Coast-to-coast storm across the US: dates, when it will arrive and affected areas

The national Storm Prediction Center is warning Americans to brace for “a concerning scenario” that appears will develop on early Friday into the night that will affect nearly 70 million people. The severe weather is brewing out of the latest system to dump even more precipitation on California as it pushes east.

Those in the Mississippi River Basin from the Gulf to the Great Lakes can expect “intense, damaging gusts and several tornadoes” as well as “very large hail.” Two areas will be of special concern at a Level four out of five on the risk scale, or “moderate” chance of severe weather, one centered over eastern Iowa and the other over northeast Arkansas.

Forecast for severe weather

As the weather system moves quickly from the central Plains into the Middle Mississippi Valley and Mid-South, rapid destabilization is forecast as the low pulls warm low-level moisture north in front of a line of cold air pushing east. This will create the conditions for the formation of thunderstorms by early to mid-afternoon Friday. Initially, there will be the conditions for “very large hail.”

While the Storm Prediction Center says that “some uncertainty remains” about the evolution of the severe weather formation over eastern Iowa and northwest Illinois, “a few semi-discrete supercells are expected” to move into the area with the potential for “a couple strong tornadoes” by late-afternoon Friday. These are expected to evolve into small clusters as they move east resulting in potentially severe and damaging winds as well as a continued threat of tornadoes and sporadic hail.

As the severe weather system moves east into parts of Indiana and southern Michigan it will weaken. But the threat of damaging wind and tornadoes will persist into the night.

In the Mid-South, in an area over the bootheel of Missouri, northeast Arkansas, western Kentucky and Tennesse and far northwest Mississippi “supercell wind profiles will support cells capable of significant and long-track tornadoes” developing by early afternoon. The system will continue into the Ohio and Tennessee Valleys through Friday night, while weakening as it goes will still bring with it “the threat for damaging gusts and a few line-embedded tornadoes.”