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 Tazmanian:
oh nos we may not see any thing for the rest of the season

Wow... 2012 final numbers:

4-1-0
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Quoting GeorgiaStormz:


so you are expecting something?

Fixed sorry the rain has got me
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oh nos we may not see any thing for the rest of the season
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Quoting GeorgiaStormz:


so you are expecting something?


Double negatives these days
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting TropicalAnalystwx13:

That's a bad pattern for when we have a developed hurricane in the East Atlantic isn't it?


If we could get the development, yes the steering would be dangerous, but obviously development in the central Atlantic is hindered by the time of year right now.
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Quoting GeorgiaStormz:
Atlanta was at 105F today for at 2 separate hour readings, i dont know if it peaked at 106F in between, but that would have been a record if we had gotten a 106F


According to TWC it did
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting STXHurricanes2012:
They still may have 1 circle for the gom blob although nothing isnt gonna happen!


so you are expecting something?
Member Since: February 11, 2012 Posts: 0 Comments: 9731
Quoting Tazmanian:




yes i no that but what dos linux have too do with weather underground


WU prolly uses it
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Atlanta was at 105F today for at 2 separate hour readings, i dont know if it peaked at 106F in between, but that would have been a record if we had gotten a 106F
Member Since: February 11, 2012 Posts: 0 Comments: 9731
Quoting weatherh98:


linux is software




yes i no that but what dos linux have too do with weather underground
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They still may have 1 circle for the gom blob although nothings gonna happen!
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Quoting Levi32:
One can see how far westward the Atlantic ridge extends, all the way through the Florida Straights and the western Gulf of Mexico, imparting a strong pressure gradient on the Caribbean, increasing trade winds. This does not allow much low-level convergence, and tends to tear apart tropical waves like 97L, which is why development chances down the road are minimal. Until the large-scale sinking which is responsible for the high pressures relaxes, tropical development chances will remain low.

One can also see a weak trough off the south Texas coast, but the anchoring convective low is inland over Mexico now.


That's a bad pattern for when we have a developed hurricane in the East Atlantic isn't it?
Member Since: July 6, 2010 Posts: 113 Comments: 32262
Quoting Tazmanian:




so what dos this Linux thing have too do with weather under ground and window 7 user


linux is software
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting JeffMasters:
Wunderground and many other web sites using Linux are experiencing server crashes that may be related to the fact that a leap second is being observed today: link

Jeff Masters




so what dos this Linux thing have too do with weather under ground and window 7 user
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Quoting MAweatherboy1:
I'm expecting a blank map with no yellow circles at the 8PM TWO... At least it should be that way.


no doubt
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting JeffMasters:
Wunderground and many other web sites using Linux are experiencing server crashes that may be related to the fact that a leap second is being observed today: link

Jeff Masters


how does that effect it?

TIA
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting Levi32:
One can see how far westward the Atlantic ridge extends, all the way through the Florida Straights and the western Gulf of Mexico, imparting a strong pressure gradient on the Caribbean, increasing trade winds. This does not allow much low-level convergence, and tends to tear apart tropical waves like 97L, which is why development chances down the road are minimal. Until the large-scale sinking which is responsible for the high pressures relaxes, tropical development chances will remain low.

One can also see a weak trough off the south Texas coast, but the anchoring convective low is inland over Mexico now.



Isnt the texas rain event mainly convergence and divergence at orrk, much like the area of disturbed weather in the BOH after beryl this year
Member Since: June 17, 2011 Posts: 11 Comments: 6539
286. JeffMasters (Admin)
Wunderground and many other web sites using Linux are experiencing server crashes that may be related to the fact that a leap second is being observed today: link

Jeff Masters
Quoting islander101010:
tw.isnt.dead.until.it.makes.landfall.western.gulf




good luck with that



97L is dead if any thing it will likey run in too MX at some point
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I'm expecting a blank map with no yellow circles at the 8PM TWO... At least it should be that way.
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Quoting Tazmanian:




YES!



wind shear is high lots of dry air around it and its olny a open wave no low now if it had a low with it. it may have stand a better ch
tw.isnt.dead.until.it.makes.landfall.western.gulf
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Quoting STXHurricanes2012:
Wow!!!! Still raining over here... been at for 4 1/2 hrs...got about 6 inches aleast


yalll need it
Member Since: June 17, 2011 Posts: 11 Comments: 6539
odd the the wunder blogs and the NWS are back too norml



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One can see how far westward the Atlantic ridge extends, all the way through the Florida Straights and the western Gulf of Mexico, imparting a strong pressure gradient on the Caribbean, increasing trade winds. This does not allow much low-level convergence, and tends to tear apart tropical waves like 97L, which is why development chances down the road are minimal. Until the large-scale sinking which is responsible for the high pressures relaxes, tropical development chances will remain low.

One can also see a weak trough off the south Texas coast, but the anchoring convective low is inland over Mexico now.

Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:

All the heat advisories/watches/warnings are gone?


I just got out of the shower, so no. :P


i havent showered since 730 this morning

I definitely smell bad
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting TropicalAnalystwx13:

All the heat advisories/watches/warnings are gone?


I just got out of the shower, so no. :P


good, its not just me, but you can still read them from below the map
i wonder whats up with it
Member Since: February 11, 2012 Posts: 0 Comments: 9731
Wow!!!! Still raining over here... been at for 4 1/2 hrs...got about 6 inches aleast
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Quoting Tazmanian:




i sure he took a bath or shower last night


idk you never know with cody...

sounds like he sits in fields all days and never leaves :P
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting GeorgiaStormz:
does anyone see anything strange at Weather.gov

All the heat advisories/watches/warnings are gone?

Quoting weatherh98:


u stink:P

I just got out of the shower, so no. :P
Member Since: July 6, 2010 Posts: 113 Comments: 32262
Quoting GeorgiaStormz:
does anyone see anything strange at Weather.gov



not me but i think taz did heres the quote
Quoting Tazmanian:
am gussing the NWS is not the olny ones have bugs today




what is up with the blogs today
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Tomorrow..18Z GFS Lifted Index and BL Winds

Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting GeorgiaStormz:
does anyone see anything strange at Weather.gov

A ridiculous amount of heat advisories and excessive heat warnings?
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Quoting weatherh98:


u stink:P




i sure he took a bath or shower last night
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does anyone see anything strange at Weather.gov
Member Since: February 11, 2012 Posts: 0 Comments: 9731
Quoting TropicalAnalystwx13:

No. :P


u stink:P
Member Since: June 17, 2011 Posts: 11 Comments: 6539
268. VR46L
Quoting wunderkidcayman:
hey guys sorry for being away for about an hour had to run off for something

anyway say what you would like but what happen if they put out another ATCF plots on 97L and for the rest of you guys that say it is dead what if the reactivated 97L again?
and what if 97L redevelops convection and shear doesen't look all that bad anymore then what?


I love you enthusiasm for the remnants of a disturbance that never had more than a generous 20% chance of ever developing and has had the tracking of it stopped while they still have TWO yellow crayons circles at 0% showing up .
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.
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Quoting GeorgiaStormz:


dude, you have all the humidity.
storms are supposed to start up by you tomorrow and move SW
NWS here doesnt even have rain in the forecast


local mets are calling for a higher chance of rain in the coming days, like 20% haha higher than 0%
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting weatherh98:


okay thats fine, whatevs

Anyone else wanna tell me what happened?

No. :P
Member Since: July 6, 2010 Posts: 113 Comments: 32262
Quoting GeorgiaStormz:


dude, you have all the humidity.
storms are supposed to start up by you tomorrow and move SW
NWS here doesnt even have rain in the forecast

Our National Weather Service is saying it will be sunny and hot tomorrow, and partly cloudy with a 20% chance of rain tomorrow night.
Member Since: July 6, 2010 Posts: 113 Comments: 32262
Quoting Tazmanian:



nop am not going to PM you



dont worry about it


okay thats fine, whatevs

Anyone else wanna tell me what happened?
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting TropicalAnalystwx13:
It is currently 103 °F with a heat index of 114 °F.


dude, you have all the humidity.
storms are supposed to start up by you tomorrow and move SW
NWS here doesnt even have rain in the forecast
Member Since: February 11, 2012 Posts: 0 Comments: 9731
Quoting TropicalAnalystwx13:

The GFS shows this one slowly fading at the same time another one develops across the Northern Plains. It moves that one east into the Northeast with time.

This heatwave will be around for at least the next 10 days.


yep because this high will be around for that long.

subsidence warming heats everything up but doesnt allow for rain
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting spathy:
Taz
Do you think 97L is dead?




YES!



wind shear is high lots of dry air around it and its olny a open wave no low now if it had a low with it. it may have stand a better ch
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Severe weather has been at all time monthly lows last two months which is the only plus with this heat, unless your looking for a quick tan. I see that's on the uptick, great........Yesterday certainly let us know that.
Member Since: April 18, 2012 Posts: 0 Comments: 2437
Quoting weatherh98:


WUmail me describing it or something i just kinda missed it. dont know what happened



nop am not going to PM you



dont worry about it
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Dew point is really a better measure of how much moisture is in the air though....
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Quoting Tribucanes:
If this heat doesn't subside in the next three to five weeks, it will be the story driving a lot of weather blogs I would think. Is another high going to replace the one doing this crap now? Long term is miserable for upper Midwest too, it's miserable here in Wisconsin. Long term forecast to be ninety to ninety five for the next seven to fourteen. Wonder if it'll break after that?

The GFS shows this one slowly fading at the same time another one develops across the Northern Plains. It moves that one east into the Northeast with time.

This heatwave will be around for at least the next 10 days.
Member Since: July 6, 2010 Posts: 113 Comments: 32262

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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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