Published: March 23,2015
The lack of severe weather so far in 2015 has pushed into "uncharted territory" in March, according to a government severe weather expert.
Not a single severe thunderstorm or tornado watch has been issued anywhere in the U.S. by NOAA's Storm Prediction Center so far in March, as of March 22.
"This has never happened in the record of SPC watches dating back to 1970," said Greg Carbin, Storm Prediction Center warning coordination meteorologist in a SPC news release Tuesday. "We are in uncharted territory with respect to lack of severe weather."
There had been only seven reports of severe weather – large hail, high winds or wind damage – nationwide this month, through March 18, all occurring on March 11.
Severe weather reports (blue dots, highlighted by yellow circles) in the U.S. from March 1-17, 2015. Through March 18, we would expect to have logged 872 reports of hail, high winds or wind damage for the month. Instead, there's been a largely blank March map.
The year-to-date number of large hail reports was also a record low. "Going into today (March 19), there had been just 5 reports of severe-sized (1 inch diameter or larger) in the U.S. in 2015 - a record low dating to 1955," said Dr. Forbes in an internal email.
Tornadoes: 0 For March, Fewest Year-to-Date in 13 Years
There has still not been a single tornado reported anywhere in the U.S. so far in March 2015, through March 22.Only one other March – in 1969 – has gone tornadoless so deep in the month, according to reliable records dating to 1950. March 1969 had its first tornado of the month on March 23.
The lowest U.S. March tornado count was six in 1951, though you could argue some weaker tornadoes may have been unobserved back then, in the pre-smartphone, pre-Doppler radar era.
While March is not typically one of the most active months, March has averaged 78 tornadoes in the U.S. over the past 20 years, according to Forbes.
This is the third March in a row with a notable tornado dearth. March 2014 had 20 and March 2013 had 18.
So far in 2015, only 27 tornadoes have been tallied through March 22, according to preliminary estimates from Forbes. Since the current Doppler radar network was installed at National Weather Service offices in the early-mid 1990s, 2002 was the only year with as few or fewer tornadoes through March 22 (23) than 2015 so far.
In February 2015, only two tornadoes were reported, a whopping 94 percent below average.
(MORE: January, February 2015 Sees Fewest U.S. Tornadoes in Over a Decade
Another way to look at this severe weather drought is comparing the number of National Weather Service severe thunderstorm and tornado warnings issued year-to-date.
That sounds like a lot until you contrast that with the past few years and the previous record low warning count:
- 2014: 657 warnings
- 2013: 1438 warnings
- 2012: 2598 warnings
- 2004: 594 warnings (previous low dating to 2003)
Not surprisingly, the SPC's Carbin also says only four tornado watches have been issued in the first two and a half months of 2015, less than 8 percent of the average number of tornado watches issued in a typical year-to-date. This is the fewest number of watches in the year's first two and a half months since 1985, when only two tornado watches were issued.
Luck to Run Out?
Not that anyone is complaining, but why has severe weather essentially disappeared recently?Severe thunderstorms require adequate moisture, atmospheric instability (colder, drier air aloft topping warm, humid air near the Earth's surface) and a source of lift (strong dryline, cold/warm front, convergence near surface low pressure, strong low and upper-level jet streams).
Those elements haven't aligned since a Jan. 3-4 mini-outbreak of 23 tornadoes in Mississippi, Alabama and Georgia.
A sharp southward plunge of the polar jet stream into the Plains and East has kept those areas generally cold, and any moisture remaining has been trapped over the Gulf of Mexico.
The southern branch, or subtropical jet stream ends up running over this cold, more stable air, instead of finding warmer, more humid air.
Thus, a steady rain, or pellets of sleet, or flakes of snow have fallen this winter in the Deep South.
Recent Marches have not been as quiet.
The March 2-3, 2012 outbreak of 75 tornadoes in the Ohio Valley and Southeast claimed 40 lives and spawned EF4 tornadoes in Henryville, Indiana and an Crittendon, Kentucky, and EF3 tornadoes in West Liberty, Kentucky, and near Harvest and Meridianville, Alabama.
Twenty-five years ago, one of the worst Plains March tornado outbreaks spawned a pair of F5 tornadoes in Kansas that struck Hesston and a long-track F4 tornado in Nebraska.
(WUNDERBLOG: Remembering An Early Outbreak For Tornado Alley)
(Dr. Greg Forbes)
When warmer, more humid air returns to parts of the southern and central U.S. in spring, any significant jet stream disturbance sweeping out of the Rockies has the potential to generate severe thunderstorms, including tornadoes.
The peak tornado months in the U.S. – April, May and June – are yet to come. On average, the U.S. tornado count more than doubles from March to April, reaching a peak in the month of May and remaining high into June.
(MORE: El Nino - Tornado Season Link?)
Despite only 18 tornadoes in March 2013, that May generated 267 tornadoes, most infamously including the Moore and El Reno, Oklahoma, tornadoes.
Destructive tornadoes and tornado outbreaks have and will continue to take place during overall low tornado count years. Cases in point last year: Pilger, Nebraska in June and Vilonia, Arkansas in April.
Despite the relatively low national tornado count, 172 people lost their lives in 50 tornadoes from 2012 through 2014.
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 you're driving or caught outside and a tornado warning is issued. Being prepared can save your life.
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