe weather within 25 miles of a point.

More Soaking Rain and a T-Storm Late into Saturday

Tonight and especially Saturday Morning will be wet. Rain develops this evening from west to east. The rain will become heavy at times on Saturday Morning and move out of the region slowly on Saturday Afternoon. There should be some thunderstorms as well. 1 to 2 inches of rain seems to be reasonable at this point. Renewed flooding across the swollen rivers, creeks, and streams is possible given how well above normal they are running.

Much of North and Central New Jersey needs 1 to 2 inches of rain in six hours to begin to cause flash flooding. Southwestern New Jersey into Monmouth County needs about 2 to 3 inches to flooding with the remainder of the region needing amounts in excess of 3 inches for problems to begin. Much of this rain will come in 10-14 hours and this is worth watching...especially with thunderstorms are possiblilty as the North American Model from 12z suggests. While this event will be not nearly as intense as last weekend...things are just saturated out there from past few soakers.

To me, on the map, while the instability is not nearly as strong as the day we had the slight risk, enough it will be present that there could be a few strong to severe thunderstorms. As of early this morning, the Storm Prediction Center has placed the region under a "see text" risk for severe thunderstorms. I would say the chances are greater than the other day despite their lower probabilities at the moment.

Legit questions I proposed are answered

NOT one thunderstorm. As I stated all day convergence was weak. Could a storm pop between now and midnight? Sure...but the chances are below twenty percent.NAM did it again!

Watching Skies to the West

Thunderstorms have begun to develop...although very scattered and disorganized so far...in Central Pennsylvania. With strong instability in place, Central and Eastern Pennsylvania have been placed under a severe thunderstorm watch as that instability can cause a t-storm or two to organize to severe limits once a thunderstorm initiates. "Can" is the key word as forcing is weak. But with a "chance", the watch has been posted for the areas out to our west.

The NAM from 18z just in continues to show that these storms remain disorganized due to a lack of strong convergence and that they diminish greatly by the time they arrive in New Jersey as night begins to approach. The instability may cause these storms to survive a bit more than the models indicate...but as I have been indicating...the threat for thunderstorms will be isolated especially with the instability to decrease when they arrive between 8 and 9 or even later.

The slight risk area has also been reduced and cut down to include less of NJ.