US 2026 Season: Record Hail and EF3 Tornadoes — Lessons for UK Chasers

What's Happening Over the Atlantic

The 2026 US severe weather season has opened aggressively. The headline event so far: an EF3 tornado tracked through the southern suburbs of Kankakee, Illinois in mid-May, damaging over 500 buildings and killing one person before crossing into Indiana and striking Lake Village. The same supercell produced what may be record-breaking hail — reports of 5 to 6-inch hailstones in the Kankakee area are being investigated by the National Weather Service.

Elsewhere, the Storm Prediction Center has issued multiple Level 4 of 5 risk days across Kansas and Nebraska, with significant tornado outbreaks across the Central Plains producing dozens of confirmed tornadoes and hundreds of large hail reports in single events.

By UK standards, this is another world. But it's worth paying attention — here's why.

The Jet Stream Connection

The pattern driving the US season is the same planetary-scale jet stream that eventually steers weather systems toward the British Isles. Amplified ridging over the Rockies and deep troughing over the Central Plains — the classic setup for tornado outbreaks — is part of a wave pattern that, as it progresses eastward, often produces a trailing trough over the Atlantic and eventually the UK.

This isn't deterministic. A US tornado outbreak on Monday doesn't mean a UK severe weather day on Wednesday. But understanding the synoptic evolution that produced the US activity helps you read the downstream implications when the same wave train appears on UK NWP output.

Scale and Ingredients

The obvious difference is ingredients. The US Plains offer surface dewpoints of 18–22°C, thousands of joules of CAPE, and 40+ m/s of bulk shear. The UK rarely sees more than 800–1200 J/kg of CAPE and works with much more modest shear values.

But the UK's challenge isn't the absence of instability — it's the rarity of sustained, deep moisture ahead of a well-defined dryline or warm front. When that moisture is present (as it increasingly is during heat plumes), and when cold upper troughs provide the trigger, UK convection can organise in ways that would surprise anyone who only expects US-style supercells.

What to Watch

The current US pattern — energetic jet, frequent trough-ridge couplets, elevated instability — tends to persist through much of spring and early summer. When those troughs eventually reach the UK (typically 5–7 days after the US active period), assess:

1. Surface moisture: Are dewpoints above 12°C across southern England? 2. Mid-level lapse rates: Is there cold air above 500 hPa? 3. Wind shear: Is there 10–15 m/s of 0–6 km shear?

If yes to all three, the same atmospheric physics that produces tornadoes in Kansas is at work in Kent. The scale is different. The mechanism is identical.