Tornado Central

What a horrible year. Moisture remains scarce and shallow, and will remain so until the ridge axis moves eastward. With continued east-coast troughing, ageostrophic curvature convergence aloft is creating large-scale subsidence across the Mississippi River Valley, maintaining a low-level high pressure system across the lower MS River Valley. This has shut the Gulf off, locking all true tropical moisture down across southern LA and TX. Heck, even the 12z CRP and BRO soundings were anything but impressive, with tropical moisture <75mb deep. It IS mid-June, right? Evapotranspiration is helping to locally increase dewpoints in some areas, but such moisture enhancement tends to be relatively shallow (especially in presence of this ridging). In addition, the main westerlies are staying north of I70. The resulting pressure gradient is yielding southwesterly 850mb flow, advecting seasonably hot air off the high Plains and effectively capping off the warm sector. With hot low- and mid-levels, combined with poor moisture (both in magnitude and depth), don't look for any significant tornado events across the Plains for a while. Wait, haven't we seen this pretty much all year? Whether it's meager moisture availability or weak flow aloft (or both), the 2005-2006 chase season pair must be the worst we've had in a decade and a half. Oh yeah, can't forget the ground-scraping 2000-4000m LCLs.

Now, that's not to say that ALL is lost. Indeed, some chasers scored big last year, and others have done okay this year. The problem is that, when setups are marginal or few-and-far-between, there's more of a chance that 'luck' will determine whether a chaser will see a tornado. All chasers will admit that, at times, they've been lucky or unlucky, in terms of whether they're on a storm that produces. There's a lot of skill in chasing, but there's also an undeniable aspect of luck. Last year, I missed out on the biggest two storms of the Plains chase season (6-9-05 and 6-12-05); this year, at least I was able to snag a cold-core tornado on 3-20 and the El Reno tornadoes on 4-24. It's also worth noting that I've had several other 'successful', yet tornado-less, chases in the past couple of years (including 8-17-05, 5-30-06, etc). In the end, however, the inability of Ma Nature to pull everything together is frustrating, to say the least.

I'm holding out about a 40% chance of chasing tomorrow, with the area between I70 and the KS/NE border looking most feasible. I'm a little concerned about the depth of the cool air, which may yield a stout cap and prevent surface-based convection. Strong upper-level flow move over western NE and WY, but that's farther than I want to drive now. The models do try to FINALLY bring tropical moisture northward out of the Gulf next week, but we'll see how that verifies. I guess I can enjoy the triple-digit heat...