Behind the late weekend cold frontal passage, colder air will begin to filter into the Northeast US/Mid-Atlantic on Monday and Tuesday as cold high pressure builds into southeastern Canada. This type of atmospheric pattern in which high pressure builds across southeastern Canada is supported by the expectation that the AO and NAO teleconnection indices will be in “negative” territory. This high pressure system to the north may very well become an important cold air source for the Northeast US/Mid-Atlantic by the middle of next week.
At the same time the high pressure builds across SE Canada, an upper-level wave of energy is likely to cross the central US and this system will be able to gather moisture from the Atlantic Ocean and Gulf of Mexico as it approaches the eastern seaboard. With the cold air source possibly locked in place to the north (i.e., strong high pressure in SE Canada), this potential setup could result in accumulating snow for at least the interior sections of the Northeast US/Mid-Atlantic by the middle of next week. “Climatology” suggests that it is quite difficult to get accumulating snow in the immediate I-95 corridor region and points to the coast in the middle of December with still relatively-warm sea surface temperatures in the western Atlantic; however, it is way too early to speculate on those kinds of details. Another factor that could play a role in the potential mid-week event will actually be a preceding storm system. This system is liable to stay just to the south of the Northeast US/Mid-Atlantic on Monday as it likely heads towards the Carolina coastline. However, any change in this early week storm system in terms of intensity and track could have an impact on the potential mid-week event.
Stay tuned…certainly an interesting weather pattern as we head to the middle part of the month.
Meteorologist Paul Dorian