Wednesday Night Snow?

There is the potential for a snowstorm to blast through the region Wednesday night into Thursday morning that may significantly affect the Thursday morning commute. 

Current signs are pointing towards rain and snow which could begin as soon as 9PM Wednesday night, and get heavier overnight into the early hours of Thursday morning.  Since the storm is still around 55 hours out, many details remain foggy, but the precipitation may start as rain around 9 PM before mixing with and eventually changing to snow between 11PM and 1AM.  The snow may fall heavy at times in the worst of the storm, which right now looks to happen anywhere between 2-6 AM.  Snow should begin to wind down by 7 or 8 AM, and by Thursday afternoon everything should be completely clear. 

Only the Thursday morning commute stands any chance of being impacted, as the sun will likely be out by around noon Thursday, and the shoveling out may begin.  Exactly how much snow will fall, though, is still unknown. 

The most likely scenario is that southwestern Connecticut sees a general 3-6 inches of snow.  However, other models don’t see much of the snow sticking, and still others show 7+ inches for the region.  One of the most reliable computer models in the approaching timeframe, the NAM (North American Model) shows what is called strong dynamic cooling.  This means that when the precipitation starts, temperatures both in the atmosphere and the surface drop very rapidly, allowing more snow to stick and for more snow to fall than rain.  The NAM nailed the dynamic cooling with the storm back in October, and it appears likely that a very similar thing could happen with this storm as well.  Whether the dynamic cooling happens or not we cannot be sure of until the storm begins, but my current forecast is calling for rapid cooling at the start of the precipitation. 

Specifically, my forecast for the Southwest Connecticut area currently calls for 4-8 inches of snow with the upcoming system, with totals closer to 4 inches right at the immediate coast and 8 inches a little further inland.  It is higher than most forecasts out there, but in the coming days a lot of professional forecasts will also trend higher. 

I have been following this specific disturbance for over a week now, and at no time has it looked better for snow than now.  The ECMWF, UKMET, GFS, NAM, CMC, and GEFS weather models now all give the region accumulating snow, and in the coming days they will hone in on the exact storm track and intensity.  A small deviation in track or intensity could be the difference between 2 and 8 inches here, which is what makes it so hard to forecast these storms in Southwest Connecticut. 

Regardless, it would appear very likely that accumulating snow is on the way for the region, and travel implications are very likely.  For students, public and private schools may either open early or be closed altogether on Thursday should conditions on the roads be poor, which is quite possible.  

More reports will be released in the coming days, and a Winter Storm Watch or a Winter Weather Advisory will likely be issued for the entire region by the National Weather Service in the coming 36 hours.