A look at next week (Dec 14 - 20)

A strong storm system will lift into Ontario tomorrow morning and northern Quebec tomorrow evening. Southerly flow will transport much warmer temperatures into the region out ahead of the storm with highs reaching the 50's across all of SNE.

An associated cold front will cross the eastern states Monday night, with rain showers likely Monday evening through Tuesday morning. Much colder temperatures (around normal) will move back into the northeast for Tuesday, with some light snow showers possible in the morning (no accumulation).

The front should begin to stall south of New England as flow becomes parallel to the boundary. This front then presents itself as a baroclinic zone for storms to develop and track along.

Ironically, we could be entering a more favorable period for snow accumulation despite a +NAO / -PNA (trough-west, ridge-east) set up. This is because we still have a -EPO resulting in split flow in the west, and the SE ridge temperature correlation diminishes up towards New England.



What happens now is storms develop in the SW along the southern jet, assisted by energy transport south from the Gulf of Alaska, then move NE toward the Great Lakes and New England region. The fast flow across the central US prevents shortwaves to amplify significantly, and consequently keeps strong ridging (and blowtorch temperatures) from building in the east. The northern jet recombines with the southern jet in SE Canada and this confluence encourages development of an arctic high. The high pressure in southern Canada causes cold air damming in the northeast. This is again a recipe for ice storms. However, if the storms are not as amplified, mid level temperatures may still be cold enough for snow north of Route 2, and wintry mixes further south.



Back to this week, we will be seeing a couple opportunities for storms like the above mentioned. The first on Wednesday, and another on Friday. Both of these will be discussed in the Winter Weather Outlook page.

Going into week 2, the 12z ECMWF advertises a major storm system cutting across the Great Lakes next Sunday (with SE Canadian high pressure in tact). This could be a third wintry threat for the region. But besides that, it could open the doors to below normal temperatures in Canada streaming into the midwest behind the storm, and maybe a temporary shot of cold air in the east.