Historic May Snowstorm on the Way (Friday, May 8, 2020 - Saturday, May 9, 2020)

For the most part, my blog posts focus on Connecticut, however, due to the historic nature of what is about to unfold as we move into Mother's Day Weekend I am expanding the focus to cover all of New England. (However, my snow map will focus on Connecticut due to time constraints).

An unprecedented air mass (for the month of May) is set to enter New England Friday into Saturday. A piece of the polar vortex is expected to break off from the main vortex and swing through southeastern Canada and move through New England. This will be associated with 500mb  heights as low as 516-518 meters. On average, the 500mb level is about 18,000 feet above the ground (and typically a bit higher as we move closer to the summer solstice), however, the 500mb level will be as low as 16,000 - 17,000 feet above the ground! This will also be associated with temperatures at this level as low as -35C to -40C...these heights and temperatures would be record breaking and perhaps record shattering.

At the surface, a cold front will be moving through the region. As the polar vortex dives in an associated shortwave trough will amplify (strengthen) as it digs through New England. This will promote strengthening jet stream dynamics aloft which will be favorable and conducive for cyclogenesis (strengthening) of a low pressure system along the cold front.

As the low pressure strengthens and with the passage of the cold front, we will see anomalous cold across southeast Canada will advect into New England. This cold will set the stage for what looks to be a historic winter storm for interior New England, however, as far south as Connecticut is not out of the woods. The biggest key will be track of the low pressure. Should this track a bit farther southeast than what forecast models indicate, heavy snow would be likely across much of Connecticut away from the shoreline.

While surface temperatures may remain as high as 33-35F, temperatures just a few thousand feet above the ground will be extremely cold which will yield precipitation to remain as all snow...the only problem is it will be very wet and heavy. For any areas which see more than 3-4'' of snow, concern will be high for widespread power outages (which could last for several days in some places) and tree damage. As of now, the greatest potential for this to happen would be; Northwest Hills of Connecticut, western Massachusetts, a large part of Vermont, New Hampshire, and Maine away from the coast.

This is an extremely complex situation due to the unprecedented and historic nature of this air mass and subsequent storm. Significant changes to this forecast are possible as the details become clearer. Right now, the greatest concern for power outages and tree damage in Connecticut is confined to the Northwest Hills.

Timeline for Connecticut:

• Showers arrive into the state by Friday afternoon with some heavier rain by the evening. 
• During the evening temperatures quickly crash, allowing for rain to transition over to heavy, wet snow in the Northwest Hills with rain changing to snow by late evening and early overnight across much of the state away from the immediate shoreline. 
• Greatest accumulations across the Northwest Hills (4-6'' possible) with highest likelihood for widespread power outages and tree damage. 
• Thundersnow is possible
• Saturday features near record-cold with scattered snow showers, snow squalls, and the potential for thunder/lightning along with grauple and small hail. 
• Below is my current thinking for Connectuct: