Storms are expected to peak on Wednesday, when more than 90 million people from New Mexico to New Jersey face a high risk of severe weather according to the Storm Prediction Center. On Thursday, storm risk will be somewhat more contained, affecting around 20 million people from the Gulf Coast to the central plains.

Extreme heat roasts from Texas to California with highs of over 110 degrees

Tuesday brought widespread instances of severe weather across much of the Central Plains and High Plains, including far eastern Wyoming, where a tornado was reported near Lusk. Baseball-sized hail was reported in Hazard, Neb., just over 40 miles west-northwest of Grand Island, with similar sized hail noted during a separate storm at Two Buttes in southeastern Colorado. A splash of supercell or rotating thunderstorms dropped significant hail; the weather service received three dozen reports of ice chunks over two inches in diameter.

By evening, some of the storms south of Interstate 80 in Nebraska had merged into a line of sloping squalls with damaging winds. They drifted toward Kansas City, Mo. Other supercells continued to rage in southwestern Kansas and in the Texas and Oklahoma panhandles; a 92 mph gust was recorded at Elkhart along the Kansas-Oklahoma border, with an 81 mph gust near Guymon, Okla.

Severe storms continued into the early hours of Wednesday morning, producing an 81 mph wind gust in Motley County, Texas shortly after sunrise. Heavy storms also brought over 5 inches of rain and flooding around Birmingham, Ala.

Ohio Valley and Mid-Atlantic:

• Areas affected: Eastern Illinois, much of southern and central Indiana, northern Kentucky, southern Ohio and western Virginia are in a Tier 2 risk area on 5 for severe storms. This includes Louisville; Indianapolis; Columbus, Ohio; and Charleston, W.Va. Broader Level 1 in 5 risk extends to DC, Philadelphia, Baltimore and Richmond.

• Synopsis: Scattered thunderstorms underway over southern Illinois and parts of the Corn Belt early Wednesday morning will increase in coverage and intensity as they move east, possibly organizing into a line. This band of storms will track eastward throughout the evening, reaching the mid-Atlantic overnight. A few more thunderstorms will develop ahead of the line.
• Hazards: Damaging 60 mph winds and quarter sized hail with the most significant storms. Frequent lightning also, especially if lines of storms form. A few tornadoes cannot be ruled out with cells upstream of the mainline acquiring supercell characteristics and remaining isolated from neighbors.

Mid South, Ozarks and Deep South

• Areas affected: A Level 2 out of 5 severe weather hazard covers areas near and south of Interstate 40 between the Texas Panhandle south of Amarillo and parts of Mississippi and Alabama. In between is most of southern Oklahoma to the Red River and across the Ozark Plateau of Arkansas. This includes cities like Oklahoma City; Wichita Falls, Texas; small stone; Memphis; Jackson, miss; and Birmingham. A level 1 in 5 risk extends from eastern New Mexico and western Texas to the east coast.
• Synopsis: Last night’s storms will re-develop and intensify with daytime heating, and additional activity is possible on the eastern fringe of the main line.
• Hazards: Damaging winds to 70 mph in the strongest storms, as well as half-dollar hail, especially during the first half of the day. Storm intensity will decrease significantly as storms drift east of the Mississippi River, but 60 mph winds and quarter-size hail are still possible.

• Areas affected: A Level 2 out of 5 severe weather hazard covers much of the Central Plains and High Plains, including the northern Texas and Oklahoma panhandles, northeastern New Mexico, Colorado to the east of Palmer Divide and much of Kansas and south-central Nebraska. The northern half of Oklahoma is also included in the risk zone. This translates to cities such as Tulsa, Wichita, Garden City and Scott City, Kansas.; McCook and Kearney, Neb. ; and Dumas, Texas. A level 1 in 5 risk surrounds the light and covers Lincoln, Neb., and Oklahoma City and extends to the Gulf Coast and covers New Orleans; Mobile, Alabama, and Tallahassee.

• Synopsis: A weak cold front will trigger thunderstorms along the Gulf Coast. Instability, or storm fuel, will be plentiful, but wind momentum will be weak. Still, a few storms could contain strong downslope winds. A greater severe weather threat will be present over the plains, where supercells in the western areas will evolve into an MCS, or mesoscale convective system – essentially, a sprawling curved squall line with strong winds.
• Hazards: Along the Gulf Coast, storms could contain wind gusts to around 50 mph and torrential downpours. Over the plains, the initial supercells could produce hail the size of chicken eggs and wind gusts to 75 mph, as well as a brief isolated tornado, before a more widespread wind hazard with the incipient MCS .

• Areas affected: A level 2 out of 5 severe weather risk covers parts of southeast Arkansas, northeast Louisiana and central Mississippi, including cities such as Jackson, Meridian, Pine Bluff and Vicksburg, Miss., and areas southeast of Little Rock. Marginal risk extends to Mobile and the Mississippi Delta along the Gulf Coast.
• Synopsis: One of two things is likely to happen. Either Thursday night’s dying MCS will strengthen again in the face of daytime warming Where a remnant eddy of low pressure on the north side of the line, known as the mesoscale convective vortex, could trigger new storms.
• Hazards: Damaging 65 mph winds, frequent lightning, heavy showers and possibly a small hail the size of a pea or penny.

An approaching trough, or dip in the jet stream in which a lobe of high-altitude, low-pressure, rotating cold air is nestled, will cross the northern Intermountain West early next week. It could trigger severe thunderstorms in the northern Rockies or Dakotas, but confidence is low.