Saturday, June 30, 2012

Analysis of the June 29, 2012 Derecho

This is an analysis of the June 29, 2012 Derecho that hit the Ohio Valley and Mid Atlantic.

The derecho's beginnings were in eastern Iowa, as a complex of thunderstorms that moved eastward into northern Illinois. As the complex moved into Illinois, a shelf cloud was observed, with this being among the many pictures taken.

From Northern Illinois, the complex began a southeast motion and passed through Indiana. As the storms moved into Indiana, they began to strengthen under the influence of more than 5000 j/kg of instability. This development was slightly hindered by the presence of a capping inversion, as noted on the 12z soundings in Indiana.
The cluster began to bow out as it entered central Indiana, as significant instability enhanced the bowing segment to the point of developing a derecho. However, in the early stages, storm reports and radar analysis indicate that hail was present on the western flank of the bowing complex before it switched to a major damaging wind threat.
Moving into the evening, the bowing complex was now a powerhouse derecho, at this time responsible for numerous reports of hurricane strength wind speeds, including a roughly 90 MPH wind gust clocked in Fort Wayne, Indiana. Needless to say, the damage form this derecho only increased as the complex continued on its way. In the evening hours, the storms encountered some fair shearing in the atmosphere, which led to rotating cells. One of them is seen below, at approximately 5:51 PM CDT. At that point in time, the derecho had become comma-shaped, with this tornado-warned cell leading the head of the comma.

Despite the presence of rotating cells, only two unconfirmed tornadoes were reported. Those reports originated from Newcomerstown, Ohio.

A composite radar image of the derecho shows just how widespread and destructive the complex was, with the strongest cells seen in Ohio. Weakening did occur after the derecho passed through Ohio, but still continued to produce damage into the Mid Atlantic states. The derecho did span roughly 600 miles when it was all set and done, not counting its presence in Iowa and Illinois.

Storm reports from the derecho were widespread, with 920 wind damage reports filed into the National Weather Service offices across the Ohio Valley and Mid Atlantic. Notice the slacking off of reports in the Mid Atlantic. That comes as the derecho hit the Appalachian Mountain range, and those mountains did indeed cut down on the power of the system. However, as observed right along the coast, there was still considerable damage from the derecho until the very end.

In summary:
A derecho formed June 29, 2012 in northern Indiana. It then fanned out into a powerful complex of damaging thunderstorms, in which at least 8 people lost their lives. This derecho spanned 600 miles and produced countless wind speeds surpassing 60 MPH. Millions of dollars in damage will likely be used to repair what has been lost.




Hello Andrew! Great post!!!!!!! This line of storms was very intense!It done alot of damage to transmission lines that feed substations in southeast Ohio.Many electric coops have no power in the eastern part of Ohio.I myself consider myself fortunate.This complex of storms missed me by a county.It went south of me in Coshocton county Ohio.Many reports of structure damage.Also alot of reports of damage to trees and power lines.I'll keep you updated!If you see this post ERNWX,please let me know if any damage occured in your area.Thanks!!!!!!!!

ERN WX said...

Mike, 12 am yesterday, I was storm chasing!!! Most of the worst was south of where I live. I drove to a bad part of the cell and measured a 64mph gust and had 0.88 in hail!!! LOTS of wind damage. People still without power. Atlantic county in state of emergency. Trees down everywhere. Unconfirmed 2 dead. Tragic. I helped later with what I could, but there is still a lot of damage.

Andrew said...

Wow! I'm glad both of you made it through OK. The pictures coming from the Ohio Valley are just incredible, with trees that are at least 3 feet wide torn out of the ground like nothing i've seen in a while.


Hello ERNWX! Thanks for answering my question.The most amazing thing about thisa Derecho was that it was moving so quickly!When it went through Tuscarawas county Ohio,it was moving 85 M.P.H.,hard to believe.Newcomertown took a hard hit in Ohio.This town is Tuscarawas county Ohio.This is east of Holmes county Ohio where i live.

Ryan said...

It was crazy we were in wv in our tent when they hit trees twisted like twigs we continued our trip north only to find the same all the way home to Michigan lucky we all were ok

Andrew said...

Ryan: That sounds pretty crazy. The photos and descriptions from yesterday are just incredible. glad you're OK!

ERN WX said...

Ryan, I am very glad to know that you are okay!!!!!!! WV got slammed. My friend in MD claims there were wind speeds in excess of 80mph. His pictures look more like 70 which is still very bad. It is confirmed that 2 people were killed in my area, by a branch that fell on their car. When I was out in the storm, people thought i was crazy with the way I handled it. Mass destruction is the best way to describe what a derecho =. I was up till 4.

Anonymous said...

It's been awhile since my absence. That was pretty destructive and it sucks the death toll is rising. The power outages during the triple digits will be a huge problem. The DC mayor is bashing the utility companies. Figures! There are people who need help and he's whining to get attention about some storm people underestimate. It's a derecho, nobody really knows what they are, yet they are as destructive as low-end tornadoes and hurricanes. Everyone needs to know and learn what derechoes are and recognize the threat they pose. Derechoes are some of the deadliest wind events because people don't know what they get into till the last second between life and death. Praise to all who are trying to help. Any weather enthusiast, chaser, spotter, meteorologist etc needs to educate the public about these events.

Anonymous said...

Yes, you are lucky! I would stand outside taking straight-line windblasts at times. Bows with 70-100 mph winds are too dangerous. There is a video showing what 100+ mph winds from microburst during previous derecho did to a tree showing the slow disfigurement in process. Hopefully people can get back on their feet. Unbelievable story and thanks for sharing! Feel accomplished going through this. That way the next time this happens, you know what to do.