Storm Prediction Center adds new severe weather intensity levels for Big Country

BIG COUNTRY, Texas (KTAB/KRBC) – Beginning March 3, the Storm Prediction Center (SPC) will issue an update to its Severe Weather Outlooks, adding more details on how severe storms could be if they develop. The changes will take effect at 16:30 UTC (11:30 a.m. CST) that day for the Day 1 Convective Outlook and will also apply for the Day 2 and Day 3 outlooks.

The primary purpose of this update is to provide the public, meteorologists, and emergency management with more information about not only the likelihood, but the potential intensity of severe weather in the Big Country.

What does it mean to stay the same?

First of all, the familiar appearance categories do not change. Terms you usually hear, such as Marginal (1/5), Light (2/5), Advanced (3/5), Medium (4/5), and High (5/5), will be used the same way and appear with the same frequency as before the update. These categories will still describe the overall potential for severe weather impacts in the Big Country.

What’s changing?

We can also expect density information with this update. “Conditional density” information will not be added. This means the SPC will communicate the severity of any potential weather event.

Here is an example:

• How strong can a hurricane be if it forms?

• If damaging winds occur, how strong can they be?

• How big can hail get if it falls?

This new intensity information will now appear in individual hazard graphs for tornadoes, wind, and hail. We will share these developments with you.

Introducing Conditional Density Groups (CIGs)

Starting in March, SPC will display density using three levels called State Density Groups (CIGs). These may also be called “Intensity Levels”.

• Intensity Level 1 (CIG1): Low-end intense intensity

• Intensity Level 2 (CIG2): Stronger, more impactful severe weather

• Intensity Level 3 (CIG3): The most intense and potentially dangerous severe weather conditions

Two intensity levels will be used for hail instead of three.

It is important to remember that all of these intensity levels are conditional. There is no guarantee that severe weather will occur when these levels are announced; They provide explanations of what might happen in such a situation.

These intensity levels will replace the current “SIGN” (important) label.

Visual Changes to Outlook Charts

This March, viewers will notice a cleaner look in SPC graphics. Some text labels will be carried directly into the legends on the map, making the maps easier to read. While the appearance of these charts will change, the meaning of the view categories will remain the same.

Expanded Wind Possibilities

Another change is the addition of higher wind probabilities. SPC now adds 75% and 90% wind probability levels, allowing meteorologists/forecasters to better highlight areas with a very high likelihood of damaging winds.

How Are Categories Still Determined?

Despite all the upcoming updates, the Storm Prediction Center says the way probabilities and intensity are combined to create the final categorical outlook is designed to closely match historical practices. This means that even though we see more information, the overall views will be familiar and consistent with what you’ve seen before.

Overall, these SPC outlooks will provide more detail on the severity of potential severe weather conditions while retaining the categories the public already knows about. This additional information is designed to improve understanding, preparedness, and decision-making ahead of severe weather events in the Big Country.

As we get closer to March 3, we will monitor the website for more updates and information and keep you all informed.

Stay on top of the weather forecast and be sure to tune in here for updates from your Big Country Storm Team.

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