The first day of the EWP has been pretty intense but very interesting. I focused on a couple of storms in Texas: the first just west of Houston died pretty quickly but the second, north-west of New Orleans, proved more interesting. One of my favourite products so far is ProbSevere but I’ve found that it can be inconsistent with the polygons and probabilities.

At 21:00Z (below) there’s a 55% probability polygon highlighted in a high 0.5 Reflectivity area. To the northeast of this is a 5% polygon shown.By 21:20Z(below) these two polygons have merged with an 82% probability. The 0.5 reflectivity does not back this up, neither do the dangerous thunderstorm alert tracks.

Twenty minutes after at 21:40Z(below) the polygon has split again: 65% to the south and 5% in the north.It is proposed that this may be due to the thresholds used to create the polygons and the proximity of polygons to each other (i.e. polygons cannot appear to overlap). This is also just one case study so further study is required!

Minnie