I know it feels like we’ve been a broken record this week with multiple rounds and multiple days of strong to severe storms either across parts of our viewing area or very close by. We have one more final round of storms to get through over the next 24-30 hours, and then we shift into a calmer weather pattern. The NWS Storm Prediction Center has outlined a Level 3 of 5 risk of severe storms across the area generally along and west of the Natchez Trace Parkway, what the locals call “The Trace”. It runs from near Spring Hill and Columbia, TN down to just west of Lawrenceburg, TN to near Cherokee, AL and back to near Fulton, MS and then west across Tennessee and north Mississippi. East of there, they have a Level 2 of 5 risk of severe storms across the remainder of our viewing area counties in southern middle Tennessee and northwest Alabama.
The main hazard types today are going to be as follows: damaging straight-line wind gusts as high as 60-70 mph possible in spots with the line and the significant potential for flooding and flash flooding are the primary threats. However, there definitely could still be a few embedded spin-up type tornadoes in the line. And while that usually means they are the smaller variety, that doesn’t always guarantee so. The Hampshire, TN EF2 from Sunday night, wasn’t a supercell tornado. It was a short-lived spin-up in the line of storms, and it still reached EF2 intensity and destroyed homes. So, even though the tornado threat is not high-end today, and we are not likely looking at large supercell type tornadoes, the tornado risk as it is still needs to be paid attention to. Large hail isn’t too much of a concern, but a few storms may have hail up to quarter size in diameter. Frequent lightning will be possible with all storms.
Unfortunately, this may be a long-duration threat for some folks because of how the line of storms may evolve as it moves into the area. Models are in pretty good agreement on an initial line segment surging into southern Tennessee in our viewing area as early as 4-6pm and then crossing portions of our Tennessee counties on through 10-11pm. How far south that line segment surges across southern Tennessee as it moves across will help determine the ending time for our Tennessee counties, and it may get a little tricky, because as that initial surge comes across, the whole line kind of lays over on itself and then just slowly sags east and southeast across the rest of the area through the overnight and predawn hours. Because of that, this is a threat that may start as early as 4-6pm in places like Hardin County TN and then potentially not end until as late as 6am Sunday morning in places like Morgan County AL.
Above is a timeline gallery of the early morning HRRR model. This is a reasonably reliable computer model simulation of how the storms may evolve and behave later today and tonight and what the radar may look like. This shows the initial surge of strong storms into southern Tennessee and northeast Mississippi as early as 4-6pm today and that coming on across southern Tennessee into maybe far northwest Alabama from then on through midnight. After that, the line of storms looks like it lays over on itself and slowly shifts east and southeast across the remainder of the viewing area through the early morning hours before exiting north Alabama just after sunrise. For our viewing area, this would have the severe threat ending in Morgan County AL (our southeasternmost viewing area county) in the 6:00am hour at some point. We are noticing signals on many of the high-res models, that as we get deeper into the late evening and overnight, the rain-cooled stable “safe” air with temps into the 60s surges out ahead of the storms itself, and the storms train on themselves back in that cooler stable air as the line slowly sinks southeast. IF that does indeed happen, that could help to reduce the severe storm and tornado threat before the line itself pushes on through. We hope that is the case, but we cannot guarantee it. We also can’t guarantee that even if that does happen, that there won’t still be a few severe thunderstorm warnings or even a couple of tornado warnings for storms that are back in the cooler stable air. That happened in northwest Alabama back on Sunday overnight, and it happened with some of the storms in middle Tennessee early on Thursday morning. When that happens, it reduces the chance of something verifying at ground level, but somethings warnings STILL have to be issued because of HAVING TO play it on the safe side if the radar signatures still look threatening.
In addition to the severe storm threat, there is a significant threat of flooding and flash flooding late today and tonight where the storms train on themselves and dump heavy rain for hours. A Flood Watch still continues for many places of western and middle Tennessee and north Mississippi into Sunday morning, and we can’t rule out that being expanded across more of the area today as confidence increases concerning where the heaviest raining from training storms setting up across the area overnight. The NWS has a Moderate (Level 3 of 4) risk of excessive rainfall and flooding as far east as Lewisburg and Pulaski in Tennessee and down to the Shoals metro and Red Bay in northwest Alabama. In our viewing area, these will be the regions with the highest likelihood of significant flooding or flash flooding, but scattered instances of flash flooding are possible areawide. Just west of our region, a rare High Risk of flooding is in place across west Tennessee and northwest Mississippi. This cones as far east as Selmer TN, and the northwest corner of Hardin County and then up toward Linden and Centreville in Tennessee. A baseline minimum expectation of 2 to 3 inches of rain for everyone looks likely, and then where the training storms set up this evening and overnight, rain totals could be anywhere from 4 to 6 inches with isolated heavier amounts possible. Keep in mind that some of these areas have already seen several inches of rain earlier this week! It is CRITICAL that you do not try to travel into flooded roadways, and it’s especially dangerous overnight when you can’t see the condition of the roadway that well. If you come across a flooded area, please turn around and seek an alternate route!
It is important that you have your severe weather safety plans in place and that you know where you will shelter if your area gets a warning later today or tonight. Remember that this cannot include mobile homes. If you live in one, it may be a good idea to work a plan to stay with a friend or relative tonight if at all possible if your location doesn’t have a community shelter or a 24/7 business a few miles down the street that you can quickly run to if a severe or tornadic storm is approaching.
It is also critically important that your severe weather plan includes multiple reliable ways of getting watches and warnings, including something that can wake you out of your sleep at night since much of this will be an overnight threat. We will be here staffed in the weather center and ready to provide LIVE coverage for any warnings that are issued in our viewing area!
