2019-11-26 EVENT: MO/AR

[Dan Robinson]

A couple of fall season events to watch and possibly chase for many of us in the Plains and Midwest this week. Models have generally increased instability across the board for tomorrow's 100kt+ jet streak moving across the Ozarks, with some areas showing 1,000+ of MLCAPE. NAM, GFS, Euro and the CAMs are in general agreement on timing and placement of features and storms, with model-to-model differences mostly on the order of only 1 to 3 hours. Directional shear and midlevel lapse rates are meager, but this is made up big time with very strong speed shear regionwide. Low-level lapse rate quality will be contingent on any cloud breaks, which may be hard to come by given the amount of lift moving across the region.

The main chasing challenges of this event are post-sunset storm organization, very fast storm speeds and unfavorable terrain/roads. The left exit region of the jet will likely make mid-Missouri the preferred target, providing meaningful instability is realized that far north. The best case scenario is if we can get the better moisture and a few cloud breaks during the afternoon along and north of I-70, as the options for roads and views are much better in that region. A possible strategy may be to move east on I-70 through the evening, intercepting storms as they cross the highway. The storm speeds may make even a straight interstate chase difficult.

My current thinking given model portrayals of this event is a starting target of Sedalia, MO, moving east back toward St. Louis to catch individual updrafts as they cross the highway. The risk of falling behind will be high however, and one may need to position farther east to await sufficient storm organization.

 

[Jesse Risley]

I've also been watching up north here more proximal to the surface low itself, partially due to work obligations through mid-afternoon. It's a synoptically favored region and there are still some good shear parameters overlapping the region out ahead of the main forcing when the broken line approaches the Mississippi River. Obviously thermodynamic profiles are very paltry, but past events like this up in NE MO, SE IA and WC IL have often yielding spin ups from low topped supercells embedded in the main line, and shear profiles certainly favor that on the latest NAM and HRRR cycles.

 

[Dan Robinson]

I scratched the idea of heading to Columbia/Sedalia due to after-dark storms and the insane holiday interstate traffic (a logistical factor I hadn't considered before today). CAMs still aren't initiating storms out there, but the cumulus field and little sbcape bubble is making me nervous about my decision. I'm skeptical of the portrayal of storms this far east thanks to the early junkvection and rain, but thinking now is to wait and see if something can fire near the back edge of the cloud deck and hope for some lightning. Again, traffic is absolutely nuts, especially in the city, so I'm not very inclined to try to go too far west. Some years, I-70 has been backed up (red and orange on Google traffic maps) from Columbia to St. Louis just due to the holiday traffic. No indications of that yet, but the city has been pretty congested all day. Not good when those are the primary chase target roads for the day.