Frigid Temps, Slight Chance of A Little Snow

Current Temps and Radar

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Note: Updates on snow chances will be found in purple below, and otherwise on Twitter @NashSevereWx.

Quick Summary: Next 48 Hours

Low 40°s This Afternoon, Then Epic Cold

Windy

Small Chance of Very Little Wednesday Morning Snow

Overnight/Early Thursday Morning — Frigid Temps, Slight Chance of A Little Snow

1.  Frigid Temps and Awful Wind Chills

The National Weather Service issued a Special Weather Statement and a Hazardous Weather Outlook in anticipation of the bitterly cold temps and subzero wind chills:

prep

After the cold front passes through Wednesday morning, arctic air will move in. Our morning temp of 22° will be the warmest we get. Temps will continuously drop throughout the day. Here is a look at the cold arctic air mass at noon using the GFS-upgrade model.

noon cold

By 5 PM, our temperature will have fallen to around 14°. With winds sustained between 15 – 20 mph (gusting to 35 mph), wind chills during the day will dip as low as -2°. A Wind Advisory may be needed.

Late Wednesday night, temps will continue to fall into the single digits. The north wind will let up some, but the wind chill could get as low as -4°.  If the wind chill gets any colder, the National Weather Service will likely issue a Wind Chill Advisory (-5° or less).

2.  Slight Chance of A Little Light Snow

The arrival of the cold front will bring us a slight chance for light snow Wednesday morning. There may be just enough moisture for a few hours Wednesday morning to “squeeze out” some snow. This is pretty iffy.

For once, surface temperatures won’t be the big IF in a snow forecast. The big if is whether this light blob of snow can make its way down the slide all the way from the N Plains:

Slide

Here’s a tour of the weather models —

NAM4 Model:

9z snow

GFS-upgrade Model:

12z snow

Canadian Model:

12z snow can

The not-pictured Euro model continues with the same theme: very light snow on approach, fizzling out upon arrival and the heavier accumulations staying north of the Tennessee/Kentucky border.

To say the chance of snow is “slight” is accurate. If we do cash in on the slight chance for snow, we expect only a dusting. Tonight, we’ll have a better view of what’s actually going on (rather than what’s modeled to go on).

Afternoon Update: The afternoon data and NWS-Nashville forecast discussion continues to emphasize the “iffy” threat of very little snow Wednesday morning. This is because:

1.  Weather models are consistently showing the potential snowmaker to be a lightweight wuss. Very low moisture content.

2.  The High Resolution Rapid Refresh (which I love) model “has backed way off.” What’s that mean? Remember the slide analogy from the model I posted above. The HRRR doesn’t think the snow will slide it all the way down:

3.  The Positive Vorticity Advection (PVA) associated with this system is weak. High PVA correlates with surface low development and upward vertical motion, which is what you want if you want some snow. PVA with this system is pathetic.

NWS-Nashville is going to put our probability of snow at 1 in 5, “but it may very well just end up producing some scattered flurry activity” in northern Middle TN and the plateau.

Sorry, snow fans. Embrace what little hope you have.

Follow us on Twitter @NashSevereWx tonight/early tomorrow, and watch local TV, for updated information.

Thursday – Bitterly Cold – Wake Up 4°, High 25°

That’s not a typo…We will begin the day at 4° and only “warm” into the mid 20°s under mostly sunny skies. The trend of stupid cold mornings and COLD afternoons will continue for the rest of the week.

extended

There is growing interest in another system moving in Sunday/Monday from our southwest. Rain is possible, but there has been some support in the models for freezing rain. This will be closely watched.

This website supplements @NashSevereWx on Twitter, which you can find here.