Dr. Jeff Masters' WunderBlog

Severe thunderstorms erupt along a swath 1,500 miles long, killing 2
Posted by: Dr. Jeff Masters, 2:48 PM GMT on July 27, 2012 +45
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
Categories: Severe Weather
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2651. wxchaser97 6:37 PM GMT on July 29, 2012    
Quoting hydrus:
Strong enough to indicate there are some significant changes coming to our part of the world, and not just the tropics. The pattern will probably return to its current state, but not until the MJO makes a pass, and a couple of tropical systems form. I will bet that we have our second hurricane out of the Central Atlantic wave, and a little action in the gulf in 4 or 5 days. I should mention that a deep trough for August will be a factor in all of this.
Thanks, the season is not over but only beginning in a way. Should be an interesting few weeks. Hopefully no US landfall and I also think a hurricane is possible from one of the waves.
Member Since: March 16, 2012 Posts: 87 Comments: 6773
2652. spathy 6:37 PM GMT on July 29, 2012    
Quoting charlottefl:


What more than likely happened with Wilma as well as a certain extent with Charley is the flow was from SW to NE, the storm was also moving in the same direction. That combined with the fact that the storm started moving in that flow out ahead of that front, as opposed to actually sitting there until the front got on top of it all acted to limit the amount of damage the shear was able to do. With all of those factors in place it allowed a window for strengthening. I will say this I know when Wilma made landfall in SWFL it's surface circulation was tilted quite a bit from the mid and upper levels, so the shear did have some impact on the storm. Just not enough to keep it from intensifying.


Thanks Charlotte.
I knew something like that was in play.
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2653. java162 6:38 PM GMT on July 29, 2012    
Quoting GTcooliebai:
We could have something develop as early as in 2 days, and I'm guessing either in the next TWO or the 2am TWO the NHC will mention the wave off the coast of Africa for possible development:



what model is this? i can see two storms
Member Since: July 24, 2009 Posts: 0 Comments: 265
2655. HurricaneDean07 6:38 PM GMT on July 29, 2012    
All the 12z Models, except the Canadian, are concluding to a path near 13N all the way to the islands... And a rebuilding LARGE and STRONG to the west, that would push the system through the caribbean, and up into the Gulf.
Member Since: October 3, 2010 Posts: 39 Comments: 4035
2657. GTcooliebai 6:39 PM GMT on July 29, 2012    
Quoting java162:


what model is this? i can see two storms
That would be the European (ECMWF) model.
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2658. gulfbreeze 6:40 PM GMT on July 29, 2012    
test
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2659. spathy 6:41 PM GMT on July 29, 2012    
Quoting gulfbreeze:
test


I see ya Gulf :O)
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2660. TropicalAnalystwx13 6:41 PM GMT on July 29, 2012    
Quoting HurricaneDean07:
All the 12z Models, except the Canadian, are concluding to a path near 13N all the way to the islands... And a rebuilding LARGE and STRONG to the west, that would push the system through the caribbean, and up into the Gulf.

I doubt it will stay that low. The CMC may get something right for once.
Member Since: July 6, 2010 Posts: 89 Comments: 25213
2661. MAweatherboy1 6:41 PM GMT on July 29, 2012    
I think the wave should at least be declared an invest; since several models develop it it would be nice to have the SHIPS, GFDL, and HWRF run on it.
Member Since: February 11, 2012 Posts: 66 Comments: 6342
2662. wxchaser97 6:42 PM GMT on July 29, 2012    
Wind shear still moderate to high in parts of the Caribbean.
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2663. Tazmanian 6:42 PM GMT on July 29, 2012    
cant wait for monday
Member Since: May 21, 2006 Posts: 5088 Comments: 111323
2664. HurricaneDean07 6:42 PM GMT on July 29, 2012    
Quoting java162:


what model is this? i can see two storms

Two LOWs, yes. European...
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2665. Civicane49 6:42 PM GMT on July 29, 2012    
Member Since: July 21, 2011 Posts: 60 Comments: 3827
2666. Skyepony (Mod) 6:42 PM GMT on July 29, 2012    
Quoting TropicalAnalystwx13:

Storm...I think, lol.


I wouldn't doubt it. I think I tried atleast twice to explain how to read the earth in graph to him.

There is the Maritime Continent (4&5)..all the little islands across South Asia.
Member Since: August 10, 2005 Posts: 144 Comments: 29266
2667. HurricaneDean07 6:43 PM GMT on July 29, 2012    
Quoting TropicalAnalystwx13:

I doubt it will stay that low. The CMC may get something right for once.

Im just going off of what the models were saying... I didn't input my thoughts. I think the CMC's resolution is a definate possibility.
Member Since: October 3, 2010 Posts: 39 Comments: 4035
2668. HurricaneDean07 6:45 PM GMT on July 29, 2012    
Quoting wxchaser97:
Wind shear still moderate to high in parts of the Caribbean.

Nothing will develop in SW caribbean anytime soon.
As long as it stays north of 15N in the Caribbean, A storm could have a shot to survive the caribbean.
Member Since: October 3, 2010 Posts: 39 Comments: 4035
2669. Tazmanian 6:45 PM GMT on July 29, 2012    
two things am looking forword too on monday


Current Operational SST Anomaly Charts update and Weekly ENSO Update
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2670. Civicane49 6:45 PM GMT on July 29, 2012    
Member Since: July 21, 2011 Posts: 60 Comments: 3827
2671. HurricaneDean07 6:46 PM GMT on July 29, 2012    
Quoting MAweatherboy1:
I think the wave should at least be declared an invest; since several models develop it it would be nice to have the SHIPS, GFDL, and HWRF run on it.

The NHC should mention it...next TWO probably.
I think they'll give it a 20% chance.
If they don't mention... well. Youre gonna have some pissed off people on the blog tomorrow xD
Member Since: October 3, 2010 Posts: 39 Comments: 4035
2672. SLU 6:47 PM GMT on July 29, 2012    
A LOW PRES IS CURRENTLY EMBEDDED IN
ITCZ NEAR 10N30W. CONSENSUS GUIDANCE HANGS ON TO THIS FEATURE
WITH THE GFS THE MOST AGGRESSIVE. ADJUSTED THE WINDS AND
ASSOCIATED SEAS DOWN TO MAX AT 25 KT NE SEMICIRCLE ON THE
EXTENDED GRIDS. LOW CONFIDENCE COORDINATED MEDIUM RANGE 12Z
POSITIONS ARE 10.5N43W WED... 10.548.5W THU...11.5N54W
FRI...12.5N60W SAT...AND 13N65.5W SUN.
Member Since: July 13, 2006 Posts: 11 Comments: 2846
2673. HurricaneDean07 6:47 PM GMT on July 29, 2012    
Be back later.
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2674. hydrus 6:48 PM GMT on July 29, 2012    
Quoting spathy:

Again....
Spathy clicks heels.
There is no storm for my home/repeats....

If we have made it 7 years cant we get through another 7 years?// Huh ... Please?
Give me all the Nadoless tropical storms you want (those are the best) but no monsters please!
Dont you mean nadless?...:)
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2675. hydrus 6:50 PM GMT on July 29, 2012    
Quoting ilovehurricanes13:
look at no big deep trough of the east coast in a few weeks
Just wait...It will be there.
Member Since: September 27, 2007 Posts: 1 Comments: 14248
2676. RussianWinter 6:51 PM GMT on July 29, 2012    
Quoting hydrus:
Dont you mean nadless?...:)


I thought he meant tornado-less... I could be wrong though.
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2677. Tazmanian 6:52 PM GMT on July 29, 2012    
looks like where going too make july with out a name storm
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2678. spathy 6:53 PM GMT on July 29, 2012    
If the wind shear in the MDR of the E and C Carib remains strong for the remainder of the season would that tend lessen the shear in the W Carib,GOM and the SE US?
Or is there no correlation?
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2679. hydrus 6:53 PM GMT on July 29, 2012    
The UK-Met in three days..Looks quite interesting to me.
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2680. hydrus 6:54 PM GMT on July 29, 2012    
3.5 day NAM..
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2681. spathy 6:55 PM GMT on July 29, 2012    
Quoting hydrus:
Dont you mean nadless?...:)

Sure
An emasculated storm is fine by me!
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2682. hydrus 6:56 PM GMT on July 29, 2012    
Quoting RussianWinter:


I thought he meant tornado-less... I could be wrong though.
Lol..I believe you are correct. I thought he meant a storm without, well ..ya know.....oh boy
Member Since: September 27, 2007 Posts: 1 Comments: 14248
2683. hydrus 6:56 PM GMT on July 29, 2012    
Quoting spathy:

Sure
An emasculated storm is fine by me!
And there is me post..:)
Member Since: September 27, 2007 Posts: 1 Comments: 14248
2685. spathy 6:58 PM GMT on July 29, 2012    
Quoting hydrus:
Dont you mean nadless?...:)


My Science teacher told me a funny story about a running-back whose nickname was Nad.
The punchline was how the cheerleaders cheered him on.
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2687. GTcooliebai 6:59 PM GMT on July 29, 2012    
Quoting hydrus:
The UK-Met in three days..Looks quite interesting to me.
These waves will likely play follow the leader, where one goes the other will follow.
Member Since: August 31, 2009 Posts: 0 Comments: 5168
2688. spathy 6:59 PM GMT on July 29, 2012    
Quoting hydrus:
Lol..I believe you are correct. I thought he meant a storm without, well ..ya know.....oh boy


I did mead Tornado less.
But I think its the same thing in my mind! LOL
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2689. Tazmanian 6:59 PM GMT on July 29, 2012    
not evere year is going too be like the last year you guys sould no this buy now


this is now going too be like 2010/2011 no way



will be luckey if we even hit 10 name storms
Member Since: May 21, 2006 Posts: 5088 Comments: 111323
2690. Tazmanian 7:00 PM GMT on July 29, 2012    
Quoting ENSO2012:
Where's the damn blogger from Mass? Child, post the rest of Euro, I DETEST being left in suspense.




watch what you say
Member Since: May 21, 2006 Posts: 5088 Comments: 111323
2691. wunderkidcayman 7:00 PM GMT on July 29, 2012    
hey Guys I feel a Caribbean storm soon to come what do you say
Member Since: June 13, 2009 Posts: 2 Comments: 5385
2692. GTcooliebai 7:01 PM GMT on July 29, 2012    
Quoting Tazmanian:
not evere year is going too be like the last year you guys sould no this buy now


this is now going too be like 2010/2011 no way



will be luckey if we even hit 10 name storms
The number of storms don't really matter, it is where they hit that matter, always remember it takes one to make it a bad season.
Member Since: August 31, 2009 Posts: 0 Comments: 5168
2693. Tazmanian 7:01 PM GMT on July 29, 2012    
Quoting wunderkidcayman:
hey Guys I feel a Caribbean storm soon to come what do you say



unless wind shear gos down vary un likey at this time
Member Since: May 21, 2006 Posts: 5088 Comments: 111323
2694. spathy 7:01 PM GMT on July 29, 2012    
Quoting Tazmanian:
not evere year is going too be like the last year you guys sould no this buy now


this is now going too be like 2010/2011 no way



will be luckey if we even hit 10 name storms


From your keyboard to Ma Natures ears.
But it only takes one!
Thats what we in harms way must always remember.
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2695. ncstorm 7:01 PM GMT on July 29, 2012    
well well..I guess the "non reliable Nogaps"
was just seeing things..

those crappy models really dont know much though huh?
12z CMC-180 hours



this will be an east coast storm..
Member Since: August 19, 2006 Posts: 7 Comments: 8363
2696. TropicalAnalystwx13 7:01 PM GMT on July 29, 2012    
Quoting ENSO2012:
Where's the damn blogger from Mass? Child, post the rest of Euro, I DETEST being left in suspense.

I laughed harder than I should have at this post.
Member Since: July 6, 2010 Posts: 89 Comments: 25213
2697. Tazmanian 7:01 PM GMT on July 29, 2012    
Quoting GTcooliebai:
The number of storms don't really matter, it is where they hit that matter, always remember it takes one to make it a bad season.



so ture
Member Since: May 21, 2006 Posts: 5088 Comments: 111323
2698. GTcooliebai 7:02 PM GMT on July 29, 2012    
Quoting wunderkidcayman:
hey Guys I feel a Caribbean storm soon to come what do you say
I'm going with just north of the Caribbean, like what the CMC is showing.
Member Since: August 31, 2009 Posts: 0 Comments: 5168
2699. TropicalAnalystwx13 7:02 PM GMT on July 29, 2012    
Quoting wunderkidcayman:
hey Guys I feel a Caribbean storm soon to come what do you say

Not anytime soon.
Member Since: July 6, 2010 Posts: 89 Comments: 25213
2700. spathy 7:03 PM GMT on July 29, 2012    
Quoting GTcooliebai:
The number of storms don't really matter, it is where they hit that matter, always remember it takes one to make it a bad season.


I hate being slow at typing.
Member Since: June 8, 2008 Posts: 65 Comments: 10474
2701. Tazmanian 7:03 PM GMT on July 29, 2012    
Quoting TropicalAnalystwx13:

Not anytime soon.



same here
Member Since: May 21, 2006 Posts: 5088 Comments: 111323

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About JeffMasters
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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