Weather Defender Documentation

Page History: Radar Product Layers

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Page Revision: 05/12/2010 5:21 PM

1 - Introduction

The following NEXRAD Level 3 Radar Products are available in Weather Defender under the Radar Category of the Layer Browser. Descriptions, usage, and tutorials are provided below.

2 - Layer Descriptions

Descriptions provided by National Climatic Data Center (NCDC).

Base Reflectivity (default)

Base Reflectivity (Default)

Base Reflectivity (Default)

A display of echo intensity measured in dBZ. This product is used to detect precipitation, evaluate storm structure, locate boundaries and determine hail potential. The 4 lowest elevations angles are available.

Learn More about Base Reflectivity »

Base Velocity

A measure of the radial component of the wind either toward the radar (negative values) or away from the radar (positive values). Negative values are represented by cool colors (green) while positive values are represented by warm colors (red). This product is used to estimate wind speed and direction, locate boundaries, locate severe weather signatures and identify suspected areas of turbulence.

Learn More about Base Velocity »

What is Range Folding (RF)?

Range Folding, the purple areas on velocity-based products, is displayed when the radar is unable to determine the wind speed.

From NOAA: Range Folding is due to the speed at which the radar transmits signals, called the pulse repetition frequency (PRF). The faster the pulses are sent by the radar the less time it has to listen for any returned signals. It occurs when the return from a prior pulse is detected during the listening period for the current pulse. Both reflectivity and velocity data are affected by this."

The occurrence of range folding can usually be detected by radar software and reflectivity data can be "unfolded" using special programs. However, velocity data cannot be accurately unfolded and therefore the effective range with which Doppler radars can detect velocity data is limited by the frequency of the radar pulses; the higher the pulse rate, the shorter the range within which the velocity field can be determined.

When the radar is unable to "unfold" the information, we paint the region purple as an indicator of the problem. There are some ways to minimize range folding and we have recently implemented a program which will sample the atmosphere with different PRF to do just that.

Storm Relative Velocity (Motion)

When the motion of storms are subtracted from the wind field, the result is a picture of the wind as if the storms were stationary. Color induces are the same as base velocity. Comparing the storm relative motion image with base velocity image helps identify the rotating storm.

Learn More about Storm-Relative Velocity (Motion)»

Composite Reflectivity

A display of maximum reflectivity for the total volume within the range of the radar. This product is used to reveal the highest reflectivities in all echoes, examine storm structure features and determine intensity of storms.

Learn More about Composite Reflectivity »

Vertical Integrated Liquid

The water content of a 2.2 X 2.2 nmi column of air which is color coded and plotted on a 124 nmi map. This product is used as an effective hail indicator, to locate most significant storms and to identify areas of heavy rainfall.

Echo Tops

An image of the echo top heights color coded in user-defined increments. This product is used for a quick estimation of the most intense convection and higher echo tops, as an aid in identification of storm structure features and for pilot briefing purposes.

One Hour Precipitation

A display of estimated one hour precipitation accumulation on a 1.1 X 1.1 nmi grid. This product is used to assess rainfall intensities for flash flood warnings, urban flood statements and special weather statements.

Learn More about One Hour Precipitation »

Storm Total Precipitation

A map of estimated storm total precipitation accumulation continuously updated since the last one-hour break. This product is used to locate flood potential over urban or rural areas, estimate total basin runoff and provide rainfall data 24 hours a day.

Learn More about Storm Total Precipitation »

3 - Tutorials

The following tutorial explains how to add individual radar products to your map in Weather Defender:

Weather Defender® - Desktop Weather Software for your PC. Weather Satellite, Weather Radar, and Street-Level Weather Tracking.

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