NOTE: This system is no longer a derecho, but just a squall line with gusty winds and heavy rain, therefore the intro section of this diary below this paragraph is no longer valid. Severe storms may form along the tail-end of this squall line later, so the severe threat still remains. See update 9 for details.
A strong derecho has been pushing across the Midwest and Ohio Valley overnight and through the morning hours today, causing extensive damage from Nebraska (where the derecho formed), all the way through Iowa, Illinois, Indiana, and now Ohio. Within the next few hours, the line of intense storms with winds possibly over 75-80 MPH will sweep through northern Ohio (north of Columbus) and impact the heavily populated areas of Cleveland and Akron.
To give you an idea as to how strong these storms are, a TV station in Iowa, WHO-TV, doesn't have a doppler radar this afternoon after the storms tore it down:
ALLEMAN, Iowa -- A strong thunderstorm passing just north of the Des Moines metro early Monday destroyed a TV radar station.
WHO-TV's weather radar was blown off its tower near the town of Alleman early Monday morning.
Parts of the radar were blown into a nearby yard, including the radar dish and the dome used to protect the dish.
This is an intense line of storms with a long history of damage, capable of uprooting very tall and very old trees, doing roof and window damage to homes and businesses, as well as knocking down power lines and blowing around anything that isn't tied or bolted down. Folks who live in mobile homes should seek shelter in a sturdy building until these storms pass, because winds of this magnitude can and will easily flip and destroy this type of home over, even if they're tied down.
The newest updates will appear at the top of the information below the fold. Check back for new updates every 20-30 minutes as these move east for new updates, especially if you live in the threat zone.
As usual, keep politics, meta, pie fights and dickish comments out of here or you'll find yourself in the hidden comments. Several folks have questioned the reasoning and validity of this promise, and G2Geek gave a pretty good explanation.
Updates
Update 9 442PM EDT
I've changed the title to reflect that this system is no longer a derecho, but the squally remnants of it. The SPC says that the tail-end of the squall line could turn severe later on through eastern Kentucky and western West Virginia later if conditions allow. The severe thunderstorm watch will stay in effect, but the derecho is essentially done.
A new severe t'storm watch might go up where the storms might regenerate if they do so. The main threat with the storms that reform will be large hail and damaging straight-line winds.
Here's the radar as of 442PM EDT:
Update 8 357PM EDT
Here's the northern part of the line about to move through the Pittsburgh metro area. Severe thunderstorm warning for more counties than I can list, so here's the TDWR radar. Click the image to enlarge in a new tab/window.
Update 7 326PM EDT
It looks like the Pittsburgh, PA area is going to get the northern side of this derecho. The Pittsburgh radar is broken right now (unrelated to this storm), so I can't post a radar image. The terminal doppler weather radar is working, but the storms are too far away to get a good picture of it right now. I'll post a radar as it gets closer.
Meanwhile, south-central and southeastern Ohio are taking the brunt of the derecho right now. It should cross the OH/WV border in an hour or two. Be on alert for very strong winds, very heavy rain and possibly some hail.
Update 6 256PM EDT
Add West Virginia to the list of stuff this derecho wants to screw up today. Severe t'storm watch up until 1000PM EDT for the counties outlined in blue. 75 MPH winds (with higher gusts), 2.00" hail and extremely heavy rain is possible with these storms.
Update 5 234PM EDT
The leading edge of the derecho is now moving through just south of downtown Columbus OH. The strongest winds will last another 10-15 minutes after the leading edge moves through, so hang in there. The line moves from Troy OH down through Columbus, over to Newark OH and up to just east of Wooster. To those of you in the smaller towns, sorry I've been focusing on the big city the most. It would be impossible to focus on each small city individually. But we love you guys just as much, you know that. :P
Update 4 225PM EDT
Another traffic cam from just south of Columbus, looking north towards the city. The city is disappearing in the wall of rain.
Update 3 215PM EDT
OHDOT traffic cam, looking north from SR-31/Ackerman Road in northern Columbus. Great googly moogly that's a creepy sky.
Update 2 152PM EDT
Okay, mea culpa time. I completely misjudged the direction of the derecho because I didn't turn the radar on animate mode, and went off the "moving east" wording in the warnings. Heh. Sorry about that. So...
The derecho is moving southeast towards areas northeast of Dayton, and everyone within 50 miles of Columbus OH needs to be alert. This intense line of storms should get there within an hour or so. This doesn't mean that Cleveland and Akron are out of the woods yet, you guys might still get the northern end of the storm (especially Akron), but the worst of it is coming into the Columbus area now.
Here's the radar (with the warning boxes in yellow) showing the position of the storms as of 1:53 PM EDT. Click the image to open a much larger, more detailed image in a new tab/window.
Update 1 129PM EDT
Here are some of the damage reports from this derecho. It's nothing to mess around with. This particular line started in Nebraska late last night, and I'll try my best to list the damage in chronological order.
Before 700AM Today
Alleman IA -- WHO-TV radar destroyed
Maxwell IA -- Mobile home's roof ripped off
Marshalltown IA -- Extensive structural damage, possible gas leaks
Montour & Toledo IA -- 70 MPH sustained winds with gusts to 100MPH
Toledo IA -- 150 foot radio tower snapped in half
Garwin IA -- Roof ripped off Legion Hall, grain bins down, gas leaks reported
Keystone IA -- 75 MPH wind
Vinton IA -- 70 MPH wind
W Vinton IA -- "2x4 flew through exterior wall of home, knocked over TV"
Urbana IA -- 8 small utility trailers blown over
After 700AM Today
Rockford IL -- 80 MPH wind
Evanston IL -- 2 foot diameter tree blown down
Mishawaka IN -- 81 MPH wind
Portage MI -- Tree uprooted on a house
Antwerp OH -- Trees blown down on a house
Initial Post @ 125PM EDT
Here is the initial radar for this post, complete with severe thunderstorm warnings (the yellow boxes on the radar).
The storms in the line are varying in speed (between 25 and 50 MPH), and the northern end of the line is moving a little faster than the southern end, so I expect the leading edge of these storms to arrive in Cleveland by 2:30-3:00 PM EDT, and about 15-20 minutes later in Akron. They may speed up or slow down, so be sure to watch the radar and listen out for warnings if you live in the impacted areas.