Back in June 2015, I posted two reference guides that could be useful when interrogating storms on radar. The first was related to tornado intensity estimation in real-time, and the second was related to analyzing tropical cyclone tornadoes. After posting these, I worked with some people with the Warning Decision Training Division (WDTD) to fine tune some of the numbers on the first reference guide. The tropical cyclone tornado reference guide remains unaltered from the initial version. You can find the initial post by clicking here.

Before I share the updated reference guide, let me reiterate these words of caution that I included with the original post. Please read them before using.

Caution should be used so that you don’t interpret these rules of thumb too specifically in real time. I repeat, caution should be used. However, they can still give you a good sense as to whether or not a strong or violent (EF2+) tornado is possible in a given situation, and therefore they do have some operational utility.

Remember, this is a reference guide with some rules of thumb, so the numbers listed aren’t intended to be taken literally in every situation. For example, a 60 knot maximum rotational velocity with a tornadic supercell doesn’t guarantee a strong tornado, but it does indicate you are in a situation where a strong tornado would be more likely. As one of the tips points out, that would be especially true if the tornado was moving fast, in a very favorable environment for strong tornadoes, or the signature was sampled poorly. The “overlap” ranges listed on the chart in the bottom left corner do not encompass all cases of overlap. Therefore, the general principle is that as your rotational velocity and/or tornadic debris signature height increases, so too does the likelihood of a more intense tornado on average.

Updated Tornado Intensity Estimation Reference Guide

A one page reference sheet for radar tornado intensity estimation.

A one page reference sheet for radar tornado intensity estimation.

This reference guide is available as a higher resolution PNG image file by clicking the image above, or as a PDF by clicking here. You can also download an updated PDF version of the 2-page combined reference guide (tornado intensity and tropical cyclone tornadoes), by clicking here.

Thank You

Thank you to the Warning Decision Training Division for the suggestions to improve this reference guide, particularly Jim LaDue and Justin Gibbs for their collaboration and expertise.