NWS Doppler radar reflectivity data shows where and how hard it is raining or snowing, and movement. Blue and green colors represent light-to-moderate rainfall. Yellow and orange show moderate-to-heavy precipitation, red is very heavy rain, while pink colors within the red indicate torrential rain with large drops and/or hail.
The image here shows KLVX 0.5 degree reflectivity on April 24, 2010 of a bow echo over central Kentucky. The line of storms bows out over southern Hardin and Hart counties due to strong straight line winds behind the leading line of thunderstorms. These winds can mix down to the ground causing strong or severe wind gusts and wind damage, which occurred on this day along the axis of the bow. Transient tornadoes also can develop along or near the apex of bow echoes). Base and storm-relative velocity data are very helpful to determine wind damage and tornado potential associated with bow echoes and other types of severe storms.