PDA

View Full Version : What's the largest documented Supercell?



mark humpage
12-16-2004, 05:57 AM
Not in terms of depth or persistence but horizontal scale. ie. width, length or diameter...or however they are scaled.

I've always wondered about this one.

Thanks

Mark

Glen Romine
12-16-2004, 10:26 AM
Not sure on total storm size, but the largest documented mesocyclone on record may be the Superior NE supercell from June 22, 2003 (the same day and just south of the famous Aurora hail event). This was sampled by the Eldora radar during BAMEX operations, and Roger Wakimoto has a few slides from preliminary analysis of the event starting here:

http://www.joss.ucar.edu/bamex/meetings/wa...ther/sld007.htm (http://www.joss.ucar.edu/bamex/meetings/wakimoto_mother/sld007.htm)

In summary, the mesocyclone diameter was ~ 20 km and had a differential velocity of ~ 118 m/s. Typical values are 3-10 km across and delta Vr of 25 m/s.

Glen

Alex Lamers
12-16-2004, 11:29 PM
That was a very interesting storm in all respects. If I remember correctly, it appeared to remain roughly stationary because it kept inhaling developing feeder cells. I remember watching it on radar and then getting that report of the giant hail. Unbelievable storm. I think the TALLEST storm on record was 70 some odd thousand feet but I'm not sure. That would be another interesting fact to figure out.

Mike Hollingshead
12-17-2004, 01:02 AM
Yeah as for the tallest on record that would be interesting to know as well. There was one in NE this year that held 65-70,000 foot tops for around an hour as it dropped south(via radar data). I'm not sure how reliable radar height detection is but I imagine it's pretty close and what is used in determining this. I had that graphic up that illustrated height but took them down. I will try and get them back up on that page. Ok, it's back up.

http://www.extremeinstability.com/04-7-12.htm

Last year NE had those big big mesos June 22 and this year we get this monster in July....I just LOVE it when locals comment, "oh you need to go to TX to see the big storms".

Mike Hollingshead
12-17-2004, 01:06 AM
http://www.crh.noaa.gov/gid/svrwx/events03..._megastorms.htm (http://www.crh.noaa.gov/gid/svrwx/events03/22jun03/22June2003_megastorms.htm)

Good link on the June 22 storms.

I love this report:

0855 PM AURORA NE 4.5 INCH HAIL
06/22/03 HAMILTON REPORTED BY STORM
SPOTTER. HOLES IN
NEIGHBORS ROOF BIG
ENOUGH TO CRAWL THROUGH.

It's worth noting just how close to the same exact spot the Deshler storm of 2003 was to that very prolific tornado producer this year May 24. It's like the scans are laid on top of one another. There is alot to note about the southern portion of that radar image. You have the Deshler beast of 2003 producing every aspect of severe weather and claiming one life(first in NE in like more then 10 years by a tornado, at least). Like was mentioned, you have the prolific tornado producer of 2004 in the same exact spot(as literally as you can be about). The May 22 monster formed in this very spot as well. The storm that produced two large wedges including the one that hit Hallam. All 3 of these in less then one years time and you could place them all ontop of each other with that radar image. Now go back to September 22, 2001(of all months) and there was a wedge .8 miles wide that passed very close to Edgar, which you can see on that map as well. That is a heck of alot of big time severe weather in a very tiny space and in a rather short time frame. June 13, 2001 you had the big big tornadic sup that went near Narka, also on that map(believe it was close to a violent wedge, if it wasn't such). The May 29, 2004 Jamestown storm(superstorm?...it was very impressive) moved up through this same region. That is some wild stuff for being in and right around that one county. All of these examples are violent tornadic supercells. Beats the hell out of eastern NE. I should just move to Thayer Co.

David Drummond
12-17-2004, 01:18 AM
Mike, where do you get the radar images like in the page you posted above found here: http://www.extremeinstability.com/stormpic...artlett2223.jpg (http://www.extremeinstability.com/stormpics/bartlett2223.jpg)

Jeff Snyder
12-17-2004, 01:26 AM
Not to answer for Mike, but I think he uses GRLevel3 or GRLevel2 ... http://www.grlevelx.com/grlevel2 or http://www.grlevelx.com/grlevel3/ ... He just started charging for the level 3 program, but it's excellent nonetheless...

Mike Hollingshead
12-17-2004, 01:27 AM
They are screen captures I saved off my cell phone. Can get this stuff in either analog or digital.

Blake Allen
12-22-2004, 02:43 AM
That is a heck of alot of big time severe weather in a very tiny space and in a rather short time frame.

There is an interesting paper on the SPC's website that makes it appear that the high frequency of strong tornadoes in that part of Nebraska isn't just a recent thing, either (unless there has been such a huge amount of tornadoes there recently as to skew the data).

EVIDENCE OF SMALLER TORNADO ALLEYS ACROSS THE UNITED STATES BASED
ON A LONG TRACK F3 TO F5 TORNADO CLIMATOLOGY STUDY FROM 1880 TO 2003 (http://www.spc.noaa.gov/publications/broyles/longtrak.pdf)

According to that paper, in Thayer, Fillmore, Seward, and Clay counties in SE Nebraska, from 1880-2003, there have been a total of 29 :!: LONG-TRACK, F3+ TORNADOES in those 4 counties alone. That seems to beat anything even a similarly sized area of Oklahoma can offer over the same time period, although the spot with the most long-track, F3+ tornadoes over the time period actually happens to be in south-central Mississippi, oddly enough.

Blake Allen

Glen Romine
12-22-2004, 05:33 PM
Can't get the paper link that you referenced to load right now, though I think I recall having seen this before. I'd offer a note of caution that rare events can play tricks on apparent signals if the sampling frequency is too short. Violent tornadoes are just so rare, and accurate F-scale ratings aside, small scale signals in the data might be looking too closely without a longer record. Might be there is something 'special' about these regions, but it could be something like a human factor, where perhaps a longtime surveyor at a local office tended to rate higher than surrounding offices. Just so many uncertainties in the storm data to look at it too literally imo.

Glen