Thunderstorms in TN just woke up my dog and thus me. Some nasty sounding thunder but no tornado watch so I think I'm good.
NWS just updated that storm in OK the other day to an EF4 NWS Norman @NWSNorman 29m29 minutes ago NEW! The May 9th Katie tornado (W of I-35) is being upgraded to EF4 based on more intensive review of survey data. Updated PNS and map soon.
Haven't had much time to look, but the cloud cover seems to be slowly eroding across Iowa and northern MO, collocated with the best shear and instability. The wind shear, at least at the moment, is very poor across much of AR, OK, and TX...I wouldn't expect too much there. Some instability so marginally severe wind and hail is possible. Could get a nice line of storms along the cold front later this evening that stretches from IL/MO into AR/OK.
I'd feel kind of silly laying in a ditch, keeping my head covered, but turned sideways to avoid some standing water, while a bunch of storm chasers were parked on the road 10 feet in front of me getting footage and moving closer.
They finally posted the story behind the intercept: http://www.cswr.org/contents/DeFlitch-20160509-TWIRL_Scout3Deployment.pdf
SPC is pretty good at what they do. Interesting to note the high slight category, although not terribly surprising given the complicated forecast setups that often occur (overnight convection, cloud cover, etc.). Violent tornado = F/EF 4-5s Sam Lillo @splillo 2m2 minutes ago Violent tornadoes by location in most recent @NWSSPC outlook category. This is pretty remarkable...
Surprising that enhanced is so low. Must not be a huge amount of difference between forecasting slight > enhanced?
I think there is some of that, but the enhanced category is a year or two old, I believe. I would suspect that has reduced the numbers.
Tomorrow could be an interesting day in the TX Panhandle/far W OK. Interesting read from Chuck Doswell (prominent severe storms scientist) on the F/EF scale and it's inherent problems. It's really hard to get an accurate representation of tornado strength based upon damage given that many houses in this country are poorly built. Typically, if a tornado completely levels a house, it's usually assigned an EF4 rating. However, many houses surveyed after the fact were never actually attached to the foundation; they were just sitting there. As a result, tornado will be rated lower because the house was not built to withstand a certain windspeed and you can only rate based upon what it could withstand...Anyway, here are his thoughts: http://cadiiitalk.blogspot.com/2016/05/can-we-do-away-with-tornado-fef-scale.html Spoiler Let me state at the outset that I have no doubt meteorology will be saddled with the curse of F/EF-scale ratings for a long time to come, so this is mostly an exercise in futility. Why do I dislike these ratings? The main problems I have with them are discussed here. The essence of why they bother me and seem so counter-productive is that they represent an effort to provide a simple summary measure of something that's very complex. I suppose having a rating is better than not having any information about the intensity (i.e., windspeeds) in a tornado and thereby assuming they're all the same. But that's not the only choice we professionals have. Consider just one damage indicator, say a particular type of framing attachment in a typical American frame home. A host of complex issues are associated with the failure of that particular type of attachment, such that if you could test a large number of such attachments by subjecting them all to the winds in a wind tunnel wherein you knew the windspeeds accurately, you would find that there's no single value of the windspeed that would cause that type of attachment to fail. Instead, because each such attachment is a unique combination of components, the failure of that type of attachment would be associated with a range of windspeeds. In doing a survey of tornado damage, you would not be able to know precisely what windspeed caused the failure of that attachment - rather, failures would occur within a range of windspeeds. This is true regardless of what damage indicator you use. At best, a given amount of damage can never be said to have a single, precise value of windspeed that would cause that amount of damage. Thus, in the absence of any way tomeasure the windspeeds that produced that damage, the best one can do is know the distribution of windspeeds that cause that amount of damage. You might choose the media (or the mean) within the distribution to represent some sort of a guess, but doing so is intrinsically wrong from a scientific viewpoint. Further, we know very little about the actual spatial and temporal distribution of windspeeds in a tornado, even for those few tornadoes sampled with mobile Doppler radars. It's common to idealize the airflow in tornadoes using some simple model, such as that of a so-called Rankine Combined Vortex. All one needs to do to convince oneself that most real tornadoes probably don't fit that model very well in detail is look at some tornado videos. The actual winds in a tornado, especially those with multiple vortices, can be vastly more complex than any simplified vortex model. It's these real winds that interact with real objects in the path of the tornado to produce the observed damage. This is a very important fact that makes it currently impossible to know by objective measurement what windspeeds are associated with any particular element of damage. The time sequence of winds experienced by some damage indicator simply isn't known. Plus the presence of debris in the wind - which alters the wind distribution - adds an additional level of complication. Thus, a complex, debris-laden windfield interacting with objects whose failure points cannot be known precisely makes this whole issue vastly more complicated than what can be expressed by some single summary number. Reality is staggeringly complex and the idea that one number can offer much insight is too absurd to consider. Except that's precisely what the existing F/EF-scale ratings are trying to accomplish. There's no hope that in what remains of my life and for the foreseeable future, it will ever be possible to have wholly objective, high-resolution measures of tornado windspeeds. Yet, we continue to use these rating systems with hard boundaries between categories, and category boundary values that are essentially arbitrary and without any real significance. Is it really plausible to say that an estimated windspeed of 199 mph (EF-4) is actually distinguishable from one of 200 mph (EF-5)? Can we really make such a distinction based on various observed levels of damage to damage indicators? Does it make sense to call a tornado an EF-5 based on a single damage indicator at one point in an extensive damage path? The science of tornadoes is riddled with uncertainties, so there can be no plausible reason to accept as meaningful some single summary measure based on making numerous simplifying assumptions and creating arbitrary categories. Science has learned how to make those uncertainties work for us in coming to conclusions, via the methods of statistics. If we're going to have a scientific data base that's of much help to the science, it shouldn't be using the F/EF-scale rating of tornado windspeeds as some sort of meaningful measure. Distributions of estimated windspeed, probabilities of windspeed values associated with particular damage observations - these are much more appropriate tools with which the science can work. Every professional knows already that such ratings have many problems and are a very crude way to think about the phenomena. I get that the public may not care about the subtleties here. There may well be pressure to produce some sort of summary measure for the masses of non-scientists. Fine. Let someone decide how to do that, hopefully based on some reasonable application of science and engineering. But professionals surely can do better than condensing all the complexity and accompanying uncertainty into one summary number. I say we should do away with the ratings, at least at the science level.
I think the Sulphur, OK was vastly underrated. Over a mile wide with measured wind speed at 216mph. But the homes it swept off the foundation wasn't anchored properly so I guess we'll give it an EF-3 rating. Reminds me of El Reno EF-3 2013.
Yep, there is a disconnect between observed data (radar) vs. the traditional method of rating tornadoes.
Are radar measurments not thought to be all that accurate? Curious why they would use on the ground surveys when they know the houses aren't built to withstand anything major rather than measurement using a radar, unless its not too reliable. I guess the distance away from the tower will change what exactly you are measuring too much?
It's more of a data continuity issue. Most tornadoes are not sampled by mobile doppler, so the only thing to go on is damage. I do believe they can add the doppler measured winds as a comment in the official database/report about the tornado, but the official rating is based on the damage.
There's an element of blaming the tornado for not hitting better constructed buildings for rating things. If the 5/3/99 tornado had spun out in a field in Minco or Pocasset, OK and scoured the ground beyond belief but only knocked over fence and never hit a house what would it have been rated? It's considered one of the most terrible tornadoes ever but sorry we can't rate it because it didn't destroy shit that we can have an engineer look at and tell us how well it was constructed.
Also, I forgot another big issue with Doppler radar ratings has to do with how Doppler works in the first place. The radar beam increases in height as it travels further from the source. So one tornado may have a mobile Doppler measured wind speed at 10 m elevation, whereas another may be measured at 75 m, and so on. There is no accepted/known equation that can accurately account for the differences based on elevation. Hard to have a consistent rating dataset because of that.
Yep. Just like the El Reno tornado as you mentioned. There is a lot of debate among meteorologists on how to best go forward rating tornadoes. That Behind the Storms podcast I've listed before had a guy who is on the team that is looking into how to best rate tornadoes. I think it's only on iTunes now, just search Behind the Storms and it's episode 6.
True. I'm sure some super smart sciency guys could do it. It was on the ground at .5 miles wide with 200 mph winds, for 5 mins and lifted. Re-cycled and dropped again at 3/4 mile wide with 200 mph winds and was on the ground for 15 mins. Put all the data in some sort of equation.
Using the common sense approach: Is the building well constructed? Yes, rate it accordingly. Is the building well constructed? No. Do we have a mobile doppler rating? Yes. Ok, look at the two components and rate accodingly. Is the building well constructed? No. Do we have a mobile doppler rating? No. OK, then do your best. To me, if you have a building swept off its foundation and a mobile doppler wind speed rating of 216mph that's an EF-5. Throw in the fact that thing was a mile wide when the wind speed was taken and it seems logical to give it the appropriate rating. I have a conspiracy theory on why they gave it an EF-3 but that's for another day.
Because they whiffed on the forecast for the 3rd time in a month and won't admit that an EF-5 could have happened outside their predicted hatched area for the 2nd time in 3 days. It's why they upgraded the Katie to an EF-4, it was a token upgrade to distract from Sulphur. I'm sure this will be refuted but I feel strongly about it.
Personally id say treat them like a hurricane. Peak wind speed and size call it good. If it recycles its a totally different tornado
There has been a ton of research, and continues to be, on how to best rate tornadoes. Obviously, tornadoes are incredibly complex and dynamic, which makes it hard to encapsulate a rating in a tidy fashion. Every tornado has a damage swath (size), but within that swath are vastly different wind speeds. Or take the El Reno tornado for example: very large tornadic circulation with embedded sub-vortices that were meters in width, yet had the strongest wind speeds. The classic question posed is if there is EF5 damage at only one location, yet all the damage within the rest of the swath is only EF3. Is a rating of EF3 a better representation? Or if EF5 winds are measured via mobile Doppler at a reasonable height, yet are only experienced for a few seconds, does that warrant an EF5 rating? Then there is the debate about wind speed duration: Is a structure better or worse off with a quick burst of 150 mph winds, or a sustained 100 mph wind? I'm not sure we'll see anything in our lifetimes that satisfies everyone. It seems that the EF-scale debate is one of the more contentious within the severe storms community.
Not an uncommon thought, really. There are some offices that have a reputation of over-rating tornadoes or making it a point to document every little EF0, even if it's a stretch.
Nice write up about the Katie, OK tornado: http://www.ustornadoes.com/2016/05/15/tornado-week-katie-oklahoma-dry-line-beast-may-9-2016/
Not sure about your neck of the woods but weve had several tornadoes and grapefruit sized hail the past two days. Suppose to storm wvery day this week with Thursday looking real shitty
Video of yesterday's monster wedge tornado in KS https://www.facebook.com/ReedTimmerTVN/videos/10154227685559169/
That thing could have had measured wind speeds of 500MPH but it will get an EF-2 rating because you know, no damage.
This chaser is just riding his driver like crazy, hilarious to listen to. The driver is getting nervous as hell
Original tor on the left, new circulation on the right Ian Livingston @islivingston 1m1 minute ago Amazing storm