Module 02: Thunderstorm fundamentals

Three ingredients make a thunderstorm and a fourth decides what kind you get. Each of them has a number attached, and the numbers are on the same forecast pages you already look at. (35 min)

An ordinary thunderstorm builds the thing that kills it. Watch the sequence once with that in mind and the timings stop being trivia. (30 min)

Same moisture, same instability, same lift, different wind profile, completely different day. Shear is the parameter that turns a forecast of storms into a forecast of a storm mode. (35 min)

The storm that will not look severe, has no rotation to report, lasts half an hour, and puts a tree through somebody's roof. Most of our summer severe weather comes from this. (25 min)

A cluster can move northeast while every cell in it moves east, or sit still for three hours while its cells race away downstream. Once you can separate the two motions, radar loops stop being confusing. (25 min)

A supercell is not a big thunderstorm. It is a thunderstorm that has solved the problem in lesson 2, and rotation is how it solves it. (35 min)

The supercell you were shown in class is a photograph from Kansas. This lesson is about the ones that actually arrive here, most of which you cannot see. (30 min)

A line of storms is not a big multicell cluster. It has its own dynamics, its own tornado problem, and a definition dispute running through the middle of it that is worth understanding rather than memorising. (40 min)