The data is from Meteogroup. They're a very capable private weather forecasting outfit, but they don't have the money for a supercomputer, so they take their base weather forecast data from… (View Post)

Have you checked the air pressure yet? (View Post)

Grid point storms then. Models of the atmosphere are designed subject to computing constraints. You want to run the model at as high a resolution as possible - i.e. with large numbers of grid points … (View Post)

It's a grid point storm. The models are run at the edge of numerical instability and so sometimes they tip over and you have a single grid point with huge vertical velocities, consequently drawi… (View Post)

Yes. It's a numerical instability in the model, which is normally caught when the model crashes after a negative number and/or a divide by zero. If it becomes quasi-stable they can persist for a… (View Post)