Wnem Radar (2024)

FAQs

How can you tell how fast a storm is moving on radar? ›

Velocity data is derived from the phase, or doppler shift of the returned energy. The radar's computers will calculate the shift and determine whether the precipitation is moving toward or away from the radar, and how fast, then apply a corresponding color to those directions and speeds.

Warm colors (red) / positive values indicate wind moving away from the radar (along a radial). Cool colors (green) / negative values indicate wind moving toward the radar. Purple indicates “range folding”— where the radar cannot determine the radial velocity. Velocity image of a large-scale weather system.

Black dots represent divergence centers. Arrow length is proportional to wind speed. Negative (positive) Doppler velocities represent flow toward (away from) the radar. (

On a weather radar map, a tornado is usually indicated by a smaller area of red surrounded by a larger area of green. However, modern radar systems can also indicate debris balls, a sign of a tornado on the ground.

It has to do with the type and intensity of the precipitation. The colors are typically a spectrum. The greens indicate light or moderate rainfall. Yellow, orange, and red indicate moderate to heavy rainfall and can also indicate hail.

In the Velocity image below, which is simply a picture of the basic wind field from the lowest ½ degree elevation scan or slice, we can determine the radar location. If the radar cannot determine (called Range Folding) inbound or outbound then it paints the wind in purple.

A patch of dark red moving toward your location means there's a thunderstorm on the way. A line of heavy precipitation moving in unison is a sign of a squall line that could pack gusty winds.

The WSR-88D is one of the most powerful and advanced Weather Surveillance Doppler Radar in the world. Since first being built and tested in 1988, it has been installed and used operationally at over 160 locations across the United States, including Alaska and Hawaii.

Red indicates the winds moving away from the radar whereas green displays the winds moving toward the radar. Brighter shades identify faster winds whereas darker shades show slower winds. Such maps typically indicate a tornado by a smaller area of red surrounded by a larger area of green.

Rotation can be detected when there is a couplet of winds moving toward and away from the radar located right next to each other. This often appears as a red area directly next to a green area as seen on the NWS image below.

How do you calculate how fast a storm is moving? ›

The basic technique for calculating the storm-relative velocity is to determine the component of the average storm motion toward/away from the radar for each azimuth and subtract that value from the measured radial velocity for each pixel along the azimuth.

Moving radar allows an officer to clock vehicles while driving on patrol. It can clock oncoming vehicles and if it has dual antennas, a departing car can also be clocked from behind, after it's passed the rolling cruiser.