Sunday, November 27, 2016

Lack of Tornadoes Continues with Only Five Reported in U.S. Since Mid-October

Linda Lam
Published: November 27,2016

The trend of the low number of tornado reports this year in the U.S. has continued through late November.
No tornadoes had developed in the U.S. this month through Nov. 21. In fact, the last tornado that occurred prior to that date was on Oct. 14, when two tornadoes were reported in Oregon.
However, the streak came to an end on Nov. 22 when one tornado was reported nine miles west-northwest of Manhattan Airport in Riley County, Kansas. An airline pilot reported that a weak funnel contacted the ground for less than two miles, but there was no visible debris or damage.
There were four more tornado reports Nov. 27 in southern Nebraska, all brief touchdowns, bringing November's tornado count to five. Some damage was reported from a tornado near Red Cloud, Nebraska, according to the Storm Prediction Center.
20-year average number of tornadoes in November, compared to the number of tornadoes through Nov. 22, 2016.
(Greg Forbes/ The Weather Channel, NOAA/SPC)
The lack of tornadoes is unusual because this time of year is considered the "second" tornado season.
(MORE: Why Much of the Nation's Weather Has Been So Quiet Recently)

Record Low Number of Tornadoes Year-to-Date

Dr. Greg Forbes, a severe weather expert at The Weather Channel, has tallied 897 tornadoes so far this year, through Nov. 21. This is about 24 percent below average, or 288 fewer tornadoes, than typically occurs, according to the 20-year average through mid-November.
Preliminary estimated U.S. tornadoes by month in 2016 (blue line) compared to 20-year average monthly counts (red line) through Nov. 22, 2016.
(Greg Forbes/The Weather Channel, NOAA/SPC)
Only three months in 2016 have experienced an above-average number of tornadoes: February, March and August. August would have also been below average except for an tornado outbreak in Indiana and Ohio.
February was 191 percent above average for tornadoes with 102 confirmed tornadoes compared to the 20-year average of 35. Interestingly, 61 of the 102 tornadoes reported occurred Feb. 23-24 from the South to the mid-Atlantic, making it the second largest outbreak of the year.
May, usually the most active month, had the most tornadoes so far this year. The U.S. experienced 216 tornadoes in May, compared with the average of 276. The largest outbreak of 2016 was May 22-26, with 73 tornadoes.
October saw a total of 20 tornadoes reported, 68 percent lower than average.
U.S. Tornado Statistics Through November 21, 2016
(Source: Dr. Greg Forbes/The Weather Channel, NOAA/SPC)
*=Dr. Forbes' estimated total; no * denotes actual number confirmed by NOAA/SPC
 Tornadoes20-year Average
January1840
February10235
March8576
April140188
May216276
June86217
July103112
August91*72
September36*71
October20*63
November-to-date1*36
2016 Year-to-date898*1186
This lower-than-average trend has led to another interesting year-to-date statistic: Year-to-date 2016 has reached the fewest tornadoes reported since records began in 1954, when tornado reports are adjusted for inflation or overcount, according to the  Storm Prediction Center.
The other piece of good news is that there have also been only 12 tornado-related deaths so far in 2016. However, December can be a dangerous month as we saw last year when 26 deaths occurred on Dec. 23 and 26. Before those dates, 2015 was on track to see the fewest tornado-related deaths since 1950.
(MORE: Weather-Related Car Accidents Far More Deadly Than Tornadoes, Hurricanes, Floods)

Second-Half of November

This autumn has been dominated by an upper-level ridge of high pressure over the central U.S. This has resulted in record-warm temperatures and relatively stable and quiet weather conditions across much of the U.S.
(MORE: Through October, Only One Other Year Has Been Warmer Than 2016 in the Contiguous U.S.)
There has been a southward dip in the jet stream over the Pacific Northwest and the Northeast at times, but this storm track has not allowed low pressure systems to tap into moisture from the Gulf of Mexico, which can help to fuel severe thunderstorms.
Areas where tornadoes typically develop in November.
Usually, in November, areas from portions of the southern Plains and mid-Mississippi Valley into the South and sections of the mid-Atlantic are at an increased risk for severe weather. The area at greatest risk for tornadoes stretches from eastern Texas and the Lower Mississippi Valley into Alabama and the western panhandle of Florida.
Late October-November is typically considered the "second" tornado season. This increase in tornadoes in the fall is due to the return of strong low pressure systems tracking farther south across the U.S., compared to summer. As colder air is pulled southward and warm, moist air flows northward, this clash can result in greater instability, which enhances the risk of severe thunderstorms and tornadoes.
(MORE: Second Tornado Season)
Changes have begun to take place. A cold front brought an end to the record-warm temperatures this past weekend and brought the first snow of the season for some areas of the Upper Midwest and interior Northeast.
Another low pressure system moved into the Plains Tuesday bringing rain and thunderstorms. One tornado was reported in Kansas which, if confirmed, brings the tornado-free streak to an end. Otherwise through Thanksgiving week, severe thunderstorms are not likely.
MORE: Indiana, Ohio August 2016 Tornados (PHOTOS)

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