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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Quoting txjac:


Got .72 inch here and low temps ...nice day
System too far south to do much of Texas any good, unfortunately High Pressure is moving back in by Monday.
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204. txjac
Quoting bohonkweatherman:
First day of any rain here in 46 days, received less than .10 but it did not hit 100, in Texas that is a great day!


Got .72 inch here and low temps ...nice day
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Quoting LargoFl:
First day of any rain here in 46 days, received less than .10 but it did not hit 100, in Texas that is a great day!
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Quoting stormpetrol:


Good one! Lmao!!
You do have a point....I can't recall seeing it, but some bit of energy that might remain could I guess develop convection as it moves into the NW Carib. Thus the need for the ZS.
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Quoting washingtonian115:
The storm was terrible.I lost power.Trees and power lines litter the city almost everywhere you go.A state of emergency has been declared.I'm currently over my relatives house.

Post 189.Some places were set on fire due to the fallen power lines and transformers.Mainly in P.G co. though.They have shelters open up for families.
Sorry to hear that.Hope it gets better.
Member Since: October 15, 2011 Posts: 0 Comments: 4229
86 is nic
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Quoting Neapolitan:
NWS says Wilmington made it to 103. That's a record for the day, of course. It's also only one degree shy of the all-time record of 104 there (6/27/52), and only the third time the temp has topped out at 103 degrees there (7/12/1879 and 8/1/1999).


I pulled that from NWS, Wilmington, NC..

and here is the latest..at 4:53 EDT..no records broken according to their website..

Wilmington, New Hanover International Airport
Lat: 34.28 Lon: -77.92 Elev: 46
Last Update on Jun 30, 4:53 pm EDT

Fair

92 °F
(33 °C)
Humidity: 62 %
Wind Speed: SE 10 MPH
Barometer: 29.85" (1010.6 mb)
Dewpoint: 77 °F (25 °C)
Heat Index: 106 °F (41 °C)
Visibility: 8.00 mi.
More Local Wx: 3 Day History:
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I'm out for a while, ya'll... gotta make a grocery store run. I really hate to go outside, into 86 degrees, when it's 74 inside...

lol
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Quoting CosmicEvents:
97L is gone.
To satisfy all why don't we add a new category for purposes of this blog anyway. In addition to AOI's, "L's", TD's......let's add ZS...a zombie storm, defined as an area that would exist if it wasn't dead, but it may come back to life.
I dub 97L as ZS1 for 2012.
ok


Good one! Lmao!!
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Quoting Hurricanes101:


partly due to the dry weather in the wake of TS Debby, I would think after all of the rain we here on the west coast experienced, we would be thankful for a bit of dry weather


Yeah, you're probably right. But we didn't have much before Debby either...and if I recall, we didn't see the usual intensity of the afternoon storms last year either.

We actually fared much better here in Lee County than they did farther up the coast as far as rain from Debby. We got a good soaking, but none of the bad flooding.
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195. VR46L
Quoting CosmicEvents:
97L is gone.
To satisfy all why don't we add a new category for purposes of this blog anyway. In addition to AOI's, "L's", TD's......let's add ZS...a zombie storm, defined as an area that would exist if it wasn't dead, but it may come back to life.
I dub 97L as ZS1 for 2012.
ok


Yep looks like a new form of category is required ..LOL
Member Since: March 1, 2012 Posts: 0 Comments: 6877
Quoting washingtonian115:
The storm was terrible.I lost power.Trees and power lines litter the city almost everywhere you go.A state of emergency has been declared.I'm currently over my relatives house.


Wow that is some crazy stuff Hope they restore power as soon as possible :)
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97L is gone.
To satisfy all why don't we add a new category for purposes of this blog anyway. In addition to AOI's, "L's", TD's......let's add ZS...a zombie storm, defined as an area that would exist if it wasn't dead, but it may come back to life.
I dub 97L as ZS1 for 2012.
ok
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Member Since: July 6, 2010 Posts: 113 Comments: 31883
Quoting iceman100:
Funny that millions are feeling the effects of the heat wave, yet here in SW Fla. everything is pretty much normal EXCEPT the lack of afternoon thunderstorms that have taken place in the past.



partly due to the dry weather in the wake of TS Debby, I would think after all of the rain we here on the west coast experienced, we would be thankful for a bit of dry weather
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Quoting Hurricanes305:


Hey wash, how bad was that storm for you last night?
The storm was terrible.I lost power.Trees and power lines litter the city almost everywhere you go.A state of emergency has been declared.I'm currently over my relatives house.

Post 189.Some places were set on fire due to the fallen power lines and transformers.Mainly in P.G co. though.They have shelters open up for families.
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Quoting washingtonian115:
I don't wanna hear that word.."Thunderstorm"


You musta been in the heart of yesterday's weather "event".

Seriously though, I was in the middle of a derecho in the 1990s in Michigan. It was crazy. The house across the street from me caught fire after the nearby transformer exploded and did something to its electrical system. The area was totally trashed and we were without power for awhile.
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Afternoon showers along the northern coast of Jamaica, as a result of Day time heating...
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Quoting washingtonian115:
I don't wanna hear that word.."Thunderstorm"


Hey wash, how bad was that storm for you last night?
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Quoting iceman100:
Funny that millions are feeling the effects of the heat wave, yet here in SW Fla. everything is pretty much normal EXCEPT the lack of afternoon thunderstorms that have taken place in the past.

I don't wanna hear that word.."Thunderstorm"
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Funny that millions are feeling the effects of the heat wave, yet here in SW Fla. everything is pretty much normal EXCEPT the lack of afternoon thunderstorms that have taken place in the past.

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Quoting stormpetrol:


I'm not saying 97L will or will not develop, but I've noticed a pattern with these T waves & Tropical lows that get tagged an Invest around 40W, usually when they get around 50W they appear to dissipate and as they near the Windwards, they same to spring to life again only to nearly dissipate after crossing the Islands until they get to 75-76 West when they start flaring again, most have a 20-30% chance to become a named a system if they have been tagged as an Invest before. Not saying this will be the case with 97L, we'll just have to wait and see!


Interesting, I notice that all the time. But this wont be a threat to develop. The waves behind it is the ones to watch as ex 97L just moisten up the atmosphere for more waves to develop.
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That area SE of previous ex 97L deserves to be looked it with several spins are noted with in large area.

Kinda old , but just saying....
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Quoting Patrap:


That map shows us under yellow and red, but it's dry as dust here, no rain anywhere near us. A nice shower would be greatly appreciated by my garden (and my wallet come time to pay the water bill.) We were under a weather statement earlier today for a tropical funnel cloud, which I've don't remember seeing before.
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Quoting MAweatherboy1:
Bust on the severe threat today... Atmosphere remains too stable from yesterday...

Yes.
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Quoting VR46L:


Sorry 97L is dead, completely dropped by the NHC while they still have yellow circled 2 with 0% see a few posts up


I not saying it isn't dead, I'm stating what I've seen happen on several occasions with Twaves declared dead in that area before that's all!
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Quoting wunderkidcayman:

weel its not deactivated we need to wait untill they say it is but I still think 97L has a good shot of trying to develop just give it some time
They took it down. I just hope there is enough moisture left to drip over the ECar as it passes...
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Bust on the severe threat today... Atmosphere remains too stable from yesterday...

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Quoting VR46L:


Sorry 97L is dead completely dropped by the NHC while they still have yellow circled 2 with 0% see a few posts up



YEP 97L is dead
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173. JLPR2
Did any of you notice the shockwave the TW that emerged yesterday created? Looks like it's pushing the SAL/Dry air rather aggressively. If you then look at the WV you notice that it's actually humid air blasting against the dry air.

SSD Catl Loop
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Quoting pottery:

You can come to the Tropics to cool off, man !
Nassau Weather at a Glance Updated 50 min 54 sec ago
Weather Station
Nassau (MYNN)Elevation
23 ft

Station Select Now
Mostly Cloudy
Temperature
91 °F
Feels Like 97 °F
Wind(mph)
6 from the South

Quoting STXHurricanes2012:
Now its coming down hard!!!
This is prolly the best news I heard all day...
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171. VR46L
Quoting stormpetrol:


I'm not saying 97L will or will not develop, but I've noticed a pattern with these T waves & Tropical lows that get tagged an Invest around 40W, usually when they get around 50W they appear to dissipate and as they near the Windwards, they same to spring to life again only to nearly dissipate after crossing the Islands until they get to 75-76 West when they start flaring again, most have a 20-30% chance to become a named a system if they have been tagged as an Invest before. Not saying this will be the case with 97L, we'll just have to wait and see!


Sorry 97L is dead, completely dropped by the NHC while they still have yellow circled 2 with 0% see a few posts up
Member Since: March 1, 2012 Posts: 0 Comments: 6877
Quoting JLPR2:
Oh and how about over there, nigel20? Any rain? :\

It's mostly cloudy, but we're not getting any rain.
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97L is dead we need to move and wait for 98L.
Member Since: October 15, 2011 Posts: 0 Comments: 4229
168. JLPR2
Oh and how about over there, nigel20? Any rain? :\
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Quoting TropicalAnalystwx13:

I noted that the other day: the ones that are well/decently organized in the east and central Atlantic are the ones that usually go on to develop in the west Caribbean. However, the difference with ex-97L is that wind shear is not conducive, nor is it forecast to be, for development by the time the wave...whatever is left of it...gets there.




yep ex 97L is RIP
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Could get winds of 75mph.
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165. JLPR2
Quoting nigel20:

Hey JLPR2...what's the weather like in your neck of the woods?


We're sunny today, kinda wondering what am I doing here since I could be at the beach... XD
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Quoting stormpetrol:


I'm not saying 97L will or will not develop, but I've noticed a pattern with these T waves & Tropical lows that get tagged an Invest around 40W, usually when they get around 50W they appear to dissipate and as they near the Windwards, they same to spring to life again only to nearly dissipate after crossing the Islands until they get to 75-76 West when they start flaring again, most have a 20-30% chance to become a named a system if they have been tagged as an Invest before. Not saying this will be the case with 97L, we'll just have to wait and see!

I noted that the other day: the ones that are well/decently organized in the east and central Atlantic are the ones that usually go on to develop in the west Caribbean. However, the difference with ex-97L is that wind shear is not conducive, nor is it forecast to be, for development by the time the wave...whatever is left of it...gets there.
Member Since: July 6, 2010 Posts: 113 Comments: 31883
wunderkidcayman am not sure what you are looking at wind shear is two high and it has a lot of dry air around it



all so i think the nhc has drop the mode runs on it any ways at 18z
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Quoting VR46L:


Wonderkid are you serious?
The NHC have completely dropped it! and have left the other two yellow crayons circles up at 0% which looks to me like 97L just dont exist anymore






i dont no what that kid is looking at but 97L dos not exist anymore too marh wind shear is dry air wish kill 97L


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Quoting wunderkidcayman:

weel its not deactivated we need to wait untill they say it is but I still think 97L has a good shot of trying to develop just give it some time


I'm not saying 97L will or will not develop, but I've noticed a pattern with these T waves & Tropical lows that get tagged an Invest around 40W, usually when they get around 50W they appear to dissipate and as they near the Windwards, they same to spring to life again only to nearly dissipate after crossing the Islands until they get to 75-76 West when they start flaring again, most have a 20-30% chance to become a named a system if they have been tagged as an Invest before. Not saying this will be the case with 97L, we'll just have to wait and see!
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Quoting JLPR2:


You're right it dissipated last night, there's nothing left of 97L. The convection east of the islands is the TW but it developed ahead of where 97L was.

Hey JLPR2...what's the weather like in your neck of the woods?
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Quoting ncstorm:
thank goodness we didnt break records today but its still HOT!! Raleigh just tied their record with 105

Wilmington, New Hanover International Airport
Lat: 34.28 Lon: -77.92 Elev: 46
Last Update on Jun 30, 3:53 pm EDT

Fair

93 °F
(34 °C)
Humidity: 58 %
Wind Speed: SE 9 MPH
Barometer: 29.84" (1010.5 mb)
Dewpoint: 76 °F (24 °C)
Heat Index: 106 °F (41 °C)
Visibility: 9.00 mi.
NWS says Wilmington made it to 103. That's a record for the day, of course. It's also only one degree shy of the all-time record of 104 there (6/27/52), and only the third time the temp has topped out at 103 degrees there (7/12/1879 and 8/1/1999).
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158. JLPR2
Quoting VR46L:


Wonderkid are you serious?
The NHC have completely dropped it! and have left the other two yellow crayons circles up at 0% which looks to me like 97L just dont exist anymore



You're right it dissipated last night, there's nothing left of 97L. The convection east of the islands is the TW but it developed ahead of where 97L was.
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157. beell
.
Member Since: September 11, 2007 Posts: 142 Comments: 16478
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Quoting beell:


Wonder how much Beryl, Chris, and Debby had to do with this low pressure anomaly over the last month.

All three low pressure systems followed roughly the same path up and out.

Alberto, Beryl, and Debby probably did influence the Mean Sea Level Pressures across the West Atlantic, but still, the models forecast high pressures across much of the Atlantic when it turned out to be the exact opposite.
Member Since: July 6, 2010 Posts: 113 Comments: 31883

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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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