Severe Potential March 2nd/3rd: OV, TN Valley, Mid-South, Deep South, Mid-Atlantic, Carolinas

[tornadotony]

WAVE Louisville is reporting the death toll has risen to 39.

[shaggy]

These guys were lucky it was weak and not one of the stronger tornadoes yesterday or they would have been in real trouble.

http://www.youtube.com/watch?v=PJ0QOCmmwXk&feature=related

[QVectorman]

I will gladly take my piece of humble pie on this event...or PIECES. This certainly played out into a major outbreak. I can't dispute that. All the pieces came together. I'm sorry to those I doubted.

I apologize to anyone I offend by reverting back to this subject but I hope you can add this to your tool box for future events and help in forecasting.

But here are 2 papers to defend my claim of using vertical velocities from models to help identify enhanced areas of risk for severe wx/tornadoes and a LITTLE better (haha to say the least) explanation of the logic behind it.

The first article mentions specifically and infers that when forecasting svr. storms and tornadoes and the Kain-Fritsch convective scheme is used in the model, optimal results from this particular scheme and in forecasting said weather is achieved when the vv's process is applied on top of the Kain-Fritsch convective scheme. Possibly explaining why Fritsch endorsed this forecasting process.

Also notes more eloquently than I did at conveying the message that the explicit timing, intensity, and location of the updrafts hence, svr. storms and tornadoes should be considered as qualitative, rather than as quantitative, forecast guidance. And that I was not and the process was not being used in an attempt to target forecast meso/microscale events rather identified geographical regions that favored such.

http://wwwtw.vub.ac....PhDDDehenau.pdf

"The author thinks the vertical velocity (VV) at the 500 hPa level is also important

when searching for areas where large updrafts at grid scale is important, especially if

a mass flux convection scheme, like Kain-Fritsch, is used. The more negative VV, the

stronger the updraft and the thunderstorm. Strong updrafts suggest severe turbulence

and a possibility of strong gusts. In some cases presented hereafter, it was a very

useful tool for diagnosing severe thunderstorms."

"Vertical velocity at 500 hPa in high resolution models gives a clear indication of

updrafts in supercells but also in other weather systems, such as fronts. As we try to

calculate the risk of supercell tornadoes as well as strong convective gusts, vertical

velocity is a good indicator of strong updrafts. Without updrafts, tornadoes are

impossible (Brooks, 1994a). It needs to be stressed the vertical velocity is strongly

correlated with the convection scheme. The vertical velocity is resolved on the

model’s grid scale. The role of a convection scheme is to remove instability. If too

much instability remains, convection on a grid scale occurs, causing updrafts in a

small area. If the vertical velocity remains large, less instability is removed by the

convection scheme. It implies the results of the STP-approach, influenced by grid

scale vertical velocity, are strongly related to the type of convection scheme and the

resolution of the model."

"A good indicator in this case is the 500 hPa vertical velocity VV, giving an idea of the

updrafts on a meso scale. The more negative VV is, the stronger the updraft and the

thunderstorm. Strong updrafts suggest severe turbulence and a possibility of strong

gusts. The maximum updraft is in the vicinity of Herne, where a strong tornado

caused extensive damage"

http://journals.amet...0.1175/WAF907.1

"Given these complicating factors, model vertical velocity and quantitative precipitation forecasts (QPFs)can aid in the assessment of band potential, providing evidence to support or refute the hypothesis of band formation. The hypothesis of band formation is supported when a narrow (relative to the resolution of the model) region of forecast ascent and precipitation corresponds to the forecast location of midlevel frontogenesis and weak moist symmetric stability (Schumacher 2003). Although the explicit timing, intensity, and placement of a model forecast precipitation band may be in question, the fact that the model dynamics are producing banded precipitation suggests the presence of a favorable environment. Precipitation fields from high-resolution models can provide additional insight into the nature (i.e., movement, intensity, and dissipation) of the precipitation event given the fine horizontal resolution and hourly accumulation periods of these fields. Similar benefits of using high-resolution model precipitation fields have been demonstrated by Roebber et al. (2002) for convective precipitation events.However, at 12–24-h forecast projections, the explicit timing, intensity, and location of the band should be considered as qualitative, rather than as quantitative, forecast guidance (Roebber et al. 2004)."

This is the 21z 700 mb VV forecast from the NAM where I noted the enhanced areas of +VV over the OH River Valley where at 21z multiple tornado warnings were being issued. Note the thin narrow band of max lift paralleling the OH River...it's shape length and wide mimics the SPC reports of a thin narrow band of tornado reports in the same region that were reported pretty much + -1 hr 21z. Other areas of enhanced +VV on the map did not enhance convection in those regions because either CAPE, sfc forcing or shear were not ample or not present together. Where all 3 are present and in combination with progged +VV enhanced threats of svr. wx and tornadoes is present.

[andyhb]

East of Charlotte, NC, more damage photos:

http://www.wsoctv.com/gallery/news/local/slideshow-storm-damage-east-meck-co/gdzB/#1333063

[andyhb]

Oh jesus, out of Lakeland, GA:

TAE: 1 W Lakeland [Lanier Co, GA] public reports TORNADO of UNK at 01:08 PM EST -- extensive roof damge to the hospital. out buildings have damage. no power and gas leak.

[wxsmwhrms]

I will gladly take my piece of humble pie on this event...or PIECES. This certainly played out into a major outbreak. I can't dispute that. All the pieces came together. I'm sorry to those I doubted.

I apologize to anyone I offend by reverting back to this subject but I hope you can add this to your tool box for future events and help in forecasting.

But here are 2 papers to defend my claim of using vertical velocities from models to help identify enhanced areas of risk for severe wx/tornadoes and a LITTLE better (haha to say the least) explanation of the logic behind it.

The first article mentions specifically and infers that when forecasting svr. storms and tornadoes and the Kain-Fritsch convective scheme is used in the model, optimal results from this particular scheme and in forecasting said weather is achieved when the vv's process is applied on top of the Kain-Fritsch convective scheme. Possibly explaining why Fritsch endorsed this forecasting process.

Also notes more eloquently than I did at conveying the message that the explicit timing, intensity, and location of the updrafts hence, svr. storms and tornadoes should be considered as qualitative, rather than as quantitative, forecast guidance. And that I was not and the process was not being used in an attempt to target forecast meso/microscale events rather identified geographical regions that favored such.

http://wwwtw.vub.ac....PhDDDehenau.pdf

"The author thinks the vertical velocity (VV) at the 500 hPa level is also important

when searching for areas where large updrafts at grid scale is important, especially if

a mass flux convection scheme, like Kain-Fritsch, is used. The more negative VV, the

stronger the updraft and the thunderstorm. Strong updrafts suggest severe turbulence

and a possibility of strong gusts. In some cases presented hereafter, it was a very

useful tool for diagnosing severe thunderstorms."

"Vertical velocity at 500 hPa in high resolution models gives a clear indication of

updrafts in supercells but also in other weather systems, such as fronts. As we try to

calculate the risk of supercell tornadoes as well as strong convective gusts, vertical

velocity is a good indicator of strong updrafts. Without updrafts, tornadoes are

impossible (Brooks, 1994a). It needs to be stressed the vertical velocity is strongly

correlated with the convection scheme. The vertical velocity is resolved on the

model’s grid scale. The role of a convection scheme is to remove instability. If too

much instability remains, convection on a grid scale occurs, causing updrafts in a

small area. If the vertical velocity remains large, less instability is removed by the

convection scheme. It implies the results of the STP-approach, influenced by grid

scale vertical velocity, are strongly related to the type of convection scheme and the

resolution of the model."

"A good indicator in this case is the 500 hPa vertical velocity VV, giving an idea of the

updrafts on a meso scale. The more negative VV is, the stronger the updraft and the

thunderstorm. Strong updrafts suggest severe turbulence and a possibility of strong

gusts. The maximum updraft is in the vicinity of Herne, where a strong tornado

caused extensive damage"

http://journals.amet...0.1175/WAF907.1

"Given these complicating factors, model vertical velocity and quantitative precipitation forecasts (QPFs)can aid in the assessment of band potential, providing evidence to support or refute the hypothesis of band formation. The hypothesis of band formation is supported when a narrow (relative to the resolution of the model) region of forecast ascent and precipitation corresponds to the forecast location of midlevel frontogenesis and weak moist symmetric stability (Schumacher 2003). Although the explicit timing, intensity, and placement of a model forecast precipitation band may be in question, the fact that the model dynamics are producing banded precipitation suggests the presence of a favorable environment. Precipitation fields from high-resolution models can provide additional insight into the nature (i.e., movement, intensity, and dissipation) of the precipitation event given the fine horizontal resolution and hourly accumulation periods of these fields. Similar benefits of using high-resolution model precipitation fields have been demonstrated by Roebber et al. (2002) for convective precipitation events.However, at 12–24-h forecast projections, the explicit timing, intensity, and location of the band should be considered as qualitative, rather than as quantitative, forecast guidance (Roebber et al. 2004)."

This is the 21z 700 mb VV forecast from the NAM where I noted the enhanced areas of +VV over the OH River Valley where at 21z multiple tornado warnings were being issued. Note the thin narrow band of max lift paralleling the OH River...it's shape length and wide mimics the SPC reports of a thin narrow band of tornado reports in the same region that were reported pretty much + -1 hr 21z. Other areas of enhanced +VV on the map did not enhance convection in those regions because either CAPE, sfc forcing or shear were not ample or not present together. Where all 3 are present and in combination with progged +VV enhanced threats of svr. wx and tornadoes is present.

Thanks for posting this. I skimmed the article and got some interesting stuff out of it. I am going to be honest, my questioning of some of your posts a few days back were more that I was not seeing the same things you were in the data (as others mentioned as well). You seemed to be indicating a lack of upward motion collocated with the strong instability in the southern part of the outbreak, and I was not seeing that at all. It seemed clear that strong jet support would be spreading over MS/TN/AL during the afternoon and evening yesterday given the model forecasts of vertical motion, jet placement, and QPF, and that in fact occurred. It was actually a really cool case where you could see the jet ascent moving into the Arklatex on water vapor during the early afternoon, and convection lit up along and ahead of the front as that happened. The models forecast that very well for several days.

Obviously, every time there is a big weather event, there will be people presenting pros and cons leading up to it as to why it will or won't happen. But one thing I think needs to be stressed is that EVERY severe weather event has potential failure modes if one looks hard enough - but that doesn't mean that the event will fail. To me, when you have as dynamic a setup as the models were forecasting with this event combined with the potent instability yielded by the fact that the lead system earlier in the week made it easy for this system to tap into, you can go too far into the weeds trying to find reasons why an outbreak won't happen. Furthermore, once you get within 36 hours of the event, I don't know why you would be looking at synoptic model forecasts of vertical motion to try to find convection as this 7 year old paper describes. We now have high resolution models such as the 4km SPC/NSSL WRF models that explicitly forecast convection. The SPC WRF did an awesome job with yesterday's event as far as convective evolution, and I have been finding it to be a great tool. Not perfect, of course (didn't do real well with the early week event), but IMO a better tool than trying to use NAM vertical motion as a proxy.

To me, you look at the synoptic models to try to get an idea of the mass fields, the synoptic vertical motion, etc., and then use high resolution modeling to try to anticipate initiation and mode as you get closer to the event. You will obviously still have severe convective forecast busts because we are not perfect and models aren't perfect, but I think we are seeing huge busts (like high risk events where nothing much happens) becoming more and more a thing of the past.

Just my two cents...

[Hoosier]

Apparently, a baby was taken by the New Pekin, IN tornado. She was found 10 miles away, injured but still ALIVE.

http://cleveland.cbs...-after-tornado/

Only survivor out of her immediate family  

http://www.wishtv.com/dpp/news/indiana/baby-found-in-field-after-storms

[andyhb]

Miracle she survived, but god that's awful.

[Baroclinicity]

Here's two videos I created from radar loops of the supercell pair that moved through Northern Kentucky and Southern Ohio yesterday. The lead storm's hook echo passed about 5-6 nautical miles from the TCVG radar with enhanced reflectivity at the end of the hook curl. Check the 1080p option to see the full size.

Scans from the TCVG radar

From the KILN radar

[CoastalWx]

Regarding using the NAM VV's, how do we know that's not the NAM seeing the convection anyways. In other words, I'm not sure we can say that those VVs were a reason why cells developed there. That could have been the NAM already depicting the convection and those VVs were just the result of the area of heavier rain and tstms. I do agree that in areas that are capped like down in the high plains..you need overall synoptic lift to help with height falls and upward motion that eventually work to cool the column and break the cap.

[fyredog28]

Sadly, the little girl in Indiana who was the only survivor of her family has died.

http://www.cnn.com/2012/03/04/us/indiana-tornado-girl/index.html?hpt=hp_t1

[JoMo]

Sadly, the little girl in Indiana who was the only survivor of her family has died.

http://www.cnn.com/2....html?hpt=hp_t1

That's sad.

But wow... :-\

"A neighbor, Andy Lanham, told CNN on Sunday that the girl, her two siblings and her parents had been invited by another neighbor to stay in his larger mobile home, in hopes that would help improve their chances of riding out the storm safely."

The twister had picked up the entire family and dropped them about 100 yards away from their home. Only Angel -- who great aunt Carol Brough said later was 14 months old -- had survived.

Lanham said the neighbor who had tried to help the family, Jason Miller, "was just walking around here. He was out of his mind."

[Hoosier]

That's sad.

But wow... :-\

"A neighbor, Andy Lanham, told CNN on Sunday that the girl, her two siblings and her parents had been invited by another neighbor to stay in his larger mobile home, in hopes that would help improve their chances of riding out the storm safely."

The twister had picked up the entire family and dropped them about 100 yards away from their home. Only Angel -- who great aunt Carol Brough said later was 14 months old -- had survived.

Lanham said the neighbor who had tried to help the family, Jason Miller, "was just walking around here. He was out of his mind."

I don't know why anyone would stay in a mobile home when they know something like that is bearing down on them. You're in grave danger even with a relatively weak one like EF1 and you have almost no chance in anything stronger.

[QVectorman]

Friend posted this on FB. Some of the best tornado footage I've ever seen especially at 2:41. Almost like TIV footage.

[Hoosier]

A bit OT but from devastation to snow

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE LOUISVILLE KY

221 AM EST MON MAR 05 2012

.TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON

.DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.

..REMARKS..

0220 AM SNOW 4 S HENRYVILLE 38.48N 85.77W

03/05/2012 E2.5 INCH CLARK IN PUBLIC

[Stebo]

Another video from Borden IN, about 4 minutes in the tornado comes in view from behind a hill. Note strong language plus I think they were kind of dumb to get in the car and try and leave at the end as it was running parallel to them although their home looked to be a pre-fab home which would have offered no real protection from the tornado.

[hm8]

Wow at those last two videos posted. I don't know if it was mentioned here or in the GLOV thread, but again its really eerie how most of the trees are all bare and grey in the background behind a monster tornado. Not the kind of stuff you see in most tornado videos.

[Hoosier]

comparison of warnings from March 2-3 and April 27-28

from SPC

[hm8]

comparison of warnings from March 2-3 and April 27-28

from SPC

That April 27-28 map is insane. The total tornado warning coverage area is the same as coverage for ALL warnings from 3/2

[Hoosier]

This outbreak gets the distinction of being the first billion dollar disaster in the US in 2012.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2068