What you need to know

The NOAA Storm Prediction Center (SPC) has issued a Marginal Risk for portions of the central and northern High Plains today, covering western Nebraska and the Black Hills of South Dakota. Isolated thunderstorms capable of large hail are the primary concern, with storm activity most likely this evening as atmospheric lift increases. Scattered storms may also develop over north and central Texas late this afternoon, though severe potential remains low.

Today's setup: moisture meets modest instability

A residual moist axis is draped across the Plains this morning, with surface dewpoints in the 60s°F extending from the southern Plains northward into Nebraska and South Dakota. The western edge of this moisture plume will see strong daytime heating despite some increasing high cloud cover, according to the SPC Day 1 outlook.

The key ingredient missing through much of the day is forcing. SPC forecasters note that "forcing will likely remain negligible through the day and limit storm coverage" even as moderate buoyancy develops over western Nebraska. Translation: the atmosphere will have fuel for thunderstorms, but not much of a trigger to get them started.

That changes this evening.

When will storms develop?

Storm coverage is expected to increase during the evening hours as a subtle vorticity maxima approaches from the west and the low-level jet strengthens. These features will provide the lift needed to overcome the cap and initiate convection.

The SPC outlook emphasizes that large hail will be possible with the strongest of these storms. Given the Marginal Risk designation, coverage will remain isolated, but any storm that does develop in the favorable environment over western Nebraska or the Black Hills could produce hail larger than one inch in diameter.

Where is the highest risk today?

The Marginal Risk area covers:

  • Western Nebraska — the primary focus for isolated severe-capable storms this evening
  • Black Hills of South Dakota — similar setup with hail potential

Outside the Marginal Risk zone, scattered thunderstorms are forecast over north and central Texas late this afternoon, as well as isolated to widely scattered storms over northern Utah into central Wyoming. SPC notes that localized gusty winds are possible with the stronger storms in these areas, but uncertainty in coverage and magnitude kept these regions out of the severe risk area in this outlook update.

What to expect: hail is the main hazard

Large hail is the dominant threat today. The combination of moderate buoyancy, adequate moisture, and evening-hour storm development favors hail production over other severe hazards.

Damaging wind gusts are not entirely off the table, particularly with any stronger cells that develop, but the environment is not especially conducive to widespread wind damage. Tornado potential is not mentioned in the SPC outlook and appears negligible given the setup.

Last night's severe weather

Overnight, a handful of severe reports came in from Oklahoma. Quarter-size hail was reported at 0033 UTC about three miles northeast of Lake Lawtonka along Meers-Porter Hill Road. Two wind reports followed shortly after, including trees down south of Midway Church and roadway damage near Hulen, with photos provided by storm chasers and broadcast media.

These reports represent the tail end of Saturday's activity. No tornadoes were reported in the last 24 hours.

Looking ahead: quiet pattern continues

SPC Day 2 and Day 3 outlooks show no severe risk areas of Marginal or higher. The pattern remains largely quiet across the Lower 48 as we close out September, with today's isolated High Plains activity representing the only organized severe threat on the national radar.

If you're in western Nebraska or the Black Hills, keep an eye on radar this evening and have a plan to move indoors if storms develop nearby. Hail can damage vehicles and crops quickly, and the strongest cells may produce stones larger than golf balls.

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