We are in the process of educating our guests on the gridded probabilistic warning concept. Our IOP will probably begin around 6pm, over the Ohio Valley. Hoping there are still storms around when we begin, as the training today is taking a little longer than we planned. We also need to take a dinner break! So I’m going take notes on the blog to capture some of the PW training discussion.

Some good questions already – what probability numbers should be used? Forecasters need to be calibrated since they haven’t really thought about this.

How will we verify events in sparsely populated areas like the desert Southwest?

The spreading polygon is opposite to a probability contour. If the initial warning is set to, e.g., 50%, as the warning grows larger down the swath, the probabilities are actually smaller due to the uncertainty. If you look at a probability grid, the 50% contour will actually come to a point rather than spread out with time.

We’ll try do a demo live case, with NSSL driving first, and then letting each forecaster try it out, before the forecasters go through the archive case with the job sheet. The archive case will be doneon Tuesday.

Greg Stumpf (EWP Weekly Coordinator, 28 April – 2 May)