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What's graupel? How that white stuff that fell in Austin forms

A person sitting on a red sled in a driveway
Patricia Lim
/
KUT News
Henry Rodriguez sleds in front of his house in Buda on Tuesday.

The Austin area woke up to what we can only describe as a “snow day.” This rare event brought along a white dusting to Central Texas, but is it actually snow?

As a born and raised Texan, I’ve seen snow only a handful of times. Anything white that falls from the sky is automatically “snow” in my books. So I was confused when my colleagues threw around the word "graupel" Monday evening.

The winter storm brought a mixture of this graupel along with snow, sleet and freezing rain. Here’s how to tell the difference between them.

A wintry mix

When moisture in the atmosphere freezes, it can take on many shapes and sizes depending on the weather. Snow forms when water vapor turns to ice without going through the liquid stage.

When water droplets get supercooled, they turn to tiny soft pellets called graupel (pronounced "grau-puhl"). The National Weather Service describes them as having the consistency of Dippin’ Dots.

Sleet is translucent and will make a hail-like noise when it bounces off objects. Sleet and frozen rain make surfaces slippery and create dangerous road conditions.

“Anything on the road that’s icy is dangerous, just because we don’t get a whole lot of winter weather around here,” Eric Platt, a meteorologist with the NWS, said. “Most folks aren’t used to driving on it.”

Platt said we saw a mixture of graupel and sleet Monday night. He advises people to stay off roads and stay home until conditions improve.

What's next? 

The NWS expects the clouds will shift east and should clear out by the afternoon. With sunny skies and a high of 39 degrees forecast, much of the white stuff will melt.

But whatever doesn't melt will likely refreeze, Platt said. Temperatures are expected to dip below freezing in Austin each night through Saturday.

“We could be looking at more ice on roads tonight if it doesn’t completely melt during the day," he said.

Maya Fawaz is KUT's Hays County reporter. Got a tip? Email her at mfawaz@kut.org. Follow her on Twitter @mayagfawaz.
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