There's an official definition of what makes a white Christmas (and Austin probably won’t have one)
Here’s a holiday fact: There is a very specific definition for what constitutes a “white Christmas.” According to the National Weather Service, it occurs when there is an inch of snow on the ground as of 7 a.m. local time on Christmas morning.
NWS' Mack Morris says this standard is useful to make sure meteorologists like him are talking about the same thing when they use the term.
“You could say, 'Oh, it snowed an inch at 11:59 [p.m.]. It was a white Christmas!'” he said. “How many people saw it? One?”
Morris, who works in the Weather Service's New Braunfels office, has been fielding more questions about this lately than usual for a Texas-based meteorologist. That's because a weather model map has been circulating online this week that shows a massive Christmas Eve snowfall in Texas and Louisiana.
It’s certainly attention-grabbing, but is it worth the attention?
“Take it with a grain of salt,” Morris said. A very big one.
The map was just one of tons of models that consider tons of different possibilities. Any model this far away from the actual date is not worth getting worked up about.
“Anything out beyond, you know, eight to 10 days is basically model la la land,” he said.
Indeed the next run of that particular model showed zero precipitation.
But that’s not to say the weather isn’t expected to change. The NWS Climate Prediction Center has a good chunk of the country, including Texas, likely getting colder as we enter the second half of December.
“We are pretty confident that's going to be colder Christmas week,” Morris said. “We just don't know if there's any precipitation with that.”
When you see a weather forecast online that looks designed to shock, consider the source.
Be wary "if they're not a verified resource such as the Weather Service or a reputable television station or something like that," he said. "Nowadays, people can access pretty much anything online, and they can post a snowfall map for 15 days out and say, 'Oh, look, it's going to snow!'"