Friday, October 30, 2020 Snowfall Forecast Update

Heavy rainfall currently across Connecticut giving us some much needed rain and putting a dent in the drought. As we move through Thursday night into Friday morning, much colder air is going to filter into the state. This combined with some pretty intense upward vertical motion will result in rain transitioning over to a period of moderate-to-heavy snow across much of the state. 

By early Friday morning, computer forecast models indicate temperatures above 5,000 feet above the ground dropping to as low as -2C to -3C with temperatures down at the surface not much above freezing:

Forecast models also indicate a band of high vertical velocities traversing the state. This is indicative of rather strong upward vertical motion...favorable for the development of precipitation (in this case snow):

Forecast models also indicate we'll see some strong upward vertical motion into the dendritic snow growth zone:

Given the signals for some rather strong upward vertical motion across the state combined with cold temperatures in the lower-levels of the atmosphere and strong lift into the dendritic snow growth zone, the signals are there for what should be a 3-5 hour window of moderate-to-heavy snow across much of the state...even down to the shoreline! Given this signal, snowfall totals have been increased slightly from Thursday's forecast:

Potential Impacts:

• Rain transitions to snow across the northwest and northeast hills between between 12:00 AM and 3:00 AM Friday morning. The remainder of the state will see rain transition to snow between 4:00 AM and 7:00 AM (perhaps as late as 8:00 AM along the immediate shoreline) 
• Expect a slow morning rush hour commute due to slick roads. Travel should not be significantly impacted, however, give yourself extra time for travel. 
• Breezy during the morning with winds subsiding through the day, however, it will be cold with temperatures only into the 30's with lower 40's along the shoreline. 
• Very cold Friday night with temperatures into the teens and 20's so slick spots will develop.