Hurricane season begins today; normal June activity expected

By: Dr. Jeff Masters , 1:38 PM GMT on June 01, 2009

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Hurricane season is upon us, and it's time to take a look at the prevailing conditions and 2-week forecast for tropical cyclone activity in the Atlantic. June is typically the quietest month of the Atlantic hurricane season. On average, we see only one named storm every two years in June. Only one major hurricane has made landfall in June--Category 4 Hurricane Audrey of 1957, which struck the Texas/Louisiana border area on June 27 of that year, killing 550. The highest number of named storms for the month is three, which occurred in 1936 and 1968. In the fourteen years since the current active hurricane period began in 1995, there have been eleven June named storms (if we include last year's Tropical Storm Arthur, which really formed on May 31). Five tropical storms have formed in the first half of June in that 14-year period, giving a historical 36% chance of a first-half-of-June named storm.


Figure 1. Tracks of all June tropical storms and hurricanes, 1851 - 2007.

Sea Surface Temperatures
Sea Surface Temperatures (SSTs) are close to average over the tropical Atlantic between Africa and Central America this year (Figure 2). These temperatures are some of the coolest we've seen since 1995, when the current active hurricane period began. This year's cool SSTs should prevent a repeat of the unforgettable Hurricane Season of 2005, which had the highest SSTs on record in the tropical Atlantic. Note also that SSTs along the Equatorial Pacific off the coast of South America are quite a bit above average, signaling the possible start of an El Niño episode. As I discussed in Friday's post, odds are increasing for a weak El Niño to form in time for hurricane season, and this should cut down on the number and intensity of Atlantic tropical storms and hurricanes this year. However, if an El Niño is developing, it shouldn't start affecting Atlantic hurricane activity until August.

Typically, June storms only form over the Gulf of Mexico, Western Caribbean, and Gulf Stream waters just offshore Florida, where water temperatures are warmest. SSTs are 26 - 28°C in these regions, which is about 0.5°C above average for this time of year. June storms typically form when a cold front moves off the U.S. coast and stalls out, with the old frontal boundary serving as a focal point for development of a tropical disturbance. African tropical waves, which serve as the instigators of about 85% of all major hurricanes, are usually too far south in June to trigger tropical storm formation. Every so often, a tropical wave coming off the coast of Africa moves far enough north to act as a seed for a June tropical storm. This was the case for Arthur of 2008 (which also had major help from the spinning remnants of the Eastern Pacific's Tropical Storm Alma). Another way to get Atlantic June storms is for a disturbed weather area in the Eastern Pacific Intertropical Convergence Zone (ITCZ) to push north into the Western Caribbean and spawn a storm there. This was the case for Tropical Storm Alberto of 2006 (which may have also had help from an African wave). SSTs are too cold in June to allow storms to develop between the coast of Africa and the Lesser Antilles Islands--there has only been once such development in the historical record--Ana of 1979, which coincidentally will be the name given to this year's first storm.


Figure 2. Sea Surface Temperature (SST) departure from average for June 1, 2009. SSTs were near average over the tropical Atlantic. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, signaling the possible start of an El Niño episode. Image credit: NOAA/NESDIS.

Tropical Cyclone Heat Potential
It's not just the SSTs that are important for hurricanes, it's also the total amount of heat in the ocean to a depth of about 150 meters. Hurricanes stir up water from down deep due to their high winds, so a shallow layer of warm water isn't as beneficial to a hurricane as a deep one. The Tropical Cyclone Heat Potential (TCHP, Figure 3) is a measure of this total heat content. A high TCHP over 80 is very beneficial to rapid intensification. As we can see, the heat energy available in the tropical Atlantic has declined considerably since 2005, when the highest SSTs ever measured in the tropical Atlantic occurred. TCHP this year is similar to last year's levels, which were high enough to support five major hurricanes.


Figure 3. Tropical Cyclone Heat Potential (TCHP) for May 31 2005 (top), May 31 of last year (middle) and May 30 2009 (bottom). TCHP is a measure of the total heat energy available in the ocean. Record high values of TCHP were observed in 2005. TCHP this year is much lower, and similar to last year. Image credit: NOAA/AOML.

Wind shear
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation. Wind shear below 12 knots is very conducive for tropical storm formation. High wind shear acts to tear a storm apart. The jet stream's band of strong high-altitude winds is the main source of wind shear in June over the Atlantic hurricane breeding grounds, since the jet is very active and located quite far south this time of year.

The jet stream over the past few weeks has been locked into a pattern where a southern branch (the subtropical jet stream) brings high wind shear over the Caribbean, and a northern branch (the polar jet stream) brings high wind shear offshore of New England. This leaves a "hole" of low shear between the two branches off the coast of North Carolina, which is where Tropical Depression One formed. The low shear "hole" has dipped down into the northern Gulf of Mexico a few times. Disturbance 90L, which almost developed into a tropical storm before it came ashore in Mississippi/Alabama on May 23, took advantage of one of these low-shear areas.

The jet stream is forecast to maintain this two-branch pattern over the coming ten days. This means that the waters offshore of the Carolinas are the most likely place for a tropical storm to form during this period, though the northern Gulf of Mexico will at times have shear low enough to allow tropical storm formation. The latest 16-day forecast by the GFS model (Figure 4) predicts that the subtropical jet will weaken and retreat northwards by the middle of June, creating low-shear conditions over the Caribbean. This is a typical occurrence for mid-June, and we need to start watching the Western Caribbean for tropical storm formation by the middle of the month.


Figure 4. Wind shear forecast from the 00Z GMT June 1, 2009 run of the GFS model for June 1 (left panel) and June 17 (right panel). Currently, the polar jet stream is bringing high wind shear to the waters offshore New England, and the subtropical jet is bringing high wind shear to the Caribbean. This leaves the waters off the coast of North Carolina under low shear, making this area the most favored region for tropical storm formation over the next 7 - 10 days. By June 17, the subtropical jet is expected to weaken and move northwards, leaving the Caribbean under low shear, and favoring that region for tropical storm formation. Wind speeds are given in m/s; multiply by two to get a rough conversion to knots. Thus, the red regions of low shear range from 0 - 16 knots.

Dry air and African dust
It's too early to concern ourselves with dry air and dust coming off the coast of Africa, since these dust outbreaks don't make it all the way to the June tropical cyclone breeding grounds in the Western Caribbean and the Gulf of Mexico. Developing storms do have to contend with dry air from Canada moving off the U.S. coast; this was a key reason why 2007's Subtropical Storm Andrea never became a tropical storm. Dr. Amato Evan of the University of Wisconsin will issue his dust forecast for the coming hurricane season later this week, and I'll be discussing his forecast in an upcoming post.

Steering currents
The steering current pattern over the past few weeks has been typical for June, with an active jet stream bringing many troughs of low pressure off the East Coast of the U.S. These troughs are frequent enough and strong enough to recurve any tropical storms or hurricanes that might penetrate north of the Caribbean Sea. Steering current patterns are predictable only about 3-5 days in the future, although we can make very general forecasts about the pattern as much as two weeks in advance. At present, it appears that the coming two weeks will maintain the typical June pattern, bringing many troughs of low pressure off the East Coast capable of recurving any June storms that might form. There is no telling what might happen during the peak months of August, September, and October--we might be in for a repeat of the favorable 2006 steering current pattern that recurved every storm out to sea--or the unfavorable 2008 pattern, that steered Ike and Gustav into the Gulf of Mexico.

Summary
Recent history suggests a 36% chance of a named storm occurring in the first half of June. The current conditions in the atmosphere and ocean are near average, so expect about a 1/3 chance of a named storm between now and June 15. The computer models are currently not forecasting development of any tropical storms over the next seven days.

I'll have an update Tuesday afternoon, when I'll discuss the Colorado State University June Atlantic Hurricane season forecast by Dr. Phil Klotzbach and Dr. Bill Gray, which will be issued Tuesday morning.

My next analysis and 2-week outlook for hurricane season is scheduled for June 13.

Jeff Masters

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Quoting jeffs713:
06.02.2009 1402 UTC
SEVERE TROLL WATCH
THE WEATHERUNDERGROUND BLOG WATCH SERVICE IS NOW ISSUING A SEVERE TROLL WATCH FOR THE WEATHERUNDERGROUND BLOG SYSTEM. DUE TO A LACK OF NOTABLE TROPICAL SYSTEMS AND ENTIRELY TOO MUCH FREE TIME, THERE MAY BE ISOLATED TO SCATTERED REPORTS OF TROLLING ON THE BLOGS. PLEASE BE AWARE, AND WHEN IN DOUBT, REMEMBER...

DONT FEED THE TROLLS!

FORECASTER JEFFS713

Heh, I have friends on YouTube who issue EAS Troll warnings. no trolls on this blog, happy. :D
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Quoting MarineMeteorologist:
92L is Extratropical with no chance of conversion. It is supported by an upper level 500mb cold-core low.




Most subtropical cyclones are. Andrea was embedded within a large 500-300 mb trough which contributed to her quasi-stationary motion. It is one of the factors that make then not fully tropical. Organize convection and winds near the center, is what makes them subtropical. The hybrid between the 2 are classified as subtropical cyclones.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
psst..

New Blog Entry
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Quoting CatastrophicDL:
Weather456, can you answer my question in post 853? Thanks!


The trough is expected to drift northwestward, over the next 24 hrs and even though a low pressure could form along the trough, development still seems unlikely over the next 28-72 hrs.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CatastrophicDL:
Any chance we could have subtropical storm Ana about 00Z? I have June 3rd as the first named storm for Ossqss's contest :o)


I don't think so! I have June 6. I have my fingers crossed that something will form, but I'm just not seeing it happen. There's always next year.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Any chance we could have subtropical storm Ana about 00Z? I have June 3rd as the first named storm for Ossqss's contest :o)
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888. IKE
Quoting Cotillion:


If it goes any further north, the lens/image frame will have snow around the edge... ;)


LOL!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
92L is Extratropical with no chance of conversion. It is supported by an upper level 500mb cold-core low.


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886. IKE
Quoting Weather456:
Disorganize showers continue over the Southern Gulf associated with a surface trough interacting with an upper ridge advancing north.



There's my relief from the heat advancing toward the north-central and NE GOM coasts.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Weather456, can you answer my question in post 853? Thanks!
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Beantech - re your link to the WX analysis. Outstanding report of likely weather impact. I note also the comments by commercial airline pilots who comment favorably on it as well. Thanks.
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Quoting CatastrophicDL:

CaneW read Bean's link in 858. Really good information!


Thanks for pointing that out. I missed it the first time around.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting IKE:
MEMO TO SSD: Please adjust the floater on 92L. It's about to go too far north to see it.

Thanks.


If it goes any further north, the lens/image frame will have snow around the edge... ;)
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Disorganize showers continue over the Southern Gulf associated with a surface trough interacting with an upper ridge advancing north.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CaneWarning:
Does anybody know if the storm may have contained hail when the plane was flying through it?

CaneW read Bean's link in 858. Really good information!
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879. IKE
I've got 90 degrees outside my window right now...inland Florida panhandle. It's hot!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Member Since: July 24, 2005 Posts: 407 Comments: 19076
877. IKE
MEMO TO SSD: Please adjust the floater on 92L. It's about to go too far north to see it.

Thanks.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting SomeRandomTexan:
Wow The blog is creeping along!

Who think CSU and Dr. Gray are right? or wrong?


Depends by what you mean as correct or incorrect.

It won't be exact, they've not yet managed that. Even if they did, it's likely to be on luck.

However, only once or twice they've been totally out of the ballpark (05-06), so they're likely to be around that area. Yes, a little on the low side... 12-13 seems a bit more predictable unless El Nino really ramps up. No real indication of that happening.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting 858 BeanTech:
I found this to be a very detailed analysis of the weather at the time of the AF 447 incident:

AF 447 Weather Analysis


Very comprehensive...
Thanks
CRS
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Quoting Kahlest:

Yes apparently there was large amounts of hail along with strong shifting winds within the storm cell and yes the plane flew through the top of the anvil of the storm


My question is this - I just flew from Seattle to Tampa a couple of weeks ago. We went about an hour out of our way to avoid thunderstorms. Why could this flight not do the same? My understanding is that fuel wasn't an issue as cross-Atlantic flights have more than enough fuel for emergency situations such as this.

My best guess is that a series of factors could've caused this plane to go down including hail and strong winds. More than likely something breached the exterior of the plane or maybe hail damaged the engines. I sure hope they find the wreckage and black boxes.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
92L remnains somewhat organize whether or not its over sub-20 waters. I think there's a EURO reccon?

Member Since: July 24, 2005 Posts: 407 Comments: 19076
it is funny because they are held as the great Know-all of hurricane season and receive so much media coverage and yet their track record is below average.
Member Since: August 30, 2007 Posts: 0 Comments: 1837
Quoting Weather456:
CSU June 2, 2009

11 storms
5 hurricanes
2 major



I think that's too Low,
I'm thinking around 13-15 NS this year.
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870. N3EG
What's up with this 92L? It's at 42N, over 60 degree water, and they're making a big thing about it? Now if was in the Pacific...yeah, I know, I say this every year. At least our storms are featured on Deadliest Catch...
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CSU June 2, 2009

11 storms
5 hurricanes
2 major

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CaneWarning:
Does anybody know if the storm may have contained hail when the plane was flying through it?

Yes apparently there was large amounts of hail along with strong shifting winds within the storm cell and yes the plane flew through the top of the anvil of the storm
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Does anybody know if the storm may have contained hail when the plane was flying through it?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Seastep:


Extremely unlikely that it was lightning. Planes are designed to handle it fine. Was actually on a flight where lightning hit a wing... went shooting out the other wing.

They're designed for it.

Turbulence? Completely separate issue.

To me, with the loss of cabin pressure at 35K feet indicates a fuselage breach for whatever reason.

In short, don't argue the lightning point. :)


Yeah all I said about the lightening was that it WAS possible for it to have been struck but unlikely as to be the cause of the crash, turbulance and windshear on the other hand those can rip a plane apart.
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Quoting SomeRandomTexan:
Wow The blog is creeping along!

Who think CSU and Dr. Gray are right? or wrong?


I don't think they are that far off. They don't have a great record though. What does Accuweather say? I'll be interested in Dr. Masters update this afternoon.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
The sole Americans on that flight were from Lafayette, La.

http://www.nola.com/news/index.ssf/2009/06/former_lafayette_residents_wer.html
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Quoting Kahlest:
Link
There is the link, This troll seems to think it is an "insult to his intelligence" to claim that lightening or "a little" turbulance had anything to do with the crash, so I said that it must mean he doesn't have a lot of intelligence to begin with


Extremely unlikely that it was lightning. Planes are designed to handle it fine. Was actually on a flight where lightning hit a wing... went shooting out the other wing.

They're designed for it.

Turbulence? Completely separate issue.

To me, with the loss of cabin pressure at 35K feet indicates a fuselage breach for whatever reason.

In short, don't argue the lightning point. :)
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Quoting BeanTech:
I found this to be a very detailed analysis of the weather at the time of the AF 447 incident:

AF 447 Weather Analysis

It would be interesting to hear Dr. Masters' take on the situation...


yeah I would like to see Dr. Master's take on this too. would be very interesting
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Wow The blog is creeping along!

Who think CSU and Dr. Gray are right? or wrong?
Member Since: August 30, 2007 Posts: 0 Comments: 1837
Quoting Kahlest:
Link
There is the link, This troll seems to think it is an "insult to his intelligence" to claim that lightening or "a little" turbulance had anything to do with the crash, so I said that it must mean he doesn't have a lot of intelligence to begin with


Thank You...
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Quoting SevereHurricane:


CBC?
Can I have a link.
Link
There is the link, This troll seems to think it is an "insult to his intelligence" to claim that lightening or "a little" turbulance had anything to do with the crash, so I said that it must mean he doesn't have a lot of intelligence to begin with
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Quoting Kahlest:


Thanks, trying to educate a troll on the CBC website lol (I know a lost cause)


Your Welcome!
CBC?
Can I have a link.
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Quoting SevereHurricane:


The area it went to was notorious for severe turbulence.


Thanks, trying to educate a troll on the CBC website lol (I know a lost cause)
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Quoting Weather456:


...Now they found the remains of the air craft we can get an idea of the clouds, lightening, wind shear and other elements.



Graphics showing flight path & wx etc.:

New York Times:

http://graphics8.nytimes.com/images/2009/06/02/world/0602-for-subAF447.jpg

National Post:

http://www.nationalpost.com/np/1654794.bin

The Brazilian air force released this map locating the debris its search aircraft spotted on Tuesday morning, the red concentric circles mark the two locations 650 km off the South American country's northern coast that could be part of an Air France plane that went missing on Sunday night.

The wreckage, which has not been confirmed to be parts from Air France flight 447, includes metallic objects and plane seats, an air force spokesman said in a televised statement. The Brazilian military reports the wreckage spotted also includes small white pieces, a drum, vestiges of oil and kerosene.

http://network.nationalpost.com/np/blogs/posted/archive/2009/06/02/graphic-brasil-air-force-discove rs-debris-near-air-france-flight-path.aspx


I tried posting these as images...
but blog STRETCHING would occur

CRS
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NexSat GOM Sector,LOOP
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So is it looking like a low could form in the BOC at the tail end of the trough that is there right now?
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-- EMC Cyclogenesis Tracking Page --

Model Cycle: 2009060212


12Z NAM


06z NAM
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Have a great one TS,just bustn your "you no whats",just like you do to me.....we are still friends though,right???,lol....looks like its going to be a rainy week here in SWFL...
Member Since: October 5, 2007 Posts: 20 Comments: 4970
Quoting TampaSpin:


Yep that is you my Friend.......LOL


LOL...
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Quoting TheCaneWhisperer:


One thing to note

Anonymously cold Florida winters are usually followed by a rather tranquil hurricane season. I also noticed the year after that, watch out.


It was cold in Florida this winter.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Kahlest:
OK Question for you guys. Does anyone happen to know what the wind shear was over the area where the Air France flight went down? and with the altitude it was flying at is it realistic to suspect lightening to have struck the plan?


The area it went to was notorious for severe turbulence.
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Also - been in a small plane and hit by lightning. Scared the heck out of us and knocked out our radios but didn't damage the airplane itself. Know of lots of stories similiar to mine. In a lifetime of flying there's lots of need for clean underwear.
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Quoting Kahlest:
OK Question for you guys. Does anyone happen to know what the wind shear was over the area where the Air France flight went down? and with the altitude it was flying at is it realistic to suspect lightening to have struck the plan?


I want to look into the wx details of the flight. Now they found the remains of the air craft we can get an idea of the clouds, lightening, wind shear and other elements.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting WPBHurricane05:


If that turns out to be true, the blog will kills itself.


One thing to note

Anonymously cold Florida winters are usually followed by a rather tranquil hurricane season. I also noticed the year after that, watch out.
Re WX being a factor in the Air France crash. Hubby and I have been light plane pilots since the early 70's. Once had the sad duty of scattering the ashes of one of our flying friends and their children because their plane was literally torn completely apart in a thunderstorm. Of course there's a difference between a jetliner in size and structural strength, but I've flown in clear air near the edge of a cell and the plane (a Cessna 182) been slapped by it like a giant hand and wound up tumbling away from it - Definitely a wake up about not getting near Tstorm tops. The violence inside a supercell is such that airline pilots use their radar to fly around them. Don't know what happened in this case but very sad.
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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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