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 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: 32286
At 3:51 we reached a temp of 106 and was still climbing. I am guessing the 4:51 reading will be around 110-108. Humidity is still 25%.
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153. VR46L
Quoting wunderkidcayman:
if 97L can rebuild it convection it would likely be noted in the TWO and I think between now and same time sunday we will see that increase in the convection


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

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151. etxwx
This is one way to stay cool in all this heat: find some shade and water. And that's no bull.
Oh...wait. That is a bull.
Hope everyone stays safe and cool today. ;-)
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150. beell
Quoting TropicalAnalystwx13:
From Levi:

"Interesting how the ECMWF and every other major global model forecasted above-normal pressures in the SW Atlantic for June (top image), but were completely wrong, as pressures have been significantly lower than normal through the 29th (bottom image). As I mentioned during the winter, the models often lock into a set pattern during ENSO events that does not always pan out correctly. Here, the continuing negative PDO is likely helping the pattern stay a bit more favorable in the tropics despite the El Nino."



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.
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Tropical Storm Doksuri?????? lol

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Quoting BahaHurican:
Afternoon, all, and thanks, Doc, for the interesting blog.

Good afternoon Baha!
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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.
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Quoting LargoFl:
....for Zero percent chance, this blob off the coast of texas sure is throwing off some strong storms, but texas needs this rain badly
This is the perfect storm for TX, with a fairly widespread rain shield and limited to no severe wind or lightning accompanying it... hope it gets into the Corpus and San Antone areas overnight....
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GULF OF MEXICO...
CLUSTERS OF SCATTERED HEAVY SHOWERS AND THUNDERSTORMS CONTINUE
TO AFFECT A GREAT PORTION OF THE WNW BASIN N OF 231 W OF 91W.
THESE SHOWERS ARE MOVING INLAND ACROSS SE TEXAS...CREATING A
COASTAL TROUGH ANALYZED FROM BEAUMONT TO CORPUS CHRISTI. THE
ACTIVITY IS SUPPORTED ALOFT BY UPPER LEVEL DIFFLUENCE BETWEEN A
NARROW UPPER RIDGE CENTERED NEAR 24N92W AND AN UPPER LEVEL LOW
SPINNING OVER THE FAR NE MEXICO TERRITORY NEAR 27N100W. TO
CENTRAL TEXAS DURING THE NEXT 24 HOURS. THE REMAINDER OF THE
GULF E OF 91W IS DOMINATED BY SURFACE RIDGE AXIS EXTENDING WNW
TO THE N-CENTRAL GULF FROM A WEAK 1018 MB HIGH CENTERED OVER THE
WRN COAST OF THE SOUTHERN FLORIDA PENINSULA NEAR 26N82W. FAIR
WEATHER CONDITIONS ARE EXPECTED TO CONTINUE OVER THIS REGION
WITHIN THE NEXT SEVERAL DAYS.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH EXTENDS E TO W ACROSS MOST OF THE
CARIBBEAN BASIN. HOWEVER...THIS FEATURE IS EMBEDDED IN DRY
SUBSIDENT AIR ALOFT NOTED ON WATER VAPOR IMAGERY. HENCE MOST OF
THE BASIN IS DOMINATED BY THIS AIRMASS KEEPING WEATHER
CONDITIONS FAIR THIS AFTERNOON. THE ONLY AREA OF SCATTERED
SHOWERS AND THUNDERSTORMS ARE OBSERVED OVER THE SW BASIN S OF
12N W OF 75W DUE TO CLOSE PROXIMITY TO THE MONSOON TROUGH
ANALYZED FROM NRN COLOMBIA ALONG CENTRAL PANAMA INTO THE ERN
PACIFIC ACROSS NRN COSTA RICA. COMPUTER MODELS SUGGEST THIS AREA
OF CONVECTION WILL TRACK NW TO ERN NICARAGUA OVER THE NEXT 24
HOURS. OTHERWISE...15-20 KT TRADE WIND FLOW IS OBSERVED ACROSS
THE DISCUSSION AREA...WITH THE STRONGEST WINDS GUSTING TO 25 KT
WITHIN 130 NM OFF THE NRN COAST OF COLOMBIA. SOME SCATTERED WEAK
CONVECTION WILL ENTER THE FAR ERN BASIN LATER TONIGHT...
ASSOCIATED TO A TROPICAL WAVE. OTHERWISE...THE OVERALL FAIR
WEATHER PATTERN ALONG WITH DRY CONDITIONS WILL LINGER ELSEWHERE
OVER THE NEXT SEVERAL DAYS.

ATLANTIC OCEAN...
A WEAKENING UPPER LEVEL TROUGH MOVES ACROSS THE WRN N ATLC...
SUPPORTING A STATIONARY FRONT EXTENDING SW INTO OUR DISCUSSION
AREA ALONG 32N61W TO 27N70W. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE WITHIN 60-90 NM AHEAD OF THE FRONT AXIS. TO
THE SE OF THIS FRONTAL BOUNDARY...AN UPPER LEVEL LOW IS NOTED ON
WATER VAPOR IMAGERY CENTERED NEAR 28N57W SUPPORTING A WEAK
SURFACE TROUGH ANALYZED FROM 25N62W TO 20N68W. SCATTERED WEAK
SHOWERS ARE WITHIN 60 NM ON EITHER SIDE OF THE SRN HALF OF THE
TROUGH AXIS. OTHERWISE...A BROAD SURFACE RIDGE DOMINATES THE
REMAINDER OF THE ATLC. THE SURFACE RIDGE IS ANCHORED BY A 1031
MB HIGH W OF THE AZORES NEAR 39N34W. HOWEVER...AN UPPER LEVEL
LOW MOVES WESTWARD ACROSS THE CENTRAL ATLC CENTERED NEAR 30N36W
SUPPORTING A WEAK SURFACE TROUGH THAT CUTS THROUGH THE SURFACE
RIDGE...ANALYZED FROM 31N33W TO 27N38W GENERATING SCATTERED WEAK
SHOWERS WITHIN 130 NM ON EITHER SIDE OF ITS AXIS. OTHERWISE...
FAIR WEATHER CONDITIONS ELSEWHERE ACROSS THE CENTRAL AND ERN
ATLC. THE BENIGN WEATHER OVER THESE REGIONS IS FURTHER ENHANCED
BY SAHARAN DUST ALOFT EVIDENT ON THE METEOSAT-9 SAL TRACKING
PRODUCT.

FOR ADDITIONAL INFORMATION PLEASE VISIT
WWW.HURRICANES.GOV/MARINE

$$

GARCIA


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Afternoon, all, and thanks, Doc, for the interesting blog.
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Quoting HurricaneHunterJoe:
Tell me the truth! This is how you all would prefer 97L to look in a few days? No?

Not only no, but H%$& no!! Did that last year, didn't buy the t-shirt because the memories were enough.... and we only got strong TS winds here in the city...
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You can almost see a swirl and a center in the gulf from where Debby stirred it up...105 degrees here in Rock Island TN, wuz 107 yesterday..really warm .
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Quoting wunderkidcayman:

no no no no no you my friend is not slowing down the blog its just that I wanted the link to that radar cause I don't have it and that one I need so if you can please post the link so I can get it thanks sooo much

OK, my bad
Link
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Quoting LargoFl:
gee just look at those straightline winds,just like what hit the midlantic states last night
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Quoting TropicalAnalystwx13:
From Levi:

"Interesting how the ECMWF and every other major global model forecasted above-normal pressures in the SW Atlantic for June (top image), but were completely wrong, as pressures have been significantly lower than normal through the 29th (bottom image). As I mentioned during the winter, the models often lock into a set pattern during ENSO events that does not always pan out correctly. Here, the continuing negative PDO is likely helping the pattern stay a bit more favorable in the tropics despite the El Nino."

I do remember the models predicting well above average pressures and so far that has not come to pass.
Member Since: August 14, 2010 Posts: 10 Comments: 17095
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...........gee Brownsville is getting hammered,all those cells have red
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Quoting nigel20:

I'm sorry if i'm slowing down the blog...

no no no no no you my friend is not slowing down the blog its just that I wanted the link to that radar cause I don't have it and that one I need so if you can please post the link so I can get it thanks sooo much
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Quoting KEEPEROFTHEGATE:


here hydrus

Link
Thank you very much.
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From Levi:

"Interesting how the ECMWF and every other major global model forecasted above-normal pressures in the SW Atlantic for June (top image), but were completely wrong, as pressures have been significantly lower than normal through the 29th (bottom image). As I mentioned during the winter, the models often lock into a set pattern during ENSO events that does not always pan out correctly. Here, the continuing negative PDO is likely helping the pattern stay a bit more favorable in the tropics despite the El Nino."

Member Since: July 6, 2010 Posts: 113 Comments: 32286
Quoting wunderkidcayman:


hey can you post the link to that thanks

I'm sorry if i'm slowing down the blog
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Quoting wunderkidcayman:

no it is not but if you Taz wants to be blind from the truth then fine be blind hey you want me to help you the blind man cross the street huh



dont be a smarty pants
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.
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I not sure if you guys know the game cricket, but our regional team (West Indies) is playing against New Zealand in Florida.
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Quoting nigel20:


hey can you post the link to that thanks
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Quoting Tazmanian:



yes it is

no it is not but if you Taz wants to be blind from the truth then fine be blind hey you want me to help you the blind man cross the street huh
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Quoting wunderkidcayman:

taz its not dead yet



yes it is
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Quoting Tazmanian:
97L is RIP done its overe

taz its not dead yet
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97L is RIP done its overe
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Have reached 104 °F here. The dewpoint is 77 °F, making the heat index 117 °F.
Member Since: July 6, 2010 Posts: 113 Comments: 32286
Quoting Tropicsweatherpr:
That impulse that left West Africa has lost a lot of convection,although conserves a nice spin.


I guess that they will moisten the environment for the future Tropical waves...
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Hi, everyone. I stitched together about 13 hours of radar imagery from yesterday's derecho. Didn't get the formation in Illinois, but got it from Indiana to the Atlantic.

It's 6.5mb, so I'm just linking it instead of loading the image directly.

Link
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if 97L can rebuild it convection it would likely be noted in the TWO and I think between now and same time sunday we will see that increase in the convection
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116. flsky
Quoting MAweatherboy1:
Second M class of the day... A sign of impending doom...



Not familiar with this graph. Could you explain a bit?
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That impulse that left West Africa has lost a lot of convection,although conserves a nice spin.

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Quoting MAweatherboy1:
97L may have been deactivated... It's floater is gone and there hasn't been an 18z update.

They'll probably deactivate it at the 0Z Update.
Member Since: July 6, 2010 Posts: 113 Comments: 32286
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Quoting hydrus:
That is one of the best satellite loops I have ever seen..Link.?


here hydrus

Link
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Quoting hydrus:
If that low over Mexico and South Texas were over the gulf...One can still see where Debby stirred up the cold water.GOES Imager Cloud Top Pressure
June 30, 2012 - 18:45 UTCGOES Imager Spectral Difference
June 30, 2012 - 18:45 UTCimg src="http://weather.msfc.nasa.gov/sport/dynamic/go es_imager/20120630_1845_sport_goesimager_conus_spec_diff.g if">NSSL WRF 4 km grid initialized 00 UTC Jun 30 2012

36 h Total Precipitation (mm)

The SST's are looking pretty warm in the western GOM.
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Quoting KEEPEROFTHEGATE:
That is one of the best satellite loops I have ever seen..Link.?
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Quoting MAweatherboy1:
97L may have been deactivated... It's floater is gone and there hasn't been an 18z update.


no longer updating i guess

still there iam sure they got one eye on it

just not two
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Quoting MAweatherboy1:
97L may have been deactivated... It's floater is gone and there hasn't been an 18z update.

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
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Quoting KEEPEROFTHEGATE:
If that low over Mexico and South Texas were over the gulf...One can still see where Debby stirred up the cold water.GOES Imager Cloud Top Pressure
June 30, 2012 - 18:45 UTCGOES Imager Spectral Difference
June 30, 2012 - 18:45 UTCimg src="http://weather.msfc.nasa.gov/sport/dynamic/go es_imager/20120630_1845_sport_goesimager_conus_spec_diff.g if">NSSL WRF 4 km grid initialized 00 UTC Jun 30 2012

36 h Total Precipitation (mm)
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Quoting Dr. Jeff Masters:
The tropical wave approaching the Lesser Antilles (Invest 97L) has dissipated due to dry air, and is no longer a threat.
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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.