The months of April, May and June are the most active for severe weather in the United States. With our first threat of severe weather in the area today, it was a a great time for Meteorologists to introduce the new risk categories from the Storm Prediction Center (SPC).
About 6 months ago the SPC launched a new change to the way they categorize severe weather. The old method had 4 categories; See Text, Slight, Moderate and High. The new method now has 5, which include Marginal, Slight, Enhanced, Moderate and High.
The "See Text" was renamed to the new marginal risk category. According the Phil Schumacher, meteorologist at the National Weather Service in Sioux Falls, he says "basically what that means is there is a very low probability that one or two storms could produce 1" hail or 60 mph wind gusts." He says by using "marginal" instead of "see text" we are giving people information that severe weather is a possibility so that they could prepare in case storms were to hit later in the day.
The new category that was added is the Enhanced category. Enhanced is just a step above a slight risk. These are occasions when we are expecting significant severe weather such as larger hail or strong winds over 75 mph. Severe storms in an enhanced risk could do significant damage, but not enough to be classified as a moderate risk. Damage would be over a smaller area instead of more widespread.
In laymen terms, marginal is the very low end of a slight risk for severe weather. It gives people a little more awareness that it is more than just a thunderstorm.
On the other hand, Enhanced is on the higher end of a slight risk for severe weather. This can do enough damage but not widespread enough to be classified as a moderate risk. This will give more awareness that it's a more significant event then what we've seen with a slight risk in the past.
National Weather Service Meteorologist Brad Temeyer says the new categories are going to draw a little more attention to severe weather. They will give you more information because we are breaking down the categories to give you an even better understanding of what type of threat is expected across the area.