Question About Cold Core Tornadoes

[Eric Wind]

I have moved to Oregon from Texas and I've been here for three months. As most know, tornadoes in Oregon are rare, but it seems I've brought the weather with me. In the last two weeks, there've been three cold-core tornadoes that spawned around the Portland area. All weak, EF0 - 1, but I also noticed that these storms were never tornado warned (or they weren't warned as far as I know.)

Me being an amateur, I've got a question that may sound stupid but: do cold core tornadoes have a radar signature similar to the tornadoes you'd see in the plains? Is it difficult for meteorologists to detect a cold-core tornado, and therefore can't tell it from any other storm?

 

[rdale]

They don't look anything alike on radar. They are very difficult to see due to their weakness, and terrain radar beam blocking.

 

[Jeff Duda]

If a cold-core tornado occurred close enough to a radar site, it would appear similar to tornadoes spawned by supercells. However, due to the smaller size of cold-core tornadoes, they are pretty much never adequately sampled by the NEXRAD network. Also, as Rob mentioned, they are generally quite weak and would not produce a big velocity couplet even if sampled adequately. These are among the reasons it is very difficult for a meteorologist to detect a cold-core tornado producing storm. They typically look like ordinary thunderstorms.

 

[Paul Knightley]

I've always had a bit of a beef with labels such as 'cold core tornado' but let's not worry about that now! That term is not used over here, but that's probably more likely because we don't feel the need to distinguish between large, warm airmass supercells and their tornadoes, and others, because the former is very rare in the UK.

Anyway, part of the reason is, of course, because colder airmasses are thinner and the tropopause lower, that radar beams may not intersect the strongest part of the rotation - another is, perhaps, because the rotation is narrower.

What we should also consider is what 'type' of convection the tornado has developed from - supercells come in a vast range of sizes and cold airmasses can certainly contain supercells - one occurring near a radar site might look much like a Great Plains monster, but on a much smaller scale. Further away, and much of the storm may be beneath the radar beam.

Tornadoes also develop from ordinary cells, in both warm and cold airmasses. The larger scale rotation tends not to show up very well at all, if at all, on radar whether the storm is in a 'warm' airmass or not.

 

[Justin Wilcox]

Welcome to the wet coast Eric lol. I lived De Kalb, TX for about 13 years off and on. Now I'm back here in Oregon. Have you noticed how overly dramatic Oregon gets about their weather?