This Week’s Winter Storm: Flood Potential Then Ice/Snow

We’re getting a clearer picture in regards to how our late week storm will pan out–but model guidance is still in disagreement on the exact track of the low as of Tuesday morning which changes the fine-tune details of when we change from rain to wintry mix to snow.

THE BIG PICTURE

An area of low pressure will continue to round the base of the Rocky Mountains and will head out into the southern Plains tonight into early Wednesday. Another low to our north in Canada will attach itself to a strong cold front bringing sharply colder temps southward into the US.

The low to the south will begin to pump in deep amounts of Gulf of Mexico moisture (see map below) resulting in widespread rain and even severe weather across the Tennessee Valley.

PWAT Forecast: (amount of moisture that can be “wrung” out of the atmosphere) Notice the surge of moisture from the Gulf taking our values up over 350% of normal this time of year. This will lead to efficient rainfall (and eventually snowfall)

Colder air will quickly move south into the storm system changing a lot of the rain over to a wintry mix of ice and snow and then eventually snow. How quickly this changeover occurs locally is still in question, but the latest guidance suggest we’ll be dealing with less ice and more snow from this one.

LATEST FREEZING RAIN/ICE FORECAST

CONCERN #1: FLOOD POTENTIAL

We have up to an inch of water content in our snow right now. Combined with a steady rain when this system arrives Wednesday night and a ground that’s still frozen underneath–there won’t be much absorption of the water we’ll have around from melting snow and falling rain. Area rivers will also experience the melt and with added runoff, ice jams are a possibility leading to river flooding potential. Here’s a look at the water-equivalent that is expected to fall from the sky:

Things you can do out ahead of the rain? Here’s our recommendation:

CONCERN #2: ICE AND SNOW POTENTIAL

As temperatures crash with the storm system Wednesday night into Thursday, our rain will quickly changeover to a wintry mix and then snow. The potential is there for some heavy, wet snow initially that changes over to a fluffier snow. Depending on the exact track of the low, we could end up with a decent snow around the Region with amounts ranging from 4-8 inches and even higher if we line up with that “sweet spot” we talked about during our last storm. Take a look at the model runs as of Tuesday morning:

THE EURO

THE GFS

THE GEM

You’ll notice the Euro puts us right in the bullseye for now with snow, the GFS has higher amounts and is further north, and the GEM is further south with the track. There’s still a lot more data to process as this storm moves through the Rocky Mountains and I’d expect the track and results to become much more clear with this afternoon’s guidance.

We’ll keep you updated as we get new info in as always!

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