NEXRAD Doppler

Radar Types

(Code in Lower Right)

  • CR - Composite Reflectivity  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.

  • BR1 - Base Reflectivity  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.

  • BV - 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.

  • SRV - Storm Relative Velocity  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.

  • SV 32 - Spectrum Width 32MN  A measure of velocity dispersion within the radar sample volume. The primary use of this product is to estimate turbulence associated with mesocyclones and boundaries.

  • ET - 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.

  • VIL - 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.

  • ZDR - Differential Reflectivity  A measurement related to the returned energy difference between the vertical and horizontal radar pulses. Large positive values indicate that targets are generally much larger horizontally than vertically. Values near zero indicate the targets are generally spherical. Negative values indicate targets are larger in the vertical than in the horizontal. 

  • CC - Correlation Coefficient  A measurement related to the similarity between the behavior of the horizontally and vertically polarized pulses are behaving within a pulse volume. Values between 0.95 and 1.0 indicate near uniformity in pulse behavior. Meteorological targets with complex shapes, or with a large degree of variety, will generally have values between 0.85 and 0.95. Biological targets, anthropogenic targets, and ground clutter tend to cause very different behaviors between the pulses, resulting in values less than 0.9 (and often less than 0.7).

  • KDP - Special Differential Phase  A measurement of difference between the horizontal and vertical pulses phase changes as they travel through the atmosphere. Interpreting Specific Differential Phase (KDP) can be very difficult. It's primary use involves detecting areas of heavy rain. KDP values are largest when going through areas dominated by large rain drops. In some cases, regions with high KDP values may also contain melting hail.

  • HHC - Hydrometeor Classification Computer algorithm output that determines the most likely classification of the targets in the radar volume. The product displays which of the pre-defined categories most likely was the cause of the radar echo at that location.

  • STR - Storm Total Rain  The estimated storm total precipitation accumulation on a 1.1 nmi x 1 Degree grid continuously updated since the precipitation event began. This product uses the PPS algorithm and is used to locate flood potential over urban or rural areas, estimate total basin runoff and provide rainfall data 24 hours a day.

  • OHR - One Hour Rain  A display of estimated one hour precipitation accumulation on a 1.1 nmi (Nautical Mile) x 1 Degree grid using the Precipitation Processing System (PPS) algorithm. This product is used to assess rainfall intensities for flash flood warnings, urban flood statements and special weather statements.

  • THR - Three Hour Rain  Same as one hour, except for a three hour period.

Radar & Weather Links

    NWS West Coast IR Image - Click to enlarge


    Weather Underground Local Radar

Back Click for Additional Radar Types

NEXRAD Doppler Radar Legend

Yellow boxes denote tornado watch.
Blue boxes denote severe thunderstorm watch.
Green boxes denote NOAA Storm Prediction Center mesoscale discussion.
Pink inverted triangles denote a tornado vortex signature.
Red boxes are severe storm warnings.
Pink boxes are tornado warning.
Green triangles denote hail.
Radar imagery in red and green is velocity radar for advanced study.


    Infrared Satellite Western United States  

    Weather Underground Infrared Satellite


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