Severe Weather Broadcast Tools

MADISON, Wis. (WMTV) - When severe weather strikes southern Wisconsin, NBC15 meteorologists closely monitor storms, and we break into programming as necessary to keep viewers informed and safe. When we break in, we will oftentimes use three primary radar products to bring the information to you:

Reflectivity with Storm Tracking
Radial Velocity, and
Correlation Coefficient

Reflectivity

The Reflectivity product is the same radar we use on a daily basis. It measures intensity of rainfall, and at the highest reflectivity levels, can detect hail. During severe thunderstorms, we can determine the speed and direction of storms and plot a track which will show estimated arrival times for communities in the storm’s path.

This is used to determine rain intensity and movement of storms. When storms are tracked, we... — This is used to determine rain intensity and movement of storms. When storms are tracked, we can determine arrival times at a specific location.(wmtv)

Radial Velocity

The Radial Velocity product is used to determine wind velocity and direction within a storm. This product measures the wind relative to the radar site. In areas of rapid and tight rotation, such as in a tornado or a rotating thunderstorm, some of the wind is moving away from the site, while some of the wind is moving toward the site. This will show up as red and green areas very close to each other. This product is also used to determine wind velocity within a non-rotating storm and can thus be used to estimate straight-line wind.

Velocity Tracker is used to determine if, and to what degree wind is rotating within a... — Velocity Tracker is used to determine if, and to what degree wind is rotating within a thunderstorm.(wmtv)

Correlation coefficient

Correlation coefficient is a Dual-Pol Nexrad Doppler product which measures the consistency in shapes and sizes of targets within the radar beam. In on-air applications it is often referred to as our Debris Product.

The idea is that in a tornado, debris of many shapes and sizes (from grass, to branches, to large pieces of wood or metal) are thrown high into the atmosphere. This product can determine if and where this is happening. Higher variability in shape and size will show up as darker colors. Correlation Coefficient can be a critical component in determining whether a storm contains a tornado especially when used in conjunction with the Velocity product.

The NBC15 First Alert Weather Team monitors and utilizes these tools and others, to relay critical information to our viewers. You can count on our team to keep you and your family safe during the severe weather season.

Click here to download the NBC15 News app or our NBC15 First Alert weather app.