On This Day: Ohio River Valley Severe Weather Outbreak

On this day on 2013, one of the larger severe weather and tornado outbreaks since 2011 took place across much of the central and northern Ohio Valley. The system produced over 70 tornadoes across 7 states, and Illinois/Indiana had 55 of those tornadoes.

The tornadoes that occurred across much of the region that day. h/t NWS Chicago

The system was well anticipated ahead of time, as the SPC started issuing convective outlooks across the region four days beyond the event itself. As the event approached, the models began to hone in on the magnitude of this event, and the SPC issued a Day 2 Moderate Risk (a rare occurrence) and a High Risk on the day of the event (just as rare).

The sequence of outlooks issued by the SPC. Day 4 is top left, day 2 is top right and day 1 is bottom left. In the bottom right is an image of the warnings issued by NWS offices that day.

Events like these don’t come along often, and this one has spectacular dynamics. The basic set up included a strong upper-level jet, a strong mid-level jet, and excellent forcing in the lower levels of the atmosphere. In the mid and upper levels of the atmosphere, the two jet streaks present were very strong, with a 120 knot jet streak at 300 mb and a 100 knot jet streak at 500 mb. In addition to this, the placement of the jet streak was key to the development and sustaining of supercellular and linear convection. The supercells initiated within the left exit region of both the 500 mb and 300 mb jet streaks, regions that are very favorable for upward motion.

The 300 mb jet streak around noon that day. The central Illinois region is well within the favorable left exit region of the jet streak. h/t SPC

The 500 mb jet streak around noon that day. The central Illinois region is well within the favorable left exit region of the jet streak. h/t SPC

As this propagated eastward with time, the convection became more linear, but was still largely sustained underneath the favorable left exit region. This widespread and favorable divergence favored the development of a strong surface low, and this low propagated quickly north-northeastward from northern Iowa into southern Canada.

The surface analysis for that evening. The strong surface low had already moved into the northern Great Lakes states. h/t WPC

The resulting low had a fairly intense cold front associated with it. This, combined with other atmospheric variables present for lift, severe thunderstorms quickly fired across central Illinois and worked their way eastward. By the time the storms made it to Indiana, they had congealed into an intense squall line that quickly worked eastward, producing plenty of wind damage along its path.

The storm reports for that day. The wind damage extended further east and was widespread. h/t SPC

While this is a brief account of what occurred that day, don’t think the magnitude was brief. This was a significant outbreak that produced multiple long track tornadoes, two of which were rated EF-4s. Additionally, significant wind damage was associated with the squall line as it moved eastward. I will leave you with some videos of this insane event.