The active weather pattern looks to continue as we move into the beginning of the work week as a fast moving storm system is expected to slide just south of the state. Unlike the big blizzard several days ago, this system will be moving at a much quicker rate with the duration expected to be less than 12-hours in total. In fact, the heaviest if the activity will only occur in a 6-8 hour window.
Computer forecast guidance suggests as this system slides south of the state it will slowly begin to intensify. With winds in the lower levels of the atmosphere coming from the southeast, this will contribute quite a bit of Atlantic moisture into the system. With sufficient lift in place, we will see a fairly large precipitation shield develop and with temperatures at all levels cold enough, at least initially, we will see snow break out.
The first flakes could begin between the hours of 11:00 PM Sunday night and 1:00 AM Monday morning. By 3:00 AM to 4:00 AM, periods of moderate to heavy snowfall will be occurring across the state and snowfall rates in the heaviest echos will approach 1’’ to 1.5’’ per hour. We will continue to see moderate to heavy bursts of snow continue up until about 10:00 to 11:00 AM before the snow begins to taper down. Across southern CT, computer forecast hints at warmer air working in the lower levels of the atmosphere. This will allow for a transition from snow to sleet and perhaps some freezing rain or even plain rain during the early morning hours, thus cutting down snowfall totals across this portion of the state.
Due to the timing of the system and the heaviest of the precipitation rates, morning travel will be extremely messy with significant impacts. Expect numerous delays on the roads and very slow travel. School closings are highly likely across many towns and cities.
While my snowfall forecast is a bit less than what many others are suggesting, to me there are a few flags which is inhibiting me from going any higher;
1) The speed of the system. When looking for snowfall totals approaching amounts such as 8’’…12’’ or higher, one of the main factors to take into account is the speed of the storm. If you have a storm system moving as fast as this one, you have to ask yourself, how long is the heaviest precipitation expected to last? What are the projected snowfall rates during this time? What kind of snow growth are we looking at? What type of lift are we dealing with? 2) There is no established mid-level circulation. Below is a graphic from today’s run of the 12z GFS. While I am using the GFS to give a visual, all other significant models are similar. Having no established mid-level low can make for some not so great lift, especially in the mid-levels. One way to get excellent snow growth and subsequent ratios is to have the presence of very strong mid-level lift.
3) Looking at bufkit profile for Windsor Locks, CT there are some definite flags to me here. There isn’t a ton of omega (the red contours) and much of the highest values remain outside of the area of best snow growth zone (area highlighted by the yellow contours). What this says to me is that much of the best lift is all mainly in the lower-levels of the atmosphere and not within the area of best snow growth. This indicates that overall we will be looking at fairly poor snow growth and snowflakes that won’t be very large in nature…small flakes take longer to accumulate. This will also lead to some poor snowfall ratios. However, with this said, some of the low-level lift is rather impressive and this will lead to a very narrow zone of extremely heavy snowfall with much better snow growth and ratios. Within this zone snowfall totals up to 10’’ will be possible and a 12’’ amount can’t be ruled out.
With this said, below is my snowfall forecast:
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