Alabama 811 | Know What's Below.

Do You Feel “Slighted” By Severe Weather Outlooks?

| February 8, 2010 @ 9:22 am | 6 Replies

Note: I want to thank everyone who gave their thoughts on my questions about weather forecasting over the weekend. Your response will give great fuel for the discussion on tonight’s WeatherBrains. Here are links to the other two posts:
Sacred Cows Make the Best Burgers
Your Thoughts Please

TODAY’S DISCUSSION…

What do you think of when you think of the word “slight”? Do you think “small”? Do you think “of little importance”? Do you think “not serious”?

That may be what you think when you hear a convective outlook from the Storm Prediction Center. Severe thunderstorm risk areas are defined as slight, moderate and high. That nomenclature has been used since 1980.

Prior to 1980, the terms “isolated,” “few,” “scattered” and “numerous” were used. When the change was made in 1980, the terms used were “low,” “moderate” and “high.” It was decided that in theory, the risk is never “zero,” it is always at least “low.” Hence the change was made that fall to make the lowest category “slight.”

In 1980, the general public was not listening to the convective outlooks. The only people who read them were National Weather Service employees, pilots and people who visited National Weather Service offices.
Today, things are different. The daily severe weather outlooks are read by hundreds of thousands of people on the internet and are a mainstay of television weather broadcasts all over the company. Perhaps it is time that the terminology be rethought.

The slight risk category corresponds to a 5-15% probability of severe weather within 25 miles of points in the outlook area. The moderate risk category corresponds to a 15-30% probability and the high to a greater than 30% probability. Monday night’s Guest WeatherBrain, Dave Freeman, says that 30% is only good in baseball.

If you could change the risk category names, what would you change them to?

Follow my daily weather history tweets on Twitter @wxhistorian.

Category: Pre-November 2010 Posts

About the Author ()

Bill Murray is the President of The Weather Factory. He is the site's official weather historian and a weekend forecaster. He also anchors the site's severe weather coverage. Bill Murray is the proud holder of National Weather Association Digital Seal #0001 @wxhistorian

Leave a Reply

You must be logged in to post a comment.