Yellow, Green — What do the SPC categories mean?

Weather

NASHVILLE, Tenn. (WKRN) — You’ll see meteorologists use maps like the one below all the time, especially during the spring and summer months. They’re the Storm Prediction Center Convective Outlook Maps. When you see them, you know there’s bad weather on the way… But what do they actually mean?

The first thing you need to know, is that these maps show the areas where severe thunderstorms are most likely over the coming days. Based on the makeup of the incoming weather system, the map is divided up into categories

Let’s break it down.

If an incoming system could spark an isolated severe storm, but not widespread severe weather, the map will call for the “Marginal” category, which is a dark green. That’s what we call, “Category 1.”

If we’re looking a small number of scattered, severe storms, but not widespread severe weather, we’ll wind up in the “Slight,” or yellow category. In this case, any storms we do see will likely be short-lived.

From there, things get a little dicier.

Once we wind up in the orange, or “Enhanced” category, we’re looking at numerous severe storms, which have the potential to be longer-lived.

Category 4, the red category, is “Moderate”… And while the word “Moderate” might not ring any alarms, that category can be rather alarming. It essentially means that we’re looking at widespread severe storms, some of which could be intense and damaging.

Finally, there’s the 5th category– the magenta, “High” category. In this category, the expectation is not just widespread severe storms, but storms that will likely be very intense, damaging, and long-lived.

No matter which category, if any, you find your home in on a given day, remember that severe weather is no joke! Stay aware, stay safe, and always know you can tune into News 2, and download the WKRN Weather App to take the latest information on the go!

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