Recently, something of a brouhaha developed over the rating of tornado intensity on the so-called EF-Scale. But there have been some important new developments. The massive, deadly tornado on 31 May 2013 in Oklahoma initially was rated an EF-5 tornado by the Norman office of the National Weather Service (NWS), largely owing to mobile Doppler radar data, because the tornado stayed mostly in open country, with a dearth of damage indicators.
The revised F-Scale, now known as the 'enhanced' F-Scale (or EF-scale) has become entirely focused on damage indicators, so the EF-Scale has become virtually completely a damage scale, not an intensity (windspeed) scale. This is, in part, the doing of the structural engineers, who believed the upper end windspeeds on the EF-scale were too high - they succeeding in a downward revision of the windspeeds associated with structural damage on the revised rating scale: e.g., EF-5 now begins at a lower bound of 200 mph, whereas the F-5 threshold was 261 mph. There are some reasons to believe this is something of a problem - i.e., rating almost exclusively on damage (with the damage indicators biased in favor of US construction practices).
In an argument evidently based mostly on the notion of consistency, NWS management is basically saying mobile Doppler data should not be used to make tornado intensity ratings. This is the ruling that dictated downgrading the rating of the El Reno tornado from EF-5 to EF-3, as well as some others.
The 'consistency' argument is, in my opinion, not very compelling. This argument is unfortunately all too common within the NWS as a reaction to
technological innovation. I could provide numerous examples of the
wrong-headedness of this policy, but I'll try to keep this as concise as
possible. Resistance to new technology, and trying to force 'consistency' with older technology is just wrong. Should we degrade the data obtained by WSR-88D
radars to that from WSR-57s simply to maintain consistency with the
older data sets? Should we disregard the dual polarity information of
the new upgrades to the WSR-88D radars just to maintain consistency with
the old versions of the radar? When something new and exciting comes
on line, its capabilities should be embraced by the agency, not rejected
as inconsistent with older technology!"
Moreover, all the bureaucratic concern about the 'consistency' of the EF-Scale ratings
strikes me as rather silly. The existing record is laced with numerous
inconsistencies for a host of reasons - too numerous to mention in detail. Denying the value of the most
direct and objective measurements of wind speed in tornadoes (apart from the extremely infrequent occasions when an anemometer record survives) in order to maintain
consistency with an inconsistent data set strikes me as silly. You can
argue we shouldn't introduce yet another source of inconsistency, but I
say we should take advantage of new technology as soon as possible and
not get trapped into this foot-dragging argument. Actually, the Doppler data are a source that can reduce inconsistency! I agree we need to develop a consensus on how to use the new data, but that shouldn't be an excuse to ignore the data until that consensus emerges. At the very least, the rating of the El Reno tornado should be EF-3+, with the + sign indicating it's a lower bound based on the limited damage indicators, so the actual rating might well be higher.
The NWS bureaucracy can, of course, make up any rules they wish to impose on the process. Their subordinates do the actual work when it comes to the 'official' record in Storm Data, and those people are subject to the dictates of their organizational managers. However, here's the rub - much is made of the records in Storm Data, and those data form a critical part of many scientific investigations. This is true of a lot of the data collected by the NWS - it's collected largely to serve immediate operational needs, but is the basis for a lot of scientific research, as well. Any decisions by the agency about data collection have impacts on science. The NWS is an agency almost totally focused on the operational application of science, not scientific research. Although some forecasters are by their own choice, involved directly in research, their agency is not very much interested in it and offers them little or no support. NWS decisions about Storm Data affect the science, but those decisions aren't necessarily made in the interest of science!
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