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

[Stuart Robinson]

Matt I don’t disagree with you re the rating on the old system – looking at the pictures (all the evidence that I have) suggests that F5 damage has indeed occurred.
My point was that if the NWS assessment team rated this as EF5 then it *could* still indicate F4 damage. However given that you can only damage something so much I think that is reasonable to say that winds were in excess of 200 mph - hence the EF5 rating.
Personally, I am struggling with this new EF scale and I need to read up on more case studies until I become confident in it . Right now (as I am sure most do) I rate on the old system and then try to fit this in with the new system – which is wrong!

 

[rdale]

Stuart - take a look at some of the training material on http://www.wdtb.noaa.gov As indicated above, an EF5 today translates to an F5 last year, that's why they kept the numeric designations the same.

 

[Jeff Miller]

Dick and Darin's Greensburg Screenshot

I think Dick and Darin may have captured one of the highest quality images - I have taken a screen capture from YouTube and reprinted it here.

 

[John Bowles]

A NWS employee I talked to said the lower wind speeds are because they believe they have been overestimating wind speeds based on observed damage, and F5 damage does not take the winds they once thought it did.

I don't know if this is the official NWS position, just what one employee told me.

 

[Kurt Wayne]

My apologies to Jim Leonard...it was the 1.3 mile wide Allison, TX tornado this resembles in the video caps.

 

[Bob Schafer]

Sorry for going off on somewhat of a tangent here, but then if wind speeds have historically been overestimated, what about about the DOW's recording of the Moore 990503 tornado at 318mph? Doesn't make the Moore tornado all the more stunning?

 

[rdale]

No, because those weren't ground level wind speeds. And that number wasn't really used in computing the new scale.

 

[Tony Lyza]

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?

This is entirely plausible. Larry Ruthi, the MIC from DDC, was interviewed by TWC earlier and said the Greensburg tornado ended 3mi N of Greensburg. A new meso formed just east of Greensburg as the original tornado entered Greensburg and quickly became extremely intense as it moved northeast.

 

[John Wetter]

The Fujita and the Enhanced Fujita are DAMAGE scales. Why are we still talking about wind speeds here? A '5' is a 5 and a '4' is a 4. We should know better than this...

-John

 

[Kevin Bowman]

aerial pictures of the damage

http://www.kansas.com/static/slides/050507tornadoaerials/pages/_MG_0319.html

 

[Bob Schafer]

No, because those weren't ground level wind speeds.

Good answer.

And that number wasn't really used in computing the new scale.

Okay, but I didn't make that implication.

 

[Bob Schafer]

The Fujita and the Enhanced Fujita are DAMAGE scales. Why are we still talking about wind speeds here? A '5' is a 5 and a '4' is a 4. We should know better than this...

-John

Why shouldn't we talk about wind speeds? It's not like there's no correlation between wind speeds and damage.

 

[John Wetter]

Why shouldn't we talk about wind speeds? It's not like there's no correlation between wind speeds and damage.

Of course there is a correlation; higher speeds=more damage, but the discussion so far has centered around this EF-5 being like an F-4, with that being based on the wind speeds, which would be an incorrect comparison.

-John

 

[Bob Schafer]

Of course there is a correlation; higher speeds=more damage, but the discussion so far has centered around this EF-5 being like an F-4, with that being based on the wind speeds, which would be an incorrect comparison.

-John

The discussion has also been about how F-scale wind speeds and EF-scale wind speeds relate to each other.

 

[John Wetter]

The discussion has also been about how F-scale wind speeds and EF-scale wind speeds relate to each other.

Yes, I know, but that just simply doesn't matter... It's well known that the winds were backed down to a level thought to be more realistic. This still is a damage scale, so it makes the whole conversation on this a moot point. a 4 is a 4, a 5 is a 5.