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May 7th-9th Severe Weather Episodes

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Boswell tornado rated at least EF2 via TSA

 

Do you have a link for that?  That's the cell I ended up following.  That tornado was definitely quite large.

 

EDIT: N/M - found their tweet.

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Looks like the two tornadoes from OK were finalized at high-end EF3 via OUN. 2016 remains without a violent tornado.

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I highly doubt OUN will pay attention to the winds recorded because the EF scale is based on damage, not on measured winds.  Think of El Reno 2013.  Yes, I know, it sucks.

 

I stand corrected as those two monster tornadoes are finalized at high end EF3.

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I stand corrected as those two monster tornadoes are finalized at high end EF3.

Agitating I know. There are two non-DI contextual evidence such as the extreme vegetation scouring and trees were completely debarked that convinces me otherwise. The videos could be used as another factor.

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I stand corrected as those two monster tornadoes are finalized at high end EF3.

still prelim. Guess those houses that got wiped must've not been well anchored, or something. We will find out...

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And yet we have this...

 

https://twitter.com/karen_kosiba/status/730137285572710400

 

Here we go again, this time with the measurements quite close to ground level.

There needs to be an overhaul to the EF scale. El reno with 300mph and here with 220mph. Both were EF5's based on wind speed. Maybe they'll take it this time due to the proximity to the ground. But I expect they hold their ground at EF3 until damage come up, EF scale should include data from DOW's if they are close enough and the beam is within a certain distance of the ground.

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Let see what happens with the 17m wind speed. On a side note, on Twitter check out #HowToStartAMetFight Andy and I are having fun.

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Remember all tornado ratings are preliminary. We are still evaluating some of the ratings. We will provide updates as needed.

 

NWSNorman on twitter, potentially citing a rating change.

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NWSNorman on twitter, potentially citing a rating change.

 

Not to go too far down this road, but they probably would've saved themselves a bunch of hassle had they just included it in the original tweet (i.e. Prelim high end EF3/etc).

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Confirmed tor near Chapman, NE not too long ago. 

 

The storm has had a couplet off and on.

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There are... rather persistent brash criticisms of Norman's ratings in the replies to their tweets today. There's discussing it here and reporting to them where damage may be that they haven't surveyed, and then there's that. Don't do that.

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Some of you may be interested in this paper by Jeff Snyder about the use of mobile radar data in assigning damage ratings.

http://journals.ametsoc.org/doi/abs/10.1175/WAF-D-14-00026.1

 

Abstract

The increasing number of mobile Doppler radars used in field campaigns across the central United States has led to an increasing number of high-resolution radar datasets of strong tornadoes. There are more than a few instances in which the radar-measured radial velocities substantially exceed the estimated wind speeds associated with the enhanced Fujita (EF) scale rating assigned to a particular tornado. It is imperative, however, to understand what the radar data represent if one wants to compare radar observations to damage-based EF-scale estimates. A violent tornado observed by the rapid-scan, X-band, polarimetric mobile radar (RaXPol) on 31 May 2013 contained radar-relative radial velocities exceeding 135 m s−1 in rural areas essentially devoid of structures from which damage ratings can be made. This case, along with others, serves as an excellent example of some of the complications that arise when comparing radar-estimated velocities with the criteria established in the EF scale. In addition, it is shown that data from polarimetric radars should reduce the variance of radar-relative radial velocity estimates within the debris field compared to data from single-polarization radars. Polarimetric radars can also be used to retrieve differential velocity, large magnitudes of which are spatially associated with large spectrum widths inside the polarimetric tornado debris signature in several datasets of intense tornadoes sampled by RaXPol.

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Incredible mammatus clouds moving over Dallas right now as the northern cell is moving more to the right. It very well could barrel down I-30 and pelt the Metroplex's densest population centers.

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Let's say it's 1916 baseball scouts wanted to know the velocity of how fast a picture could throw and based it on how much damage he could do to plywood on an old barn. Let's say he threw right through a layer of plywood and the engineering data of the day said that would be 100 MPH.

Then the debate would be well was the plywood old and rotten? Was it thinner then the average peice of plywood? Was the barn invested with termites? Etc etc etc blah blah blah

Now jump ahead to 2016 lets say a picture threw a fastball through a side of an old rotten barn and made a hole in it. Well you can't call it 100 MPH

The argument would be because of the above mentioned factors. Or let's say the picture missed the piece of plywood all together and hit nothing

But wait we have radar guns these days that can measure how fast that pitch really was and several had that pitch at 102 MPH

Doesn't matter your fastball is only ranked on the damage it can do to a new at least one inch thick piece of plywood not the actually velocity measured by today's technology

You are not in the 100 mph club sorrry

EF scale needs to adjust with the times

Note I'm on my iPhone forgive the typos

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NAS JRB Fort Worth gusting to 71mph.

 

KNFW 110028Z 22030G61KT 1/2SM +TSRA FG FEW038CB SCT048 18/17 A2990 RMK AO2 PK WND 23061/0020 WSHFT 2357 RAB10 PRESRR FRQ LTGICCCCG OHD TS OHD MOV E P0062 T01780172 VISNO N $

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Some of you may be interested in this paper by Jeff Snyder about the use of mobile radar data in assigning damage ratings.

http://journals.ametsoc.org/doi/abs/10.1175/WAF-D-14-00026.1

 

Great read there.

 

Kind of interested to see what will come out of this latest episode, given that radar measurements were actually made <20 m AGL. That whole thing about the difference between Bluestein's and Wurman's findings regarding the height for max VR was intriguing.

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Great read there.

 

Kind of interested to see what will come out of this latest episode, given that radar measurements were actually made <20 m AGL. That whole thing about the difference between Bluestein's and Wurman's findings regarding the height for max VR was intriguing.

Given the true definition of the EF-scale as a scale derived from damage inflicted, I doubt they will use it, however they very well could use it given the 17m height of the beam and this could very well be why they tweeted out that ratings could change. But as stated given the definition of the EF-scale I doubt the DOW measurement will be used. However, if I had to make one change to the EF scale, it would be to allow DOW radar measurements as indicators if under a certain height (say 75ft off the top of my head) to more accurately gauge the true intensity, not just the intensity at the given time and location when it caused damage.

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NWS Norman:

 

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.

 

 

Also:

 

The Bromide tornado rating is being modified to EF3. Updated map and PNS coming soon.

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The 17m 220mph DOW measurement had no effect on rating, as expected. Norman has no plans to change any other ratings.

 

But says they are still preliminary, and Stillwater still ongoing. 

 

At this time we have no plans to modify any other tornado ratings. (But, all ratings are preliminary.) Stillwater tornado survey ongoing.

 

... so things could change if they find something else...

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So from Monday we got one EF-4, two EF-3s, and one EF-2?

Three EF3s now. Boswell tornado has been upped to EF3 based on metal truss tower damage.

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NWS Tulsa:

From storm survey team: Boswell #OKwx tornado to be rated EF3, w/max winds 135-145 mph Hugo OK tornado to be rated EF1, w/max winds 95-105

 

I thought Boswell and Hugo might have had the same tornado. I guess not.

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Let's say it's 1916 baseball scouts wanted to know the velocity of how fast a picture could throw and based it on how much damage he could do to plywood on an old barn. Let's say he threw right through a layer of plywood and the engineering data of the day said that would be 100 MPH.

Then the debate would be well was the plywood old and rotten? Was it thinner then the average peice of plywood? Was the barn invested with termites? Etc etc etc blah blah blah

Now jump ahead to 2016 lets say a picture threw a fastball through a side of an old rotten barn and made a hole in it. Well you can't call it 100 MPH

The argument would be because of the above mentioned factors. Or let's say the picture missed the piece of plywood all together and hit nothing

But wait we have radar guns these days that can measure how fast that pitch really was and several had that pitch at 102 MPH

Doesn't matter your fastball is only ranked on the damage it can do to a new at least one inch thick piece of plywood not the actually velocity measured by today's technology

You are not in the 100 mph club sorrry

EF scale needs to adjust with the times

Note I'm on my iPhone forgive the typos

 

The EF scale is not a measurement of the tornado's speed so this analogy is flawed. It measures the strength of the tornado based on the damage observed and has done a great job of this so far. The wind speeds are then estimated based on this scale.

 

If people want an objective measurement of wind speeds with radar so they can slap 'SUPER TWISTER 5 RATED 350mph!!' on their monetized youtube videos to get more views, I'm fine with that if they can come up with a consistent and standard way of doing it, but that scale should have a different name - no modification to the EF scale should be done - that just causes confusion otherwise.

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