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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Well, Spain just slammed the door shut on Italy in soccer, Euro World Cup. 3 to 0
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Quoting redwagon:



Thanks, red. Well, right now it isn't only the atmosphere suffering from "verical instability." I think I will check out for awhile and go horizontal. My upward MJO is beginning to affect my CONUS. Thanks for the greetings everybody and watch the tropics.

Member Since: July 17, 2009 Posts: 71 Comments: 26814
853. etxwx
Quoting redwagon:



LOL. Redwagon...that looks like a Texas style birthday cake.

Happy Birthday Grothar!! May you have many many more!
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Quoting jamesrainier:
424 PM EDT SUN JUL 1 2012

THE NATIONAL WEATHER SERVICE IN RALEIGH HAS ISSUED A

* TORNADO WARNING FOR...
EAST CENTRAL SAMPSON COUNTY IN CENTRAL NORTH CAROLINA

* UNTIL 500 PM EDT

* AT 418 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 7 MILES NORTH OF TURKEY...OR 8 MILES NORTHEAST OF
CLINTON...MOVING EAST AT 20 MPH. GOLF BALL SIZED HAIL AND
DESTRUCTIVE WINDS IN EXCESS OF 70 MPH ARE ALSO LIKELY WITH THIS
STORM.


Its getting real..
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Is it just me, or if the Carolina storms get much stronger tornadoes are going to be a major threat. Lots of updrafts with most all of these Carolina meanies.
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Quoting Grothar:


Twit!
You are jealous of my twitdom...:)
Member Since: September 27, 2007 Posts: 1 Comments: 21734
424 PM EDT SUN JUL 1 2012

THE NATIONAL WEATHER SERVICE IN RALEIGH HAS ISSUED A

* TORNADO WARNING FOR...
EAST CENTRAL SAMPSON COUNTY IN CENTRAL NORTH CAROLINA

* UNTIL 500 PM EDT

* AT 418 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 7 MILES NORTH OF TURKEY...OR 8 MILES NORTHEAST OF
CLINTON...MOVING EAST AT 20 MPH. GOLF BALL SIZED HAIL AND
DESTRUCTIVE WINDS IN EXCESS OF 70 MPH ARE ALSO LIKELY WITH THIS
STORM.
Member Since: June 1, 2010 Posts: 0 Comments: 175
We hit a high of 96 here today.. Currently it's 93.... with 48% humidity
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Quoting GeorgiaStormz:


wow, we never have anything like that, even in our last serial derecho with 80mph winds that was oriented W-E and moved SE taking forever to leave the area.
Not even in the April 4th derecho last year.

I hope everyone gets power back soon, it is brutal out there.


Our AC stopped working this morning and it is now 89F with 57% humidity inside, and 106F feels lie 1ike 108F outside.
I cant imagine not having power for days
Have backup generator? One at least capable of running a small a/c window unit, and keeping refrigerator running?
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Quoting Grothar:


Isn't is funny, my birthday July 1, is the same as Canadian Independence day. :)

Member Since: August 4, 2007 Posts: 0 Comments: 3278
Quoting weblackey:
From a lurker (I am not worthy ;-)

Happy Birthday Grothar, a name I'm always happy to see since finding this place during Katrina.


Thanks, web. Happy to still be blogging after all this time.
Member Since: July 17, 2009 Posts: 71 Comments: 26814
It had looked to be weakening over the last two hours, but it was just consolidating into, yeah, what looks like the beginnings of a bow echo. The warnings have really dropped off along with the wind too. I'm really hoping we get lucky and this continues to weaken. Meso discussion says it's headed into very unstable air, so I don't see how it weakens. Ohio might see it strengthen and micro burst of severe to very severe winds occur according to the latest Meso too. Not to mention the Carolina storms are looking meaner by the minute.
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Quoting hydrus:
Happy 895,576,236,937,949,953,963,963,245,298,936,843,98 3th birthday Gro !


Twit!
Member Since: July 17, 2009 Posts: 71 Comments: 26814
Quoting Grothar:


Thanks, yep, I made it another century, I mean year!
Happy 895,576,236,937,949,953,963,963,245,298,936,843,45 8th birthday Gro !
Member Since: September 27, 2007 Posts: 1 Comments: 21734
From a lurker (I am not worthy ;-)

Happy Birthday Grothar, a name I'm always happy to see since finding this place during Katrina.
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Quoting Tribucanes:
I bet your a lot like the father-in-law in the movie Meet The Parents played by De Niro Grothar. You do get around, I do envy you that. How many languages do you speak? By yourself, never that, we're your weather family and your like our Great, Great, Great, Great............


Good thing you stopped at four greats. But last March I did become a great-great-great Uncle for real. My one twin nephew became a great-grandfather.
Member Since: July 17, 2009 Posts: 71 Comments: 26814
838. MZT
Flash flood warnings in Fayetteville now. I reckon we'll see more of these due to slow moving storms. That line is even building out gradually to the west.

Starting to see some -75 C cloud tops in these storms now.

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Grothar,
It's your birthday??!! Happy Birthday! May we be wishing you the same for another hundred years!
Member Since: August 22, 2009 Posts: 0 Comments: 3159

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Quoting ncstorm:
SPC updated discussion

...CNTRL/ERN CAROLINAS INTO ERN GA...
EXPANDED THE SIGNIFICANT WIND PROBS ACROSS THE ENTIRE AREA. 18Z
SOUNDINGS SHOW EXCESSIVE INSTABILITY WITH LI VALUES OF -15 TO -18
AND HIGH PRECIPITABLE WATER APPROACHING 2.00 INCHES. STORMS SHOULD
CONTINUE TO GEL FROM CNTRL/ERN NC ALONG AND AHEAD OF THE
OUTFLOW...AS WELL AS INTO CNTRL SC AND ERN GA WITHIN THE SFC TROUGH.
DAMAGING WET MICROBURSTS ARE LIKELY...AND ONE OR MORE SMALL CLUSTERS
OF STORMS MAY EVENTUALLY FORM AND PROPAGATE SWD PRODUCING DAMAGING
WINDS. ALTHOUGH SHEAR IS WEAK...LARGE HAIL UP TO AROUND 2.00 INCHES
DIAMETER WILL BE POSSIBLE DUE TO EXTREME UPDRAFT VELOCITIES. A FEW
LARGER STONES COULD OCCUR WITH ISOLATED SUPERCELLS MOVING S OR SWWD
OFF THE HODOGRAPH

Good grief, reads like something you'd see from somewhere in the central plains!
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Yep, this is a developing derecho, the line is now starting to bow.. It's gonna be a long day for people in the Ohio Valley.

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Quoting Ameister12:
Happy birthday, Gro!


Thanks, big A!
Member Since: July 17, 2009 Posts: 71 Comments: 26814
I bet your a lot like the father-in-law in the movie Meet The Parents played by De Niro Grothar. You do get around, I do envy you that. How many languages do you speak? By yourself, never that, we're your weather family and your like our Great, Great, Great, Great............
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Quoting Grothar:


You got it Jed! A lot of people think we have those temperatures all the time. Here is a little shocker for you. I'd rather be in in summer than anywhere else.

Excerpt:

A heat advisory is in effect until 7 PM tonight and we could be near the all-time record highs. That means we will be near the hottest temperatures that have ever been recorded in South Florida. The highest ever recorded in Miami and Ft. Lauderdale was 100 degrees back on July 21, 1942 and August 4, 1944 respectively. West Palm Beach's highest recorded temperature was 101 degrees on July 21, 1942 as well. Yesterday records were broke all across South Florida and Ft. Lauderdale shattered their old record by 4 degrees with a high of 98, hottest June temperature ever recorded.



Exactly man, its the same thing around here. The hottest temp ever near here was 104 way way back, and it was a "dry heat" too in May...

People have to remember that Florida is surrounded by water, which will always limit heat regardless of the situation. Whereas the continental U.S. is a breeding ground for extreme heat during the summer because its a large continental landmass.

Because we are in a peninsula here in Florida it pretty makes makes an overall more enjoyable climate in every way. This little miniature peninsula here in Pinellas County also accounts for this.


BTW, mosquitoes and bugs in general can get horrible here though. Like now after having 16 inches for the month of June and 10 from tropical storm Debby, now that we've had a period of drier weather since it has allowed mosquito populations to explode from what has already been a bad year for mosquitoes despite that we were in a drought, which we obvious aren't in one anymore.
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Quoting KEEPEROFTHEGATE:
how young are ya today


hehehehe!
Member Since: July 17, 2009 Posts: 71 Comments: 26814
SPC updated discussion

...CNTRL/ERN CAROLINAS INTO ERN GA...
EXPANDED THE SIGNIFICANT WIND PROBS ACROSS THE ENTIRE AREA. 18Z
SOUNDINGS SHOW EXCESSIVE INSTABILITY WITH LI VALUES OF -15 TO -18
AND HIGH PRECIPITABLE WATER APPROACHING 2.00 INCHES. STORMS SHOULD
CONTINUE TO GEL FROM CNTRL/ERN NC ALONG AND AHEAD OF THE
OUTFLOW...AS WELL AS INTO CNTRL SC AND ERN GA WITHIN THE SFC TROUGH.
DAMAGING WET MICROBURSTS ARE LIKELY...AND ONE OR MORE SMALL CLUSTERS
OF STORMS MAY EVENTUALLY FORM AND PROPAGATE SWD PRODUCING DAMAGING
WINDS. ALTHOUGH SHEAR IS WEAK...LARGE HAIL UP TO AROUND 2.00 INCHES
DIAMETER WILL BE POSSIBLE DUE TO EXTREME UPDRAFT VELOCITIES. A FEW
LARGER STONES COULD OCCUR WITH ISOLATED SUPERCELLS MOVING S OR SWWD
OFF THE HODOGRAPH

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Ii'm in central Raleigh A storm just grazed us to the north, but still solid clouds. And our temp fell to 86 ! Just like that. What are the chances we still get some rough weather today or tonight?

And yes, having trouble getting radar maps to load on WU.
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Quoting Tribucanes:
I would wish you a happy birthday Grothar, but I just assumed you got sick of celebrating them several centuries ago. Did you think you'd make it this age when you were a wee thing like must of us. (compared to you) Celebrating later? Party at your place later, sending out invites? Whatever you do, I'm glad you made it to another one.


Thanks, T. No, I never thought I will last this long.

And here I am alone in a strange place with all these people speaking foreign languanges and and different customs. I feel so out of place.
Member Since: July 17, 2009 Posts: 71 Comments: 26814
Quoting Jedkins01:


I think I'll pass, and people always complain about the heat in Florida, I'd rather be here in the summer then much of the continental U.S.

Heat index of 100 to 105 is common here, and yes, the sunlight here is much hotter than further north, but really I don't recall ever seeing a 120 to 130 heat index in the Tampa Bay area, so you guys can keep it.

It's warmer here in the winter and cooler in the summer, I really do like living here, lol.


You got it Jed! A lot of people think we have those temperatures all the time. Here is a little shocker for you. I'd rather be in in summer than anywhere else.

Excerpt:

A heat advisory is in effect until 7 PM tonight and we could be near the all-time record highs. That means we will be near the hottest temperatures that have ever been recorded in South Florida. The highest ever recorded in Miami and Ft. Lauderdale was 100 degrees back on July 21, 1942 and August 4, 1944 respectively. West Palm Beach's highest recorded temperature was 101 degrees on July 21, 1942 as well. Yesterday records were broke all across South Florida and Ft. Lauderdale shattered their old record by 4 degrees with a high of 98, hottest June temperature ever recorded.

Member Since: July 17, 2009 Posts: 71 Comments: 26814
Well after staying over at my sisters house the power has been restored for me!!.I'm currently at my house with sweet,sweet A/C!.Some neighbors of ours still don't have power.Trees are still down in some places and street lights are out.Parts of Virginia and Maryland along with D.C still don't have any power and it could take up to a week or more :(.
Member Since: August 14, 2010 Posts: 10 Comments: 17474
I would wish you a happy birthday Grothar, but I just assumed you got sick of celebrating them several centuries ago. Did you think you'd make it to this age when you were a wee thing like must of us. (compared to you) Celebrating later? Party at your place later, sending out invites? Whatever you do, I'm glad you made it to another one.
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821. MZT
Bad combination... strong storm, high winds, large hail, and not moving very quickly.


SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE COLUMBIA SC
330 PM EDT SUN JUL 1 2012

THE NATIONAL WEATHER SERVICE IN COLUMBIA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
WESTERN CHESTERFIELD COUNTY IN CENTRAL SOUTH CAROLINA
NORTHEASTERN KERSHAW COUNTY IN CENTRAL SOUTH CAROLINA
EASTERN LANCASTER COUNTY IN CENTRAL SOUTH CAROLINA

* UNTIL 430 PM EDT

* AT 324 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING GOLF BALL SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR
PAGELAND...OR 20 MILES SOUTHEAST OF MONROE...AND MOVING SOUTHEAST
AT 5 MPH.

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Happy birthday, Gro!
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eastern nc here,30 mile winds,just got dark,lightning everywhere,i mean rough
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Quoting weatherdogg:


Goldsboro has a temp of 103F, with a 83F dewpoint, yielding a heat index of 131F! 50% humidity above 100F is insane. Link


I think I'll pass, and people always complain about the heat in Florida, I'd rather be here in the summer then much of the continental U.S.

Heat index of 100 to 105 is common here, and yes, the sunlight here is much hotter than further north, but really I don't recall ever seeing a 120 to 130 heat index in the Tampa Bay area, so you guys can keep it.

It's warmer here in the winter and cooler in the summer, I really do like living here, lol.
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Does Arctic Amplification Fuel Extreme Weather in Mid-Latitudes?

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Now in addition to a 30% hatched hail, I'm in a 30% hatched wind. At least there are no tornado probabilities...



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Quoting Grothar:


Isn't is funny, my birthday July 1, is the same as Canadian Independence day. :)
how young are ya today
Member Since: July 15, 2006 Posts: 175 Comments: 54827

I live in SE Massachusetts and while out getting groceries spotted a beauty of a severe thunderstorm taking shape.

So I get home and pull up the radar to see the structure of that baby and I'm getting a broken image icon. Tried the same from two other stations and got the same icon.

Anyone else having trouble seeing the radar through wunderground?

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Quoting TropicalAnalystwx13:

Really? Happy Birthday Gro!


Thanks, yep, I made it another century, I mean year!
Member Since: July 17, 2009 Posts: 71 Comments: 26814
Quoting MZT:
Those CAPE values in S.C. are something else. 5000 j/kg could easily produce 100 MPH updrafts. That's the kind of hail you normally associate with midwestern "storm chaser" events.



It doesn't necessarily mean particularly large hail, large hail requirement is far more than just instability.
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Member Since: July 17, 2009 Posts: 71 Comments: 26814
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Quoting Grothar:


Isn't is funny, my birthday July 1, is the same as Canadian Independence day. :)

Really? Happy Birthday Gro!
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Thanks for that update GerogiaStormz, and it's only just begun today. I really hope we're not looking at an additional million without power from today's SW. Backside of this threat will fire nasty line later for Southern Minnesota, parts of Northern and Central Iowa and then eastward again. 200K without power all ready is not a good start to today's event.
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Quoting TropicalAnalystwx13:

Today is their independence day like July 4 is ours.


Isn't is funny, my birthday July 1, is the same as Canadian Independence day. :)
Member Since: July 17, 2009 Posts: 71 Comments: 26814
Quoting TropicalAnalystwx13:

Today is their independence day like July 4 is ours.


You mean they just go from July 3rd to July 5th. LOL
Member Since: July 17, 2009 Posts: 71 Comments: 26814
Quoting ncstorm:
try a heat index of 127..


I walked outside to go get the mail and by the time I got back in, I was soaked from sweat.
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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.

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