Bright banding is the enhanced radar echo of snow as it melts to rain.


What You Need To Know

  • Bright banding can create the appearance of heavy precipitation

  • It is a good indicator of where the freezing layer is aloft

  • Bright banding happens on radar more often during winter storms

Our first shot of wintry weather back on Nov. 15-16 is actually the inspiration for this blog post. The storm brought a shot of snow, followed by a transition to rain that happened from south to north on the night of the 15th.

While following the storm on radar, I noticed the bright banding occurring down toward New York City. 

Radar image from KOKX at 7 p.m., Nov. 15. The shades of yellow and orange over NYC and CT show bright banding occurring. (RadarScope)

To the untrained eye, this looks like a pocket of heavy rain or even snow. What’s actually happening is snow is melting as it’s falling aloft. When this happens, a film of water forms around the snowflake.

This can trick the radar into thinking it’s large raindrops or even hail, hence the higher radar reflectivity. That’s exactly what’s happening near New York City and southern Connecticut in the radar image above.

(Photo: National Weather Service)

So the next time you hear a meteorologist use the term “bright banding” on TV, you’ll know it’s likely because there’s snow aloft beginning to melt and thus showing heavier precipitation on radar that’s actually occurring at the surface.

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