Severe weather days are always marked by the Storm Prediction Center (SPC) with an outlook, several days in advance with different categories for how high the threat for an area is.
You may have seen them before, an example of the old style is the first on the attached images, but now a change is coming and you need to know to understand what the new categories mean.
First off, there are always Day1-Day3 outlooks that say severe weather is possible.
We get this info and make a graphic like the first image and tell you there is a Slight, Moderate, or High risk for severe weather.
General thunderstorms have always been shaded in green.
NOW, the SPC has issued brand new categories to pinpoint specific ares of interest a bit better.
Basically, it all comes down to percentages and an attempt to be more accurate to specific areas.
For those of you who want to see what those are you can look at the last picture that shows where each severe weather type is and how its percent chance affects the risk category.
The middle picture is an example of what the first image would look like under the new style.
General thunderstorms would now be shown with a blue highlight, something not on this picture since regular thunderstorms are expected with severe weather anyway.
The green is now the Marginal threat, meaning basically strong winds may happen, a weak Severe Thunderstorm, or more commonly Significant Weather Advisories.
From Marginal we go to Slight risk.
Slight will basically move up in severity a bit and could cover Severe Thunderstorms, wind damage events, and small tornado chances.
From Slight we go to the new Enhanced risk.
Enhanced is what moderate use to be but also covers the low level High risk now.
Enhanced will cover widespread Severe Thunderstorm possibilities, most likely a tornado watch or thunderstorm watch, and also a higher risk for tornadoes.
Moderate is the next step up and means there is a large risk for severe weather to occur.
What we had occur in November, the strange severe weather outbreak, would classify as a high level Enhanced or low level Moderate under the new system.
Areas in the High risk that day would still be under the High risk with the new system.
High risk on the new system means there is a highly significant chance for severe weather and will most likely be reserved for days where tornado outbreaks are expected.
Now you know what to watch for this coming year.
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