A potent Arctic cold progresses across New England Sunday. While the brunt of the Arctic air remains confined to the central United States, upper-Midwest, Ohio Valley, and Tennessee Valley regions, it will still be very cold and wintry across southern New England behind the front.
The leading edge of the Arctic air will be defined by elongated and potent vorticity. A vorticity maximum will round the base of an amplifying trough across our region and strengthen, resulting in a great deal of positive vorticity advection across New England Sunday:
This system will be associated with vigorous dynamics characterized by a 500mb mid-level jet streak which may approach or exceed 150 knots. This is about as strong of a mid-level jet you'll ever see and will help promote vigorous lift across the region:
Associated with the feature will be steep mid-level lapse rates ranging between 6.5 C/KM to as high as 7.7-7.8 C/KM. These lapse rates will help aid in weak instability within the region. This weak instability will aid in lift:
In addition, there will be a very steep lapse rate from the surface to about 15,000 feet above the ground. This bufkit sounding for Windsor Locks, CT illustrates this well. This look is suggestive of instability:
The response from the strengthening shortwave and positive vorticity advection will be a strengthening southerly flow in the low-levels of the atmosphere which will help transport sufficient moisture into the region to interact with the front. The steep low-level lapse rates will also help to promote the mixing down of stronger winds aloft:
What are we looking at?
As moisture increases along and ahead of the Arctic front, scattered snow squalls are likely to develop ahead of the cold front with potential for a line of moderate-to-heavy snow to develop along the Arctic front. This can be thought of like summer downpours and thunderstorms where you get a 15-30 minute period of heavy precipitation, but in this case instead of rain you have snow occurring.
These snow squalls could produce 2-3 inches of snow in a very short amount of time on a local level. Strong wind gusts would occur as well and this would contribute to extremely dangerous travel conditions for a brief period of time as visibility drops to almost zero and roads become icy very quickly. There is even potential for thunder and lightning given the steep lapse rates and instability. If you are caught in a snow squall the best thing you can do is pull over or off the road (in a safe spot) and let the squalls pass. Snow under squalls becomes intense very quickly and conditions can deteriorate in the blink of an eye.
The time frame for these snow squalls is between 1:00 - 5:00 PM.
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