The marriage of a plucky Midwestern U.S. low and a sultry Carolina system will create a powerful Nor’Easter on Friday.
This is certain to be a high impact storm for millions in Canada and the U.S.
Southern Ontario’s snow will come courtesy of the Midwest U.S. low which is tracking toward Lake Erie. Like many storms that take such a track, this one will feature warm air that will move over top of cold air, creating the set-up for a period of freezing rain in extreme southwestern Ontario and along the north shore of Lake Erie into the pre-dawn hours of Friday.
However, the key difference is that this low will slow down as the courtship (in meteorology we call it ‘phasing’) with the Carolina system starts to occur on Friday.
The slowing of the system, and eventual union with the east coast low, means two things:
First, the warm air won’t make it far enough north to spare places like Toronto from a pure snow storm.
Second, it will snow for a longer period of time than usual with this type of system.
All this adds up to a substantial snowfall from Lake Huron/Georgian Bay to Lake Ontario and the Seaway.
While the wind won’t be as strong as in some storms, snowfall amounts will likely exceed 20 cm in many places by the time the snow tapers off later Friday. The fireworks really being Friday evening as the merged lows explode off Cape Cod.
Winds gusting over 100 km/h will accompany heavy snow in much of coastal New England. Boston is in the crosshairs of this storm – while it is likely to be substantial for Toronto, it’s more like paralytic for Boston.
Winds will also be strong for the Maritimes as the storm builds in overnight Friday. Snowfall amounts will be impressive, 20-30 cm in much of Nova Scotia, but likely not substantially more than some of the higher totals in southern Ontario.
It’s New England that will feel the peak intensity of the storm with potentially historic snowfall amounts that should easily exceed 50 cm.