SPC severe weather risk today through 6:00 a.m. Wednesday
Threat of severe wind (red area is 30%)
Threat of tornado (brown area is 5%)
Threat of hail (brown area is 5%)
The threat of severe thunderstorms arrives to western parts of Middle Tennessee around midnight Tuesday. It's likely that the weather will already be very active in Arkansas and West Tennessee during the late afternoon and evening. As a matter of fact, the Storm Prediction Center has enlarged the moderate risk area for severe weather for those areas with their late morning update (see first image).
This looks like a classic winter set-up for potentially strong weather: lots of wind energy and a small-to-medium amount of instability. The lack of instability does not mean that we can rest easy; it's likely that severe thunderstorm warnings will be issued while many people are asleep. That's never a good combination, and despite the forecast, some will be caught off guard by the overnight storminess. Because we can't rule out an isolated tornado warning tonight, make sure your NOAA weather radio is turned on before you hit the sack. Members of the News 2 weather team will be on hand to continuously monitor the situation through early Wednesday.
Because the evening and overnight low-level jet stream will be howling at 60 to 70 knots at just a few thousand feet overhead, a wind advisory has been issued for 45 mph wind gusts. That advisory includes most of the Mid-South and actually runs from noon today through 6 p.m. Wednesday.
Per the Storm Prediction Center's late morning severe weather outlook, there's now a 30% to 45% chance that somewhere within 25 miles of any location west of I-65 will sustain wind damage tonight (see updated second image). Areas east of I-65 run between a 15% to 30% chance of that happening. Right now we believe that the line of storms will approach Nashville and the I-65 corridor between 1 a.m. and 2 a.m.
The tornado threat will be the greatest around Arkansas and West Tennessee during the evening time frame. Folks in those areas will want to watch this threat closely. Here in Middle Tennessee we can't rule out an isolated spin-up tornado developing within the anticipated overnight squall line, particularly in the northwest corner of Middle Tennessee. The chance of that happening within 25 miles of your house is around 5% (see third image). The chance has been upgraded to 10% for areas along the Tennessee River on the border between West and Middle Tennessee. Although 5% or 10% seems like a small threat, it has our attention and hopefully yours as well.
While some hail will be possible with this system, that aspect of the storms is the least impressive. There's about a 5% chance of severe 1" diameter hail within 25 miles of a point (see fourth image). The chance is around 15% for areas toward West Tennessee.
It's anticipated that the line of strong storms will gradually weaken as it moves across the Cumberland Plateau in the vicinity of 4 a.m. or 5 a.m. but we'll have to monitor the situation as it develops overnight.