Perhaps one of the most critical pieces of information model data can give us is information concerning the exact track of the low pressure center; that big “red L” you see on the weather map. A deviation in the track of that low by just a few tens of miles can change the weather forecast dramatically. That’s why model data that stretches out to 4 or more days is useless when it comes to the finer details. The computer just can’t be all that precise with the exact track of the low.
Unfortunately for us on the plateau, we always seem to be on that rain/snow/ice line. If only we could know with better certainty were each low was going to track our forecast would be improved. A deviation of 20 miles makes the difference between rain, ice, or snow for us.
But, we’re lucky to have the data that we have! I hope you all enjoy the Sunday Story!
The Track of the Low
Forecasting winter weather is challenging, especially for the Cumberland Plateau. The exact timing of the cold air meeting up with the moisture can mean the difference between snow or rain.
Timing is important, but it’s not everything. Perhaps the most important factor to consider is the track of the center of low pressure, hereafter referred to as a “low”.
Thankfully, models have improved their skill on tracking lows. The slightest deviation in that path can easily lead to a busted snow forecast or a surprise snow.
An ideal snow scenario involves a low that tracks south of an area. For instance, a track from Alabama to Georgia is an ideal path for the plateau to get snowfall. A track to our south keeps our surface winds northerly, bringing in colder air, while the low throws lots of moisture from the Gulf up and over that cold air. Keep in mind that the air flow around an area of low pressure is counter-clockwise.
If a low tracks over the top of the plateau we get rain on the east side of the low, the part of the storm system referred to as the “warm sector”, as it pulls up warm, moist air from the Gulf. As the low moves east of us and colder, north winds return, we may see a changeover to some light snow, with little or no accumulation.
A low that tracks to our north gives us rain, as we stay in the warm sector of the storm for nearly the entire duration of the storm. We may get some snow flurries but that’s about it.
So, keep your eyes on those weather maps and pay attention to the tracks of those lows. Their track can have a big impact on your winter weather!