TL;DR

The Storm Prediction Center has issued a Slight Risk for severe thunderstorms across two regions today: the Mid-Atlantic and Northeast, and the Central Plains. Large to very large hail—some exceeding 2 inches—and severe gusts are possible across southwest South Dakota into western and central Nebraska and northwest Kansas. Peak activity is expected between 1 PM and 8 PM local time in the Northeast, and late afternoon into evening across the Plains.

Where is the highest risk today?

The Storm Prediction Center's Day 1 Convective Outlook places a Slight Risk across two distinct regions:

  • Mid-Atlantic and Northeast: From eastern Pennsylvania northeastward through western New England and southern Vermont.
  • Central Plains: Southwest South Dakota into western and central Nebraska and northwest Kansas.

Both areas face organized severe thunderstorms capable of producing damaging winds and large hail. The Plains corridor could see hail exceeding 2 inches in diameter with any sustained supercells.

A Marginal Risk surrounds both Slight Risk areas, extending south into the central Mid-Atlantic, west across the northern Rockies and High Plains, and south into parts of the Colorado Front Range and south-central Texas.

Northeast and Mid-Atlantic: damaging winds and hail

A mid-level shortwave trough will advance northeastward through the day, embedded within a larger trough stretching across the eastern United States. At the surface, a weak low over eastern Ontario will track into Quebec this afternoon, dragging a cold front southeastward across the Mid-Atlantic and Northeast.

Stronger daytime heating is forecast across the Mid-Atlantic ahead of the front, with some cloud cover potentially limiting instability farther north. Even so, moderate instability should develop by this afternoon, paired with sufficient deep-layer shear for updraft organization.

Storms should fire between 1 PM and 4 PM EDT, initially across the northern Mid-Atlantic and spreading northeast into the region and vicinity.

Hazards

  • Damaging winds and severe hail are the primary threats, especially from northern Maryland northward.

Storms should be a mix of multicells and supercells, tracking generally eastward through the evening.

Central Plains: large hail and supercells

The Central Plains will sit between upper-level ridging over the Southwest and troughing over eastern Canada, with modest northwesterly flow aloft. A weak mid-level impulse is forecast to aid convective initiation across southwest South Dakota into western and central Nebraska this afternoon.

Surface dewpoints in the 60s°F, combined with daytime heating and steep mid-level lapse rates, will foster moderate to locally strong instability. SPC notes that "a rather favorable environment for supercells will exist" despite weak large-scale forcing.

Timing and hazards

Storms should initiate between 19Z and 21Z—roughly 2 PM to 4 PM CDT—across southwest South Dakota and western Nebraska, then track south-southeastward through the late afternoon and evening.

  • Large hail is the primary threat. SPC warns that "any sustained supercells will be capable of producing large hail (some 2+ inches)."
  • Severe gusts are also possible, though SPC notes uncertainty about whether storms will cluster into a damaging wind-producing complex this evening.

Cities in or near the threat zone include North Platte and Scottsbluff in Nebraska, and areas near the Kansas-Nebraska border.

An isolated severe hail and gust threat also exists farther west and south across the Colorado Front Range to the Raton Mesa vicinity, though deep-layer shear will be weaker in those areas.

Other areas to watch

Northern Rockies and High Plains

A mid-level jet will translate northeastward across the northern Rockies today, aiding isolated to scattered thunderstorm development this afternoon. Activity should spread into the adjacent High Plains through the evening.

Low-level moisture will remain limited, but steep lapse rates and strong deep-layer shear support a threat for isolated severe gusts with high-based convection.

Great Basin

High-based thunderstorms should develop this afternoon across northeast Nevada into northwest Utah and southeast Idaho. Steep lapse rates and large DCAPE (downdraft convective available potential energy) will support potential for strong to severe outflow gusts as convection spreads northeastward into the early evening.

South-central and coastal Texas into southern Louisiana

Ongoing thunderstorms across southern Louisiana may produce gusty winds this morning before moving offshore. Additional storms may develop this afternoon from south-central Texas toward the upper Texas Coast, with isolated severe downburst winds possible given ample moisture and instability. Weak deep-layer shear should limit the overall severe threat.

Yesterday's severe weather

No tornadoes were reported in the last 24 hours. However, 75 wind reports and 22 hail reports were logged across 15 states, concentrated in the Southeast, Midwest, and southern Plains.

Notable reports include:

  • 2-inch hail (golf ball size) near Higginson, Arkansas, at 1900 UTC and near Gun Barrel, Wyoming, at 2250 UTC.
  • 1.75-inch hail near Summerfield, Oklahoma, at 2241 UTC.
  • 1.5-inch hail near Searcy Municipal Airport, Arkansas, and near Haslet, Texas.

Wind damage was widespread across Alabama, with multiple trees and power lines downed in Lawrence, Morgan, and Limestone counties. Additional wind damage was reported across Arkansas, Missouri, Mississippi, Illinois, Indiana, and Florida. A 61 mph gust was measured at Melbourne International Airport in Florida at 2013 UTC.

What to expect tomorrow

SPC's Day 2 outlook shows a Marginal Risk for parts of Nebraska, the central Plains, and portions of the Northeast on Friday, August 28. A Slight Risk returns to the northern Plains on Day 3 (Saturday, August 29).

Severe weather activity should remain relatively scattered through the weekend, with no high-end threats currently anticipated.

How to stay safe

If you're in the Slight Risk area today, monitor radar closely this afternoon and evening. Severe thunderstorms can develop quickly, especially in environments favorable for supercells.

  • Have multiple ways to receive warnings. Wireless Emergency Alerts for tornado warnings will break through Do Not Disturb on most phones, but third-party weather apps are silenced by silent mode.
  • Move to a sturdy shelter if a tornado warning is issued. Interior rooms on the lowest floor, away from windows, offer the best protection.
  • If large hail is approaching, move vehicles under cover and stay indoors away from windows.
  • Avoid driving through flooded roadways. Turn around, don't drown.

Outdoor warning sirens are designed for people outside and may not be audible indoors, especially in modern well-insulated homes or with air conditioning running.

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.