Weather Update on Today’s Surprise Snow

I knew it was going to snow this morning. I knew it the moment I saw that first snowflake (ha). Seriously, no matter how much forecasting improves, there will always be some surprises. At least I’m in good company. This even caught the National Weather Services in Nashville and Morristown by surprise.

If you remember, there was a time last week when I mentioned the possibility of snow flurries for Monday night. There was never any indication that anything would happen Monday morning.

In fact, ALL guidance said there was nothing to even worry about tonight. Obviously, faith in that guidance is a bit weak now.

Even today, the models say we’ll be partly cloudy and dry as a bone today. Obviously, we’re not.

Last night, this system, a typical and quirky upper-level low, dived south. I’m talking a total, both feet in, dive-as-hard-as-you-can southward to TN. There was no good reason too, but do you really need a good reason to visit our beautiful state? As the moisture from the system interacted with the plateau, flurries fell….at times they fell hard!

Remember how clear the skies were last night for the ISS flyover? How quickly things change!

You’ve heard the saying that one inch of rain equals 10 inches of snow, right? Well, when snow is super “dry”, like today’s, one inch of rain can equal 20 or more inches of snow. When the airmass is this cold and dry, it only takes a very, very little bit of moisture to make some snow.

To make matters worse, we can’t even track today’s snow because it’s coming from such low-level clouds that the radar can’t see it! It’s quite the conundrum, I tell ya.

This just emphasizes the point of the IMPACTS mission that I just returned from Wallops to learn all about. We desperately need improvements in snow forecasting. That mission intends to do just that!

This whole situation ties in perfectly to the MASTER Class for kids this week! What an excellent way to emphasize the importance of snow research! So, for that, I thank Ma Nature for the surprise. ha

We’ll likely do it all over again tonight and tomorrow morning. The core of this system should swing through tonight. I don’t expect anything more than a dusting, but some places could see a really good coating. No advisories have been issued and I’m not sure any will. At most, a winter weather advisory would be needed….at most.

These dry snows usually just blow off the roads, but be careful if you drive on any of this. Dry snows have a tendency to be super slick if enough of it collects on anything.

So, I hope you enjoyed your surprise snow today. Thankfully, as is typical with these events, the impacts have been quite small. It has been kinda nice seeing some of those pretty flakes fall, though.

Below is a current view of radars. Notice nothing is showing on the plateau. Also notice all the “blotches’ that appear around Nashville and around Morristown (east of Knoxville). Those blotches are the only places the snow shows up because that’s where radar sites are. These snow flurries are falling from such low-level clouds that by the time the radar gets away from the site, the beam is too high up to “see” the snow. Radar beams increase in altitude with increasing distance from the radar site.

weatherTAP_RadarLab_Image_20200120_1952

The weather calms back down after tomorrow, with our next system waiting in the wings for Thursday night. That system will be a wet one, though we may see some of that end as some wintry precip on Saturday, per the latest data. I’ll keep an eye on it!

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