Jesse Risley
Staff member
Source: http://www.weather.com/storms/tornado/news/tornado-drought-january-february-2015
The siege of bitter cold, snow and ice in the East in early 2015 has had one benefit: Year-to-date tornadoes in the U.S. are the fewest in over a decade.
Through February 28, a preliminary 28 tornadoes had been documented across the nation, according to statistics from the Storm Prediction Center. This is the slowest start to the year, tornado-wise, since only 12 tornadoes were recorded in January and February 2004.
According to severe weather expert, Dr. Greg Forbes, this tornado tally so far in 2015 is merely one-third of the 20-year average number of year-to-date tornadoes (84).
February was eerily quiet, with only two tornadoes reported during the month; one in California, the other in Florida. According to statistics kept by Dr. Forbes, only three other Februaries since 1950 saw two or fewer tornadoes in the U.S.: 2010 (1), 2002 (2) and 1964 (2).
Greg Carbin, warning coordination meteorologist at the Storm Prediction Center (SPC) noted only four tornado watches were issued by the SPC in January and February combined, the fewest in the year's first two months since 1985 required only two tornado watches.
The SPC went 51 straight days without issuing either a tornado or severe thunderstorm watch through February 25. This was the longest such watch-less streak since late 1986, according to Carbin.
(Watch Greg Carbin on Weather Geeks, Sunday, March 8 at 12 p.m. EDT on The Weather Channel)
This continues what has been a general U.S. tornado drought since the spring of 2012.
When removing "tornado inflation," the rise in mainly weak tornadoes detected in recent decades due to meteorological and technical advancements such as Doppler radar and social media, as well as larger spotter networks, the three-year period from 2012-2014 was considered the least active three-year period on record dating to 1953, according to Carbin.
We'll come back to an important point about this tornado drought later.
Aren't Winter Tornadoes Always Sparse?
While the core winter months of January and February are among the least tornadic months of the year, the complete absence of any severe weather for weeks at a time so far in 2015 is quite impressive.
You can blame the persistent jet stream pattern. Namely, the sharp southward plunge of the polar jet stream into the Plains and East has kept those areas generally very cold, with any moisture remaining trapped over the Gulf of Mexico.
The southern branch, or subtropical, jet stream, when sending any disturbances into the nation's Gulf Coast or southern tier of states ends up running over this cold, more stable air, instead of finding warmer, more humid air.
Thus, a steady rain (or even pellets of sleet or flakes of snow) have fallen this winter in the Deep South -- not generally strong thunderstorms.
Some recent winters have been violent in the South.
Both January 2013 (75) and 2012 (79) were more tornadic than average. The Super Tuesday 2008 outbreak contributed to a February record 147 tornadoes. January 1999 featured an incredible 212 tornadoes in the U.S., including 107 tornadoes in the state of Arkansas, alone.
Quiet Start = Quiet Spring/Summer?
In two words, not necessarily.
We mentioned this was the quietest start since 2004. That year went on to produce a record-setting 1,819 tornadoes in the U.S., including 509 tornadoes in May and another 476 from August through September. Many of those late summer/early fall tornadoes were spawned by Florida's big four hurricanes of 2004.
There were two other years since 1995 that started off as slowly as the first two months of 2015. One of those, 2003, finished well above average for U.S. tornadoes (1375), including a record-setting 542 tornadoes in May. The other, in 2002, finished below average, with only 941 tornadoes.
We cannot predict how the rest of the year will shape up, tornado-wise. The final tallies depend on how persistent the western ridge-eastern trough pattern described above remains into the spring, as we head toward the April-June U.S. tornado maximum.
As we saw in 2004, landfalling tropical cyclones introduce another wild card to the U.S. tornado count going forward.
Furthermore, impactful tornadoes and outbreaks do occur in low U.S. tornado count years.
Just ask those in Pilger, Nebraska (Jun. 2014), Vilonia, Arkansas (Apr. 2014), Moore, Oklahoma (May 2013), and Henryville, Indiana (March 2012).
Despite the relatively low national tornado count, 172 people lost their lives in 50 tornadoes from 2012 through 2014. This doesn't sound like a "drought" anymore, does it?
Once the jet-stream pattern changes, allowing warmer, more humid air into the central, southern and eastern U.S. in spring, severe thunderstorms will follow suit.
Now is a good time to remind yourself of the basic safety tips for severe thunderstorms and tornadoes. Know where to go in your home, apartment, or office, or if driving or caught outside if a tornado warning is issued. Being prepared can save your life.
The siege of bitter cold, snow and ice in the East in early 2015 has had one benefit: Year-to-date tornadoes in the U.S. are the fewest in over a decade.
Through February 28, a preliminary 28 tornadoes had been documented across the nation, according to statistics from the Storm Prediction Center. This is the slowest start to the year, tornado-wise, since only 12 tornadoes were recorded in January and February 2004.
According to severe weather expert, Dr. Greg Forbes, this tornado tally so far in 2015 is merely one-third of the 20-year average number of year-to-date tornadoes (84).
February was eerily quiet, with only two tornadoes reported during the month; one in California, the other in Florida. According to statistics kept by Dr. Forbes, only three other Februaries since 1950 saw two or fewer tornadoes in the U.S.: 2010 (1), 2002 (2) and 1964 (2).
Greg Carbin, warning coordination meteorologist at the Storm Prediction Center (SPC) noted only four tornado watches were issued by the SPC in January and February combined, the fewest in the year's first two months since 1985 required only two tornado watches.
The SPC went 51 straight days without issuing either a tornado or severe thunderstorm watch through February 25. This was the longest such watch-less streak since late 1986, according to Carbin.
(Watch Greg Carbin on Weather Geeks, Sunday, March 8 at 12 p.m. EDT on The Weather Channel)
This continues what has been a general U.S. tornado drought since the spring of 2012.
When removing "tornado inflation," the rise in mainly weak tornadoes detected in recent decades due to meteorological and technical advancements such as Doppler radar and social media, as well as larger spotter networks, the three-year period from 2012-2014 was considered the least active three-year period on record dating to 1953, according to Carbin.
We'll come back to an important point about this tornado drought later.
Aren't Winter Tornadoes Always Sparse?
While the core winter months of January and February are among the least tornadic months of the year, the complete absence of any severe weather for weeks at a time so far in 2015 is quite impressive.
You can blame the persistent jet stream pattern. Namely, the sharp southward plunge of the polar jet stream into the Plains and East has kept those areas generally very cold, with any moisture remaining trapped over the Gulf of Mexico.
The southern branch, or subtropical, jet stream, when sending any disturbances into the nation's Gulf Coast or southern tier of states ends up running over this cold, more stable air, instead of finding warmer, more humid air.
Thus, a steady rain (or even pellets of sleet or flakes of snow) have fallen this winter in the Deep South -- not generally strong thunderstorms.
Some recent winters have been violent in the South.
Both January 2013 (75) and 2012 (79) were more tornadic than average. The Super Tuesday 2008 outbreak contributed to a February record 147 tornadoes. January 1999 featured an incredible 212 tornadoes in the U.S., including 107 tornadoes in the state of Arkansas, alone.
Quiet Start = Quiet Spring/Summer?
In two words, not necessarily.
We mentioned this was the quietest start since 2004. That year went on to produce a record-setting 1,819 tornadoes in the U.S., including 509 tornadoes in May and another 476 from August through September. Many of those late summer/early fall tornadoes were spawned by Florida's big four hurricanes of 2004.
There were two other years since 1995 that started off as slowly as the first two months of 2015. One of those, 2003, finished well above average for U.S. tornadoes (1375), including a record-setting 542 tornadoes in May. The other, in 2002, finished below average, with only 941 tornadoes.
We cannot predict how the rest of the year will shape up, tornado-wise. The final tallies depend on how persistent the western ridge-eastern trough pattern described above remains into the spring, as we head toward the April-June U.S. tornado maximum.
As we saw in 2004, landfalling tropical cyclones introduce another wild card to the U.S. tornado count going forward.
Furthermore, impactful tornadoes and outbreaks do occur in low U.S. tornado count years.
Just ask those in Pilger, Nebraska (Jun. 2014), Vilonia, Arkansas (Apr. 2014), Moore, Oklahoma (May 2013), and Henryville, Indiana (March 2012).
Despite the relatively low national tornado count, 172 people lost their lives in 50 tornadoes from 2012 through 2014. This doesn't sound like a "drought" anymore, does it?
Once the jet-stream pattern changes, allowing warmer, more humid air into the central, southern and eastern U.S. in spring, severe thunderstorms will follow suit.
Now is a good time to remind yourself of the basic safety tips for severe thunderstorms and tornadoes. Know where to go in your home, apartment, or office, or if driving or caught outside if a tornado warning is issued. Being prepared can save your life.
