NOAA’s claim on El Reno tornado may not hold up

Tornado Widths– NOAA Makes Changes In Procedure

By Paul Homewood

El_RenoNOAA have claimed that the El Reno tornado, in Oklahoma in May, was the widest tornado on record. As I pointed out at the time, there was evidence to suggest that the width of earlier tornadoes had been underestimated. One tornado, in particular, Hale County, Texas, in May 1968, was officially categorised as 3000 yards wide, but the original Storm Data Publication described the width as “between two to three miles wide”. Vague at best, but also indicative that the width varied between two to three miles.

Thanks to a reader, I have discovered that there was a policy change at NWS in 1994, to report “maximum width” instead of “mean path width”.

The reference to this was contained in a paper by Harold Brooks, “On the Relationship of Tornado Path Length and Width to Intensity”, published in 2003. (Page 318)

http://www.nssl.noaa.gov/users/brooks/public_html/papers/lengthwidth.pdf

Although, according to Brooks, the policy change occurred in 1994,  this does not explain why a tornado in 1997 was similarly underestimated – see here.

Either way, it is clear that claims of “widest ever” for the El Reno tornado need to be taken with a pinch of salt.

Here is what NOAA says:

On May 31st, a cold front moving through the Central and Southern Plains spawned severe weather from Oklahoma to Indiana. There were 30 preliminary reports of tornadoes in eight states. The hardest hit areas included the Oklahoma City Metro area, the St. Louis metro area, and locations north of Tulsa, Oklahoma. In the Oklahoma City area, three tornadoes were confirmed, including an EF-0 and EF-1 which hit part of Moore, Oklahoma. The deadliest tornado of the outbreak hit just west of Oklahoma City, in the town of El Reno.

El_RenoThe EF-5 tornado had estimated winds well over 200 miles per hour (estimated from Doppler radar), was on the ground for 16.2 miles and had an estimated path width of 2.6 miles. The 2.6 miles width surpasses the Hallam, Nebraska tornado of May 2004 as the widest tornado on record for the United States and subsequently the world. The Hallam EF-4 tornado was 2.5 miles wide. It was also the 60th confirmed EF-5 (or F-5 prior to 2007) tornado in the U.S. in the 1950-present record. Parts of El Reno were also hit by an EF-5 tornado in May 2011, and prior to the Moore EF-5 was the last EF-5 confirmed in the nation.

Highways in the area had severe traffic congestion due to the rush hour commute, creating a very dangerous scenario. The tornado resulted in at least nine fatalities, seven of which were in automobiles. The fatality count might have been higher, but the tornado hit a relatively sparsely populated area on the south side of El Reno. The storms in Oklahoma were also accompanied by heavy rainfall that led to flash flooding. Numerous people had to be rescued from the flood waters, and an estimated 100,000 homes and businesses lost power during the event. An additional nine people were killed due to severe winds and the flash flooding. More information on this tornado is available from the National Weather Service.

Source: http://www.ncdc.noaa.gov/sotc/tornadoes/2013/5

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16 Responses to NOAA’s claim on El Reno tornado may not hold up

  1. Pamela Gray says:

    hmmm. I wonder what other changes were made and whether or not this changes the historical tornado data. Could this be another slight of hand “splice” event? Don’t laugh or role your eyes readers. Splicing data without labels is so common as to be a near daily thing in climate/weather data.

  2. OldWeirdHarold says:

    At first glance, I though Janet Reno was back in the news.

  3. wws says:

    How about “Widest ever since our short attention spans were engaged.”

  4. BFL says:

    This implies that the EF-5 portion was 2.6 miles wide/16.2 miles long. Usually the more severe Ef-5/4 parts of the tornado are relatively narrow, up to a couple of hundred yards wide with a taper off to EF-0 at the outer boundaries. In addition, the track becomes much less intense and narrower at the beginning and end of the tornado. Much like the method of counting the number of tornadoes (if one lifts and then sets down again, even for a short distance, it is counted as a new tornado), this looks like a severe misrepresentation.

    http://abcnews.go.com/US/oklahoma-town-devastated-tornado-razed-1999/story?id=19226754

  5. OK S. says:

    Would that we would do away with the sensationalist seeking EF scale, and use either of the F/f scales.

  6. M. Schneider says:

    Wikipedia: “However, a possible contender for the widest tornado as measured by radar was the F4 Mulhall tornado in north-central Oklahoma which occurred during the 1999 Oklahoma tornado outbreak. The diameter of the maximum winds (over 110 mph (49 m/s)) was over 1,600 feet (490 m) as measured by a DOW radar. Although the tornado passed largely over rural terrain, the width of the wind swath capable of producing damage was as wide as 4 mi (6.4 km).”

  7. Maybe it’s in part a matter of semantics to make your AGW case stronger? Most folks aren’t going to realize that 3000 yards is a little under 3.5 miles…Using the word “mile” makes it all so much bigger don’t you know?

  8. James McCown says:

    I was in downtown oklahoma city the evening of May 31 and it was a very scary situation. Just 11 days after the May 20 tornado that devastated Moore.

    The El Reno tornado was huge and looked posed to rip right through the heart of Oklahoma City. Fortunately it dissipated.

  9. Camburn says:

    I believe the tornado of March 1925 would put any recent tornado to shame in regards to width. Not only was it extremely long in duration, but I have read that it was up to 6 miles wide in damage.

    Just sayin.

  10. Txomin says:

    Widest? Are you calling my tornado fat?

  11. Rob JM says:

    The width of the El Reno tornado is problematic to say the least. The tornado was in fact a series of much weaker vortexes rotating quickly in large circulation. Effectively at any moment in time you would have two separate tornados 2.6 miles apart rather than a 2.6mile wide tornado. The EF5 winds would be restricted to narrow strips in the forward moving part of the circulation (southern sector) where the forward movement of the vortexes combines with their rotational winds.
    When you compare that to the beastly Moore EF5 a few weeks earlier it seems unfair to put them in the same category!

  12. u.k.(us) says:

    ka47) says:
    August 16, 2013 at 1:07 pm
    Maybe it’s in part a matter of semantics to make your AGW case stronger? Most folks aren’t going to realize that 3000 yards is a little under 3.5 miles…Using the word “mile” makes it all so much bigger don’t you know?
    ================
    No,
    3,000 yards =9,000 feet.
    3.5 miles= 18,480 feet.
    A mile (us) is 5280 feet.
    Just thought I would put some numbers up, for “most folks”.

  13. shras789 says:

    Watts Up With That is Watts up with the fact that it is already getting cold outside to. Crazy weather right

  14. Mike Bromley the Kurd says:

    Move the goalposts at every whim, NOAA. Atta do science. Atta feed the Sheeple MSN. Good onya.

  15. joshuah says:

    Well when tornado counts are at record lows you gotta have something to hype

  16. Fanakapan says:

    As Samuel Clemens pointed out, America is a Young Country, and its fair to say that Oklahoma and to a lesser extent Texas are even Younger. Certainly the period in which Tornadoes may have been recorded with any degree of accuracy will be so short, that to claim any indication of trends is a nonsense :)

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