Mar 082011

Monday, 7 March 2011

The last twelve hours have been as much of a blur as an adrenaline high. It began with staying up very late looking at weather data, to purchasing a last minute flight to Wichita, KS. Then, getting stuck in traffic on the way to JFK due to an accident on the interstate. I arrived at my gate just in the nick of time to catch the flight, too, but only after running through a decent stretch of the terminal (the flight left early, too, so the running was most certainly warranted!). And now the adrenaline is wearing off a bit. But that doesn’t matter, because the prospect of tornadic supercells tomorrow will keep me going. And I’ll be there, hopefully in the right place at the right time.

My friend and long time chasing partner Simon Brewer was kind enough to offer to pick me up at the airport tonight (Monday). Once we finally get to his place in Norman very late tonight, the updated computer models will be available. Hopefully, the data will be good news for us, but we’ll see. Every setup is risky with different things that can go wrong, and this one is no different.

I decided to pull the trigger on this chasing trip for the cold core tornado setup. I’ve seen many of these produce amazing tornadoes over the years, but just never had the opportunity to chase a classic one before. I do believe this is one of those setups, which is why I’m heading out there. All the synoptic scale features seem to be in place, with some small, but key differences between the WRF and GFS models.

Probably the most notable difference is the low level moisture. The GFS (at least at 12z this morning) was more enthusiastic with bringing deeper moisture into Oklahoma, while the WRF backed off a little bit from the 00z run. The only positive thing I can say about that is it’s normal for low level moisture to be a concern leading up to a cold core event. It’s the cold temperatures aloft that usually save the day. So I’m hoping moisture isn’t a problem even though the concern is in the back of my mind.

Another concern that really goes for any cold core tornado setup is the relatively short window of opportunity you sometimes have for tornadoes. While these types of setups have a high probability of producing tornadoes, it’s usually within a 1-3 hour (or less) window of time. Not only that, but all the features have to line up precisely, or you don’t get the tornado-producing storms from some of the more classic events.

Finally, I’d love to see the WRF and GFS agree on the exact location of the surface low. I’m getting a little picky here, but that is vital for tomorrow’s setup. With such intense dynamics in place, you really can’t expect two separate models to completely agree on this 36 to 48 hours in advance. But it would give me even more confidence in this setup if they come to agreement tonight (wishful thinking).

Well, my fingers are crossed!

- Jim