EF vs. F Scale

 

UPDATE:

1) THANKS TO OUR KEEN BLOG READERS…MY ORIGINAL PHOTO OF THE YAZOO CITY TORNADO WAS NOT FROM THAT TORNADO. I HAVE REPLACED IT.

2) THE TORNADO PATH IS NOW BELIEVED TO BE 149 MILES LONG AND SOME DAMAGE HAS BEEN RATED EF4. IF INDEED THE PATH IS 149 MILES LONG, THAT WOULD MAKE IT THE SECOND LONGEST TORNADO PATH KNOWN IN THE UNITED STATES.

THANKS. MARK

Happy sunny Monday. Nice to have the sun after a crummy weekend. The rain was needed, but I wish it did not happen over the weekend. Thankfully, we missed the severe weather outbreak that ravaged a huge portion of the country. There were damaging storms from Colorado to New York with the worst damage from the tornado outbreak on Saturday in the deep south. Yazoo City, Mississippi was the hardest hit. Tragically, 10 people were killed in the tornadoes. It had been a quiet start to the storm season, but that has now changed. It is a good reminder for all of us of the power and devastation of mother nature.

The above picture is of the tornado in Yazoo City. At one point the tornado was a mile 1/2 wide and the path of destruction was almost 50 miles. The tornado was rated EF-3. I will have more on that later in the blog.

The above picture is of the damage in Yazoo City. This picture was from the New York Times. It’s fascinating that the picture shows the massive destruction yet the books are still on the bookshelf.

Tornadoes are rated by the destruction they create using the Fujita Scale. The “F” scale as it is known has now been replaced by the “EF” scale. This is the enhanced Fujita scale. It is an improvement over the “F” scale which overestimated wind speeds in tornadoes. The only problem I have with the change to the “EF” scale is the lack of understanding by the general public. I personally think the National Weather Service should have just changed the scale but left the same “F” scale name.

Here is the old vs. the new scale:

FUJITA SCALE DERIVED EF SCALE OPERATIONAL EF SCALE
F Number Fastest 1/4-mile (mph) 3 Second Gust (mph) EF Number 3 Second Gust (mph) EF Number 3 Second Gust (mph)
0 40-72 45-78 0 65-85 0 65-85
1 73-112 79-117 1 86-109 1 86-110
2 113-157 118-161 2 110-137 2 111-135
3 158-207 162-209 3 138-167 3 136-165
4 208-260 210-261 4 168-199 4 166-200
5 261-318 262-317 5 200-234 5 Over 200

*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure. Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, “one minute mile” speed.

Our weather remains quiet for much of the week. Chilly temperatures at night with patchy frost inland tonight and Tuesday night. Much warmer for Thursday with highs near 70. Thunderstorms are possible on Friday. Stay with weather watch 12 for the latest. Thanks for reading.

Mark

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7 Responses

  1. Mark – nice blog…wrong tornado picture.

    http://www.meteorologynews.com/2008/06/14/fake-tornado-photograph-falsely-attributed-to-boy-scout-camp-storm/

    It has made its rounds.

    • Thanks, Scott. See my earlier reply. Have a good one.
      Mark

  2. Also…ehhh EF scale. I guess it is an improvement, but so much is still reliant on understanding the structures affected. Because of the diversity between building codes and how things are put together in different parts of the country, determining EF scales is very tough. I guess it is the best we have for now..but hope we can get better at this as more and more financial decisions are made of these assessments [eg. insurance premiums etc.]

    • Thanks, Scott. In my haste I did not give the pic due diligence. I have a lot of problems with the EF scale. I think even though it is not supposed to be subjective it still is. More importantly, the renaming has done nothing but create confusion.

      Mark

      • The renaming has caused more confusion. Seems with the efforts that NOAA is doing in trying to understand public views – this slipped through appropriate review. That said, until there is wind instruments on each house, I am not sure we will ever get away from the subjective nature of determining wind speed of tornadoes.

        Seems as objective as meteorology can be at times, it is equally as subjective in how it is translated to society.

  3. lrcweather’s right…. That picture was debunked as fake, a year or two ago. Infact, I think it was on Gary Lezak’s blog, where I read it was fake.

    • Thanks, Nicole. I have fixed it.

      Mark

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