Severe thunderstorms erupt along a swath 1,500 miles long, killing 2

By: Dr. Jeff Masters , 2:48 PM GMT on July 27, 2012

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A huge outbreak of severe thunderstorms hit the nation on Thursday, causing damage in fifteen states and knocking out power to over 250,000 customers. Two people were killed, one by a falling tree in Pennsylvania, and one due to a lightning strike in New York. Two possible tornadoes touched down: one in Elmira, New York and another in Brookville, PA. The severe storms covered an unusually large area, erupting along a 1,500-mile long swath of the country from Texas to Connecticut. The intensity of the thunderstorms was increased by a very hot and moist airmass; temperatures in the mid to upper 90s were common across the region Thursday. A number of record highs for the date were set, including a 98° reading at Washington D.C.'s Dulles Airport. The threat of severe weather continues for Friday afternoon over portions of the Ohio Valley and mid-Atlantic, as NOAA's Storm Prediction Center has placed these regions in their "Slight Risk" area for severe thunderstorms.


Figure 1. A rare sight: at 7 pm EDT on July 26, 2012, severe thunderstorm warnings were in effect for 132 counties in 15 states along a swath 1,500 miles long.


Figure 2. Visible satellite image taken at 7:02 pm EDT July 26, 2012, of the line of severe thunderstorms that extended from Texas to Connecticut. Image credit: NASA/GSFC.


Figure 3. An imposing sight: A squall line of severe thunderstorms with two bowing segments takes aim at New York, Connecticut, and New Jersey on July 26, 2012. The tip of a bow echo typically has the most violent winds in a severe thunderstorm.

Was Thursday's outbreak a derecho?
Thursday's outbreak of severe thunderstorms was not nearly as violent as the June 29 - 30 Mid-Atlantic and Midwest derecho, since the atmosphere wasn't as unstable. The June 29 storm was one of the most destructive and deadly severe thunderstorm complexes in North American history. It killed 22 people, knocked out power to at least 3.7 million customers, and did hundreds of millions in damage. There were 871 reports of damaging winds logged by the next day, and 36 of the thunderstorms had wind gusts in excess of hurricane force--74 mph. In contrast, yesterday's event had only two thunderstorms with wind gusts in excess of 74 mph, and 383 reports of damaging winds. We can probably classify yesterday's severe thunderstorm event as a weak derecho, since it met the main criteria, as defined by NOAA's Storm Prediction Center: "A derecho is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. Although a derecho can produce destruction similar to that of tornadoes, the damage typically is directed in one direction along a relatively straight swath. As a result, the term "straight-line wind damage" sometimes is used to describe derecho damage. By definition, if the wind damage swath extends more than 240 miles (about 400 kilometers) and includes wind gusts of at least 58 mph (93 km/h) or greater along most of its length, then the event may be classified as a derecho."


Figure 4. NOAA's Storm Prediction Center logged 374 reports of damaging winds from Thursday's severe thunderstorms. Two of these thunderstorms had winds in excess of hurricane force (65 knots, or 74 mph.)


Figure 5. The climatology of derecho events over the U.S. Image credit: NOAA Storm Prediction Center.

Quiet in the Atlantic
There are no tropical cyclone threat areas to discuss in the Atlantic. A strong tropical wave is expected to bring heavy rains to the Lesser Antilles Islands and Puerto Rico on Monday and Tuesday, but none of the models are developing the wave. The NOGAPS computer model is suggesting development of a second tropical wave between Africa and the Lesser Antilles Islands August 2 - 3.

Have a great Olympic weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters

Intense (jerseyshoretoo)
We had high winds and heavy rain, but fortunately not serious damage. Prayers for everyone in the path of this massive storm.
Intense
Crazy Lightning in Rhode Island (ExitPupilCreative)
Lightning from storms that slammed the Northeast today. This is at Charlestown Beach in Charlestown, Rhode Island.
Crazy Lightning in Rhode Island
BeforeTheStorm (CalicoBass)
at times there were gust of wind that would stir up the dirt as you can see to the right in this photo. We finally got a real good rain that lasted a while. Was under one Severe Thunderstorm Warning.
BeforeTheStorm
Swirling clouds (Crisred)
As the strom approaches the clouds are rolling over themselves and swirling into each other. Rapidly!
Swirling clouds
Shelf Cloud over the Bronx (JimTheWunder)
Taken just before thunderstorm.
Shelf Cloud over the Bronx

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Pretty view of Storms headed toward Charleston.
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Quoting BahaHurican:
Anybody else see the sun-streak in this post 2706? Pretty cool...



Yup. It's pretty cool.
Member Since: July 21, 2011 Posts: 83 Comments: 7167
2829. LargoFl
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
345 PM EDT SUN JUL 29 2012

SCC015-029-035-292000-
/O.CON.KCHS.SV.W.0186.000000T0000Z-120729T2000Z/
DORCHESTER SC-BERKELEY SC-COLLETON SC-
345 PM EDT SUN JUL 29 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR NORTHEASTERN COLLETON...WEST CENTRAL BERKELEY AND CENTRAL
DORCHESTER COUNTIES...

AT 345 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS ALONG A LINE EXTENDING FROM
HARLEYVILLE TO HIOTTS...MOVING EAST AT 20 MPH.

PREPARE NOW FOR THE FOLLOWING HAZARDS...
DAMAGING WINDS IN EXCESS OF 60 MPH...

SOME LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...CANADYS...
COTTAGEVILLE...DORCHESTER...GIVHANS...GIVHANS FERRY STATE PARK...
HARLEYVILLE...INDIAN FIELD...JEDBURG...RIDGEVILLE...ROUND O...SAINT
GEORGE AND SLANDS BRIDGE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FREQUENT LIGHTNING IS OCCURRING WITH THIS THUNDERSTORM. MOVE INDOORS
IMMEDIATELY. IF THERE IS NO SAFE SHELTER AVAILABLE...STAY AWAY FROM
ISOLATED HIGH OBJECTS AND BODIES OF WATER. IF YOU CAN HEAR THUNDER...
YOU ARE WITHIN STRIKING DISTANCE.

TO REPORT SEVERE WEATHER SUCH AS HAIL...DOWNED TREES...LIMBS...AND
POWER LINES...PLEASE CONTACT THE CHARLESTON NATIONAL WEATHER SERVICE
TOLL FREE AT 1-888-383-2024 OR EMAIL YOUR REPORTS TO
CHS.SKYWARN@NOAA.GOV.

&&

LAT...LON 3328 8048 3326 8043 3327 8039 3327 8037
3328 8035 3327 8030 3329 8027 3328 8017
3285 8028 3286 8040 3302 8071 3333 8052
3333 8049
TIME...MOT...LOC 1945Z 280DEG 17KT 3321 8044 3300 8050

$$
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tracks for this system I think will follow like:

Charley 04
AUG 9th-15th



Earl 04
AUG 13th-16th



Ivan 04
SEPT 2nd-24th



Dennis 05
05-13 JUL



Emily 05
11-21 JUL



Ernesto 05
24 AUG-01 SEP



Dean 07
13-23 AUG



Felix 07
31 AUG-05 SEP



END OF PART 1
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Little one just reminded me I owe her a burger at Five-Guys.......... See Yall Tomorrow....... :)
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Quoting Gearsts:
Anybody else see the sun-streak in this post 2706? Pretty cool...

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Member Since: July 21, 2011 Posts: 83 Comments: 7167
2822. nigel20
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2821. LargoFl
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2820. ncstorm
Quoting ENSO2012:


That is not the latest one.


today is the 29th and the CMC has two runs..00z and 12z..read the intialized date..
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Member Since: June 20, 2012 Posts: 0 Comments: 2169
2818. LargoFl
ULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHARLESTON SC
337 PM EDT SUN JUL 29 2012

THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTHERN CHATHAM COUNTY IN SOUTHEAST GEORGIA...
EASTERN EFFINGHAM COUNTY IN SOUTHEAST GEORGIA...
SOUTHWESTERN BEAUFORT COUNTY IN SOUTHEAST SOUTH CAROLINA...
SOUTHERN JASPER COUNTY IN SOUTHEAST SOUTH CAROLINA...

* UNTIL 430 PM EDT

* AT 337 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
SEVERE THUNDERSTORMS...ALONG A LINE EXTENDING FROM EBENEZER TO
BELLINGER HILL AREA...MOVING SOUTHEAST AT 15 MPH.

PREPARE NOW FOR THE FOLLOWING HAZARDS...
DAMAGING WINDS IN EXCESS OF 60 MPH...

* SOME LOCATIONS IN THE WARNING INCLUDE...
EBENEZER...STILLWELL...PURYSBURGH...HARDEEVILLE... SAVANNAH HISTORIC
DISTRICT...TILLMAN...BELLINGER HILL AREA...PRITCHARDVILLE...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE SHELTER AS THUNDERSTORMS APPROACH.

REPORT HAIL...DOWNED TREES...LIMBS...AND POWER LINES DIRECTLY TO THE
CHARLESTON NATIONAL WEATHER SERVICE AT 1-888-383-2024...WHEN IT IS
SAFE TO DO SO.



LAT...LON 3256 8133 3255 8129 3258 8124 3216 8073
3210 8083 3211 8084 3204 8091 3207 8137
3219 8141
TIME...MOT...LOC 1937Z 304DEG 14KT 3244 8121 3221 8106
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2817. hydrus
Quoting stormpetrol:


Nice vorticity with the wave near 15N/57W
That one has had a good twist for a week..I am watching it for gulf development.
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2816. ncstorm
this is the JMA at hour 144

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2815. hydrus
This is hard to see, but CMC in 144 hours has a low in the gulf, and what appears to be a tropical storm or hurricane north of Puerto Rico. There is a frontal system that may focus some energy over the S.E. from the gulf low. This will be interesting.
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Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting ENSO2012:
My apologies, y'all. I just cannot stand know-it-alls.

No back to Ernesto.



we dont have Ernesto
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Quoting Caribbeanforecaster:


If develops rapidly a)
if not b)
Agree with you I think the Gfs will be the winner with the track.
Member Since: October 15, 2011 Posts: 0 Comments: 4467
Quoting washingtonian115:
Sorry y'all.
Welcome to the "sorry" club Wash........ The story of my life
Member Since: October 3, 2008 Posts: 0 Comments: 6000


Nice vorticity with the wave near 15N/57W
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Quoting TropicalAnalystwx13:

Well....it's Monday somewhere. Do you poll on Monday's?
It is Monday in China.
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Then again it is hard to go against the GFS after it pinned down Debby.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Good Afternoon. Bone dry out there in the Atlantic. I don't think these two waves stand a chance; if any tries to spin up, dry air entrainment will choke them off. Just my opinion. I am still looking towards mid-August at this rate.
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2802. ncstorm
txhurr..here are the frames

156 hours..nothing


168 hours..you see the storm coming into the frame at a much higher altitude


180 hours


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Quoting TropicalAnalystwx13:

Well....it's Monday somewhere. Do you poll on Monday's?



yes
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Quoting Tazmanian:
i dont poll on sundays

Well....it's Monday somewhere. Do you poll on Monday's?
Member Since: July 6, 2010 Posts: 113 Comments: 32807
Quoting spathy:


Yes it is.
And its the same month we dig up our sweet potatos.
spathy. Were you in the same spelling class as Dan Quayle? Sorry, It jumped out in front of me
Member Since: October 3, 2008 Posts: 0 Comments: 6000
i dont poll on sundays
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Quoting stormchaser19:
where you think will go ernesto if develops?
a) CMC
b) GFS

A cmc
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2795. hydrus
Quoting Caribbeanforecaster:


If develops rapidly a)
if not b)
My thoughts exactly.
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2793. ncstorm
Quoting washingtonian115:
If you were engaged you wouldn't be on a blog TROLLING rather than focusing on your life a head real sad.


let it go Wash..thats what they want for you to get upset..put him on ignore..
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2790. hydrus
Quoting AussieStorm:
It seems like the United Kingdom has been getting whacked for a very long time.
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Quoting washingtonian115:
And your nothing but a sick little man that wishes for death and destruction just so your sorry excus for a being self can be happy.Gotta HATE how you keep coming back ban after ban after ban and causing disruptions on the blog.Now GTFO and go find a girlfriend somewhere to keep you busy.
Ignore him washi you are loosing your time.We all know in here you are a respectable blogger , and to tell you the truth you are one of the bloggers opinion I respect the most and like the most.
Member Since: October 15, 2011 Posts: 0 Comments: 4467
Sorry y'all.
Member Since: August 14, 2010 Posts: 10 Comments: 17801
Quoting stormchaser19:
where you think will go ernesto if develops?
a) CMC
b) GFS


A. CMC.
Member Since: July 21, 2011 Posts: 83 Comments: 7167
A.
Quoting stormchaser19:
where you think will go ernesto if develops?
a) CMC
b) GFS
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2785. ncstorm
The GFS still dosent have a handle on the potential storm because it dropped it and just picked it back up..
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Quoting stormchaser19:
where you think will go ernesto if develops?
a) CMC
b) GFS


If develops rapidly a)
if not b)
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If you were engaged you wouldn't be on a blog TROLLING rather than focusing on your life a head real sad.
Member Since: August 14, 2010 Posts: 10 Comments: 17801

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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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