Archive March 18-20th, 2018 Severe Weather

[South AL Wx]

I'm curious, how close was the path of the Ashville-Ohatchee EF2 to that of the Shoal Creek/Ohatchee/Piedmont EF4 (next member of the same family as TCL-BHM) of April 27, 2011? That's another corridor that seems to get hit on a fairly regular basis (also notably on Palm Sunday 1994).

It looks like at the point where the tornadoes crossed Alabama Highway 77, the paths were only about 3 miles apart. The March 19 EF-2 crossed Highway 77 about 3 miles north of where the April 27, 2011 EF-4 crossed Highway 77. (This is based on comparing the initial survey for March 19 with the path map of the April 27 tornado. I measured the distance using Google Earth. It is possible that the tracks were closer at some point).

 

[Mr. Clark]

Ashville-Jacksonville EF3 (upgraded late yesterday) path was only a few miles or less from the path of the EF4 that hit Shoal Creek-Piedmont. That corridor has seen several tornadoes through the years in which you can see here.......http://www.tornadohistoryproject.com/tornado/Alabama/Calhoun/map

This storm actually moved from NW to SE, in which most all others moved from SW to NE. You can use the map above in the link and zoom in and this storm moved from Southside down through AL hwy 204 through Jacksonville continuing across the mountain through Nances Creek across hwy 9.

Having grown up in Calhoun County, I know a little about the storms that have hit there. Interestingly, there are at least three tracks on that map that are not entirely accurate. The track for 4/27/11 is too far north where it crosses Highway 431. The track for the Palm Sunday Tornado is too far south where it crosses Highway 431. Finally, the track of the 12/3/83 tornado is simply wrong in just about every way - except that it was mainly in Oxford.

I was also interested in the 12/11/61 F3 that hit Jacksonville. My mother was sitting in the cafeteria at JSU when that storm hit and blew the roof off the building.

 

[Mike S]

HUN is back out in the field today so the tornado number may go up later today.

 

[Mike S]

 

[rolltide_130]

There were some AWFULLY impressive path lengths and widths with some of the tornadoes on Monday. The Ardmore tornado had a path length of 23.54 miles, and the Jacksonville tornado hit 34.29 miles and was over a mile wide, as well as the St Clair County storm which also had a path width of over a mile.

 

[CSimonds]

Ashville-Jacksonville EF3 (upgraded late yesterday) path was only a few miles or less from the path of the EF4 that hit Shoal Creek-Piedmont. That corridor has seen several tornadoes through the years in which you can see here.......http://www.tornadohistoryproject.com/tornado/Alabama/Calhoun/map

This storm actually moved from NW to SE, in which most all others moved from SW to NE. You can use the map above in the link and zoom in and this storm moved from Southside down through AL hwy 204 through Jacksonville continuing across the mountain through Nances Creek across hwy 9.

Didn’t it move from NW to SE because it was riding the warm front that draped across the area from NW to SE? I noticed the same thing with the Cullman-Arab-Albertville-Boaz storm. They usually move from SW to NE and this one started to - then began to move to the ESE instead. in April 2011, the Cullman-Arab tornado came over our house in Guntersville. When the storm went warned with this event I figured it would track the same. But It appeared to travel the warm front instead.

 

[rolltide_130]

Didn’t it move from NW to SE because it was riding the warm front that draped across the area from NW to SE? I noticed the same thing with the Cullman-Arab-Albertville-Boaz storm. They usually move from SW to NE and this one started to - then began to move to the ESE instead. in April 2011, the Cullman-Arab tornado came over our house in Guntersville. When the storm went warned with this event I figured it would track the same. But It appeared to travel the warm front instead.

Well, the predicted storm motion was expected to be due E to Just S of due E. This one did go a little bit more SE however, and it very well may have been riding some sort of boundary.

 

[Former Member]

It looks like at the point where the tornadoes crossed Alabama Highway 77, the paths were only about 3 miles apart. The March 19 EF-2 crossed Highway 77 about 3 miles north of where the April 27, 2011 EF-4 crossed Highway 77. (This is based on comparing the initial survey for March 19 with the path map of the April 27 tornado. I measured the distance using Google Earth. It is possible that the tracks were closer at some point).

That would be pretty accurate on the points where they crossed 77, and the 1994 storm was probably close to the same distance to the south of the 2011 storm when it crossed 77.

 

[Mike S]

8 tornadoes for HUN

 

[Kory]

Didn’t it move from NW to SE because it was riding the warm front that draped across the area from NW to SE? I noticed the same thing with the Cullman-Arab-Albertville-Boaz storm. They usually move from SW to NE and this one started to - then began to move to the ESE instead. in April 2011, the Cullman-Arab tornado came over our house in Guntersville. When the storm went warned with this event I figured it would track the same. But It appeared to travel the warm front instead.

Definitely locally enhanced shear along the warm front that aided those storms.

 

[HazardousWx]

Unfortunately I agree... I am just east of Murfreesboro by about 40 miles. The sun is poking out here and it’s 55.

Looks like the sweet spot was to your south as predicted.

 

[Mike S]

Now up to 11 tornadoes across North Alabama.

 

[Mike S]

FWIW - the only thing I've seen from BHM is Jacksonville obviously. They had to suspend that survey yesterday due to darkness but was supposed to pick back up today. They are also checking 2 other areas today - Blount/Etowah and Cherokee/Cleburne.

 

[Taylor Campbell]

Unbelievable, and absolutely crazy! I'm so happy I didn't get under that in my car! I was very close, but thankfully only got hen egg size.

https://www.weather.gov/hun/event_03192018_hail

 

[South AL Wx]

FWIW - the only thing I've seen from BHM is Jacksonville obviously. They had to suspend that survey yesterday due to darkness but was supposed to pick back up today. They are also checking 2 other areas today - Blount/Etowah and Cherokee/Cleburne.

Looks like BMX confirmed 5 tornadoes in their CWA (3 of which came from the same supercell that produced the Jacksonville tornado - numbers 2, 3, and 5 in the list below).

1. Thomas Yates Road Tornado - Blount County (EF-0)
2. Blount Mountain Tornado - Blount and St. Clair Counties (EF-1)
3. Ashville/Southside Tornado - St. Clair, Etowah, and Calhoun Counties (EF-2)
4. Centre Tornado - Cherokee County (EF-1)
5. Jacksonville Tornado - Calhoun and Cleburne Counties (EF-3)

 

[Fred Gossage]

From what I've seen, Monday's tornado count for Alabama now stands at 14, including one EF3 and two EF2s. I think we can safely call this a localized "outbreak". To put the event into perspective...

The SPC used to use report criteria per square mileage to verify their categories back several years ago (even a few years after probabilities became operational). For a High Risk to verify, per a 50,000 square mile area (roughly the size of Oklahoma without the panhandle): at least 20 tornadoes were to be expected, with at least two of them being (E)F3+ or greater. The Moderate Risk area at 20Z Monday was 20,898 square miles in size. That means that, per square mileage, we exceeded the tornado count needed to verify a High Risk on the old method by 5 or 6 tornadoes... we are just one EF3 short.

 

[Bamamuscle]

So I have two questions.. Did the warm front ever get north of the Tennessee River? And why did the storms stay close together?


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[Fred Gossage]

So I have two questions.. Did the warm front ever get north of the Tennessee River? And why did the storms stay close together?


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At least over the western half of the Tennessee Valley, the warm front did nudge up into Tennessee. I think it was actually somewhere near you as the storms were approaching from the west. As far as the storms staying so closely spaced, I kinda get the idea that it was because the initiating boundary to the west was more NE to SW oriented, instead of more N to S. That means there was a little less of an angle across with boundary with the deep-layer shear vectors that were pointed W to E. There was enough of an angle to fully support supercells, and even longer-tracked ones, but I think we would've seen more spacing had the dryline back in Mississippi been more N to S oriented.

 

[Mike S]

From what I've seen, Monday's tornado count for Alabama now stands at 14, including one EF3 and two EF2s.

HUN confirmed 11 plus the 5 from BMX.

 

[Fred Gossage]

HUN confirmed 11 plus the 5 from BMX.

Wow, then we're definitely at the point... given the coverage on the map... where this is only lacking one more EF3 or higher to verify a High Risk.