Unit 10 of 12 · 1 of 5 lessons published
Forecasts, watches and warnings
What the National Weather Service and its Storm Prediction Center issue, from outlooks days ahead to warnings minutes ahead, and how to read each product: what it means, who writes it, and what the text says that the map does not.
The products form a sequence that narrows in time and space: a convective outlook for the day, a mesoscale discussion for the next hours, a watch for a region, a warning for a storm. The lessons follow that sequence. Past warnings can be read as issued in the alert archive.
- Tornado watch vs. tornado warning
What each product means, who issues it, every level from a marginal risk to a tornado emergency, and how good the warnings are.
- How to read SPC convective outlooks
The categories, the probabilities behind them, and the discussion text.
- Mesoscale discussions
The Storm Prediction Center’s short-fuse reasoning, and how to read one.
- Area forecast discussions
The forecaster’s own reasoning behind your local forecast.
- The Enhanced Fujita scale
How tornadoes are rated from damage, and what the ratings can and cannot tell you.