Reed Timmer's Rocket Deployment Paper Preprint

Very interesting data. Especially the very high vertical velocity of 65 m/s at just 1 km AGL on the northwestern edge of the tornado, which agrees with idealized numerical simulations of strong tornadoes regarding the position (northwest), height (1 km AGL) and magnitude (65 m/s) of this feature.

One of the differences between strongly tornadic and weakly or non-tornadic supercells is the presence of very high updraft velocities at low altitude. In ordinary thunderstorms, updraft velocities at 1 km AGL are generally only on the order of 10 m/s. This remarkable difference is presumably caused by large amounts of wind shear between the surface inflow layer (about 0 - 200 m AGL) and higher layers (> 500 m AGL). The air from the surface layer is ingested by the updraft and blocks the airflow at higher levels (due to conservation of linear momentum), causing a positive vertical pressure perturbation in front of the updraft (forcing the air to descend), and a negative vertical pressure perturbation inside the updraft (increasing low level updraft velocity). So that is what low level wind shear actually does to an updraft.

In summary, if a strong tornado spawns, the low level updraft velocity is high. However, the converse is not always true. One can have a high low level vertical velocity and still no strong tornado!
Feb 19, 2021
Reed deserves a lot of credit for this. The combination of the valuable science and the initiative to create this instrumentation system should be celebrated.
Apr 23, 2010
There has to be a place for tinkerers, and outsiders. This hasn’t been done since—when? Sterling Colgate and paper rockets?