Threat For Strong/Severe T'storms to Continue Tuesday...Strong to Damaging Winds, Large Hail, Isolated Tornadoes, Flash Flooding

On Sunday I had discussed that today (Monday) we would have the threat for strong to severe t'storms across southern New England with the hazards of strong to damaging winds, hail, flash flooding and perhaps even the threat for a few isolated tornadoes.  Well at this time of this writing (7:40 PM EDT) we have seen nothing of this variety occur.  However, there were a few strong t'storms which moved through Fairfield County in southwestern CT.  We were not able to realize this potential because one major ingredient was missing, a decent amount of surface-based instability.

One big question coming into today was how much instability we would be able to generate give the likelihood of substantial cloud cover.  While the day did begin with numerous breaks of sunshine, as the sun rose and began to heat the surface, clouds quickly began to develop.  These clouds were able to develop so quickly and rapidly because of the very tropical airmass we have in place, characterized by dewpoints into the lower 70's and an uncapped airmass.  An uncapped airmass virtually means that water vapor can easily reach the condensation temperature, therefore, beginning the cloud development phase.

There was also a boundary in place which was draped right over southern CT.  This boundary was leftover from the showers and t'storms which moved through portions of CT last evening.  This leftover boundary was just another focus for lift which further aided in quick development of cloud cover.

The vast development of clouds worked to keep surface heating to a minimum which resulted in minimal instability from developing.  While we had and have the wind shear in place for t'storms to produce strong to damaging winds and even an isolated tornado, we did not have the instability in place to generate t'storms and strong enough t'storms to tap into these stronger winds aloft and utilize them.

With this said as we move through the overnight hours we still run the risk for some isolated t'storms and if we do see any t'storms they would pose a threat for severe weather.  However, the #1 threat tonight will be flash flooding as any shower/t'storm will produce excessive rainfall.

This now brings us to Tuesday...

On Tuesday we will be dealing with the same potential weather wise which we were faced with on Monday.  However, all latest indications are pointing in the direction that the potential on Tuesday will be much greater than on Monday and we could also be dealing with the possibility for widespread strong to severe t'storms, especially across western and central southern New England.

Some computer forecast models are hinting that we will see more in the way of surface heating tomorrow as some mid-level dry air works into the region.  With this increased surface heating, computer forecast models also generate much more instability.  Below is the 15z SREF mean for mixed-layer cape tomorrow centered around Windsor Locks, CT.  The mean is around 1000-1500 J/KG of mixed-layer cape:

In addition to the potential of stronger instability tomorrow, wind fields aloft will also be a tad stronger than what we had in place on Monday.  In fact, some guidance develops a low-level jet at 850mb with winds exceeding 35-40 knots out of the southwest while surface winds may hang more southerly or even southeasterly:

Winds of this magnitude are very strong and when coupled with strong instability will mean any thunderstorm would quickly become strong to severe posing a risk for strong to damaging winds.  With the potential for surface winds to be south to southeast and 850mb winds backing to the southwest this will create a great deal of "spin" within the lowest levels of the atmosphere.  If adequate instability does develop not only will t'storms have the potential to produce strong to damaging winds but any individual cells "discrete cells", could utilize this atmospheric spin and become what are called supercell t'storms.  These t'storms would have the potential to produce strong to damaging winds, large hail, and even tornadoes.

All in all the potential on Tuesday for strong to severe t'storms appears higher than Monday's potential.  We will also be looking at the potential for widespread strong to severe t'storms which means more of the region has a higher risk of getting nastier storms.  The threats tomorrow will be strong to damaging winds, large hail, isolated tornadoes, and especially flash flooding.

As was the case Monday, the extent of the threat and potential hinges on how much sunshine and surface heating we are able to generate on Tuesday.  The more surface heating, the higher the surface temperatures, the greater the likelihood for strong to severe t'storms and the higher the tornado potential, especially if we get discrete cells to develop.