Light Snow Wednesday Night (02/27/2019)

A weak weather system moving overhead Wednesday night will bring some light snow to the state. While some flurries are possible by late afternoon or during the evening, much of the falling snow will be during the overnight. This may lead to a slick early Thursday morning commute; however, no major impacts are anticipated.

A very fast mid-level jet will be overhead with a 500mb (~18,000 feet off the ground) jet stream exceeding 90 knots. Embedded within this jet will be some shortwave energy. As this shortwave energy moves over the Great Lakes it will acquire some moisture and this will set the stage for some light snow:

The degree of lift or ice crystal production appear to be rather weak with this system. When assessing the NAM and GFS 700mb forecast vertical velocities for Wednesday night, you’ll notice that the GFS is a bit more impressive with the NAM…the GFS has a much more widespread coverage of these green and yellow shadings (indicating about 5 to 10 units of omega and upward vertical motion), however, the NAM is only a bit more sporadic:

There are a couple things to consider here. While the surface flow may be a bit more southeast, the low-level flow will be more northwesterly. This will establish a downsloping component (sinking air) down the east flakes of the Berkshires. This will result in subsidence and drying air. The NAM being a much higher resolution forecast model than the GFS will be able to pick up something like this much better.

Bufkit soundings for Windsor Locks, CT also show a quite a bit of dry air within the snow growth zone; relative humidity values generally less than 95% with relative humidity only sporadic areas where relative humidity with respect to ice exceeds 100%. To save time I am just showing the NAM, however, the GFS in fact is even less with respect to relative humidity:

The result…poor lift and lack of sufficient moisture within the snow growth zone combined with some subsidence will make it difficult for great snow production. There may be some pockets of some heavier lift which could make for brief spurts of near moderate snow. All in all, this should be rather unimpressive.