On a Tuesday afternoon in late April, storm chasers and National Weather Service offices spanning Oklahoma, Missouri, and Arkansas are tracking a cluster of supercells already dropping hail up to 3.25 inches in diameter — roughly the size of a baseball.
The hail is dangerous, but it may not be the most pressing concern. In north-central Arkansas, temperatures are quietly climbing into the 70s and moisture is building, creating a subtle but significant shift in the atmosphere. Forecasters are watching one supercell in particular — and what it might become as it moves into that warming air.
Supercells unleash giant hail across the watch area
Severe Thunderstorm Watch 169 covers a broad swath of the central U.S., and the storms firing beneath it are producing. Multiple supercells — both right-moving and left-moving — have developed across northeast Oklahoma, central and southern Missouri, and northern Arkansas. Hail up to 3.25 inches in diameter has already been confirmed on the ground, and forecasters at the Storm Prediction Center expect the largest stones to reach between 2 and 3.5 inches before the event winds down.
The engine driving this activity is a combination of low-level warm advection and differential cyclonic vorticity advection, or DCVA, downstream from a short-wave trough currently moving through Kansas. Two energy sources are loading the atmosphere simultaneously, giving storms the fuel they need to grow tall and violent.
Because the short-wave trough is progressive — meaning it moves quickly rather than stalling — the storm cluster is expected to push east and northeast throughout the afternoon. Watch 169 may not be large enough to contain it. Forecasters have indicated that an additional downstream watch will likely be required to cover areas not yet included in the current boundary.
A shifting atmosphere raises the tornado threat in Arkansas
This is where the situation gets more complicated. Most of the active supercells are what meteorologists call “elevated” — riding above a cool, stable boundary layer where surface temperatures sit in the 50s and 60s. That cap on surface heat limits the connection between the storm and the ground, which in turn limits tornado potential. For most of the watch area, hail remains the primary hazard.
Northeast and north-central Arkansas are a different story. Filtered sunshine there has pushed surface temperatures into the 70s, a meaningful departure from the cooler air dominating elsewhere. A surface front draped across central and northeast Arkansas is also slowly lifting northward, allowing dewpoints to climb into the mid-60s just north of the boundary — warmer surface temperatures and rising moisture combining into a substantially more favorable environment for surface-based thunderstorm activity.
One storm is drawing particular attention. A supercell tracking through Searcy County, Arkansas, is expected to become increasingly surface-based as it moves east into this warmer, moister air mass. RAP forecast soundings — short-range model data used to assess atmospheric structure — show low-level wind shear gradually strengthening in response to an intensifying low-level jet across the state. Greater shear means greater rotational potential, and that raises the concern for tornadoes.
Watch expansions and what forecasters expect next
The Storm Prediction Center has signaled that current watch boundaries may not hold. An areal extension of Tornado Watch 170 could become necessary to cover north-central into northeast Arkansas as the Searcy County supercell and others move into the more favorable boundary layer. The eastward spread of the hail-producing supercells makes an additional Severe Thunderstorm Watch to the east and northeast of Watch 169 likely as well.
The numbers attached to this event deserve careful attention. Peak tornado intensity is estimated at 100 to 125 mph. Peak wind gusts are forecast at 55 to 70 mph. Peak hail size is expected between 2 and 3.5 inches. These aren’t marginal figures — they represent a genuinely dangerous afternoon for anyone in the affected corridor.
What this situation also illustrates is how quickly a severe weather event can shift character. What began as a hail-dominant outbreak, anchored by a straightforward forcing mechanism, has evolved into a tornado-capable event in one corner of the watch area — simply because surface air warmed a few degrees and moisture crept northward. Residents across north-central and northeast Arkansas should monitor updated watch and warning products closely throughout the rest of the afternoon. The next few hours will determine whether the atmospheric setup delivers on what the models and soundings are currently suggesting.