Tuesday's Southern New England Thunderstorm Potential

A cold front which was responsible for producing numerous strong to severe thunderstorms across southern New England on Thursday has cleared the area and brought in much drier air to the region.  The departure of Hurricane Arthur to the east of southern New England has also worked to usher in drier air for the weekend.  However, as we begin the start of the work week we will see an increase in both the heat and humidity as another cold front approaching from the west will allow for surface winds to become more southwesterly allowing for hotter and more humid air to return.  We will feel these effects beginning on Monday.

On Tuesday the cold front will continue sliding east towards southern New England.  With the cold front approaching and a hot and humid airmass in place, this will set the stage once again for the potential for showers and thunderstorms across the region and a few of these storms will have the potential to become strong to severe.

In Depth Meteorological Analysis

Our current computer forecast models are developing a moderately unstable atmosphere on Tuesday with SBcape values potentially exceeding 1500-2000 J/KG, MLcape values approaching 1500 J/KG, and LI values approaching -4C.  All these values indicate an airmass which will be fairly unstable and indicate an airmass which will be supportive of not only thunderstorms but the possibility for a few strong to severe thunderstorms.

GFS forecast model showing SBcape values for 5:00 PM EDT Tuesday afternoon.  GFS indicates anywhere from 1000-1500 J/KG of SBcape.  The NAM forecast model has as much as 1500-2000 J/KG of SBcape.

Computer forecast models are also indicating more than adequate wind shear aloft with 500mb winds in the 40-50 knot range, 700mb winds in the 30-40 knot range, and 850mb winds in the 15-25 knot range.  500mb winds in the 30-40 knot range and 700mb winds in the 30-40 knot range should yield 0-6km shear values in the 30-40 knot range.  These values are solid enough to support organized thunderstorms.

GFS forecast model showing 500mb wind speeds for 5:00 PM EDT Tuesday afternoon.  The GFS has 30-40 knots across western portions of southern New England with as much as 40-50 knots just west over NY and PA.

At this point in time a major severe weather outbreak is not anticipated, however, thunderstorms can be expected and a few of these storms would have the potential to become strong to severe.  In addition to the main threats of torrential downpours and cloud-to-ground lightning, the strongest of storms would be capable of producing strong to damaging winds and perhaps some hail.

The extent of the threat and potential will all depend on the actual timing of the cold front, and extent of any cloud cover which could not only limit the amount of surface heating we see but could limit the degree of instability.