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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Can we please get an Invest on the former Ms. Senegal at 10 west? She looks solid, with 3 days of favorable conditions in front of her.

Avila and the guys are at the beach today?
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Wow, that's some crazy stuff right there.

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Does the MCS in Indiana moving into Ohio have a chance to be a Derecho all the way into VA again?
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Quoting beell:


Level of Free Convection-where a lifted parcel becomes warmer than the environmental temp after it becomes saturated and cools at the slower "moist lapse rate"-meaning it will rise (updraft).


by moist laps rate do you mean wet adiabatic lapse rate? i think that 6.8 degrees per 1000 meters
Member Since: June 17, 2011 Posts: 11 Comments: 6539
keep us posted cody
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting presslord:
Brad...I'm gonna walk up to th edock house to buy more beer for the storm....please gimmee 10 mins before the bottom falls out


You're good.
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Quoting MZT:
Wow, those facts just speak for themseleves. Those are simply unreal heights.

*Twice* cruising altitude for big jets going cross-planet. Downbursts after a 70K fall... good gravy..
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898. etxwx
Quoting TropicalAnalystwx13:
...and there goes the text scrolling across the bottom of the television screen.


It's hard to hit "like" when a post is about bad weather. We need an "I sympathize" button. Hope everyone gets through this okay.
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Quoting Grothar:


Isn't is funny, my birthday July 1, is the same as Canadian Independence day. :)
Happy birthday Gothar hope you had more birthdays to celebrate have a blast today and God bless you.
Member Since: October 15, 2011 Posts: 0 Comments: 4455
Great...

Quoting US National Weather Service Wilmington NC:

* AT 510 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 70 MPH. THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM 8 MILES NORTH OF MAPLE HILL TO
20 MILES WEST OF POINT CASWELL...AND MOVING SOUTHEAST AT 35 MPH.
Member Since: July 6, 2010 Posts: 113 Comments: 32524
895. beell
Quoting weatherh98:


LFC?


Level of Free Convection-where a lifted parcel becomes warmer than the environmental temp after it becomes saturated and cools at the slower "moist lapse rate"-meaning it will rise (updraft).
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Brad...I'm gonna walk up to th edock house to buy more beer for the storm....please gimmee 10 mins before the bottom falls out
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Quoting Tribucanes:
Um, I just glanced at the Alabama radar, that doesn't look particularly good. Discreet, everywhere, Birmingham radar shows it well. What's their status, are they going to become a big threat too?
Member Since: June 17, 2011 Posts: 11 Comments: 6539
892. MZT
The NC mountains are firing off some storms like commonly would occur in the summer afternoons. Looks like most parts of the state will see some rain tonight.
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Link

"A cool-looking swirly thing over western Canada on satellite water vapor imagery."

Love the weather channel....

In other news, scientists say that there are a lot of fluffy looking wet things hovering over "the carolinas" and that there is lots of wet coming out of people who are exposed to that yellow ball in the blue thing over our heads.

In the oceans, more swirly things that look like donuts are expected later this year.
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Quoting beell:
Cap over CHS? Convective temp of 103°F-all you need is a bit of an outflow or seabreeze to get a parcel to the LFC...



LFC?
Member Since: June 17, 2011 Posts: 11 Comments: 6539
889. beell
Cap over CHS? Convective temp of 103°F-all you need is a bit of an outflow or seabreeze to get a parcel to the LFC...

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its getting dark here now..
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Um, I just glanced at the Alabama radar, that doesn't look particularly good. Discreet, everywhere, Birmingham radar shows it well. What's their status, are they going to become a big threat too?
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Quoting presslord:


Keep up the good work, mon!!!!


Sorry about the crawl, we're trying to limit it to top and bottom of the hour until we get our first warning.
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Quoting TropicalAnalystwx13:


...you got it you got it bad...
Member Since: June 17, 2011 Posts: 11 Comments: 6539
884. MZT
Quoting Chucktown:


We're here for ya Press. Impressive instability just to our north and west. Tops near Florence are between 60 and 70 K feet. Still haven't busted the cap yet
Wow, those facts just speak for themseleves. Those are simply unreal heights.
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Quoting Chucktown:


We're here for ya Press. Impressive instability just to our north and west. Tops near Florence are between 60 and 70 K feet. Still haven't busted the cap yet, but a special 18 Z sounding was done at CHS and CAPE and LI's are off the charts. Its going to take another hour or two to break the cap, but once we do, things are going to blossom rather quickly. Also, the seabreeze is pretty pinned to the coast this afternoon, just another added factor to the impending convection. The developing MCS will probably effect us here in the tricounty around 7 PM.


Keep up the good work, mon!!!!
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...and there goes the text scrolling across the bottom of the television screen.
Member Since: July 6, 2010 Posts: 113 Comments: 32524
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Quoting presslord:
Dear Mr. Jesus: Please let this part of the Carolinas get some rain!


We're here for ya Press. Impressive instability just to our north and west. Tops near Florence are between 60 and 70 K feet. Still haven't busted the cap yet, but a special 18 Z sounding was done at CHS and CAPE and LI's are off the charts. Its going to take another hour or two to break the cap, but once we do, things are going to blossom rather quickly. Also, the seabreeze is pretty pinned to the coast this afternoon, just another added factor to the impending convection. The developing MCS will probably effect us here in the tricounty around 7 PM.
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Hello 2 TVS popping up in Eastern NC
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Link Current Convective Watches

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Quoting presslord:
Dear Mr. Jesus: Please let this part of the Carolinas get some rain!
For you Press and those who need that water.Link
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Spain wins Euro Cup, 4 zip. What an embarrassment for Italy!
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Member Since: July 6, 2010 Posts: 113 Comments: 32524
Long time Lurker, first post. I'm in eastern NC close to Greenville. Strong winds and lightning. Saw it coming but got bad quick. Winds died down but a lot of lightning still. Friends reported dime sized hail not too far from here. Crazy stuff. But the temps dropped a bit!
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Quoting bohonkweatherman:
Get use to these Storms with the Intense Heat throughout the Country, we had a great chance of rain for 3 days here and I received little over a tenth of an inch, more than any family member living around me. Send Some Storms to Texas please, we could use a break, only people getting decent rains are along the Coast.
Has been nice here in Houston today--mostly overcast with some sun breaks, occasional light passing showers. Temprature actually nice outside, but humidity high. I was soaking wet after planting 3 trees, from sweat, not rain.
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Quoting Grothar:


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.


I think the MJO must be taking a quick 240hr nap, too, not on top of things. All these storms sneaking up that shouldn't be. And thick moisture over TX.
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wow...


Link Storm Prediction Center Mesoscale Discussions

p.s. happy birthday brothar, I mean Grothar!
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Dear Mr. Jesus: Please let this part of the Carolinas get some rain!
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Energy flow out in front of the line in North Central Indiana seems to still be stealing a lot of energy from the system. Cross your fingers but it looks a little less bowed now and still looks to be weakening. Maybe eastward outflow will continue to diminish it before it can explode because of conditions.
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Quoting TropicalAnalystwx13:

Sigh...Don't tell me about it. :(
Get use to these Storms with the Intense Heat throughout the Country, we had a great chance of rain for 3 days here and I received little over a tenth of an inch, more than any family member living around me. Send Some Storms to Texas please, we could use a break, only people getting decent rains are along the Coast.
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Grothar:

I was watching the movie Amadeus & they were throwing flaming candelabra at each other.

Don't you miss those days?
Happy Birthday!
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Quoting Tribucanes:
How long till your under the gun ncstorm? Close to an hour and a half? Or are they moving even slower than that? Scary stuff this week.


Dont look like they moving much..the nearest storm to me is in Bladen County and that is over an hour away..sitting here waiting and unfortunately its going to be the round 2 tomorrow..
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I know where 13 is, where are the rest of you guys in NC in relation to these storms?
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Very strong thunderstorms.
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Quoting Tribucanes:
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.


Although instability is quite high and supportive of strong updrafts that can cause wind/hail, wind shear is not particularly supportive of tornadoes. Sometimes in low shear, high instability regimes tornadoes do still occur, but the chance is not particularly high.
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862. MZT
Not just the Carolinas, really. There are scattered microbursts all the way back into Alabama. Some of this will throw surprises here and there, outside the warning zones. There's just so much going on.

Beginning to get cloudy here in Charlotte...
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How long till your under the gun ncstorm? Close to an hour and a half? Or are they moving even slower than that? Scary stuff this week.
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Quoting Ameister12:
These storms are insane!

Sigh...Don't tell me about it. :(
Member Since: July 6, 2010 Posts: 113 Comments: 32524
Happy Birthday Grothar and have many many more.
Member Since: April 29, 2009 Posts: 75 Comments: 14559
from facebook

Frank Strait Fan Club
Seriously bad thunderstorms are about to hit Beaufort County, NC with the potential for 100 mph straight-line wind gusts...
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These storms are insane!
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Quoting washingtonian115:
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 :(.


Last night 80,000 people in the Richmond/ Tri-Cities area were without power after that bout of storms moved through, once again not including me. One of them actually dropped a tornado not too far from Mechanicsville (suburb on NE side of Richmond). That storm and others were packing big hail. I had a decent storm too, they were actually training over me and it poured over an hour. Picked up nearly 2" of rain. Not to mention the lightning was almost constant and had a few periods of small hail (dime or pea sized). I wish we were done... but it looks like that complex in Indiana is headed this way. Local mets are saying it could have similar impacts to that of Friday night.... ugh really?? Not to mention it's 100 outside with a heat index of 107. I'm so done with this heat and severe weather.
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.