We are looking at a very long duration snowstorm to impact the state beginning on Monday and lasting through much of the day on Tuesday. As the system begins to develop just to the south of CT and slowly sort of slide northeast, the system will stall out. During this process, the system will undergo rapid cyclogenesis (strengthening), with a great deal of thanks to a strong thermal (temperature) gradient that will be in place in the lower levels of the atmosphere and at the surface. A strong area of high pressure to the north will continue to pump in very cold air aloft over the state (and this high will also work to keep the storm movement very slow) and warm and moist air working into the storm will setup this gradient. As the system strengthens rather rapidly, the precipitation field will begin to blossom rather quickly and precipitation rates will rapidly begin to increase.
The first flakes are expected to break out across the state perhaps as early as noon Monday afternoon. As the afternoon progresses, light snows will begin to overspread the state, however, snowfall rates should remain on the lighter side. As afternoon progresses towards evening, we will begin to see more in the way of moderate bands of snowfall begin to work into the state. As the evening progresses, we will begin to see periods of moderate to heavy snowfall become much more common across the state. In addition to snowfall rates intensifying, the winds will begin to pick up as well. The heaviest of the snowfall rates are expected to occur between the hours of 11:00 PM Monday night and 9:00 AM Tuesday morning. During these hours is when the majority of the snowfall accumulations will occur. Snowfall rates could approach 2-3'' per hour with snowfall rates up to 4-5'' per hour possible in any bands containing thunder and lightning. Winds during this time will also become sustained between 25-35 mph gusts as high as 45-55 mph possible. In fact, coastal CT, especially SE CT, could see gusts as high as 65 mph! The combination of very strong winds will lead to blizzard conditions at times and will also cause numerous power outages due to downed trees and utility poles.
While snowfall intensities and rates will be decreasing during the morning hours of Tuesday, periods of light to even moderate pockets of snow will continue into the early evening hours. Winds will also remain rather strong through much of the day on Tuesday before beginning to subside in the late afternoon hours.
Snowfall totals may be lower across the southeastern part of the state and far northwestern CT and back in Fairfield county towards New York City. Across southeastern CT, there may be a pocket of dry air which works in aloft, but this depends on the exact track of the 700mb low. This pocket of dry air could cut-off snow for a period across this area leading to lower totals. Back across northwestern CT and southwestern CT, there may be an area of subsidence (sinking air) which cuts off precipitation. This will occur just to the northwest and west of the heaviest banding that will set-up known as a cold conveyor belt (CCB). In fact, where this band sets-up and pivots is where the highest snowfall totals will occur and these totals could approach two-and-a-half to three feet. However, at this time it's very difficult, if not impossible, to determine where this band will setup and we may not 100% know until the event is on-going. This is due to the fact that they are typically very narrow in nature and our computer forecast models aren't coarse enough to accurately depict where they will setup. However, as we get closer we can zero in on a specific area and can have a general idea of where the highest totals may occur.
Below is the first call snow map and expect another updated map tomorrow evening, and with a little more detail of where perhaps the heaviest banding will occur.
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