By Paul Homewood
As I noted earlier today, the Washington Post's Capital Weather Gang have reported that last year is the first on record to have no EF-4 and EF-5 tornadoes in the US.
The Capital Weather Gang long ago sold their souls to the global warming religion, and are usually very loathe to admit that sometimes the weather might be better because of a bit of warming.
At the very end of the above article, they get in their little dig:
Despite the downward trend in annual numbers, studies continue to find that more tornadoes are happening on fewer days. In that light, it is certainly possible this drought won't last much longer.
In fact the study they refer to is hopelessly flawed, as I proved at the time.
But just to rehash, this is the narrative Climate Central published in 2016:
The impact of climate change on tornadoes is still an active topic of study. Early research suggests that the warming earth will provide more energy to produce the storms that generate tornadoes, but less shear to give the necessary spin. Observations over the past few decades have yielded a couple of interesting trends. While there are now fewer days with tornadoes in a given year, there are more tornadoes on the days when they do occur.
A 2014 NOAA study examined trends in the tornado record for a possible climate change signal.
Since the early 1970s, the nationwide average annual number of days with at least one (E)F1 or stronger tornado has dropped from 150 to 100. Yet, there has been an increase in the number of days with a very high number of tornadoes. In the 1970s, the average number of days with more than 30 (E)F1 or stronger tornadoes was less than one. In the last decade, that number had jumped to 3.
Only two years in the record had more than 750 (E)F1+ tornadoes – 1973 and 2011. But even during the active year of 1973, only 2 of those days had more than 30 tornadoes that rated (E)F1 or stronger. In 2011, that number ballooned to 9. Further, 2011 had as many days with more than 30 (E)F1+ tornadoes than the entire period between 1961 and 1981.
http://www.climatecentral.org/gallery/graphics/tornado-days-in-the-us
What the study did not reveal was the fact that many more of the weaker EF-1 tornadoes are now reported than in the past, because of changes in reporting practice, such as Doppler radar, storm chasers, cell phones and the rest.
It is well accepted that the historical numbers of the weakest EF-0 tornadoes should be ignored for this reason. For more detail, check out my post here.
But as NOAA themselves admit, the data on EF-1s was also unreliable in the past. Here is what they say:
Tornado reports have increased, especially around the installation of the NEXRAD Doppler radar system in the mid 1990s. This doesn't mean that actual tornado occurrence has gone up, however. The increase in tornado numbers is almost entirely in weak (EF0-EF1) events that are being reported far more often today due to a combination of better detection, greater media coverage, aggressive warning verification efforts, storm spotting, storm chasing, more developmental sprawl (damage targets), more people, and better documentation with cameras (including cell phones) than ever. Modern averages of roughly 1200 per year nationwide probably are as close to the truth as we've ever seen. Another few decades of well-documented tornadoes will tell us more. To compare tornado counts before Doppler radars, we have to either adjust historical trends statistically to account for the unreported weak tornadoes of before, or look only at strong to violent (EF2-EF5) tornadoes, whose records are much better documented and more stable. When we do that, very little overall change has occurred since the 1950s.
https://www.spc.noaa.gov/faq/tornado/index.html#Climatology
In fact, it is incorrect to say very little overall change has occurred since the 1950s. Below is the true picture:
https://www.spc.noaa.gov/wcm/#data
This is in direct contrast to the number of EF-1s, which indicate a broadly flat trend, with record numbers set in 2011 and 2017.
https://www.spc.noaa.gov/wcm/#data
The contrast is even more stark when we examine the proportion of EF-1 tornadoes of the total, which has gone up from the 50%s in the 1970s to the 70%s in recent years. It should be noted that the number of EF-1s dwarf the number of stronger ones – typically 400 pa of EF-1s, compared to about 100 of the rest.
Reporting of EF-1s has probably only been consistent since the late 1990s. Prior to that, many EF-1s occurred without actually being reported.
Given the preponderance of EF-1s in overall totals, I find it astonishing that the authors of the NOAA 2014 study were allowed to get away with publishing a report using EF-1 data, and claiming that more tornadoes occur now on tornado days.
But, just supposing the EF-1 data is correct, the unmistakable conclusion is that, on average, tornadoes are becoming weaker.
But I doubt whether you will hear any of this from the Capital Weather Gang.
from Climate Change Skeptic Blogs via hj on Inoreader http://bit.ly/2QhpN4O
No comments:
Post a Comment