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Long-term remains quiet, with a few diamonds in the rough
Looking out 2 weeks into the future, there still isn't any sign of the classic western trough bringing multiple quality tornado setups to the Great Plains. As such, my optimism for a Plains trip happening out to at least the 17th remains very low. A deep *eastern* US trough instead looks to get established for a while.
Now the situation for the next few days depends on your observing status. If you're more of a 'spot' observer like I am, saving money for the higher-probability, multi-day, more-success-guaranteed setups to materialize, then you're looking at some long-term downtime. However, if you're 1.) an all-season observer with unlimited resources, 2.) one that has taken a fixed chase vacation during this week, or 3.) one that's just feeling adventurous and willing to take a gamble, you might have some reason to be optimistic. That's because a small western trough will begin overspreading west-southwesterly upper flow over decent moisture in southern Texas from Tuesday through Thursday (see 500mb GFS forecast for Thursday evening below).
Any time midlevel flow at or above 30-35 knots moves overtop of even marginally good moisture at the surface (on the dryline especially), you've got yourself an storm observation day - a day where something worthwhile can indeed happen. So if you're going to be observing out there anyway this week, you might just have a nice day or two. Beautiful supercell structure at the minimum looks like it's on the table for at least one of the days this week, and I'd say a tornado or three is likely to happen somewhere in southern Texas between Tuesday and Thursday. I've been out during similar setups in the past and have not been disappointed.
So why am *I* not observing this? Although the "distance to setup quality" ratio looks a little too much for me (going to south Texas is like my drive to the Plains from West Virginia used to be), my primary reason is work. I have a client job that will keep me tied to the St. Louis region until Saturday. Furthermore, I'm not like many storm observers with seemingly unlimited funds - I must pick and choose my Plains storm observing expedition dates carefully. Therefore, since I believe there will be much better Plains setups later in the season, it's probably best to save the money for those. Lastly, while upper support in the Midwest region will be too weak for severe weather, thunderstorms and lightning are likely to occur in the St. Louis region this week, providing yet another good reason to stay put.
One more point to make. The upcoming eastern troughing pattern is not too much different than that of May 2005 - and we know what happened the following June that season: several very good tornado events in the Plains once the pattern changed. It's definitely too soon to count out this season, but it's still impossible to tell whether we'll have such a 2005-like turnaround. Again, like with all seasons, we just have to wait and see.
The following table charts the probability of a Great Plains storm observing expedition for the indicated date ranges:
|2013 Plains Storm Expeditions - Probabilities as of May 6|