Strong to Severe T'storms Possible on Monday. Strong to Damaging Winds, Hail, Isolated Tornadoes, Flash Flooding All Possible.

While at this time the potential for a widespread significant severe weather outbreak appears on the low side the potential will exist for thunderstorms tomorrow and some of these thunderstorms will have the potential to become strong to severe posing a threat for strong to damaging winds, hail, flash flooding, and even the potential for isolated tornadoes.

Computer forecast models are generating some modest instability with surface-based cape values approaching 1500 J/KG and perhaps even upwards of 2000 J/KG depending on the degree of surface heating that we see occur:

Projected SBcape values across much of southern New England of up to 1500 J/KG

Computer forecast models also generate upwards of 750-1000 J/KG of mixed-layer cape values across the region:

Typically when becoming "excited" over the possibility for strong to severe t'storms we would like to see Cape values higher than what is forecasted.  While 1000 J/KG is usually a decent starting point, you want to start seeing values (especially mixed-layer cape) approach and exceed 1500 J/KG.  However, in the case of tomorrow we will be dealing with very strong winds throughout the atmospheric column and this will compensate for the lack of stronger instability.

Below is a point-and-click forecast sounding from northern CT.  Looking at the wind barbs on the right hand side we can see some pretty strong wind shear will reside over the region.  What really jumps out is the 30-35 knots of wind shear in the 850-925mb level.  These values are pretty high, especially when combined with the projected Cape values.  These values within this level will provide the threat for any thunderstorms to produce strong to damaging winds.

What also jumps out is the "backed" winds at the surface.  Notice how winds at the surface and just above go from SE to SW up around 1000mb.  This is pretty significant as this would lead to high amounts of helicity (a measure of atmospheric "spin"):

 
Looking at a hodograph we can see the backed wind profile.  Notice the long curvature in the hodograph.  This tells us that the potential will exist for supercells tomorrow along with the threat for isolated tornadoes so we will have to closely monitor any thunderstorm that develops:

The atmosphere will also be full of moisture, characterized by dewpoints into the lower 70's across the region.  This will lead to precipitable water values approaching 2.0'' with is quite high.  This indicates that any showers and t'storms will produce torrential downpours and this will lead to the threat for flash flooding, especially the typical flood prone areas.

For tomorrow we will have to closely monitor how much sunshine we see and how much instability develops.  The wind profiles aloft will be more than favorable for strong to severe t'storms with the threat for strong to damaging winds, hail, and even a few tornadoes.  It's all a matter of how much instability we can manage to develop.

Looking ahead into Tuesday we could once again see a threat for strong to severe t'storms with all the same hazards.