2018-03-19 REPORTS: AL/GA/MS

[Quincy Vagell]

Going against better logistical logic, I started the day in Tupelo, MS and decided to wait for the "main action" to begin in northeastern Mississippi. Once it did, it was fairly unimpressive at first, so knowing the road network and terrain was quite challenging, I moved east toward the AL state line, near Red Bay. A cluster of supercells began to evolve, but visibility was fairly low due to hills and the close proximity of storms.

I found a clearing just east of Red Bay and pulled off to watch the supercell that apparently produced an intermittent EF-0 in the area. After watching and re-watching video footage several times, I cannot find anything remotely conclusive to a tornado, so I assume any tornado was rain-wrapped or otherwise not visible, unless you were almost directly underneath it. Regardless, the cell did have some noteworthy structure from a distance, but I didn't stay long, knowing that the one direct route to Russellville was about to be trampled over by multiple tornado-warned, embedded supercells. The photo below was taken at 4:55 p.m. and lines up exactly with the time that the NWS confirmed an EF-0 tornado:


Several photos and reports circulated that a "tornado" was ongoing well before the storm reached Russellville, but it was apparent that terrain was blocking any clear views of the storm. LCLs were quite low (in the 400-500m ranged, based on mesoanalysis) and from a few glimpses that I had of the storm, it was simply sporting a low, rotating wall cloud. The below screengrab was from 5:15 p.m. about midway between Red Bay and Russellville and shows the wall cloud was clearly well above the ground, considering the elevation and terrain of the area:


The storm chase was getting quite challenging considering that there was close to no visibility on the storm and I had to make a quick decision of either core punching/bear caging it up into Russellville, or diving south in hopes of maybe catching up to the storms later on. The terrain and road networks do improve from Russellville and points east/northeast, but the trajectory of the storms was pushing them from the southern edge of reasonably chaseable areas, into more "typical" Alabama terrain to the southeast.

I reached I-65 in the Cullman area shortly before sunset and a semi-discrete, small supercell rapidly developed just to my west. I went down to Good Hope and the storm was tornado warned. The visual on the storm wasn't anything overly impressive, as it appeared that most of the rotation of elevated, but radar data, including a pronounced hail spike, suggested the little cell was producing some significant hail.

In Good Hope, once the core had safely passed, I started seeing larger and larger hailstones on the road, in the range of golf ball to tennis ball-sized. I pulled off and snapped off a few photos. The larger stones were about baseball-sized, approximately 2.75 inches in diameter. Based on reports, some hail just to the north of where I was (around Cullman) was 3 to 4 inches in diameter and caused significant damage.



This was my first legitimate chase of the season and featured some modestly interesting structure early on and the icing on the cake was the very large hail at the end. The event essentially performed as modeled, although I will note that the position and axis of the warm front may have been modulated by midday convection in northern Alabama. All of the model data suggested W-E or even WSW-ENE moving UH tracks across northern Alabama, northwestern Georgia and Middle Tennessee. The warm front was oriented in more of a NW-SE axis and storm clusters moved along the warm front, arcing ESE/SE into western Georgia. Maybe the southern end of the Appalachians also worked to wedge the front to the south a bit as well. Instability was largely displaced south of Tennessee, such that most of the state remained severe storm-free, with just the one isolated tornadic supercell near the AL/TN border.

All in all, SPC did a great job based on verification, as there were well over a dozen reports of tornadoes and multiple strong tornadoes, including the first EF-3 since last May.

 

[Clarence Bennett]

Started my day near Decatur, generally looking for the nose of the higher ThetaE and then eventually sliding west toward Russellville. I spent the mid-day watching surface obs and visible satellite and ended up west of Russellville just after 5pm, finding a nice high spot which afforded me the luxury of catching the Cedar Creek Lake tornado. This was taken at 5:20pm and just as a small g2g couplet showed up on radar. I am not sure how Huntsville got their times wrong on their survey, but they are off by 10 minutes (10 minutes too fast).

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I drove east from here on hwy 24, stopping on the overpass at Russellville and watching power flashes as the tornado crossed hwy 43 just north of my location. From here it was further east to Moulton and then southeast to Cullman, where I made a last second decision to drive just north of downtown, avoiding the 3" to 5" hail that fell. (I tried to upload hail pictures, but file size is too large). I witnessed numerous cars that had been destroyed by the hail and was thankful I chose to go north by a quarter mile. Aside from seeing two tornadoes and giant hail, one of the highlights of the day was seeing NOAA 42 of the Hurricane Hunters flying overhead, zig zagging out ahead of the ESE moving supercell. They are currently working with the Vortex-SE project.

 

[cdcollura]

Good day all,

This is my report on the storms this day in Northern Alabama.

Summary:

March 19 was the main chase day of this trip, with the primary target area forecasted to be in north-central Alabama and possible a small portion of south-central Tennessee. The SPC had this area in an enhanced-risk that was later upgraded to a moderate risk on their 1630z outlook. The tornado probabilities were 15% (hatched for significant), along with a 30% (also hatched) hail and 15% wind risk. I left Atlanta back down I-75 and I-85 to avoid traffic and onto I-20 west into Alabama and near Birmingham. I then took I-65 north to near Decatur and the Tennessee River area to wait for storms (and that area was near the warm front). This gave Highway 72 and I-65 / I-565 as directional options.

The SPC (Storm Predictions Center) issued MCD (mesoscale discussion) 146 and subsequent PDS (particularly dangerous situation) tornado watch box 13 valid until 11 PM CDT covering much of north-central AL and south-central TN. Another tornado watch (number 14) was also valid in central Tennessee. The first storms developed near and west of Courtland as upper air support glanced the warm front. The storm was followed from near Courtland and north of Decatur, and finally east and northeast to near Huntsville and Meridianville in Madison County where large hail was observed. The second, and main round of storms, then developed later near the MS / AL border, and this area was targeted after abandoning the first round of storms near Huntsville.

I headed back west via Highways 231, then I-565 out of Huntsville, and west on Highway 72 to near Tuscumbia, then south on Highway 34 to Russellville, and west on Highway 24 for the main supercell storm of the day. From there, the storm was followed east and southeast from Franklin county along Highways 24, 157, and 278 to Cullman County near Summitt. A rain wrapped tornado was observed in poor contrast looking west and east of Russellville on Highway 24. The storm was abandoned after dark near Summitt and Blountsville (eventually it split and did more damage in Jacksonville, AL with another tornado at night). I finished the chase by heading back down Highway 231 and southwest on Highways 79 / 75 to I-59 / I-20 in Birmingham. I spend the night just SW of Birmingham near Bessemer.



Above: Chase map for this trip ... The chase track is in blue (which includes the long "ferry" trip from Florida and to the target areas). The target areas appear as yellow outlines for the main chase days, with storm intercepts denoted by the red "X's". The main chase day was March 19. The total mileage for this chase was 2042 miles.

Chase logs:

1). March 23, 6:30 PM - Interception and observation of a very severe thunderstorm north of Huntsville and near Meridianville in Madison County, Alabama and along Highway 231. The storm was a high precipitation supercell storm, which initiated much farther west earlier near Courtland west of Decatur in Lawrence County and was followed east on Highway 72 and through Huntsville via I-565. The storm was fast moving. The core of the supercell was encountered near Meridianville and contained 60 MPH, frequent lightning, heavy rains, and hail to golfball sized (covering the ground at a gas station off Highway 231). A low area of rotation was also observed with this storm, but no tornadoes developed. Conditions causing the storm were a warm front, surface heating, low pressure trough, and upper trough. Documentation was still photos and digital HD video. A 2016 Jeep Wrangler was used to chase the storm. A PDS (particularly dangerous situation) tornado watch was also valid for the area until 11 PM CDT.

2). March 24, 8:30 PM - Interception and observation of an extremely severe and tornadic thunderstorm from west and through Russellville in Franklin County Alabama along Highway 24 and east and southeast through Moulton and Culleman along Highway 157 and ultimately near Summit in Cullman County and Highway 231. The storm began as a powerful classic supercell that evolved to HP near Russellville as it turned right (moving ESE). The main core of the storm was not penetrated, but contained hail to at least baseball sized (with record breaking hail sizes exceeding 5" near Cullman). The storm had a striking visual appearance as well, with rapidly rotating wall cloud and striated updraft and vault to the right when viewed west of Russellville. The storm produced a rain wrapped tornado that caused damage in Russellville. This tornado was barely visible from the east on Highway 24 looking towards Russellville. The storm continued rapidly east and southeast and a split occurred near Brooksville and ultimately caused another tornado that hit Jacksonville, AL. Conditions encountered were heavy rains, small hail (main core avoided), frequent lightning with close hits, and winds near 60 MPH (mainly inflow and RFD). This is the same storm that caused extreme hail near Cullman, where a record breaking (AL state record) hailstone of 5.25" fell! Conditions causing the storm were a stationary front / outflow boundary, surface heating, low pressure area, and upper trough. Documentation was still photos and digital HD video. A 2016 Jeep Wrangler was used to chase the storm. A PDS (particularly dangerous situation) tornado watch was also valid for the area until 11 PM CDT.



Above: Hail up to golfball sized affecting Meridianville, Alabama north of Huntsville around 4 PM on March 19.



Above: View of impressive anvil blowoff from an intensifying tornadic supercell west of Russellville, Alabama after 6 PM in Franklin County.



Above: Supercell storm (in classic mode) to the west of Russellville, Alabama on Mrch 19. This is an intensifying storm and will produce a weak tornado soon.



Above: Intense rain-wrap and hail core while looking west towards Russellville, Alabama. There is a developing rain-wrapped tornado in there, and significant damage was being done in Russellville at the time.