Brad: Snow on radar, but no snow falls

By Brad Sowder
Published On: Jan 14 2013 10:28:22 AM CST
Updated On: Jan 14 2013 10:56:05 AM CST

If you got up this morning and checked the radar you would have seen what appeared to be snow moving into Oklahoma, but when the snow bands got to your house nothing fell. Why was that?  

This happens often in the wintertime when precipitation falling from the clouds is light and air temperatures are cold at the surface.  Precipitation is falling from the cloud but as soon as it falls from the cloud base it encounters a very dry layer of air and simply disappears.

This morning’s upper-air profile showed us that the cloud base was 14,000 feet, and that is where the air is 100 percent saturated.  At 12,000 feet, the air was 18 degrees but the dew point temperature was a bone-dry minus 31.    

Sublimation is the process where a solid (snowflake) transitions directly into a gas (water vapor). This can also happen on a cold winter’s night where a light snow falls in the evening and creates a dusting of snow, temperatures stay below freezing all night, but when you wake up in the morning the dusting of snow has simply vanished.  

This is exactly what was happening this morning way up above our heads.  In order for snow to fall to the surface when a pattern looks like this, moisture would have to continue to fall into this dry air to fully saturate the air all the way to the surface.

-- Brad



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