Tornado Outbreak Aftermath: April 26th-30th, 2014

[Calderon]

NWS Little Rock (LZK) is holding a press conference this evening on the Mayflower-Vilonia tornado. I'm thinking it's a safe bet they'll announce the rating as EF5, probably a 65/35 bet to me.

[Ground Scouring]

NWS Little Rock (LZK) is holding a press conference this evening on the Mayflower-Vilonia tornado. I'm thinking it's a safe bet they'll announce the rating as EF5, probably a 65/35 bet to me.

I'm guessing that the reason why the rating has taken some time to release is because an EF5 rating would be a big deal in AR. Hopefully, unlike (perhaps) on 05/24/2011, the rarity of such an event will not have an influence on whether to select the EF5 rating if the data point toward an EF5.

 

Another irony: yesterday was the anniversary of the only F5 on record in AR, that of Sneed (1929).

[Ground Scouring]

Some stills of the areal footage of the Vilonia tornado are incredible. 

 

There actually does appear to be slabs/wind rowing in some frames:

The lack of debris (or at least large debris) near the two slabbed foundations in the center of the second photograph, combined with the impressive scouring and wind-rowing, is to me perhaps the strongest possible indicator of EF5 intensity.

[tornadotony]

Prelim EF3 in Cullman County, AL per NWS Huntsville Twitter.

[Calderon]

The lack of debris (or at least large debris) near the two slabbed foundations in the center of the second photograph, combined with the impressive scouring and wind-rowing, is to me perhaps the strongest possible indicator of EF5 intensity.

I've said it on other pages, I firmly believe that this subdivision in SW Vilonia is what the rating is riding on.

[Donnie Beasley]

I'm guessing that the reason why the rating has taken some time to release is because an EF5 rating would be a big deal in AR. Hopefully, unlike (perhaps) on 05/24/2011, the rarity of such an event will not have an influence on whether to select the EF5 rating if the data point toward an EF5.

Another irony: yesterday was the anniversary of the only F5 on record in AR, that of Sneed (1929).

The Snead, AR tornado of 1929 occured on April 10th.

[Superstorm93]

More drone footage:

 

[ArkieOkie]

FB post from a Fort Smith met: The National Weather Service will announce the rating of the#Mayflower / #Vilonia tornado with a live press conference at 6pm. #5wx #arwx

[ArkieOkie]

Faulkner County press conference at 4:00. http://www.thv11.com/videos/news/2014/02/10/5367277/

[OceanStWx]

I'm guessing that the reason why the rating has taken some time to release is because an EF5 rating would be a big deal in AR. Hopefully, unlike (perhaps) on 05/24/2011, the rarity of such an event will not have an influence on whether to select the EF5 rating if the data point toward an EF5.

 

Another irony: yesterday was the anniversary of the only F5 on record in AR, that of Sneed (1929).

 

More likely this has taken some time to release is because storm surveys take a significant amount of time to complete. When you couple that with many tornadoes and significant damage, it can easily take days to complete all the work. Given the expected media attention, you also want to make sure you've done your due diligence when it comes to rating a violent tornado.

 

[Ground Scouring]

FB post from a Fort Smith met: The National Weather Service will announce the rating of the#Mayflower / #Vilonia tornado with a live press conference at 6pm. #5wx #arwx

Where can I find a link to the live press conference?

 

The Snead, AR tornado of 1929 occured on April 10th.

Thanks for the correction…I should have checked my big green book twice!

[Ensō]

Where can I find a link to the live press conference?

 

 

 

Thanks for the correction…I should have checked my big green book twice!

 

THV11 said they were streaming it live, but I don't see a link for it. Not sure.

 

http://www.thv11.com/

[Ground Scouring]

Prelim EF3 in Cullman County, AL per NWS Huntsville Twitter.

So is another one in Scott County, MS, per NWS Jackson. That makes at least seven EF3s and one EF4 thus far for the entire outbreak…with an EF5 likely to be announced shortly in AR.

[Ensō]

http://www.katv.com/

 

KATV also mentioned streaming the press conference.

[Chicago Storm]

Mayflower/Vilonia, AR rated as EF-4.

[thewxmann]

Honestly, at this point there's no difference between mid/upper-end EF4 and EF5 anymore.

[Hoosier]

Mayflower/Vilonia, AR rated as EF-4.

 

What we've learned...press conference does not necessarily mean EF5.

[Ensō]

Honestly, at this point there's no difference between mid/upper-end EF4 and EF5 anymore.

 

Well, the difference is mid/high EF4 actually gets assigned occasionally.

[Buckeye05]

From what iv'e heard, they only found one house that was well-built enough to even consider EF5, and went EF4 in the end. 

[OceanStWx]

From what iv'e heard, they only found one house that was well-built enough to even consider EF5, and went EF4 in the end. 

 

This is usually the problem. One damage indicator is not going to tip the scale on a survey.

 

And really should it? If a large tornado is on the ground for several miles and only comes close to doing EF5 damage at one point in the path, was it really an EF5?

[Ensō]

This is usually the problem. One damage indicator is not going to tip the scale on a survey.

 

And really should it? If a large tornado is on the ground for several miles and only comes close to doing EF5 damage at one point in the path, was it really an EF5?

 

If it only comes close to causing EF5 damage at that one point, no. But if it causes EF5 damage, even to just one structure, it's an EF5. In this case, there were several areas of very intense damage and at least a few places that certainly warranted a very close look. I know it all hinges on construction quality now, but all of the surrounding context points to an extremely violent tornado at times.

[Buckeye05]

If it only comes close to causing EF5 damage at that one point, no. But if it causes EF5 damage, even to just one structure, it's an EF5. In this case, there were several areas of very intense damage and at least a few places that certainly warranted a very close look. I know it all hinges on construction quality now, but all of the surrounding context points to an extremely violent tornado at times.

Agreed, I think even if the quality of construction fell short, it was definitely capable.

[blackjack123]

Agreed. If one home meets EF5 criteria. Then the tornado should be rated EF5. They always nit pick every little detail.

[Buckeye05]

This is usually the problem. One damage indicator is not going to tip the scale on a survey.

 

And really should it? If a large tornado is on the ground for several miles and only comes close to doing EF5 damage at one point in the path, was it really an EF5?

As Enso mentioned, i'm pretty sure that's not how it works. The 2011 St. Louis and 2013 Hattiesburg tornadoes were rated EF4 based on a single house in each case.

 

Edit: New Minden 2013 was as well now that I think about it.

[OceanStWx]

If it only comes close to causing EF5 damage at that one point, no. But if it causes EF5 damage, even to just one structure, it's an EF5. In this case, there were several areas of very intense damage and at least a few places that certainly warranted a very close look. I know it all hinges on construction quality now, but all of the surrounding context points to an extremely violent tornado at times.

 

Not really though. There is definitely a fetish with EF5 ratings whenever these "slabbed" homes show up.

 

From SPC's site on the EF-scale:

 

The Enhanced Fujita Scale

When the committee met to develop the Enhanced Fujita Scale (see original document) one point was made very clear: it must continue to support and maintain the original tornado database.; In other word, there must be some conformity to that of the F-Scale that is listed in the database. Other ideas were agreed to including:

• Consistent Assessment of Damage
  • enhance description of damage with examples and photos
    • include not only structures, but also vegetation
  • base damage assignment on more than one structure, if available
  • develop a PC-based expert system
  • develop training materials
• Data Collection
  • maintain current tornado database
  • surveys should include additional data
    • mean and maximum damage path width
    • basis for damage assignment
    • latitude/longitude of where the path began and ended
    • number of hours spent on the damage survey
    • names of survey team member(s)

 

You can have EF5 damage to a home, but if a nearby structure doesn't add up (say garage still mostly intact) then it won't be rated an EF5.

 

Never mind that within the one or two family residence Damage Indicator, there Degree of Damage corresponding to a slabbed home can range from 165 to 220 mph (EF3 to EF5).

[thewxmann]

Well, the difference is mid/high EF4 actually gets assigned occasionally.

 

Actually, the difference is where the tornado hits: only if in a big city will an EF5 rating get assigned. Unless there's mobile doppler data, in which case it might tip the scale.

[Buckeye05]

Actually, the difference is where the tornado hits: only if in a big city will an EF5 rating get assigned. Unless there's mobile doppler data, in which case it might tip the scale.

I don't know if i'm misinterpreting your post, but only one or two (calling Joplin a big city is a stretch) of the 10 official EF5s hit large metro areas. The rest were rural/small towns.

[Ensō]

Not really though. There is definitely a fetish with EF5 ratings whenever these "slabbed" homes show up.

 

From SPC's site on the EF-scale:

 

The Enhanced Fujita Scale

When the committee met to develop the Enhanced Fujita Scale (see original document) one point was made very clear: it must continue to support and maintain the original tornado database.; In other word, there must be some conformity to that of the F-Scale that is listed in the database. Other ideas were agreed to including:

• Consistent Assessment of Damage
  • enhance description of damage with examples and photos
    • include not only structures, but also vegetation
  • base damage assignment on more than one structure, if available
  • develop a PC-based expert system
  • develop training materials
• Data Collection
  • maintain current tornado database
  • surveys should include additional data
    • mean and maximum damage path width
    • basis for damage assignment
    • latitude/longitude of where the path began and ended
    • number of hours spent on the damage survey
    • names of survey team member(s)

 

You can have EF5 damage to a home, but if a nearby structure doesn't add up (say garage still mostly intact) then it won't be rated an EF5.

 

Never mind that within the one or two family residence Damage Indicator, there Degree of Damage corresponding to a slabbed home can range from 165 to 220 mph (EF3 to EF5).

 

Of course a slabbed home by itself is not indicative of EF5 damage. It isn't necessarily even EF4 depending on construction quality. And surrounding context absolutely matters, which is what I've been saying. My point is that if you have damage that you can credibly rate EF5 (i.e. the context supports the rating), the tornado is an EF5. Tornadoes have always been rated on the maximum damage caused, even if that damage is only in a very isolated area (which doesn't even apply here). I thought you were saying the opposite, but maybe I misunderstood you.

 

In any event, my original point relates directly to the point that you bolded: the EF-scale is not consistent with the F-scale. Not at all. I suspect if all historical F5s were re-rated by the ultra-conservative current standards, we'd have a lot fewer F5s. Conversely, many of the current high-end EF4s would be no-doubt F5 ratings in the past. It simply isn't consistent at all. Although the surveyors on the ground obviously have much more information than we can possibly glean from photos/video, I think there's enough information (including, most importantly, surrounding context) to say that this tornado would almost certainly have been an F5 on the old scale. I'd tend to think it may have even been rated EF5 today if it had been a different group surveying it. It's just very puzzling.

[Ensō]

Actually, the difference is where the tornado hits: only if in a big city will an EF5 rating get assigned. Unless there's mobile doppler data, in which case it might tip the scale.

 

Unless something has changed, the latest official word that I saw was mobile radar data will not be used to rate a tornado, but instead will only be noted in the Storm Data entry as additional info. This despite the fact that the EF-scale paper clearly states remote sensing info should be used if deemed reliable.

[OceanStWx]

The ironic part about the Hattiesburg example is that nowhere in the damage survey can I find EF4 damage listed, besides a narrative. All I see is high end EF3 mentioned, even in the KML file of surveyed points.

 

LSX indeed seems to only have one damage indicator listed at EF4, but I'm sure that it was consistent with nearby damage indicators in order to make that call.