Spring 2009 tornado season sunset
While good upper flow has returned to the Great Plains, it is trying to transition to more of a westerly-northwesterly configuration - not as ideal for tornadoes. While the next two days don't look all that bad, the setups later this week look more like summer northwest flow events than tornado outbreaks. While I think that the Front Range will continue to see off-and-on tornado events, and the rest of the Plains may see supercells and a tornado or two daily (pretty much the last four days repeated into next week), it is not going to get to the point where we'll have several solid tornado setups to make a trip worth undertaking. The models are also nudging the jet northward in what would likely be a permanent change to end the southern-central Plains chase season. The GFS model and its ensembles are even trying to set up another ridge (in the form of an Omega block) by next weekend, which would also mean the final curtain for the 2009 season.
I have never embarked on a Plains chase trip after June 12, and I've always been home and done with spring tornado season by June 15 each year. I don't expect this year to be any different, that is, June 15 being the realistic cutoff for my Plains 'standby' period. With nothing spectacular evident on model forecasts through this 'cutoff date', I think it is safe to say that my 2009 spring tornado season is a wrap. As always, by the very nature of the atmosphere, I have to leave a slim probability for the unexpected.
So, it's time to move on to summer - to hurricane season, Midwestern severe weather days and mountain flash flood season. Barring a major change in the forecast pattern, this will be my final 'Tornado Alley 2009' blog post.
Based on the current outlook, this probability table charts the chance of the second Plains chase trip starting on a particular date:
