Definition of a Classic Supercell

[Chris Lott]

I really don't have any problems with HP supercells and lp supercells, but what defining points make up a classic supercell? What characteristics or special features does it have to make it a classic supercell? Anyone have pictures of one?

 

[nickgrillo]

Classic supercells are the biggest tornado producers (and are responsible for the most violent tornadoes)... They have very well defined hook echoes on radar (and give the classic "flying eagle" appearance on radar) and defined wall clouds and RFDs. They are also often the biggest hail producers (although CAPE, elevation etc. will determin on how large of hail you'll get). Classic supercells are what a chaser wants.

<img src=http://midwestchase.com/13-May-2005/13-May-2005-4-tn.jpg>
A classic supercell at maturity... About an hour in duration (it slowly began to transition into a high-precip sup about an hour after this shot was taken).

<img src=http://midwestchase.com/6-7-05-7976.jpg>
Notice the huge inflow band stretching from the storm.

<img src=http://midwestchase.com/june12-still.jpg>

Those are a few examples of classic supercells... Notice on the third picture, a barrell tornado is seen under the wall cloud in the distance. That supercell was a very strong, persistant cyclic supercell and produced at least seven different tornadoes in just a couple hours.

 

[Shane Adams]

IMO the distinguishing characteristic of a classic supercell is a healthy precip core with a well-separated updraft region. I also look for a flanking line with a classic storm, as opposed to a tiered edge with the other types. No supercell stays a certain mode, as they're always evolving.

 

[mikegeukes]

Source:
http://www.spc.noaa.gov/faq/tornado/scelllbl.html

SUPERCELL TYPES: LP, CLASSIC, HP
http://www.theweatherprediction.com/habyhints/42/

RADAR CHARACTERISTICS OF SUPERCELLS
http://www.theweatherprediction.com/habyhints/237/

Classic Supercell
http://www.srh.noaa.gov/oun/severewx/figure7.php

Mike

 

[Andrew Khan]

Originally posted by nickgrillo
Classic supercells are the biggest tornado producers (and are responsible for the most violent tornadoes)... They have very well defined hook echoes on radar (and give the classic "flying eagle" appearance on radar) and defined wall clouds and RFDs. They are also often the biggest hail producers (although CAPE, elevation etc. will determin on how large of hail you'll get). Classic supercells are what a

I thought HP supercells had the biggest history of producing strong/violent tornadoes, and largest number of deaths.

 

[Michael Auker]

Originally posted by Andrew Khan+--><div class='quotetop'>QUOTE(Andrew Khan)</div>

<!--QuoteBegin-nickgrillo

Classic supercells are the biggest tornado producers (and are responsible for the most violent tornadoes)... They have very well defined hook echoes on radar (and give the classic "flying eagle" appearance on radar) and defined wall clouds and RFDs. They are also often the biggest hail producers (although CAPE, elevation etc. will determin on how large of hail you'll get). Classic supercells are what a

I thought HP supercells had the biggest history of producing strong/violent tornadoes, and largest number of deaths.[/b]

It was my understanding that HP supercells have too much rain cooled air wrapping around the mesocyclone, therefore they don't produce as many violent tornadoes as classics do. According to some literature i've read, HP's have more giant hail potential then classics or LP. Something to do with more ice crystals falling into the up-draft...

 

[Joe Zemek]

As far as deadly tornado producers, this is likely related to right-moving nocturnal HP storms, especially in the South. A right mover encounters better LL shear, can sustain itself longer, and in a nocturnal environment driven more by shear than by CAPE, the rain cooling effect would be minimized. So these HP-generated tornadoes are killers not because they're especially violent but because they're harder to detect and escape.

 

[Andy Wehrle]

I've heard some fairly nasty things about hail from LP storms as well...a fairly innocent-looking thin precip core can contain damaging hail. And don't count out HP tornadoes...Plainfield IL 1990 (F5) was so shrouded in precip as to be invisible as a funnel, and Nashville 1998 (F3) looked about twice as wide as it really was. Many of the WI storms on August 18, 2005 cycled back and forth from HP to classic.

I would agree with the definition that a "classic" supercell has a distinct separation between precip area and updraft area, as well as the dominant updraft/meso area at the back right flank (instead of forward flank as in many HPs), but still maintaining a stout, visible precip core (unlike LPs). These storms can last the longest and produce the most severe weather because of this balance between updraft and downdraft, inflow and outflow.

 

[Andrea Griffa]

Originally posted by Michael Auker+--><div class='quotetop'>QUOTE(Michael Auker)</div>

Originally posted by Andrew Khan@
<!--QuoteBegin-nickgrillo

Classic supercells are the biggest tornado producers (and are responsible for the most violent tornadoes)... They have very well defined hook echoes on radar (and give the classic "flying eagle" appearance on radar) and defined wall clouds and RFDs. They are also often the biggest hail producers (although CAPE, elevation etc. will determin on how large of hail you'll get). Classic supercells are what a

I thought HP supercells had the biggest history of producing strong/violent tornadoes, and largest number of deaths.

It was my understanding that HP supercells have too much rain cooled air wrapping around the mesocyclone, therefore they don't produce as many violent tornadoes as classics do. According to some literature i've read, HP's have more giant hail potential then classics or LP. Something to do with more ice crystals falling into the up-draft...[/b]

I agree with the fact that HP supercells don't produce violent tornado because they've too much rain cooled air wrapping around the mesocyclone. Besides that is because HP formation is due to a minor quantity of shear available for the storm: so there's not a well separation from updraft and downdraft.
Anyway, it seems to me strange that according to some literature you've read, HP's have more giant hail potential then classics or LP: less shear means also hail smaller than classic and LP. Moreover, the termodynamic profile of the troposphere is often very wet and that increases water loading decreasing cape and buoyancy(with smaller hail) but increasing precipitation efficiency.
That is not always true, because often Nature is too much various, but as to definition hail is smaller.

 

[Aaron Kennedy]

Besides that is because HP formation is due to a minor quantity of shear available for the storm: so there's not a well separation from updraft and downdraft.

Don't get too hung up on the shear quantitites... many times supercells go HP when they are "seeded" by convection upwind.

Aaron

 

[Andrea Griffa]

Originally posted by Aaron Kennedy

Besides that is because HP formation is due to a minor quantity of shear available for the storm: so there's not a well separation from updraft and downdraft.

Don't get too hung up on the shear quantitites... many times supercells go HP when they are "seeded" by convection upwind.

Aaron

Certainly, but once a supercell is born HP, it remains HP because overall mid level and upper flow isn't so strong to mantain classic structure and to carry hydrometeors away from the updraft .

 

[Shane Adams]

Originally posted by Andrea Griffa+--><div class='quotetop'>QUOTE(Andrea Griffa)</div>

<!--QuoteBegin-Aaron Kennedy

Besides that is because HP formation is due to a minor quantity of shear available for the storm: so there's not a well separation from updraft and downdraft.

Don't get too hung up on the shear quantitites... many times supercells go HP when they are "seeded" by convection upwind.

Aaron

Certainly, but once a supercell is born HP, it remains HP because overall mid level and upper flow isn't so strong to mantain classic structure and to carry hydrometeors away from the updraft .[/b]

That's not true, as a storm can easily move into an area with enhanced upper shear. Remember, no supercell remains in a constant state for long, they are always changing.

 

[Andrea Griffa]

Originally posted by Shane Adams+--><div class='quotetop'>QUOTE(Shane Adams)</div>

Originally posted by Andrea Griffa@
<!--QuoteBegin-Aaron Kennedy

Besides that is because HP formation is due to a minor quantity of shear available for the storm: so there's not a well separation from updraft and downdraft.

Don't get too hung up on the shear quantitites... many times supercells go HP when they are "seeded" by convection upwind.

Aaron

Certainly, but once a supercell is born HP, it remains HP because overall mid level and upper flow isn't so strong to mantain classic structure and to carry hydrometeors away from the updraft .

That's not true, as a storm can easily move into an area with enhanced upper shear. Remember, no supercell remains in a constant state for long, they are always changing.[/b]

That is true but it's just more frequent the opposite case; it's more frequent that a classic supercell became HP or a HP becomes a bow echo.

 

[Mickey Ptak]

Originally posted by Andrew Khan

I thought HP supercells had the biggest history of producing strong/violent tornadoes, and largest number of deaths.

That statement could very well be true, although I have no stats to prove it. Considering tornadoes in HP supercells are wrapped up in rain it would be very hard for most spotters to visually confirm the tornado unless they punched the core and I am not real sure most spotters (firefighters, police, etc..) do that. A few hard-balled chasers may though.

As far as the classic supercells producing the most violent tornadoes I would again speculate that to be good bet. There are only two dates that come to mind for me though, May 3 1999 and Oct 9 2001.

If I recall right the May 3 1999 Chickasha, Bridge Creek, and Moore supercell transformed itself a number of times. When I first saw it, as the tornado(s) where hitting the Chickasha airport, it was a well-defined classic supercell with the well-defined updraft / rain free base and to the east north east the rain shaft.
However, as we where driving aimlessly through many back road (Bridge Creek area) I recall seeing very little of a rain shaft and almost a mothership like appearance to the supercells low level structure. That was one bad supercell tornado wise and structure wise.

Mick

 

[Shane Adams]

Many times when classic supercell is in the process of cycling, as the RFD becomes filled with precip, it can briefly take on the look of an HP cell. Newer chasers can be fooled into dropping off the storm if they aren't patient.