Colorado just can't catch a break. When it's not burning or flooding, it's catching hell from the sky, with hailstones the size of baseballs and a constant conga line of tornadoes raking the eastern half of the state. How common is extreme weather in Colorado, and is this the new normal?
A good way to see the trend in severe weather is to look at how many severe weather warnings have been issued by the National Weather Service.
For reference, a tornado warning is issued when meteorologists detect rotation in a storm using radar, or spotters report a tornado on the ground. A severe thunderstorm warning is issued when meteorologists detect (or spotters report) a storm producing large hail or damaging winds.
Since January 1, the National Weather Service office in Denver has issued more tornado warnings than any of the other 122 offices in the country, save for Jackson, Mississippi. They've issued 62 tornado warnings for northeastern Colorado, falling just shy of the 65 seen around central Mississippi and far beyond the region in third place, Paducah, Kentucky, which has seen an even 50.
Where were we this time last year?
NWS Denver had only issued 17 tornado warnings between January 1 and June 9 last year, a far cry from the 62 seen so far this year.
This is easily the earliest tornado season in recent memory in eastern Colorado. 2009 saw a total of 81 tornado warnings issued by NWS Denver, and only 10 of those were issued by June 9 that year. The tornado activity that year didn't pick up until later in the month.
It's worth noting that the first half of June is historically the most active period for tornadoes, with the second week of the month seeing a 90% chance of at least one tornado touching down anywhere in the United States.
Severe weather isn't an uncommon sight in eastern Colorado. The eastern half of the state is in a "sweet spot" for tornado formation, as the region often sees thunderstorm activity forming in areas of favorable wind shear, allowing the storms to grow into supercells that produce extreme hail and tornadoes.
Looking at severe thunderstorm and tornado warning data issued around Denver as far back as 1986, it's clear that the region sees bad storms on a regular basis.
In fact, the county that saw the most tornadoes between 1952 and 2010 isn't in Oklahoma or Kansas or Alabama — it's Weld County, Colorado, which covers the area just north of Denver. Two other counties near the Denver metro area — Adams and Washington — also have some of the highest overall tornado counts in the United States.
Whether or not this is "the new normal," it's extremely doubtful. Severe weather (meaning large hail-/damaging wind-/tornado-producing thunderstorms) is highly variable from year-to-year. Case in point: 2011 was one of the worst year for tornadoes in recent memory, and it concerned people that it would only get worse from there. Then 2012 rolled around and it saw a near-record lull in tornado activity, and 2013 was even slower. Barring any surprise summertime outbreaks or a really bad fall tornado season, 2014 is on track to follow suit.
[Top image of piles of hail left behind by a severe thunderstorm in Denver via AP, other images via IEM / IEM / author / SPC / SPC]