TWC: Lack of Tornadoes Continues with None Reported in U.S. Since Mid-October

The trend of the low number of tornado reports this year in the U.S. has continued through the first half of November.

No tornadoes have developed in the U.S. this month through Nov. 16. In fact, the last tornado that occurred was on Oct. 14, when two tornadoes were reported in Oregon.

20-year average number of tornadoes in November, compared to the number of tornadoes through Nov. 14, 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. 14. This is about 23 percent below average, or 271 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. 14, 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.

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.

Roger Pielke Jr. Fun fact: As of today 2016 US tornadoes are fewest in a calendar year since record-keeping began in 1954 #goodnews http://www.spc.noaa.gov/wcm/adj.html

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 are beginning to take place, with an area of low pressure expected to track across the U.S. into this weekend, ending the record-warm temperatures and bringing the first snow of the season for some areas.

Even with this cold front moving across the central and eastern U.S., the chance for severe thunderstorms and tornadoes is low due to limited moisture and very dry air aloft holding down instability, according to Dr. Forbes.

Another low pressure system is expected to move into the Plains Thanksgiving week. However, instability once again appears to be too low at this point to expect much in the way of organized severe thunderstorms.