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.

The color scale seen on radar reflectivity displays is a representation of the power return: The highest values represent the most intense part of the storm or highest precipitation rates. Not all values are created equal: you may see hail with 55 dBz in January but only heavy rain with the same value in July.

Red shows winds blowing away from the radar, and green shows winds blowing toward it. Stronger winds usually equate to brighter colors on the radar imagery. You can spot rotation and a possible tornado in a thunderstorm by looking for strong winds blowing in different directions right next to each other.

Radar Beam Exercise

When navigating using VOR's, they used the 1-In-60 rule (i.e. if an aircraft is 60nm from a VOR and 1° off-track, the aircraft is 1nm off-track). But there is a more generic form of the rule that is useful for radar. Just take the radar range and add two zeros to find out what one degree equals.

Doppler Velocity Measurements » Principles » Color Schemes

Purple denotes range-folding (RF), which is when the return from a prior pulse is detected during the listening period for the current pulse, and the radar is unable to determine the wind's velocity.

In precipitation mode, low dBZ values (blue and green colors) indicate light precipitation, while higher values in the yellow, orange, and red colors mean heavier precipitation. Values above about 45 dBZ signify intense precipitation and are nearly always caused by thunderstorms.

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.

VIP 1 (Level 1, 18-30 dBZ) - Light precipitation. VIP 2 (Level 2, 30-38 dBZ) - Light to moderate rain. VIP 3 (Level 3, 38-44 dBZ) - Moderate to heavy rain. VIP 4 (Level 4, 44-50 dBZ) - Heavy rain.

Target information is displayed by numerical values and vectors on the Radar screen. For the reading of vectors, they point in the direction of the target while the length of the vector indicates the speed of the target.

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. Whites or blues mean snowfall and pink indicates freezing rain, sleet, or a wintry mix.

Does rain affect radar? ›

Based on our observations, rain can cause false readings or interfere with the radar's ability to determine a vehicle's speed. Despite these challenges, radar devices are still used in rainy conditions, although officers may rely more on visual cues and other forms of speed measurement.

Yes, moving radar can clock other vehicles speeds while the officer's vehicle is moving both going in the same direction or even in opposing directions. These radar guns have a second antenna that measures the patrol cars speed while the other antenna tracks the target vehicle.

By convention, green colors indicate winds blowing toward the radar and velocity values are negative. Red colors indicate winds blowing away from the radar and velocity values are positive. This convention comes from the early days of Doppler radar when radars pointed vertically.

How is STM determined? The storm speed is calculated as 75% of the mean wind speed between the surface and 6 km. The storm moves slower than the ambient wind speed since a storm has a large mass of water that has to be pushed along. The turbulence within a storm also makes it more difficult to push along.