November 11th is usually a day of Patriotism, Thanks, and Remembrance; and not usually a day associated with severe weather. By no means is a tornado in Iowa during the month of November unheard of. In fact, in 2005, a tornado outbreak hit the state, with 12 tornadoes confirmed by the NWS.
Forward to 2015… A well advertised and very strong storm system moved across the Central Plains, bringing a interesting mix of weather to the state. Pre-front – conditions were warm, with spotty showers. Skies were partly to mostly cloudy across the state, with dew points climbing into the 50’s due to southerly winds. Post-front- it was snowing, with winds of 40-50kts. It was a classic triple point setup, with an usually strong area of low pressure serving at the focus mechanism. Storm motions were from the SW, at speeds of 40-50mph. Leading to dangerous conditions across the area. Shear parameters were high as well, leading to the increased potential for tornadoes.
Storms initially fired in SE NE/NW KS/SW IA and began their march E/NE. Things quickly turned messy as the storms quickly evolved into a line, spanning from North to South across almost the entire state. It was quickly apparent that today would be a tornado type of day. Numerous areas of gate/gate shear were visible on radar, with some obvious signs of tornadoes on the ground.
Due to the speed and nature of the event, lots of small tornadoes occurred, some lasting only a couple of minutes and some only a few yards wide. One such tornado impacted my hometown of Knoxville, Iowa. The tornado would later be classified as a high end EF1 tornado. Knoxville’s tornado touched down just SW of town and quickly made it’s way through town, lasting a total of 4 minutes and having a max width of 100 yards. A big box store, several homes, and a couple of businesses were damaged during the event. No fatalities, with only 1 injury.
More information on all of the tornadoes on Nov 11, 2015 can be found by clicking here.
Below are a few photos of the damage, 2 days after the storm: