The Greensburg Wedge - What's The Rating Going To Be??

[Kurt Wayne]

Last year the Marmaduke, AR-Caruthersville,MO tornado looked for a few moments like the Red Rock, OK tornado of 1991, captured on video by Dr. Howard Bluestein's crew.

This Greensburg tornado, from the video stills, looks like the Kellerville,TX tornado of 1995 which also was 1 mile wide, but occurred over open country. Hideous to see that it went right over a county seat.

 

[Carrie Halliday]

Seeing how many homes were stripped from their foundations, or collapsed into the basement....should be a big push for storm shelters for new construction in tornado prone areas. The images are horrific, I am at a loss on how alot of the folks walked away from this! Over whelming sadness and hopelessness, and amazing that the loss of life wasn't much larger.

I know someone who called Greensburg home, and had many family members there. I do know that everyone is OK, but many generations of 2 families have lost everything. He said there is no way this town can rebuild, sad to hear. Hoping it is just the overwhelming shock of the destruction talking and that they can come together and start over. We may be starting a way to donate to the good people of Greensburg on my Texans site, will post links if/then we get something going.

The video images are sending chills down my spine. What a monster. Really odd it wiped out all the churches but left the town pub standing.....

 

[jason kissam]

CNN just said it was an official EF 5 winds at approx 205 MPH and a wedge of 1.7 miles. confirmed after the meteorologist on air spoke with the NWS prior to her segment.

 

[B Ozanne]

....I am at a loss on how alot of the folks walked away from this! Over whelming sadness and hopelessness, and amazing that the loss of life wasn't much larger.

Good warnings, long lead time, educated citizens and lots of luck. Don't expect too much praise for the NWS though, only criticism when the people aren't this lucky next time.

 

[Jeff Miller]

NWS Verification of the EF-5 is now on the Dodge City, KS web site.

Greensburg Tornado Officially Rated


The National Weather Service announced during a press briefing earlier today that the tornado which struck Greensburg, Kansas, Friday evening (5/4/07) has been officially rated as an EF-5. The derived EF scale rating of 5 means that a 3 Second Wind Gust (mph) was estimated to range from 200-234.

Our first EF-5 ever, and I believe the first "5" rating in years.

 

[Jeremy Bower]

This is the first "5" rating (Fujita or Enhanced Fujita Scale) since the May 3, 1999 Moore, OK tornado (over 8 years between 5s is a record, climatologically the U.S. averaged 1 F5 tornado every 2 years betwen 1950 and 1999 according to Tom Grazulis).

 

[Stuart Robinson]

I Actually I disagree – The Greensburg Tornado would have been rated F4 under the old system and we can not directly compare this tornado to previous F5 events.

Indeed looking at the new EF scale, the wind rating for a EF5 is between 200 -234 mph (old F5 was 261-318mph) which does indeed rate this tornado as a F4.

As the upper end of the EF scale is 234mph we will never again have a true F5 rating (as the EF scale ends before the F5 scale begins). Therefore at *some* stage in the future there will have to be a EF6 rating in order to handle proven (radar sampled) wind speeds over 234mph.

 

[Matt Grantham]

I'm not sure how one could think this would have an F4 on the old scale. It would have been F5 based on the damage. The scale has always been based on damage. Maybe I am missing something here.

 

[Darren Addy]

This is a big can of worms that we have been over many times before.

The old Fujita scale (while containing wind speed estimates) was specifically a rating scale based upon damage. Regardless of the differences in estimated wind speeds, I don't think anyone can look at the damage (and the Fujita definitions for that damage) and think that this was less than an F5, under the "old" system. Given that, I think we can compare it with earlier events.

 

[Stuart Robinson]

Matt,
I share your sentiments – but if the NWS damage team have rated this tornado as an EF5 then the maximum wind speed possible are 234mph. The old F5 rating does not even start until 261mph – hence why I think that it would have been rated as an F4 under the old system.
Perhaps the new EF-Scale needs time to bed in? but given that the damage is not total (it is not that far off however) and the tornado was wide – meaning that the town was under tornado force winds for longer then an narrow tornado then I don’t think that F4 is unreasonable.

Perhaps it should have been EF6 ???

 

[afischer]

Reviewed video tonight and noticed something intriguing about the wedge tornado entering Greensburg. A powerflash (the only one I saw that night) illuminated what appeared to be a stovepipe tornado that was definitively to the right (east) of the wedge. (I remember thinking this while viewing it that night, too... that the powerflash was occurring "away" from the wedge). Makes me wonder if it wasn't another satellite/sister tornado. It seemed like over the next two minutes the wedge grew even larger, though, so maybe they merged. Or, maybe it was all one circulation... impossible to tell what really happened, but interesting nonetheless. Anyone else notice this and have any thoughts?

 

[Matt Grantham]

Matt,
I share your sentiments – but if the NWS damage team have rated this tornado as an EF5 then the maximum wind speed possible are 234mph. The old F5 rating does not even start until 261mph – hence why I think that it would have been rated as an F4 under the old system.
Perhaps the new EF-Scale needs time to bed in? but given that the damage is not total (it is not that far off however) and the tornado was wide – meaning that the town was under tornado force winds for longer then an narrow tornado then I don’t think that F4 is unreasonable.

Perhaps it should have been EF6 ???

The operational EF-scale says that an EF5 has a 3 second gust of 200+, not 200-234. The 200-234 is part of the derived EF-scale. It has probably been concluded that it is impossible to determine wind speeds beyond 234mph based on damage, and therefore no EF6 is needed.
http://www.spc.noaa.gov/efscale/ef-scale.html

This is all beside the point, because the scale is still based on damage. It would have been an F5 on the old scale.

 

[Rick Smith]

The operational EF-scale says that an EF5 has a 3 second gust of 200+, not 200-234. The 200-234 is part of the derived EF-scale. It has probably been concluded that it is impossible to determine wind speeds beyond 234mph based on damage, and therefore no EF6 is needed.
http://www.spc.noaa.gov/efscale/ef-scale.html

This is all beside the point, because the scale is still based on damage. It would have been an F5 on the old scale.

That is correct. The wind speeds would not have been a consideration when determining the F-Scale rating. The rating would have been determined by the damage observed.

Rick

 

[Jim Tang]

Reviewed video tonight and noticed something intriguing about the wedge tornado entering Greensburg. A powerflash (the only one I saw that night) illuminated what appeared to be a stovepipe tornado that was definitively to the right (east) of the wedge. (I remember thinking this while viewing it that night, too... that the powerflash was occurring "away" from the wedge). Makes me wonder if it wasn't another satellite/sister tornado. It seemed like over the next two minutes the wedge grew even larger, though, so maybe they merged. Or, maybe it was all one circulation... impossible to tell what really happened, but interesting nonetheless. Anyone else notice this and have any thoughts?

I agree with this. I haven't reviewed velocity data, but from the reflectivity data, it is clear that the storm was cycling as it was hitting Greensburg. The old updraft curled northward and got engulfed by a new updraft that developed to the immediate west, which then grew to form that monstrous hook. So it is not out of the realm of possibility that there were two tornadoes at once, the bigger one hitting Greensburg, and the old tornado/meso merged into the bigger tornado.

 

[Jeremy Bower]

This would coincide with the debate from the Moore tornado on whether that should have been rated an F6. Since an F5 would have completely swept away a well built home, there was no way of depicting the difference, so an F6 rating is impossible, just like an EF-6 would be impossible to figure out.

Larry Ruthie from the Dodge City NWS was interviewed on the Weather Channel and he said the reason why mostly the EF-5 was given was due to the "complete" destruction of the Junior/High School along with the water tower in town being brought down, which didn't even happen in the Hesston tornado from March 1990. So it seems they took a lot into consideration before giving the EF-5 rating, they took the physical damage into play along with previous damage surveys of major events.

With all this being said and from what I've seen in photos and Ruthie's interview, that would have been an F5 on the old scale no doubt about it.