4/9/2015 - Flag Center-Fairdale, IL EF4 TORNADO

4/9/2015 - Flag Center-Fairdale, IL EF4 Posted: 14 Apr 2015 06:55 PM PDT For about a 7-8 days prior to April 9th, the models had suggested the potential for severe weather in the northern Illinois region.  The only thing clear up till the morning -- even afternoon! -- of what would become a memorable event was that the models were all over the place with their handling of precipitation and severe weather ingredient fields. I.e., nothing was clear and confidence in tornadoes was low.  By early afternoon, visible satellite imagery did suggest a narrow window of clearing/surface heating would occur across the region and that the warm front would remain anchored between I-88 and the IL/WI state line.  NWS LOT summarizes the severe weather setup nicely in this graphic, with a more detailed forecast provided in the 1630 SPC outlook.  The big question by afternoon was whether you could get an isolated storm ahead of the cold front, which was causing a mess of severe convection in eastern Iowa.  By mid to late afternoon, I became confident enough to roll the dice west on I-88 from DeKalb ... heading to Dixon to hang out and grade papers (no really, I did grade!).  As I sat in Dixon, I kept an eye on the radar and noticed several isolated storms form ... the first series of storms formed south of Dixon but never organized as they moved northeast. Then, another cell formed east of the Quad Cities, shifting north of Dixon and then onto Rockford. I actually followed this storm north of Dixon for a bit, but it was laminar and appeared to be sucking on cool outflow.  I couldn't follow it northeast as I was cutoff by the Rock River.  Moreover, I had noticed that this isolated storm, which eventually became tornado warned south of Rockford, had laid down a nice boundary along I-88.  Hmmm ... I thought. Based on my observation, this was a critical feature (boundaries provide localized areas of enhanced low-level shear that can be critical for assisting with tornadogenesis and possibly sustenance) and was the reason why we ended up with a high-end event that evening.  Soon, a new cell formed south of Dixon and appeared to split, producing a healthy right mover that got "that" shape just east of Dixon. The radar evolution is provided here.  I watched a nice updraft base south of Dixon, waiting patiently for the hail core to pass to my east before I jumped on I-88. Once I was on I-88 and scurrying around the south side of the storm, things ramped up quickly ... the base produced a narrow but distinct lowering that eventually coalesced into a funnel and then tornado.  After calling 911 to report, I stopped a couple times along I-88 to snap some pics. I had to then push it east on I-88 to I-39, then north, never losing visibility of what was a large wedge northwest of Rochelle. As I moved north on I-39, I got closer to the beast, eventually jumping off at sr-64. I watched it cross the interstate at this time. Then I played catch-up for the next 30 minutes as the relatively fast-moving storm traversed largely rural areas. Unfortunately, as we all know, it did hit the very small community of Fairdale, IL -- I was several miles south as the town was hit. After witnessing a couple of satellites in the decaying light, I finally called it a chase north of Kirkland and drove home. I participated in the storm survey the next day with the National Weather Service, assessing damage northwest of Rochelle and in the town of Fairdale.  As always, it is humbling to see the damage up close, but such perspective helps us assess the intensity of the tornado, as well as provide evidence of what works and doesn't work in mitigation.  I won't post my damage pictures in this blog -- instead, visit Stephen Strader's (NIU Ph.D. student and my advisee) wonderful account here. Below are my pics, as well as shaky video. Just after formation, the tornado intensifies and strikes Crest Foods in Ashton, IL.  Tornado with Ashton in the Foreground. New perspective as I head north on I-39. Exit 104 on I-39, looking north. Backlit wedge with satellite (between wedge and tree) north of Kirkland My video of the event -- note, I'm not a big videographer and it shows. Taking pictures and video at the same time usually means both are of degraded quality, I've learned. ******************************************