Rain, Severe Storms, Flooding Possible For South

As the spring ramp-up of severe weather arrives, it’s important to know your risk. According to NOAA, there are roughly 10,000 thunderstorms every year in the U.S., and roughly 10% of those reach severe criteria.

The Storm Prediction Center and National Weather Service work tirelessly to make sure any threat of tornadoes, large hail or damaging thunderstorm winds is highlighted and well-communicated.

This year, the Storm Prediction Center is offering more specific details within its daily severe weather outlooks that will hopefully allow you to better understand and plan for severe weather.

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What’s Staying The Same

The SPC’s color-coded system to highlight the overall potential for severe weather is staying the same.

You may be familiar with the five different levels of severe potential:

• Level 1 (green): Marginal risk
• Level 2 (yellow): Slight risk
• Level 3 (orange): Enhanced risk
• Level 4 (red): Moderate risk
• Level 5 (Pink): High risk

Level 1 is used to communicate that there is a low-end, isolated threat of severe weather for a particular area. Whereas, a Level 5 threat is typically issued only two to three times a year and is reserved for days when confidence is high for a widespread severe weather outbreak with long-lived tornadoes and/or widespread damaging winds.

These threat levels will remain the same and will mean the same as they did before.

Here's What Is Changing

What’s changing in the SPC outlooks has to do with what it refers to as “hatched areas.”

Before now, these areas on the outlook maps simply showed where the area for increased concern was, not how strong the intensity of the impacts could be.

Hatched areas are areas of elevated concern — where forecasters think there’s a higher chance of either strong winds, hail and/or tornadoes.

Now, these hatched areas will also be given an intensity level. These areas will be referred to as “conditional intensity groups" (CIG) or more simply, "intensity levels."

The intensity will range from 1-3, and will be shown by different black patterns to reference which threat level is forecast. They will be added to the Day 1, 2 and 3 convective outlook maps.

“High-end severe weather like intense and violent tornadoes cause by far the greatest loss of life and property, and this improvement allows us to highlight days when these specific threats are more likely," said Evan Bentley, warning coordination meteorologist for NOAA’s Storm Prediction Center. Adding, “Now, even when the probability of a severe hazard is low but the intensity is high, we can convey that threat.”

For example, if a tornado threat exists for any given day, and the hatched area is:

• Level 1: The maximum expected tornado intensity would be at least an EF2 tornado.
• Level 2: The maximum expected tornado intensity would be at least an EF3 tornado.
• Level 3: The maximum expected tornado intensity would be at least an EF4 tornado.

According to the SPC, 88% of tornado deaths and 75% of tornado injuries are from tornadoes rated EF3 or higher.

This is what the new intensity level forecasts will look like on SPC convective outlooks:

Intensity Levels Will Also Be Given To Wind And Hail

Wind and hail threats will also come with intensity levels. Wind will be categorized by all three levels and hail will be categorized by levels 1 and 2.

Wind:

• Level 1: Peak gusts expected to top 74 mph
• Level 2: Bow echo/derecho possible.
• Level 3: Derecho (usually ongoing)

According to the SPC, 57% of all derechos over the past 10 years have resulted in at least one death or injury.

Hail:

• Level 1: Supercell enviornment with hail larger than 2 inches in diameter.
• Level 2: Long-track supercells with hail greater than 3.5 inches in diameter.

SPC forecasters have been experimenting with these new outlook changes since 2021 and have built the confidence during the last four years to release them to the public and officially make them operational.

Keep in mind that while meteorologists have made great strides in severe weather forecasting over the last few decades, it is still not a perfect science. Knowing what to do if your area is under the treat for severe weather could save your life.

(MORE: 15 Severe Weather Tips You May Not Know)

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.