Thundersleet

John writes from Oklahoma:

Hey Marc,

We've had some odd weather here today. A major winter storm moved in and combined with energy from the Pacific system that dumped rain on CA yesterday. Today's high was around 15F but we had a fairly large amount of thundersleet. Previously I had seen and heard thundersnow at temperatures near freezing (in New Mexico and here in Oklahoma) but thundersleet, particularly at such a low temperature was a new experience for me. There are a few videos of it in Norman (just south of OKC). I'm linking one below.

Currently the city is pretty much shut down. Snow/sleet accumulations are only about 2" but it's packed on the streets and very slick. All schools and state offices are closed tomorrow. I guess I'll go up to the shop and sit around and drink coffee...

John

I reply:

Hi John:

That’s real interesting. If the maximum temperature was 15 F (-9.4 C), and the zone of maximum charge separation is generally at -15 C (5 F), and since typical lapse rate is 6.5 deg C/km, it means the zone of maximum charge separation was no more than one kilometer above the ground. So, you were very nearly within the lightning-producing zone of the storm.

Rainfall amounts in Northern California were fairly modest. There was more rain in Southern California, but even there, the amounts were not close to records.
Marc