First off, for tonight's storm: Precipitation will overspread the state before midnight. The feeling is that precipitation should begin as snow everywhere, since the dew points are low and the column is cold (minus the surface, but that should be overcome by evaporative cooling). The changeover to rain will probably progress more west to east than south to north. The reasoning for this is that we have high pressure to the North, which will probably keep winds Easterly or Northeasterly, and not incorporate much of a fetch off Long Island Sound. Warm air may travel more south to north in the upper levels. As the surface low passes well to the west of the area, southwesterly or southerly winds will be established aloft. Based on the above, here is the general thinking (no drastic changes from before):
Along the south coast, although a burst of snow could develop tonight, temperatures at the surface will be above freezing and will not fall to freezing. Warmer air moving in aloft will quickly change precipitation over to rain before any accumulations.
In Central Connecticut, snow will develop tonight and could accumulate, mixed with sleet at times, up to an inch or two. After that, a brief period of freezing rain is possible with a tenth of an inch of ice or less.
Northern Connecticut will be split into two groups, with I 91 being the dividing line. In Northwestern Connecticut, snow and sleet could accumulate an inch or two, before changing to freezing rain. A tenth or two of an inch (0.1-0.2") of ice is then possible before changing over to rain. For Northeast Connecticut, the snow and sleet will hold on longer, and could accumulate 2-4". This area should see a changeover directly from snow and sleet to freezing rain, with little or no ice accumulation. (The surface may actually warm before the upper levels in this region, due to their distance from the low).
New Years outlook.. For those with plans heading into New Years, here is a general outlook of what to expect. A frontal system will bring a shot of rain mostly late Wednesday night into very early Thursday morning. A secondary cold front may touch off a few showers later in the day on Thursday, especially to the Northeast. These showers will likely fall as snow or a snow/sleet mix, but will be very light and inconsequential. High temperatures on Thursday will range from the mid 40s to the low 50s.
For New Year's Day, much cooler air gets ushered into the region on Northwest breezes. Highs will range from the mid 30s to low 40s. A rogue snow flurry is also possible in the Northwest hills, from some blowoff from Lake Effect streamers.
Long Range Discussion: The pattern continues to be in a state of change, and is rapidly changing into a pattern more favorable for winter-like temperatures, and eventually, significant winter storms. The first week of January should feature chilly temperatures, with perhaps a bit of a moderation in the 2nd week of January, then we could plunge into the freezer after that! Initially, the trough orientation favors most of the cyclogenesis to be out to sea, east of the area. However, as we head deeper into January, by the 2nd or 3rd week of the month, this changes, and there could be more of a pattern supporting East Coast cyclogenesis... stay tuned!
-GP and thanks to TW for the map!