Map Porn: Counties That See the Worst Weather (on Average) Every Year

A severe thunderstorm watch covering much of the state of Maine last Monday brought out the typical "this NEVER happens!" commentary, but really, how common are severe weather watches around the United States?

The Storm Prediction Center has your answer, and it's not too surprising. The SPC's Warning Coordination Meteorologist has his own webpage that keeps track of interesting maps and statistics related to severe weather in the country. Two of the maps on the page includes the average number of severe thunderstorm and tornado watches issued every year for the past 20 years.

A refresher, first: a severe thunderstorm watch is issued when conditions are favorable for the development of storms that could produce large hail or damaging winds, and a tornado watch is issued when conditions are favorable for storms to produce a tornado.

Map Porn: Counties That See the Worst Weather (on Average) Every Year

The average number of tornado watches per year might come as a surprise to some folks, with Washington County, Alabama topping the list at an average of 17 watches per year. Southern Alabama and Mississippi see a large number of watches because the area is in both Dixie Alley, the region of the southeast susceptible to violent tornadoes, and the path of many landfalling tropical cyclones, which are known to produce small tornadoes as they come ashore.

Going from watches to warnings, the average date of the year's first tornado warning is pretty illuminating with regard to the pattern of tornado activity in the United States.

Map Porn: Counties That See the Worst Weather (on Average) Every Year

Severe thunderstorm watches, on the other hand, are less surprising. The center of the country — with a bullseye on Oklahoma — is the prime target for severe weather each year, with Osage County, Oklahoma seeing the highest average number of severe thunderstorm watches, with 23 per year.

Another striking pattern that shows up on the map is the influence that the mountains have on severe weather. The Rocky Mountains act as a sharp dividing line for severe weather, with the almost all severe weather in the United States occurring east of the continental divide. The Appalachian Mountains also have a strong effect on severe weather from northern Georgia through West Virginia, as the mountains tend to disrupt organized severe weather as it moves through the area.

As for Maine, tornado watches are exceedingly rare, but on average The Pine Tree State couple of severe thunderstorm watches each year.

It's worth noting that the Central Plains, including the Kansas City metro area, will live up to its reputation on Tuesday as the region could see a pretty significant severe weather outbreak if the forecasts are correct.

[Top image of severe thunderstorms in Maine last week via Gibson Ridge, others by the SPC]