Tuesday morning what we call “overrunning” snow will develop across Connecticut with relatively mild, moist air “running over” cold dense air locked in at the surface. At this point it looks like 3″-6″ of snow Tuesday morning through Tuesday evening. Snow should break out around daybreak.
The 15z SREF snow probabilities show a decent probability of >4″ of snow over most of the state but also show very low probabilities of >8″ of snow. 3″-6″ seems like a safe call.
By Tuesday night and Wednesday morning the weather setup gets much more complex. A strong area of low pressure will ride up west of New England. Normally this is a warm storm track that would flood New England with mild temperatures but high pressure to the north will not allow that to happen. A very strong temperature gradient about 7,500 feet above the ground will setup over southern New England while the ground remains quite cold. This is a classic ice storm setup.
To be honest the worst possible situation for Connecticut is a major ice storm on top of the 2 feet of snow depth most towns will have Wednesday morning. Though some towns will see ice I’m not convinced it’s widespread or severe. Some computer models (for example the 18z NAM) have kept cold temperatures above the surface locked in and will deliver more snow and sleet than freezing rain. Other models show a deep enough layer of cold near the surface that sleet is more likely than freezing rain.
Details about the sleet/freezing rain/snow lines will have to be worked out over the next 24 to 36 hours. All of us in Connecticut should have our fingers crossed for a lot of sleet. 12″+ of snow or a big ice storm would cause BIG problems here. At this point I think a big ice storm is possible but not the most likely solution.