Thread by @derecho_series

A powerful system targets the Great Lakes basin Wed-Fri. #onwx
A tremendous region of Canadian Arctic high-pressure precedes a potent wave of Pacific energy. The trough is poised to dig lee of the Rockies producing an amplified response. A low-p system will form in Colorado 1/ twitter.com/i/web/status/1…

before dipping south-eastwards into the Texas Panhandle region. The area of low-pressure will track towards the great lakes basin, rapidly deepening. Under a combination of tapped Gulf moisture, and record territory cold air advection. Before occlusion occurs, warm air will 2/

dominate the eastern progression of the low. The current setup and analog support supports a track from the plains into Michigan then traversing Ontario. The western side of the low will feature heavy snow & the entry area of excessive windchill/cold air. The plains to great

lakes should prepare for a blockbuster blizzard. The ones talked about decades ago. The real ones - blizzards with deadly wind chills. That risked freezing those stranded to death. The amounts of snow stateside in the plains isn't significant 15-30cm on the western side of the 4/

low as most deepening occurs over the GL basin. This is where the next variable comes in, a continuation of a strong high-pressure system over eastern Canada. A strong low tracking towards a strong high with no exit region. This will keep the powerful system blocked over ON. 5/

Until occlusion/troughing arrives.
For S.ON this begins as rain on the eastern side. Becoming hvy snow w/ arctic front arrival. Heralding wrap-around blizzard cond thereafter, further enhanced by LES across southwestern Ontario. Localized winds 80-110km/hr. Snow 15-40cm. #onwx

It's to early to tell who will see the worse of this storm at this point. But, anyone living in Michigan, Wisconsin, Ontario, Ohio, & Pennsylvania should be paying close attention.

It should be noted. Current guidance suggests that the worse conditions are localized to southwestern & northern Ontario. The GTA wil see snow - but this is not a blockbuster system for you by any means, at least currently.