Messy Winter Storm to Impact CT 2/12/2017

Typically when writing up blog posts I love to get really scientific with them and I try to do my best so anyone who reads them can sort of try and understand the process of making a forecast and see just how complex and challenging forecasting can be.  I understand that most people don't understand the scientific background but my hopes is always to give the reader an understanding of why forecasting can be challenging.  Unfortunately, due to time constraints I don't have the time to really get into the scientific background here which is a shame because this is a very complex forecasting event.  With that said I will briefly describe what went into making my forecast.

I see I am on the lower side of some forecasts, however, I have reasoning.  One reason is I think this system really strengthens too late for us here in CT to really cash in on heavier snowfalls.  Computer forecast guidance suggests that the surface low, 925mb low, 850mb low, 700mb low, and 500mb lows all don't really strengthen and close off until the system is east of CT.  That's a red flag for big snows here.  Also, looking at some bufkit profiles across Windsor Locks, CT and Waterbury, CT while we will have excellent snowgrowth, snow rations will be extremely poor (maybe 8:1) given warmer surface temperatures.  There also isn't a tremendous amount of lift present within the snowgrowth zone which means poor flake size and that coupled with poor ratios will make big accumulations tough.  I will illustrate by just using the 12z NAM computer forecast model bufkit profile for Windsor Locks, CT:

Given track and late timing of strongest development we will also have some temperature issues across the state with temperatures warming enough along the southern third of the state to promote a mixture of sleet and even rain.  We could even see sleet perhaps through the central portion of the state with the extreme northern third of the state remaining cold enough for snow.

Timing...snow should begin early to mid-morning and then increase rapidly through the afternoon.  Snow will come down moderate to heavy at times with rates nearing 1'' per hour rates.  Expect a very slow travel commute tomorrow and travel is not recommended unless absolutely necessary.  The system winds down late evening with leftover snow showers.  Delays possible Monday morning.  Below is my map: