Severe Weather Forecast

I drove my eldest daughter back to Oxford this afternoon, a horrible drive through ceaseless rain which was interlaced with snow on the way back home. The matrix signs on the M40 said "Severe Weather Forecast Today", so we were in no doubt about the conditions we were driving through. However, I did wonder about the grammatical structure of this very straightforward message. I imagined the weather forecaster shouting and wagging a stern finger at the audience - not sure how one actually wags a stern finger, but I guess it is part of their meteorological training (they strengthen their fingers by lifting isobars) - and telling them that woe betide them if they don't heed the advice to wind-proof and water-proof themselves. That is a severe weather forecast, rather than a forecast of severe weather.