I've wasted a lot of gas driving toward storms that looked angry on the horizon and turned out to be glorified rain showers with an attitude. The supercells that actually keep me up at night share a pattern. I keep this checklist in my notes app. Yes, I'm that guy.
The Seven Signs
- Rotating wall cloud — organized, persistent, not just scud doing scud things.
- Clear slot / rain-free base — that visual gap under the storm where the inflow is feeding the beast.
- Large hail report on radar or spotter net — golf ball and up means serious updraft.
- Hook echo holding together — two, three, four scans. Not a blip.
- Velocity couplet tightening — the red/green hug getting closer on radar velocity.
- Storm motion that's not drifting — supercells have purpose. They commute at 30-40 mph like they're late.
- PDS wording in alerts — Particularly Dangerous Situation. When the NWS uses that, I stop debating.
Seeing one or two of these isn't automatic panic. Seeing four or more together, in the golden tornado corridor, on a day with high CAPE and good shear? That's when I make sure my go-bag is in the truck and my interior room is cleared of the junk we swore we'd organize last year.
Supercells are beautiful. They're also the reason Oklahoma has more storm shelter vendors than coffee roasters. Respect the checklist.