4/27-4/28 Tornado Outbreak Damage Assessment Thread

[AtticaFanatica]

Some opinions from Chuck he wrote a few days after the outbreak regarding the QRT's readiness.

http://cadiiitalk.bl...of-program.html

[aslkahuna]

He makes some important points.

Steve

[hm8]

Looks like Discovery will be airing a special on this outbreak on May 22.

[HSVWx]

Some opinions from Chuck he wrote a few days after the outbreak regarding the QRT's readiness.

http://cadiiitalk.bl...of-program.html

I would have to strongly agree with Dr. Doswell. I live in Huntsville, AL. and have traveled all along the Hackleburg/ Phil Campbell/ Tanner/ Harvest EF5 path, and have taken over 275 photos total, and I still question some areas along the path that the NWS has deemed F3 and F4 damage in some areas. I'm no expert, but I've seen my share of tornado damage over the last 35 years and have some idea of what F3/F4/F5 damage looks like. It would have been interesting to know if someone of Dr. Doswell's experience, how he would deem the following damage below.... low end EF5 or high end EF5? Like he was suggesting to some degree, someone dropped the ball to in not requesting someone of his expertise/ and or a high end QRT team to come into the damage path areas of Alabama and allow him to make his/ their own determination of the damage from this historic outbreak. I do think KHUN has done a very good job .Maybe some have came into the area and I have just missed the information as such.

The Wrangler Plant just outside of downtown Hackleburg. 1 death and 14 injuries occured here.

View as tornado headed into the northern side of downtown Hackleburg and EF5 damage was determined.

[HurricaneJosh]

Wow-- totally awesome clip. Just awesome. So cool that that guy was able to muster the nerve to just stand there and film that.

[BadgerWXman]

Wow-- totally awesome clip. Just awesome. So cool that that guy was able to muster the nerve to just stand there and film that.

The thing I find crazy about that video is that the cars don't budge and the trees hold their ground... as violent as it looks, the winds you see there are probably EF-0, EF-1 AT WORST. I can't imagine what it must have looked like along the main damage path. Although the tower going down was pretty impressive... looks like that type of wind didn't make it to the parking lot where he was filming.

There are multiple reports of EF-4 damage just WSW of that guy's house.

[HurricaneJosh]

The thing I find crazy about that video is that the cars don't budge and the trees hold their ground... as violent as it looks, the winds you see there are probably EF-0, EF-1 AT WORST. I can't imagine what it must have looked like along the main damage path. Although the tower going down was pretty impressive... looks like that type of wind didn't make it to the parking lot where he was filming.

There are multiple reports of EF-4 damage just WSW of that guy's house.

Yeah, clearly what we can see in the video is not the actual core circulation but some inflow jets or whatever. But I still find it d*mn impressive because the P.O.V. is very, very close-- maybe within a city block.

I pretty-much agree with cyclone 77 (above) that that's a good 90- or maybe even 100-mph wind for a few seconds-- at the far end of the parking lot, after the center passes and the direction shifts (~1:22-1:30).

[Ed Lizard]

I'm still impressed by the little horizontal rolls/vortices that start near the ground and get sucked up in the updraft into the cloud base.

[knuckle66]

I'm not sure if the scouring of pavement is used to determine wind speeds on the EF scale but I don't think it takes alot of wind velocity to recreate some of the results in these pictures. Although impressive, the construction of the roads themselves should at least have a determining factor. For instance this picture depicts at best a 2 inch layer of asphalt over a sandy gravel base, pretty weak IMO. I don't know if it is a county or state road which is a major factor on the standard it was constructed.

The last pictures on this chart show a road with two layers, the top one being scoured. The clue I see to its construction is that the layer of oil that would be added to the top layer to make it adhere was light or missing. Also how much of the top layer was broken apart from the track hoe driving on it to clean up debris. You can see the tracks if you look closely.

I should mention that I have built roads/highways for 20 years so I understand how they are constructed. Aphalt by its nature is a plyable material, and I have achieved similar results in my own experience. One example would be using an industrial compressor and blowpipe to clean roadways or parking lots. If you can get under and edge or a pothole with the blowpipe it can literally blow the aphalt apart depending on its age and contruction. I would guess that the industrial compressor does not generate anything over EF0 wind speeds.

By no means am I saying that there was not EF5 damage at these locations, I am curious if road scouring is used at all to determine some of these ratings.

[HurricaneJosh]

I'm not sure if the scouring of pavement is used to determine wind speeds on the EF scale but I don't think it takes alot of wind velocity to recreate some of the results in these pictures. Although impressive, the construction of the roads themselves should at least have a determining factor. For instance this picture depicts at best a 2 inch layer of asphalt over a sandy gravel base, pretty weak IMO. I don't know if it is a county or state road which is a major factor on the standard it was constructed.

The last pictures on this chart show a road with two layers, the top one being scoured. The clue I see to its construction is that the layer of oil that would be added to the top layer to make it adhere was light or missing. Also how much of the top layer was broken apart from the track hoe driving on it to clean up debris. You can see the tracks if you look closely.

I should mention that I have built roads/highways for 20 years so I understand how they are constructed. Aphalt by its nature is a plyable material, and I have achieved similar results in my own experience. One example would be using an industrial compressor and blowpipe to clean roadways or parking lots. If you can get under and edge or a pothole with the blowpipe it can literally blow the aphalt apart depending on its age and contruction. I would guess that the industrial compressor does not generate anything over EF0 wind speeds.

By no means am I saying that there was not EF5 damage at these locations, I am curious if road scouring is used at all to determine some of these ratings.

Wow-- interesting. It's cool to have the perspective of someone who actually knows how these roads are constructed.

[Calderon]

The Americus, GA tornado back in March 2007, same day as the Enterprise EF4 was a mid-riange EF3 when it ripped asphalt off a road and it was of similar construction.

[U_Thant]

I've pinpointed the Duarte video location. It is on a small cul-de-cas between 25th and 27th Streets directly behind the Nat'l Guard Armory, literally the property adjacent to the NW corner of Charleston Square and across the street to the NE of the Rosedale housing project.

The tower seen taken out at 0:43 seconds is located directly beside the NB lanes of I-359 between 29th and 30th Streets.

I made a quick screen grab on Google Earth looking toward the SSW (the N in the compass is at 5 o'clock, mostly obscured by my drawing of I-359). Would you place Duarte in the bottom center of this image, below the "N33 11'18.24" notation, close to the large clump of trees, or would it be one street over to the right (westward) closer to the armory? Thx

Edit: NM...looks like I'm confused - I mislabeled the Rosedale Projects as the Charleston Square Apts, which means I'm too far west by a couple blocks.

[U_Thant]

Let's try this again...I panned to the east a couple blocks. Now...would you put Duarte in the lower center in/near one of those two black-roofed buildings beneath the N33 11'18.24" notation? Thx again.

[cyclone77]

Let's try this again...I panned to the east a couple blocks. Now...would you put Duarte in the lower center in/near one of those two black-roofed buildings beneath the N33 11'18.24" notation? Thx again.

Nice. The cameraman of the Duarte vid is just below (north) of the N in that pic.

[cyclone77]

Let's try this again...I panned to the east a couple blocks. Now...would you put Duarte in the lower center in/near one of those two black-roofed buildings beneath the N33 11'18.24" notation? Thx again.

Using the image you posted I superimposed the track of the tornado based on aerial imagery with some basic photo editing software. The orange circle is where I believe the Duarte video was shot. The Charleston Square apartments just southeast of where the Duarte vid was shot suffered severe damage, including at least two fatalities.

[Chicago Storm]

Here's what I have...

April 27th - 12AM-11:59PM (Local Time)

Tornado Count: 177

Tornado Count Per CWA:

MRX: 51

HUN: 31

JAN: 30

BMX: 30

MEG: 12

FFC: 10

OHX: 9

SHV: 4

LWX: 4

AKQ: 3

GSP: 2

LMK: 2

MOB: 1

RNK: 1

RLX: 1

ILN: 1

CTP: 1

BMG: 1

Some additional info...

14 tornadoes featured a multi CWA track.

Two of the 14 featured a track through 3 CWA's.

[BadgerWXman]

It's unbelievable how lucky the Duarte guy was... that main damage path was about a block away.

[Master of Disaster]

Using the image you posted I superimposed the track of the tornado based on aerial imagery with some basic photo editing software. The orange circle is where I believe the Duarte video was shot. The Charleston Square apartments just southeast of where the Duarte vid was shot suffered severe damage, including at least two fatalities.

I cant believe you guys were able to pinpoint a location based off of some random pan shots. Great job, and it does appear that that was indeed where he was.

[mcalvert]

I'm not sure if the scouring of pavement is used to determine wind speeds on the EF scale but I don't think it takes alot of wind velocity to recreate some of the results in these pictures. Although impressive, the construction of the roads themselves should at least have a determining factor. For instance this picture depicts at best a 2 inch layer of asphalt over a sandy gravel base, pretty weak IMO. I don't know if it is a county or state road which is a major factor on the standard it was constructed.

--- image removed to save space ---

The last pictures on this chart show a road with two layers, the top one being scoured. The clue I see to its construction is that the layer of oil that would be added to the top layer to make it adhere was light or missing. Also how much of the top layer was broken apart from the track hoe driving on it to clean up debris. You can see the tracks if you look closely.

--- image removed to save space ---

I should mention that I have built roads/highways for 20 years so I understand how they are constructed. Aphalt by its nature is a plyable material, and I have achieved similar results in my own experience. One example would be using an industrial compressor and blowpipe to clean roadways or parking lots. If you can get under and edge or a pothole with the blowpipe it can literally blow the aphalt apart depending on its age and contruction. I would guess that the industrial compressor does not generate anything over EF0 wind speeds.

By no means am I saying that there was not EF5 damage at these locations, I am curious if road scouring is used at all to determine some of these ratings.

There are definitely a lot of variables and I don't think that a survey can be 100% sure on anything regarding how much wind was actually required to create a certain level of damage on a structure for which there is no complete information about pre-storm structural properties and even the sequence of damaging events during the storm.

All structures have members that are under different combinations and varying amounts of compression, tension, stress, strain, shear, and torsion. The members work together to support the weight of the structure and its contents under normal conditions and abnormal conditions within a given range. In normal scenarios, the forces placed on the structure are directed into the foundation along load-bearing walls, both internal and external. When a structure undergoes a new set of externally applied forces such as the winds of a tornado, the force distribution changes greatly and structural flaws that might not have been exposed before suddenly undermine the stability and integrity of the entire structure. In other cases, the structure is holding on barely and then a large piece of debris fractures a load bearing wall at a critical spot and the entire house is torn apart. The wind wasn't adequate to cause the damage alone, but it got assistance from a well-placed piece of debris and the wall may be so damaged that this collision isn't recognized.

Just because a house "appears" to have been well-constructed doesn't mean that it doesn't have ticking time-bombs in its structure, such as knots in stressed areas of trusses, joists and studs, torsion and bending of walls and floors due to unequal settling on "fill" lots, and structural weaknesses introduced by home "improvements" performed by homeowners and contractors that don't completely understand how their changes affect the force distributions within the frame of the house.

[Witness Protection Program]

Excellent work putting this all together. Fascinating watching the Duarte video knowing that the apts seen are about as close as you can get without being in the actual core.

Helps confirm my instincts that if a tornado ever looks that close, I'm heading for the mattresses, not a camera.

[cyclone77]

A couple more images here. The first is a closeup aerial image of the damage at the Charleston Apartments. If you look in the upper right part of the picture I put a red arrow pointing at the building that you infamously see in the Duarte video. You can only see the far eastern edge of it at the top of the picture, but it shows just how close the damage path came to the Duarte location.

The second picture is from higher up, but you can see the Duarte's location in relation to the damage path as well.

And finally here is fairly detailed damage survey around the Charleston Apartments. This was shot by one of the Charleston Apartment residents as they sifted through their damaged apartment. What's interesting is if you pause the video at 3:39 you can see the damaged row of trees behind the building seen in the Duarte video. The cameraman is pointing northwest at this point, right in the direction of where the Duarte video was shot.

[MGorse]

Incredible damage! While watching that video, it is like where do you even start with the clean-up. Debris is everywhere.

[Ellinwood]

Just a heads-up, The Discovery Channel is airing a special called "Tornado Rampage 2011" on the tornado outbreak that spanned 4/25-27. It will be on tonight at 10pm ET / 9 CT.

http://dsc.discovery...1.403.26406.0.0

[NaoPos]

There are definitely a lot of variables and I don't think that a survey can be 100% sure on anything regarding how much wind was actually required to create a certain level of damage on a structure for which there is no complete information about pre-storm structural properties and even the sequence of damaging events during the storm.

All structures have members that are under different combinations and varying amounts of compression, tension, stress, strain, shear, and torsion. The members work together to support the weight of the structure and its contents under normal conditions and abnormal conditions within a given range. In normal scenarios, the forces placed on the structure are directed into the foundation along load-bearing walls, both internal and external. When a structure undergoes a new set of externally applied forces such as the winds of a tornado, the force distribution changes greatly and structural flaws that might not have been exposed before suddenly undermine the stability and integrity of the entire structure. In other cases, the structure is holding on barely and then a large piece of debris fractures a load bearing wall at a critical spot and the entire house is torn apart. The wind wasn't adequate to cause the damage alone, but it got assistance from a well-placed piece of debris and the wall may be so damaged that this collision isn't recognized.

Just because a house "appears" to have been well-constructed doesn't mean that it doesn't have ticking time-bombs in its structure, such as knots in stressed areas of trusses, joists and studs, torsion and bending of walls and floors due to unequal settling on "fill" lots, and structural weaknesses introduced by home "improvements" performed by homeowners and contractors that don't completely understand how their changes affect the force distributions within the frame of the house.

Excellent point in the last paragraph. New construction( truss, wooden I beams, glued as compared to nailed etc) are far weaker when it comes to destructive forces such as flooding, storms and fire. While they are just as strong when it comes to compression forces, or downward natural forces of gravity ) it takes away from the structural integrity of the house itself.

For example, take two popular roof construction methods, truss and then rafter construction. Truss construction holds up well as long as it's undisturbed Ad remains a whole component. Take away one of these components and the truss roof fails. Now, take a rafter style roof, take away 1 rafter, and the whole roof doesn't fail.

In essence, newer construction is in favor of the builder. Cheaper, easier and at the minimum rating allowed by code. It affects the safety of the occupants and emgncy responders. While the "new construction" takes over, while the house looks well built, it in essence, could not have the same ratings against forces of vertical and horizontal nature as "old construction" .

I'm sure survey teams take this well into consideration. But for the publics education, it's worth noting.

[Isopycnic]

Excellent point in the last paragraph. New construction( truss, wooden I beams, glued as compared to nailed etc) are far weaker when it comes to destructive forces such as flooding, storms and fire. While they are just as strong when it comes to compression forces, or downward natural forces of gravity ) it takes away from the structural integrity of the house itself.

For example, take two popular roof construction methods, truss and then rafter construction. Truss construction holds up well as long as it's undisturbed Ad remains a whole component. Take away one of these components and the truss roof fails. Now, take a rafter style roof, take away 1 rafter, and the whole roof doesn't fail.

In essence, newer construction is in favor of the builder. Cheaper, easier and at the minimum rating allowed by code. It affects the safety of the occupants and emgncy responders. While the "new construction" takes over, while the house looks well built, it in essence, could not have the same ratings against forces of vertical and horizontal nature as "old construction" .

I'm sure survey teams take this well into consideration. But for the publics education, it's worth noting.

I have to take issue with this. In the 80's and early 90's this statement would have been correct but FEMA wind load ratings for specific areas are a lot more stringent than they used to be. In all areas, especailly in coastal/mountainous regions, the ICC codes are now very stringent with the amount of metal "simpson strongtie straps" that are required. After each major event the ICC (pushed on by the insurance companies) institute newer rules after analyzing damage. What's been being added since the mid 90's and especially after Katrina are a lot more metal brackets and specialized connectors to the homes and decks. As a contractor we attach the first floor walls to the foundation (every 4 feet here in central nc, every other studbay in eastern NC), the first and second floor walls (every 4 feet here in central nc, every other studbay in eastern N) then the top plates to the rafters (every 3rd rafter central nc, two per rafter in eastern NC). Straps across the ridge/ hips and valleys to attach the rafters together are also required. Sheathing is to span between floors (gapped at mid band) and nailing patterns on plywood sheathing are also specified in the ICC code. Most code enforcement divisions require a "pre-siding/roofing" inspection to inspect that this nailing pattern is followed. . The ICC code is what all state/regional govt's set their building codes standards to. and this is all required by new ICC codes While building the frame of a home we no longer have just two inspections, a rough-in and a final. We have multiple inspections so the code enforcement depts can see if everything is properly being installed. (pre-floor, pre-siding, pre-roofing. Pretty much if you are going to cover it up get it inspected beforehand or the crew will have to tear it apart to provide access later)

[NaoPos]

I have to take issue with this. In the 80's and early 90's this statement would have been correct but FEMA wind load ratings for specific areas are a lot more stringent than they used to be. In all areas, especailly in coastal/mountainous regions, the ICC codes are now very stringent with the amount of metal "simpson strongtie straps" that are required. After each major event the ICC (pushed on by the insurance companies) institute newer rules after analyzing damage. What's been being added since the mid 90's and especially after Katrina are a lot more metal brackets and specialized connectors to the homes and decks. As a contractor we attach the first floor walls to the foundation (every 4 feet here in central nc, every other studbay in eastern NC), the first and second floor walls (every 4 feet here in central nc, every other studbay in eastern N) then the top plates to the rafters (every 3rd rafter central nc, two per rafter in eastern NC). Straps across the ridge/ hips and valleys to attach the rafters together are also required. Sheathing is to span between floors (gapped at mid band) and nailing patterns on plywood sheathing are also specified in the ICC code. Most code enforcement divisions require a "pre-siding/roofing" inspection to inspect that this nailing pattern is followed. . The ICC code is what all state/regional govt's set their building codes standards to. and this is all required by new ICC codes While building the frame of a home we no longer have just two inspections, a rough-in and a final. We have multiple inspections so the code enforcement depts can see if everything is properly being installed. (pre-floor, pre-siding, pre-roofing. Pretty much if you are going to cover it up get it inspected beforehand or the crew will have to tear it apart to provide access later)

Your in a hurricane prone area, hence the stringent building codes. I applaud you guys for your effort. Seems like NC and areas down to Florida have been positive strides to make the safest building possible.

But there are contractors out their that do their best to go by the minimum allowed by local code(it's money). If i'm not mistaken, and maybe you can help me out, but building codes are enforced by the township/county/city and no FEMA correct? I would assume that FEMA is more of a guideline

I'm not from the area, just stating what has been going on. As a FF, we're constantly updated on new building construction types.

[Thunderhead Hawkins]

I drove down to Hackleburg and Phil Campbell, Alabama to see how the recovery process was coming along . There were work crews cleaning up piles of debris. I saw several FEMA trailers scattered about. Many residents had already moved large piles of debris to the side of the road for pick up. It's coming along but still a real long way for these people to go. It was interesting to see cars still strewn about in fields were they seem to be forgotten heaps of metal. Part of some metal debris from the Wrangler plant was still scattered in trees and even along the roadway in some gutters.

[Hoosier]

I was looking at the Wikipedia entry and it says that losses could reach $10 billion. That is unbelievable for a tornado outbreak.

[thewxmann]

Two more tornadoes have just been surveyed by HUN. It's especially hard for them since they have practically no low-elevation radar data from their CWA after 22Z.

PUBLIC INFORMATION STATEMENT

NATIONAL WEATHER SERVICE HUNTSVILLE AL

602 PM CDT TUE JUN 7 2011

...TWO ADDITIONAL TORNADOES CONFIRMED IN DEKALB COUNTY FROM APRIL 27TH EVENT...

A PRELIMINARY STORM SURVEY OF ADDITIONAL DAMAGE INCURRED ACROSS

DEKALB COUNTY FROM APRIL 27TH HAS BEEN COMPLETED BY NATIONAL WEATHER

SERVICE AND LOCAL EMERGENCY MANAGEMENT PERSONNEL. INITIAL FINDINGS

FOR THE TWO ADDITIONAL TORNADO EVENTS ARE INCLUDED BELOW:

* EVENT TYPE: TORNADO

* EVENT DATE: 04/27/11

* EVENT TIME: 905 PM TO 910 PM /ESTIMATED BASED ON EYEWITNESS

ACCOUNTS AND RADAR/

* ESTIMATED PEAK WIND: 120.0 MPH

* PRELIMINARY RATING: EF-2

* PATH LENGTH: 6.5 MILES

* MAXIMUM PATH WIDTH: 250.0 YARDS

* BEGINNING POINT: 34.4059 / -85.7294

* ENDING POINT: 34.4427 / -85.6250

* SUMMARY: THE TORNADO FIRST TOUCHED DOWN ALONG DOGTOWN ROAD/COUNTY

ROAD 89 JUST SOUTH OF JENNINGS ROAD WHERE TWO SMALL BARNS WERE

COLLAPSED. THE TORNADO THEN CROSSED JENNINGS ROAD AND SNAPPED AND

UPROOTED TREES ALONG BEAR CREEK ROAD AND ADAMSBURG ROAD. A LARGE

NUMBER OF TREES WERE SNAPPED OR UPROOTED ALONG KELLY ROAD AND A

BARN SUSTAINED DAMAGE ALONG MCCURDY DRIVE.

THE TORNADO BEGAN TO STRENGTHEN RAPIDLY AS IT APPROACHED WALLACE

AVENUE/HIGHWAY 35. A LARGE METAL FARM BUILDING WAS LEVELED TO THE

GROUND HERE AND FOUR POWER POLES WERE SNAPPED OFF COMPLETELY. IN

THIS AREA...THE TREE DAMAGE WAS SUBSTANTIAL. THE DAMAGE WAS DEEMED

TO BE EF-2 INTENSITY IN THIS LOCATION. A HOME ON THE NORTH SIDE OF

HIGHWAY 35 SUSTAINED DAMAGE AND TREES WERE ALSO DOWNED ALONG

PATRICIA DRIVE. THE TORNADO CONTINUED TO MOVE NORTHEAST UPROOTING

AND SNAPPING A LARGE NUMBER OF TREES ALONG PUMPKIN CENTER ROAD.

TREES FELL ON SEVERAL HOMES JUST WEST OF THE INTERSECTION OF PUMPKIN

CENTER ROAD AND FISCHER ROAD. MINOR DAMAGE WAS NOTED TO HOMES ON THE

EAST SIDE OF FISCHER ROAD AS THE TORNADO BEGAN TO LIFT.

* EVENT TYPE: TORNADO

* EVENT DATE: 04/27/11

* EVENT TIME: 718 AM TO 722 AM /ESTIMATED BASED ON RADAR/

* ESTIMATED PEAK WIND: 100.0 MPH

* PRELIMINARY RATING: EF-1

* PATH LENGTH: 4 MILES

* MAXIMUM PATH WIDTH: 50.0 YARDS

* BEGINNING POINT: 34.6004 / -85.5835

* ENDING POINT: 34.6519 / -85.5496

* SUMMARY: DURING THE MORNING HOURS...A TORNADO TOUCHED DOWN JUST

WEST OF COUNTY ROAD 89/SCENIC HIGHWAY NORTH OF DOWNTOWN MENTONE.

THE TORNADO APPEARED TO RIDE ALONG THE RIDGELINE UPROOTING MANY

SOFT AND HARDWOOD TREES AND SNAPPING TREES SPORADICALLY. THE

TORNADO EVENTUALLY STRADDLED THE ROAD FURTHER NORTH PARTIALLY

REMOVING A ROOF TO A RESIDENCE AND SNAPPING NUMEROUS TREES IN THIS

AREA. THIS TORNADO APPEARED TO LIFT ABOUT A MILE SHY OF THE GEORGIA

LINE.

IT SHOULD BE NOTED THAT THE SURVEYOR ALSO FOUND SPORADIC TREE

DAMAGE FURTHER SOUTH ALONG COUNTY ROAD 89 NEAR AND SOUTH OF

DOWNTOWN MENTONE. HOWEVER...THE CONTINUITY OF THE DAMAGE WAS TOO

INCONSISTENT TO EXTEND THE TRACK FURTHER SOUTH.

THESE FINDINGS ARE PRELIMINARY AND ARE SUBJECT TO ADJUSTMENT.

PICTURES AND SUMMARY MATERIALS WILL BE MADE AVAILABLE ON OUR WEB PAGE

AT WEATHER.GOV/HUNTSVILLE /ALL LOWER CASE/.

SURVEYED BY: DARDEN

[tornadotony]

We will never know the true tornado count for 4/27/11. A good friend of mine was just hired as an intern at HUN and was out doing surveys her first week. She did some surveys in Marshall County and said the amount of damage is extraordinary. She said that between past damage, straight-line wind damage, and all the tornadoes together, it's an incredible feat to try to survey specific paths.