Extreme storms and extreme heat hit the U.S.

By: Dr. Jeff Masters , 5:50 PM GMT on June 30, 2012

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A violent line of organized severe thunderstorms called a derecho swept across the U.S. from Illinois to Virginia on Friday, damaging houses, toppling trees, bringing down power lines. The storms killed six people in Virginia, two in New Jersey, and one in Maryland, and left at least 3.4 million people without power. The thunderstorms in a derecho (from the Spanish phrase for "straight ahead") create violent winds that blow in a straight line. The traditional definition of a derecho is a thunderstorm complex that produces a damaging wind swath of at least 240 miles (about 400 km), featuring a concentrated area of thunderstorm wind gusts exceeding 58 mph (93 km/hr.) A warm weather phenomenon, derechos occur mostly in summer, especially June and July in the Northern Hemisphere. They can occur at any time of the year and occur as frequently at night as in the daylight hours. As seen on our wundermap with the "go back in time" feature turned on, Friday's derecho began near Chicago in the early afternoon, then marched east-southeast, peaking in intensity over Virginia and Washington D.C. on Friday evening. The derecho was unusually intense due to the extreme heat, which helped create an unstable atmosphere with plenty of energy to fuel severe thunderstorms.


Figure 1. Radar image from our wundermap with the "go back in time" feature turned on for 11 pm EDT Friday June 29, 2012, showing the derecho over Washington D.C. and Baltimore. Click on the "hour" button above the wundermap to advance the time by one hour to watch the progress of the derecho across the country.


Figure 2. NOAA's Storm Prediction Center (SPC) logged 871 reports of damaging winds on Friday. Twenty one of these reports were for winds over 80 mph. The highest wind gust was in Oswego, Illinois: 92 mph.



Figure 3. A dramatic change in the weather in Buckeye land: the temperature at Ohio State University in Columbus, Ohio dropped from 97°F to 68° after passage of Friday's derecho. The storm brought a wind gust of 82 mph to campus, and 0.86" of rain.

Historic heat wave topples Dust Bowl-era extreme heat records
A historic heat wave on a scale and intensity not seen in the U.S. since the great heat waves of the 1930s Dust Bowl era set new all-time heat records for at least ten major cities Friday. According to wunderground's weather historian Christopher C. Burt, fifteen of the 303 major cities he maintains records for on the wunderground extremes page have set all-time heat records in the past four days. The only year with more all-time heat records is 1936, when 61 cities set all-time heat records. In 2011, which had the 2nd warmest summer in U.S. history, only ten of the 303 cities set all-time heat records during the entire summer. With the the hottest month of the year (July) still to come, 2012 threatens to rival the great Dust Bowl summer of 1936 for extreme heat.

All-time records for any date tied or broken on Friday:

109° Nashville, TN (old record 107° 7/28/1952
109° Columbia, SC (old record 107° on two previous occasions)
109° Cairo, IL (old record 106° on 8/9/1930)
108° Paducah, KY (ties same on 7/17/1942
106° Chattanooga, TN (ties same on 7/28/1952)
105° Raleigh, NC (ties same on 8/21/2007 and 8/18/1988)
105° Greenville, SC (old record 104° 8/10/2007 although 106° was recorded by the Signal Service in July 1887)
104° Charlotte, NC (ties same on 8/9 and 10/2007 and 9/6/1954)
102° Bristol, TN (ties same on 7/28/1952-this site now known as `Tri-State Airport')
109° Athens, GA. This is just 1° shy of the Georgia state record for June of 110° set at Warrenton in 1959.

All-time state June heat records set Friday:

113° Smyrna, TN (old record 110° in Etowah in June 1936)
109° Cairo, IL (old record 108° in Palestine in June 1954)

Also of note: Atlanta, GA hit 104° (its all-time June record), and just 1° shy of its all-time record of 105° set on 7/17/1980. The forecast for Atlanta on Saturday calls for a high of 105°F, which would tie for the hottest day in the city's history.

Wunderground's weather historian Christopher C. Burt has a new post called The Amazing June Heat Wave of 2012 Part 1: The West and Plains June 23 - 27 summarizing the early portion of this week's historic heat wave. He plans to make a follow-up post on Sunday summarizing the records set on Friday and Saturday.

Relatively quiet in the Atlantic
An area of heavy thunderstorms, associated with an upper level low pressure system, has developed in the Gulf of Mexico along the Texas coast. This disturbance will probably move ashore over Texas before development into a tropical depression can occur, and NHC is giving it a 0% chance of development. The tropical wave approaching the Lesser Antilles (Invest 97L) has dissipated due to dry air, and is no longer a threat. None of the reliable computer models are developing anything during the next seven days.

Jeff Masters

Chicago Shelf (LarrySmit)
Chicago Shelf
Summer Heat (gardner48197)
Summer Heat
Smokey Clouds (LarrySmit)
Asperatus Clouds
Smokey Clouds
And the Sky Opened Up! (webgal)
Much needed thunderstorms came through west-central Illinois late this evening. The lightning was absolutely incredible!
And the Sky Opened Up!

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currently 103-104 at my house, supposed to feel hotter tomorrow with more moisture, might even be a storm or 2 from a SW propagating storm cluster:


yesterday it was 104F felt like 102F at atlanta, currently it is 102 feels like 104F

out in Athens GA it is 102 feels like 106, supposed to reach 110 feels like 115
Member Since: February 11, 2012 Posts: 0 Comments: 9731
Woodlands, tx here sitting here enjoying a very nice thunderstorm with plenty of rain and cooler temps.
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Quoting WxGeekVA:
My dad and I decided not to clean up storm damage yet because of the threat for more later. Hopefully it doesn't happen but we don't want to waste our time. So then we wanted to go to the pool. We get there, and there is an oak tree in the pool and it's closed. And that's annoying, because it's already almost 95 degrees again.
I can tell..YOUR GONNA HAVE A BAD TIME.Don'tAnnoyMe I thought you were banned.
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Quoting Articuno:
I just went outside to see a Big OAK TREE snapped in half from last night's storm..and it was snapped near a main road, luckily it didn't land on anybody's house and nobody lives there, also the tree branches on my street were bare and the bark was took right off of it


Doubt it was an oak tree if it snapped, they come out roots and all. Its the pine trees that snap.
Member Since: September 6, 2007 Posts: 0 Comments: 6599
Prefer 97L look like this? No?
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Quoting Chapelhill:
Thanks. That was pretty impressive. Lost power only a few hours here in Chapel Hill. Quite a few trees and limbs down.


No power out in my part of Carrboro. Not sure why, we're usu. the first to lose it. Woulda been nice if we'd gotten some rain too, but it fizzled b4 getting here.
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My dad and I decided not to clean up storm damage yet because of the threat for more later. Hopefully it doesn't happen but we don't want to waste our time. So then we wanted to go to the pool. We get there, and there is an oak tree in the pool and it's closed. And that's annoying, because it's already almost 95 degrees again.
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting STXHurricanes2012:
Wow still dry lol just wind and rumbles of thunder so far


Where at in Texas? In west Houston here and we got a shower earlier, about 20 minutes worth, and hten nothing since. Seriously hoping for more
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I just went outside to see a Big OAK TREE snapped in half from last night's storm..and it was snapped near a main road, luckily it didn't land on anybody's house and nobody lives there, also the tree branches on my street were bare and the bark was took right off of it
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Wow still dry lol just wind and rumbles of thunder so far
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Quoting DontAnnoyMe:
Here's a nice radar loop of the derecho winds coming into NC last night (thin blue line out ahead of storms).

NEXRAD radar image(s) [KRAX BREF1]

Thanks. That was pretty impressive. Lost power only a few hours here in Chapel Hill. Quite a few trees and limbs down.
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Quoting pottery:

You can come to the Tropics to cool off, man !


...and today's headline of note is:

Archaic pottery could change history of mankind


: )
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Thanks Dr. Masters!
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Quoting washingtonian115:
I haven't seen you in a minute.


Or two ;-)
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Quoting KEEPEROFTHEGATE:


no damage to the house i hope

trees and such dont matter it can grow back
most important is you are safe
and have a place to go
till the lights come back on
Thanks Keep.I can't say the same for others though.A tree smashed into the house of a 90 year old women and killed her.Their are damage to houses around here.
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Quoting washingtonian115:
Yes Keep.I had lost power yesterday night.Those winds were a howling.The tree branches on the tree in the back yard were snapping and the rain and hail were coming down hard.I'm over a relatives house.As my house does not have power yet.


no damage to the house i hope

trees and such dont matter it can grow back
most important is you are safe
and have a place to go
till the lights come back on
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I'm thrilled to see the Gulf action that Texas is getting in on. Besides throwing a bit of much-needed rain their way, it's so great to have moisture impinging on this "roaster ridge" high! It'd be great if the Gulf and Caribbean moisture could chip away at the continental high, especially since the Caribbean folks don't seem to be having much luck getting rain out of the skies right now.

I don't mean this disrespectfully to anyone in North Florida, but here in the Cape Debby's mostly been a good thing. It is so frightening to see how dry we are when our rainy season should have started up before now. Debby is the only thing that has saved my trees this summer.

Stay safe this weekend, you East-Coasters in the path of t-storms!
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Quoting KEEPEROFTHEGATE:
hey wash what happen last night ya disappeared as it knock on the door

did ya lose power i guess
Yes Keep.I had lost power yesterday night.Those winds were a howling.The tree branches on the tree in the back yard were snapping and the rain and hail were coming down hard.I'm over a relatives house.As my house does not have power yet.
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Quoting pottery:

You can come to the Tropics to cool off, man !
naw iam moving to greenland as soon as the ice melts
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Quoting washingtonian115:
Ha ha very funny.This will certainly catch people off guard.I'll one more be waiting my impending doom.
hey wash what happen last night ya disappeared as it knock on the door

did ya lose power i guess
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Quoting DontAnnoyMe:
Here's a nice radar loop of the derecho winds coming into NC last night (thin blue line out ahead of storms).

NEXRAD radar image(s) [KRAX BREF1]

I haven't seen you in a minute.
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Quoting tropicfreak:


I'm in the hatched area... again. Really mother nature cannot give us a break here in Central VA.


Were I superstitious, I might think it was Mother Nature having her revenge on Cooch.
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Quoting KEEPEROFTHEGATE:
thanks doc well no tropical activity thats all right there is lots of heat 100 degrees here in toronto canada with the humidex to talk about

and more heat for the next 7 days or longer

You can come to the Tropics to cool off, man !
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Picture of wind damage in my hometown of Cambridge, OH from yesterday's storms:

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thanks doc well no tropical activity thats all right there is lots of heat 100 degrees here in toronto canada with the humidex to talk about

and more heat for the next 7 days or longer
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Here's a nice radar loop of the derecho winds coming into NC last night (thin blue line out ahead of storms).

NEXRAD radar image(s) [KRAX BREF1]

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Quoting LargoFl:
nws says winds of 50 mph, stay safe down there

thx
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Quoting redwagon:

Thank you, blob and Doc, too!

lol
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1260. stormpetrol 6:10 PM GMT on June 30, 2012 +0
I see 97L has been dropped in TWO by the NHC.
Action: Quote | Modify Comment
Member Since: April 29, 2007 Posts: 0 Comments: 5770
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we just had several power surges here..I seriously will be sitting in my car with the A/C if the power goes out..
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Quoting ncstorm:
the images posted in today's blog are unreal..


And they are about to get more crazy.

Lightning over the Richmond skyline.



A tree ripped part of a wall off in the "Fan" area of Richmond.

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Quoting STXHurricanes2012:
Wind just picked up here!
nws says winds of 50 mph, stay safe down there
Member Since: August 6, 2011 Posts: 4 Comments: 39309
Quoting STXHurricanes2012:
Storms about to hit...thanks blob & doc

Thank you, blob and Doc, too!
Member Since: August 4, 2007 Posts: 0 Comments: 3276
Quoting RetiredPWB:


yes it sure poured rain non stop, winds were bad at times but had that been a 125 mph hurricane, the whole STATE would have been destroyed, sticking around and hitting all the area's of florida over days and days...people would have been talking about it 100 years from now lol...but all in all..we needed that rain..just not the flooding it brought along with it
Member Since: August 6, 2011 Posts: 4 Comments: 39309
Quoting MAweatherboy1:

You're in for more fun today...

Quoting MAweatherboy1:

You're in for more fun today...

Ha ha very funny.This will certainly catch people off guard.I'll one more be waiting my impending doom.
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Wind just picked up here!
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Quoting MAweatherboy1:

You're in for more fun today...



I'm in the hatched area... again. Really mother nature cannot give us a break here in Central VA.
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Thanks, Doc. Hope you enjoyed your vacation.
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the images posted in today's blog are unreal..
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Quoting washingtonian115:
Thanks Doc.Did you have to show it over my area?Lol.

You're in for more fun today...

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Incredible photos!!
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Quoting LargoFl:

I'm curious...did Debby ring some peoples bells in Pinellas last week? I lived there for 10 years and I couldn't believe the complacency when it came to the Tropics. Imagine if Debby had 125mph winds? I hope it sent a message to a lot of people.

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heads up brownsville it just about on you folks
Member Since: August 6, 2011 Posts: 4 Comments: 39309
So I guess TWC isn't the only source of media that jips Richmond...
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Quoting PackManWx:
Last night about 11PM in Raleigh, we didn't get a drop of rain at my house, but the wind started blowing like something crazy.

I got up and went out on the porch and it was very very eery. It was still pretty warm and the wind was blowing TS force.

It was over in about 30 minutes. No doubt part of that gust front blowing through.


Kentucky Speedway actually had a similar situation that occurred. Even though the line passed to their north they felt the gust front and it did some damage, knocked some tents and other items blown around. They had to halt Sprint Cup Qualifying temporarily until the wind ceased.
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Storms about to hit...thanks blob & doc
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Quoting LargoFl:
look at that line of red about to hit brownsville texas
Member Since: August 6, 2011 Posts: 4 Comments: 39309
Thanks Doc.Did you have to show it over my area?Lol.
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Member Since: August 6, 2011 Posts: 4 Comments: 39309
thanks Dr. M
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Thank you Dr Masters. Atlantic may be quiet for a while despite some good waves rolling off Africa,but conditions downstream are not the best at this time as 97L demonstrated. Maybe we may have to wait until early August?
Member Since: April 29, 2009 Posts: 75 Comments: 14338

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.