The first development of a line of discrete cells has popped up in E PA, moving northeastward.
Current Bulk Richardson Number is showing most of the area has favorable conditions for the development of supercell thunderstorms. Additionally, CAPE is exploding to values larger than forecasted.
As a cold front moves eastward towards an unstable environment over New Jersey, some discrete cells are possible embedded in a squall line that is expected to move eastward across northern and central New Jersey at the very least. It is currently 80F with a dewpoint of 71F in central Jersey with peaks of sunshine and winds very light and variable. Current surface conditions showing moisture bulging from the south with the cold front still in Ohio at this point.
An incredibly strong vort max is associated with this low pressure system and as the day moves forward some pieces of energy will be able to shape today’s severe weather outbreak.
Later on today, CAPE will be able to build from south to north as MLCAPE > 2000 J/kg infiltrate much of the state. Updraft velocities will be strong enough for storms reaching severe weather thresholds.
The next component we need is wind shear. The 0-3km SRH has a bullseye in southern New York. This demonstrates that North and Central New Jersey will be on the battleground for ideal conditions for the development of supercells. The infiltration of unstable air to the north where the greatest wind shear is will result in some supercells in southern New York. On the other hand, the shift of the greatest wind shear to the south could mean supercells in northern New Jersey.
A sounding in South Plainfield, NJ demonstrates what conditions will be like on the battleground. Additional instability or wind shear thrown into this could result in an increased probability of severe storms. Now, while there is no dry layer near 700mb, the hail growth zone CAPE is higher than we have seen. This increases the probability of hail across the northern part of the state of New Jersey.
Now, looking at the HRRR simulated radar for tonight, we see both supercells and a squall line forming. The details shift with the new model run every hour so I wouldn’t place any bets on any particular set up. I do think we will see some supercells in northern New Jersey and two squall lines moving in, with one affecting northern and central Jersey and one affecting southern New Jersey as well as most of the state.
So the thinking is that 4pm is the around the time of the first wave that will move through with another squall line then moving through around 6 pm. Finally around 9 pm another less severe squall line moves through the state.