Fig. 1: ARW model projection of the coldest time of the incoming Northeast U.S. arctic outbreak is 5AM EST Saturday.
Discussion: The core of an arctic air mass moving toward South-central Canada today will move east-southeast and into New England with limited, if any moderation. The coldest point of the arctic air presence across the Northeast is around 5AM Saturday morning. At that time, Boston could plummet to -16F, Portland, ME -24F, and Burlington, VT -30F (Fig. 1). New York City dips to 6F while Philadelphia/Baltimore/Washington are in the teens. Having no snow cover will moderate this air mass. The coldest wind chill forecast by the HRRR model (Fig. 2) projects -34F at Boston, -10 at New York City, and -45 at Manchester, NH with -54F at Caribou, ME. The wind chill is based on sustained wind. Higher gusts mean colder than indicated peak wind chill.
Fig. 2: HRRR model projection of the coldest wind chill time for the incoming Northeast U.S. arctic outbreak is 1AM Saturday morning.