Another very fast moving system will arrive Tuesday evening with another chance for some light snow. Unlike the last system, this one is faster, drier, and more compact. The result will be some light snow accumulation across Northwest Arkansas on Tuesday evening; far less than we experienced Sunday night.
Here’s a look at the timeline and what’s causing it.
A strong trough in the upper levels will be digging across the area. If you imagine the black line is a stick in a river, it will rotate counterclockwise due to the stronger winds across the Gulf coast. The result in weather is both directional and speed shear which causes the air ahead of it to grow vertically. We call this vorticity or vorticity advection. Because it’s being elongated, it rises and generates lift. This is what will cause the snow.
Notice that the latest model totals are not much for Northwest Arkansas. Models are notorious (especially the North American Model snow) for over estimating snow in our area so ignore the numbers on the right. The key is to look at the placement. It’s mostly in Northwest Arkansas.
At Noon, the clouds will begin to increase at that trough approaches from the northwest. A flurry or two will be possible.
By 6pm, the are areas of light rain in the River Valley and some light snow in Kansas. The feature that will move into our area is still to the northwest.
By 8 or 9pm, the light snow will quickly move across Northwest Arkansas.
At midnight, it’s out of our area entirely.
One thing that concerns me is the temperature. It will likely be in the 20s and indicated by Futurecast, but it could also be a few degrees lower than this due to the existing snow cover on the ground. This will be plenty cold enough for snow to stick to roads; especially bridges and overpasses.
It won’t be much. Right now, it looks like trace amount to maybe 1/2 of an inch. But with temperatures that cold and a very cold ground… it will likely be enough for road problems late Tuesday and maybe into Wednesday morning.
Fort Smith may see some flurries but the best lift and moisture will be passing to the north so no problems are currently anticipated in the River Valley.
Bottom line: Expect a quick snow shower late Tuesday, a handful of slick spots on roads, and another very cold day on Wednesday as northwest winds filter back into the area.
-Garrett