National Severe Weather Workshop Notes

[Master of Disaster]

Spent the last few days at the National Severe Weather Workshop in Norman and thought there were a few interesting presentations given which could lead to some discussion here.

James LaDue of the SPC gave a presentation on identifying EF5 damage from EF4. Out of 1,200 miles of tornado tracks from the April 2011 Super Outbreak, he has surveyed over 400 miles. He mentioned that out of all the high end EF4 events, Tuscaloosa was the most difficult to survey and was the closest to EF5. Specifically the Chastain Manor Apartments area near Holt where EF5 damage was suspected. He said three different teams surveyed the damage there and 2 ended up with high end EF4. The final 6 man team split evenly on EF5 and EF4 but there were 4 specific damage indicators missing which led to the EF4 rating. He said these same 4 indicators were missing in several other EF5 suspect events from April as well. The four indicators beyond the EF DOD scales were vehicles tossed long distances, shrubs (not trees) debarked, ground scoured, and home debris pulverized. He said there were several events where slab remained from the home BUT vaulting of the home was suspected and the home was not scoured off the foundation. Not one of the other indicators were present so the tornado was given an EF4 rating. He said the easiest to survey was Smithville MS where a Ford Expedition was picked up, carried 1/2 a mile, smashed against the top of the town water tower where it left a paint sample and then carried another 1/4 mile to its final resting place. He did mention they considered giving Tuscaloosa a 199MPH wind rating but decided to go with 190 to avoid the issues with a 1 MPH difference in EF5 and EF5.

There was a really great discussion about why no one died in the St Louis EF4 and they mentioned it was because a majority of the track was EF1-2 damage. Only ONE home damage areas were given EF4.

There was a presentation about Tornado Emergency. Since 1999, 24 of 83 tornado emergencies issued resulted in no tornado touchdown what so ever. Of the remaining ones, 2 were for EF5s, 8 were for EF4s and 23 were for EF3s. A majority were issued for rural areas with WFO Birmingham being the most prolific user of the term AND every one of their Tornado Emergencies ended where their forecast area ended. The presenter, Patrick Marsh, recommended ending the use of the term.

Finally, a presentation on different recovery approaches to EF5 strikes. Greesnburg Kansas has only had 53% of the town return while Parkersburg IA has had 95% return. The difference is that Greensburg decided to build a whole new town. Parkersburg decided to rebuild as was only better. Greensburg depended heavily on outside ideas while Parkersburg depended on each other to rebuild. Kind of interesting how the approaches have gone for both of those towns.

[dan11295]

A Lot of information there. A few thoughts:

EF4 vs EF5 damage: There will always be some grey area when it comes to assigned EF-ratings. Obviously some storms will simply not impact locations where damage can occur that would meet DOD criteria. If a tornado only goes thorough woods and then hits a mobile home park before lifting, It will never be assigned an EF5 rating, regardless of how strong it actually was. As far as Tuscaloosa 4/27/11, there is no question it was a violent tornado, but scientifically we simply do not have the capability to make definitive calls in such borderline cases. That being said, being conservative with the rating is the right way to go if there is doubt.

Tornado Emegencies: Unless there is a unified criteria as to when they should be used, maybe they should be dropped. I know yesterday at least once TOR-E was issued based on a debris signature alone without a confirmed TOG. Also worth remember that a TOR-E was never even issued for Joplin as it spun up so fast and so close to the city. Took 2 scans to go from a weak couplet to 180 kt gate-to-gate w/debris ball. Personally I would like to see them restricted to confirmed large TOG heading to some center of population (i.e. a town). Were some cells where they were justified, IMHO (i.e, Henryvile & Marysville, IN, West Liberty, KY), but just may be a tad too loose with the term.

[Master of Disaster]

Yea, def agree about the borderline events. It seems they are using Jarrell Texas as the benchmark for all EF5s now and he did mention that all 4 indicators were present with Jarrell. He briefly mentioned scouring of asphalt as a possible indicator but warned they dont use that because it all depends on substrate under the top layer.

With Joplin they mentioned that the EHI was 2 leading up to the event but went off the scale within minutes due to cell merger within the system.

[JoMo]

Finally, a presentation on different recovery approaches to EF5 strikes. Greesnburg Kansas has only had 53% of the town return while Parkersburg IA has had 95% return. The difference is that Greensburg decided to build a whole new town. Parkersburg decided to rebuild as was only better. Greensburg depended heavily on outside ideas while Parkersburg depended on each other to rebuild. Kind of interesting how the approaches have gone for both of those towns.

Did they give any other information?

Joplin's approach has been to allow people to rebuild back on their own land using whatever method they choose. There are ICS and 'green' homes, traditional stick built homes, etc.. built next to each other.

The CART (Citizen's Advisory Recovery Team) was made up of a variety of professionals and non-professionals within our community. They had meetings you could go to and give ideas as well as a website. They would write the ideas down and in subsequent meetings the ideas were narrowed down by popularity from both a feasibility standpoint and your everyday Joe Citizen that went to the meetings and stuck stickers on the ideas they liked. The ideas that were most popular were taken to the next 'round'.

Now I believe CART is interviewing master developers in order to make those visions come to life.

[Master of Disaster]

Did they give any other information?

Joplin's approach has been to allow people to rebuild back on their own land using whatever method they choose. There are ICS and 'green' homes, traditional stick built homes, etc.. built next to each other.

The CART (Citizen's Advisory Recovery Team) was made up of a variety of professionals and non-professionals within our community. They had meetings you could go to and give ideas as well as a website. They would write the ideas down and in subsequent meetings the ideas were narrowed down by popularity from both a feasibility standpoint and your everyday Joe Citizen that went to the meetings and stuck stickers on the ideas they liked. The ideas that were most popular were taken to the next 'round'.

Now I believe CART is interviewing master developers in order to make those visions come to life.

Yea, they talked about that a little with allowing the citizens to select how they want their community zoned. One of the factors in the high fatality rate was the housing stock in Joplin was over 75 years old and not up to current code. But on the flip side even a house up to code would stand little chance of surviving an EF5 and we all know it.

[JoMo]

Yea, they talked about that a little with allowing the citizens to select how they want their community zoned. One of the factors in the high fatality rate was the housing stock in Joplin was over 75 years old and not up to current code. But on the flip side even a house up to code would stand little chance of surviving an EF5 and we all know it.

Were there any other differences between the two towns that were mentioned? Did distance from neighboring larger towns play a role?

I'm genuinely curious, not trying to give you a hard time or anything.

Also, not all the houses and neighborhoods were that old but a section of them were. Some of the older houses did better than some of the newer ones :-\

[andyhb]

He said the easiest to survey was Smithville MS where a Ford Expedition was picked up, carried 1/2 a mile, smashed against the top of the town water tower where it left a paint sample and then carried another 1/4 mile to its final resting place.

That is unbelievable, a Ford Expedition is a huge vehicle.

[battlebrick]

That is unbelievable, a Ford Expedition is a huge vehicle.

It weighs 3 tons.

Holy ****.

[Master of Disaster]

Were there any other differences between the two towns that were mentioned? Did distance from neighboring larger towns play a role?

I'm genuinely curious, not trying to give you a hard time or anything.

Also, not all the houses and neighborhoods were that old but a section of them were. Some of the older houses did better than some of the newer ones :-\

Why would I take it that you were giving me a rough time? If there was anyone here who would be expected to have an interest here, its you. I hope they load the presentations, def worth checking out. One difference mention was the psychological impact. Of a town being wiped off the map and one where parts of the town remained. They mentioned that this certainly has some merit in the willingness to rebuild and return.

Another thing they mentioned with Joplin was that a thousand residents were surveyed and each of them required between 2 and 9 different forms of validation that the threat was real. Some heard the sirens, checked Facebook, walked outside, called a friend and then turned on the TV. WOW, really?

[JoMo]

Why would I take it that you were giving me a rough time? If there was anyone here who would be expected to have an interest here, its you. I hope they load the presentations, def worth checking out. One difference mention was the psychological impact. Of a town being wiped off the map and one where parts of the town remained. They mentioned that this certainly has some merit in the willingness to rebuild and return.

Another thing they mentioned with Joplin was that a thousand residents were surveyed and each of them required between 2 and 9 different forms of validation that the threat was real. Some heard the sirens, checked Facebook, walked outside, called a friend and then turned on the TV. WOW, really?

I just didn't want you to think that I was questioning what you were saying.

I guess that probably does make a large difference, Greensburg was totally destroyed and Parkersburg wasn't totally destroyed. Some people probably just felt it would be easier to move away since there was nothing there in Greensburg.

I do hope they put the presentations online. I watched the AMS presentations online and I was disappointed in them for the most part since the presenters that were supposed to be there couldn't come for various reasons and they had to have others step in who were unprepared.

We get a lot of warnings in Joplin each year, most of those turn out to not produce anything. The tornado just happened to drop on the west side of the city which led to very little actual warning from something other than the usual run of the mill 'tornado warning' that leads to nothing. Call it optimism bias, warning fatigue, but to most people, this was nothing other than the run of the mill tornado warning.....until it wasn't....

I do know more people would have taken it more seriously had there been enhanced wording or a report of a touchdown before it reached Joplin (which that had not occurred yet). The 2nd siren was outside the 'norm' and alerted people (including me) that this wasn't what normally happens.

[Master of Disaster]

I just didn't want you to think that I was questioning what you were saying.

I guess that probably does make a large difference, Greensburg was totally destroyed and Parkersburg wasn't totally destroyed. Some people probably just felt it would be easier to move away since there was nothing there in Greensburg.

I do hope they put the presentations online. I watched the AMS presentations online and I was disappointed in them for the most part since the presenters that were supposed to be there couldn't come for various reasons and they had to have others step in who were unprepared.

We get a lot of warnings in Joplin each year, most of those turn out to not produce anything. The tornado just happened to drop on the west side of the city which led to very little actual warning from something other than the usual run of the mill 'tornado warning' that leads to nothing. Call it optimism bias, warning fatigue, but to most people, this was nothing other than the run of the mill tornado warning.....until it wasn't....

I do know more people would have taken it more seriously had there been enhanced wording or a report of a touchdown before it reached Joplin (which that had not occurred yet). The 2nd siren was outside the 'norm' and alerted people (including me) that this wasn't what normally happens.

Yesterday, the Director of the SPC spoke for 30 minutes when his own office had a pending HIGH risk event. I thought that was kind of impressive considering what he had on his mind. He didnt take question though.

[Master of Disaster]

That is unbelievable, a Ford Expedition is a huge vehicle.

Yep, he said they were lucky and were able to locate the vehicle owner who showed them exactly where he parked it before the tornado hit. That kind of power is just jaw dropping. I mean their water tower has to be at least 200 feet high at the top where the impact occurred.

[JoMo]

Recalling back for me personally (since I was watching the radar and storms for hours):

1. Tornado Warning issued for north of my location

2. Tornado Sirens

3. Couplet forming

4. Tornado Warning issued for my area

5. Joplinmet on TV circling the area where the couplet was

6. Looking outside and seeing a dark as night sky to the northwest. (the tornado was forming southwest of me at this time, i had judged that the tornado would go right over me or slightly to the north based on the last velocity scan I saw, lucky for me it dropped just to the south on the next scan that I didn't get to see.)

7. Hearing a rumbling sound that sounded like rolling thunder that was getting louder.

8. Hearing the siren go off again, once that went off, I knew there was something on the ground.

The last 3 probably happened within 2 minutes with the last 2 happening about the same time.

I had the optimism bias that it was just elevated since that 'couldn't' happen to my house.

I do remember looking back at the HRRR and thinking that the situation was just going to become a large complex of storms since the HRRR was blowing storms up along the SE and S flank of the parent supercell so the biggest threat would probably be wind and hail due to storm interference. Guess not, lol

[AtticaFanatica]

A Lot of information there. A few thoughts:

EF4 vs EF5 damage: There will always be some grey area when it comes to assigned EF-ratings. Obviously some storms will simply not impact locations where damage can occur that would meet DOD criteria. If a tornado only goes thorough woods and then hits a mobile home park before lifting, It will never be assigned an EF5 rating, regardless of how strong it actually was. As far as Tuscaloosa 4/27/11, there is no question it was a violent tornado, but scientifically we simply do not have the capability to make definitive calls in such borderline cases. That being said, being conservative with the rating is the right way to go if there is doubt.

Tornado Emegencies: Unless there is a unified criteria as to when they should be used, maybe they should be dropped. I know yesterday at least once TOR-E was issued based on a debris signature alone without a confirmed TOG. Also worth remember that a TOR-E was never even issued for Joplin as it spun up so fast and so close to the city. Took 2 scans to go from a weak couplet to 180 kt gate-to-gate w/debris ball. Personally I would like to see them restricted to confirmed large TOG heading to some center of population (i.e. a town). Were some cells where they were justified, IMHO (i.e, Henryvile & Marysville, IN, West Liberty, KY), but just may be a tad too loose with the term.

Good post, though I'd probably say "...a lot of grey area when it comes to assigned EF ratings."

[AcworthWx]

Now as for the TOR-E goes, did Patrick Marsh discuss the new Enhanced Severe WX Products (http://products.weather.gov/PDD/PDD_CR_IBW_011012.pdf) in how it affected his findings(If at all)? I know these products are in its trial phase (Trial WFOs are TOP, EAX, SGF, LSX and ICT) and it will be at least a year until we can get some good concrete evidence on the validity of these products, but I believe the Dual-Pol upgrades are going to make TOR-Es have higher Verification percentages. The science is really starting to make some very positive advances in the last couple years and maybe his findings are a little skewed because he uses data over a decade old to come to his conclusion, IMO.

[MGorse]

Tornado Emegencies: Unless there is a unified criteria as to when they should be used, maybe they should be dropped. I know yesterday at least once TOR-E was issued based on a debris signature alone without a confirmed TOG. Also worth remember that a TOR-E was never even issued for Joplin as it spun up so fast and so close to the city. Took 2 scans to go from a weak couplet to 180 kt gate-to-gate w/debris ball. Personally I would like to see them restricted to confirmed large TOG heading to some center of population (i.e. a town). Were some cells where they were justified, IMHO (i.e, Henryvile & Marysville, IN, West Liberty, KY), but just may be a tad too loose with the term.

This is what currently is listed in the NWS Directives regarding a tornado emergency.

"In exceedingly rare situations, when a severe threat to human life and catastrophic damage from a tornado is imminent or ongoing, the forecaster may use the terminology "TORNADO EMERGENCY FOR [GEOGRAPHIC AREA]" in the third bullet of the warning. Additionally, in such a situation, this terminology should only be used when reliable sources confirm a tornado, or there is clear radar evidence of the existence of a damaging tornado such as the observation of debris."

Section 3 (sub-section 3.3.4).

http://www.nws.noaa.gov/directives/sym/pd01005011curr.pdf

[OceanStWx]

Now as for the TOR-E goes, did Patrick Marsh discuss the new Enhanced Severe WX Products (http://products.weat..._IBW_011012.pdf) in how it affected his findings(If at all)? I know these products are in its trial phase (Trial WFOs are TOP, EAX, SGF, LSX and ICT) and it will be at least a year until we can get some good concrete evidence on the validity of these products, but I believe the Dual-Pol upgrades are going to make TOR-Es have higher Verification percentages. The science is really starting to make some very positive advances in the last couple years and maybe his findings are a little skewed because he uses data over a decade old to come to his conclusion, IMO.

Keep in mind that dual-pol TDSs will only be a little more useful than current debris balls. Sure we'll be able to see some TDSs that might otherwise be masked by heavy rain, but the storm in question will still have to be within close proximity to the RDA. Storms at long ranges from the radar will still be just as "blind" to near surface processes as before.

[OceanStWx]

I had the optimism bias that it was just elevated since that 'couldn't' happen to my house.

You being a weather savvy person having optimism bias is a good example of just how hard it is to reach the rest of the population.

Almost all of the social science studies conclude that people need at least one other form of confirmation beyond a warning from their local WFO. You had that second siren, in Pitcher it was reported to be many neighbors jumping into their cars and racing out of town.

At this point I believe that major strides in lead time will be difficult given current technology, but the area of greatest improvement can be made with preparedness.

[AcworthWx]

Keep in mind that dual-pol TDSs will only be a little more useful than current debris balls. Sure we'll be able to see some TDSs that might otherwise be masked by heavy rain, but the storm in question will still have to be within close proximity to the RDA. Storms at long ranges from the radar will still be just as "blind" to near surface processes as before.

This I don't doubt. It's still a positive move in the right direction, IMO. I will admit that TOR-Es can and have been used very loosely.a Now as for distances, would your definition mean the following: Close proximity < 20 miles, Long Ranges > 60+miles ?

[OceanStWx]

This I don't doubt. It's still a positive move in the right direction, IMO. I will admit that TOR-Es can and have been used very loosely.a Now as for distances, would your definition mean the following: Close proximity < 20 miles, Long Ranges > 60+miles ?

We're talking around 60 nm for strong tornadoes, even closer for the non-significant tornadoes.

It is no doubt an improvement, because a reflectivity spike near the hook is by no means a confirmation that a tornado is on the ground an doing damage. However, a TDS is. And it will be most useful in situations where the clear debris ball is not obvious. When storms become rain wrapped and differentiation between rain and debris becomes difficult, CC should perform the best. Detection depends on the target's dielectric constant, so wet wood, painted wood and metal have the largest impact on CC. Basically, stuff that would be lofted by a tornado doing damage, as opposed to RFD dust, etc. It's definitely a very neat upgrade.

[AcworthWx]

We're talking around 60 nm for strong tornadoes, even closer for the non-significant tornadoes.

It is no doubt an improvement, because a reflectivity spike near the hook is by no means a confirmation that a tornado is on the ground an doing damage. However, a TDS is. And it will be most useful in situations where the clear debris ball is not obvious. When storms become rain wrapped and differentiation between rain and debris becomes difficult, CC should perform the best. Detection depends on the target's dielectric constant, so wet wood, painted wood and metal have the largest impact on CC. Basically, stuff that would be lofted by a tornado doing damage, as opposed to RFD dust, etc. It's definitely a very neat upgrade.

OceanSt, Thank You so very much for that explanation and the other one in the Assessment thread! I think I learned more in these two post, than I have the last five years. These are definitely going into my SVR/TOR file on my computer.