TL;DR

The Storm Prediction Center has issued a Marginal Risk for severe thunderstorms from the southern Plains to the Mid-Atlantic coast today, September 10. Sporadic damaging wind gusts are the primary threat this afternoon and evening, with isolated large hail possible over south-central Colorado, northeast New Mexico, and the Oklahoma and Texas Panhandles. No tornado activity was reported in the last 24 hours, but 59 wind reports came in as a cold front pushed through the central US.

What's driving today's severe weather?

A cold front stretches from the St. Lawrence Valley west-southwestward through Lower Michigan, northern Illinois, and southern Iowa, then shifts more southwestward through central Kansas and into the central Oklahoma and northwest Texas Panhandles. The front is the focal point for today's thunderstorm activity.

Showers and thunderstorms are already underway this morning from southwest Kansas and the eastern Texas and Oklahoma Panhandles through the Lower Missouri Valley and into the middle Ohio Valley. Much of this activity is ahead of the cold front, supported by modest low-level warm-air advection and convergence along southward-progressing outflows.

Strong heating is expected south of residual cloudiness and lingering storms. According to the NOAA Storm Prediction Center (SPC), temperatures will climb well into the 90s to around 100°F over the southern Plains and into the lower Mississippi Valley, with upper 80s to mid-90s from the Tennessee Valley to the Mid-Atlantic. Dewpoints in the 60s to low and mid-70s will yield a moderately unstable air mass by afternoon, with mixed-layer CAPE (convective available potential energy, the atmospheric fuel for thunderstorms) ranging from 1000 J/kg across the Mid-Atlantic to 2000-2500 J/kg across the southern Plains.

This increased buoyancy, combined with convergence along the synoptic front and any existing outflow boundaries, should keep thunderstorm activity going throughout the afternoon and evening.

Where is the highest risk today?

The Marginal Risk area covers a broad swath from the southern High Plains to the Mid-Atlantic coast. Within this zone, the SPC highlights a few sub-regions with slightly elevated potential:

  • North-central Texas to the Mid-South: Buoyancy will be highest here, and the presence of a relatively deep, well-mixed boundary layer will support sporadic damaging winds with isolated severe gusts.
  • Mid-Atlantic region: Buoyancy will be more limited farther east, but vertical wind shear will be stronger. Some more organized bowing segments are possible, with damaging gusts as the primary severe risk.
  • South-central Colorado to northeast New Mexico and the Oklahoma/Texas Panhandles: Upslope flow of a moist boundary layer beneath mid-level lapse rates of 7-8°C/km will yield moderate afternoon instability with MLCAPE of 1000-1500 J/kg. Isolated to widely scattered thunderstorm development is anticipated by mid-afternoon along the high terrain, with isolated hail as the primary hazard.

Cities to watch today include Dallas–Fort Worth, Little Rock, Memphis, Nashville, Louisville, and the Mid-Atlantic corridor.

When will the storms hit?

Thunderstorms are already ongoing this morning across portions of Kansas, Missouri, and the Ohio Valley. Intensity is expected to increase through the afternoon as heating peaks and instability builds.

The SPC outlook notes that thunderstorm activity should persist throughout the afternoon and evening, with some increase in intensity possible, particularly from north-central Texas into the Mid-South vicinity where buoyancy will be highest. Over the Raton Mesa vicinity in Colorado and New Mexico, isolated storms are expected by mid-afternoon along the high terrain. The threat should diminish after sunset as the boundary layer stabilizes.

What happened yesterday?

The last 24 hours brought 59 wind reports across nine states—Arizona, Colorado, Kansas, Kentucky, Missouri, Ohio, Pennsylvania, Texas, and West Virginia—as the cold front marched eastward. One hail report came in from Colorado, with 1.75-inch hail (roughly golf ball-sized) reported 8 miles southeast of Colorado City at 0600 UTC.

No tornadoes were reported. Wind damage included downed trees, utility lines, and power outages from the southern Plains through the Ohio Valley. Multiple reports of downed trees and wires came from the Kansas City metro area, including Baldwin City, Louisburg, and Pleasant Hill, Missouri. In Ohio, trees and utility wires were downed in Huron, Hartville, and Alliance.

The highest measured wind gust was 72 mph, recorded by an XCEL Energy weather station 1 mile south-southeast of Booker, Texas, at 2040 UTC. Two other XCEL Energy sites near Booker gusted to 71 and 59 mph at the same time.

What to expect today

Today's severe weather threat is lower-end. The Marginal Risk designation means isolated severe storms are possible, but widespread or significant severe weather is not expected. If you're in the risk area:

  • Monitor radar and local NWS forecasts through the afternoon and evening.
  • Secure outdoor items that could blow away or become projectiles in gusty winds.
  • If a severe thunderstorm warning is issued for your location, move indoors and away from windows.
  • Hail is most likely over the southern Rockies this afternoon. If you're in south-central Colorado or northeast New Mexico, be prepared for hail up to the size of quarters or golf balls if storms develop overhead.

Damaging winds are the primary concern elsewhere. Gusts strong enough to snap tree limbs, down power lines, and cause localized outages are possible with the stronger storms.

Looking ahead to Friday

The SPC Day 2 outlook (valid Friday, September 11) shows a Slight Risk across portions of the Northern Plains, Midwest, and Northeast as the cold front continues to push eastward. A separate Slight Risk area covers parts of the Southeast. Friday's setup will bring a slightly higher severe weather threat than today, with damaging winds again the primary hazard.

Stay tuned to the VORTEX blog for updates as the forecast evolves.

VORTEX is a free web app at vortexintel.app that monitors severe weather nationwide. Pro ($4.99/month) places phone calls to your phone when a tornado or flash flood warning is issued for a location you care about — calls can ring through Do Not Disturb once you enable Emergency Bypass for the number, unlike most third-party app notifications.