Multiple rounds of rotating thunderstorms are set to hit central states

Spring severe-weather season has begun across the Plains and Mississippi Valley, with multiple days of significant severe weather potential in the near future, as well. There’s a chance Thursday for rotating supercells across the Texas Panhandle and western Oklahoma, while a broader expanse of the Plains, Ozarks and mid-South is at risk Friday.

Any of the storms could produce large, damaging hail the size of hen eggs - or bigger. Rotating cells could spawn tornadoes, too, and there’s an outside chance of a significant (EF2+) tornado or two. Tornadoes are rated on the Enhanced Fujita Scale, which assigns a 0-through-5 rating to the damage they produce.

Friday’s storms look to be more widespread, potentially merging into a lengthy squall line that could trek from Kansas City and Dallas all the way to Chicago and Paducah, Kentucky. The squall would contain damaging straight-line wind gusts of 60 to 70 mph and probably a few quick-hitting tornadoes, too.

There could be additional storms across the central states toward the middle of next week, with at least some potential for severe weather.

March represents a key transition time in Earth’s atmosphere. Summer’s warmth attempts to build north from the gulf, marked by periodic insurgences of moisture and mildness. But winter is slow to retreat, with frigid air banked up in the Rockies. The result? The seasons wage war, with each battle punctuated by severe thunderstorms that come to be a staple of the springtime.

On average, there’s a fivefold increase in tornado activity between February and April, meaning March is the time when things ramp up markedly.

Outlook for Thursday

On Thursday, the Storm Prediction Center had drawn an enhanced (Level 3 out of 5) risk of severe weather across portions of the Texas Panhandle and adjacent Oklahoma. The zone includes Altus, Woodward, Elk City and Weatherford in Oklahoma; and Childress, Wellington and Pampa in Texas. A broader slight (Level 2 out of 5) risk spans from Wichita south to Lubbock, Texas, and also includes Amarillo and regions west of Oklahoma City.

There are two key elements for severe storminess. The first is a tightening dryline, or the leading edge of dry air from the west impinging on gulf moisture to the east. That will kick up scattered storms, including a few rotating supercells, by 4 or 5 p.m.

There’s also an outflow boundary, or the leading edge of cool-air exhaust, from earlier downpours over Oklahoma. It’s sagging southwest and will probably reach the Highway 287 corridor in North Texas by midafternoon. Any thunderstorms that sprout near this boundary may gobble up extra helicity, or twist, along the boundary, bringing an increased tornado threat to the Red River Valley through about 9 p.m. Thereafter, thunderstorms will lift north, riding atop a shallow lip of cool air and primarily producing large hail over northwest Oklahoma and southwest Kansas.

Some of the hail could exceed hen egg size.

Outlook for Friday

Friday features a broader risk of severe weather. Central and eastern Oklahoma, eastern Kansas and western Missouri are encapsulated in an enhanced (Level 3 out of 5) risk of severe weather. A slight (Level 2 out of 5) risk stretches from southern Wisconsin, Chicago and Des Moines all the way to Dallas-Ft. Worth and Waco in Texas.

An elongated low-pressure system spanning the central and northern Plains is lifting moisture northwards. That’s leading to an expansive warm sector, or zone of warm, humid air ahead of the fronts. That in turn means ample instability - or thunderstorm fuel.

An approaching upper-level low - or pocket of cold air, low pressure and spin - will eject out of the Rockies on Friday. That will help to lift the air, generating thunderstorms.

Meteorologists aren’t yet sure about the exact shape of the trough and how it will be tilted. That will determine how much of a kick the system has and subsequently how nasty the storms will be.

Confidence is greatest in the potential for a QLCS, or quasi-linear convective system, to form along a crashing cold front - essentially a squall line with straight-line winds and embedded kinks of spin. Any areas of rotation could produce brief tornadoes.

Uncertainty exists with regard to more discrete, isolated supercells that could form ahead of the main line. If any supercells form, they would have the potential to produce large, damaging hail and a sporadic significant tornado, too.