Saturday, February 11, 2012

2/11 - 5pm - A Wintry West Tennessee Forecast

A front that passed through West Tennessee last night brought rain showers during the overnight hours and snow showers this morning across the region. These have since moved out of the area, but the snow came down in some heavy bursts at times even though there was really no accumulation. High pressure will provide the setup for a very cold couple of days with highs in the 30's and overnight lows in the teens. Yikes! Tonight could be the coldest night of 2012 so far, which really isn't saying much since we've been pretty mild as of late.

Monday's forecast is flat-out complicated. Warm air overriding the retreating arctic air mass in place from this weekend will set the stage for a storm that could put down snow, sleet, and even freezing rain. Most indications are that this will start off as snow across most of West Tennessee on Monday afternoon as the lower layers of the atmosphere moisten up, but this snow could switch over to a period of wintry mix later on in the evening as the atmosphere warms up more (notice the warm "push" at 850 mb - 5000 ft on the left). Once we reach a certain threshold of warming on Monday night into the wee hours of Tuesday morning, all the snow, sleet, and freezing rain should transition to plain rain and the wintry weather headaches will be no more. Before everything switches over to rain an inch or so of snow could be on the ground around the I-40 corridor, including Jackson, according to the latest forecast models. Areas in Northwest Tennessee will switchover to rain a little later on than I-40, so there may be up to two inches on the ground. This is nowhere near set in stone yet and I'm willing to bet we'll see a few small changes in this forecast before the weekend is over.

The models agree that snow will fall across West Tennessee on Monday, but there are differences in when exactly this warm layer aloft will come in enough to switch the snow and wintry mix over to rain. The 18z NAM seems the most conservative on snow amounts at this point, with only a half inch in Jackson on Monday night. It also suggests that we might avoid a wintry mix and switch immediately over to rain. There's even a brief shot of rain just before the snow starts on that model. The GFS is bullish on snow amounts with over an inch in Jackson with the aforementioned wintry mix period (depicted as freezing rain on the BUFKIT output to the right) before the switchover to rain. The main issues seem are the timing of the warm air intrusion aloft and how strong it will be. So while this won't be a huge winter weather event by any stretch of the imagination, a few travel issues may crop up on Monday evening as the snow and wintry mix is falling.

Check out the video below from this morning's newscast on WBBJ for more details on your forecast!

No comments: