Fig. 1: NOAA/NWS weather watch, warning, and advisory areas.
Discussion: An unusually intense storm system with central pressure plummeting to 970 MB just northeast of the Great Lakes by tomorrow evening while a 1055 MB arctic high enters Montana today propels a large list of hazardous weather (Fig. 1) which will include life threatening intensity beginning today and lasting into early weekend just ahead of Christmas. The list of hazardous weather includes heavy snow including blizzard conditions today and tomorrow in the Midwest stretching to the northern Appalachians by tomorrow night, strong to excessive wind affecting the Great Plains today, East-central U.S. to Gulf States tonight and sweeping across the Northeast Corridor tomorrow. Wind gusts to 60-70 mph are possible across the northern Great Plains, Midwest U.S. and Great Lakes region to the Appalachians causing significant power outages while temperatures are plummeting. Wind chills up to -70 could occur across the northern Great Plains.
A major snowstorm occurs in the Midwest but coupled with high wind, snow drifts of many feet can occur in favored areas.
Heavy rain precedes the arctic front in the East. However, with the arctic front rapidly falling temperatures will cause lingering precipitation to quickly change to heavy snow with brief blizzard conditions possible due to high wind (all the way to the East Coast on Friday).
Immense lake-effect snows set-up over the Great Lakes region.
Temperatures in Texas to the Gulf Coast plummet to the single digits and teens by later this evening.
In the rainfall area developing in the Mid-Atlantic States today and into the Northeast late tonight, 1-3 in. of rain is possible coupled with a strong south wind which will cause coastal flooding into the Mid-Atlantic/Northeast coasts.
In the Northwest, a significant freezing rain episode develops.
Overall, 46 of the 48 contiguous states have weather alerts issued with well over 200 million Americans affected.
Fig. 2: NOAA/WPC 7PM Thursday forecast map indicating the arctic front is through Texas and the heavy snow/blizzard is moving through the Midwest.
Fig. 3: NOAA/WPC 7PM Friday forecast map indicating the arctic front is off the East Coast.