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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Pat, how many keyboards have you gone through?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
I know of one Higher,but Im not saying..
Member Since: July 3, 2005 Posts: 421 Comments: 127679
Signed Up: 2006-05-29 10:38:21
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting StSimonsIslandGAGuy:
Signed Up: 2005-07-07 15:58:51


Pat beat you it looks like.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
439. IKE
Quoting Patrap:
Signed Up: 2005-07-03 16:37:50

Community Participation:

You have posted 180 entries in your own blog.

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View Your WunderBlog!
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1778 comments and 44 entries posted by all members in the last 24 hours.



60,000 posts...lol.

Member Since: June 9, 2005 Posts: 23 Comments: 37858
I had a Lot to say in,2006,..LOL

Plus,I can be long-winded
Member Since: July 3, 2005 Posts: 421 Comments: 127679
Quoting Patrap:
Signed Up: 2005-07-03 16:37:50

Community Participation:

You have posted 180 entries in your own blog.

You have posted 59184 comments in all blogs.

View Your WunderBlog!
Blog Statistics:

1778 comments and 44 entries posted by all members in the last 24 hours.



Pat you smeared everybody lol.
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Quoting Patrap:
Signed Up: 2005-07-03 16:37:50

Community Participation:

You have posted 180 entries in your own blog.

You have posted 59184 comments in all blogs.

View Your WunderBlog!
Blog Statistics:

1778 comments and 44 entries posted by all members in the last 24 hours.



Wow - amazing.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Signed Up: 2005-07-03 16:37:50

Community Participation:

You have posted 180 entries in your own blog.

You have posted 59184 comments in all blogs.

View Your WunderBlog!
Blog Statistics:

1778 comments and 44 entries posted by all members in the last 24 hours.

Member Since: July 3, 2005 Posts: 421 Comments: 127679
433. IKE
You have posted 18480 comments in all blogs.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Don't be jealous...

Signed Up: 2009-04-26 18:46:05
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Quoting CaneWarning:


Where do you find the join date? I lurked forever before joining. I've been here lurking since before Katrina but can't remember the exact date.


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Member Since: July 24, 2005 Posts: 407 Comments: 19076
430. IKE
Signed Up: 2005-06-09 19:14:12
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Apparently no one cares about it anymore, but here's a great place to watch the Azores low:

http://wind.met.fu-berlin.de/cgi-bin/meteosat.cgi?speed=16&count=48&intervall=30&refresh=10&playmod e=Endlos

Takes forever to load (few minutes on Broadband) but its worth it. I doubt it will get any stronger but it'll stay around for a few days. Fade into history like all the other unnamed subtropical storms...
Member Since: July 29, 2006 Posts: 28 Comments: 1777
I can't find my weather radio. I haven't had it out since Wilma was headed toward the Florida coast in 2005.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
424.

Just click on "settings" at the top of the page and it'll be on the right.

Signed Up: 2005-11-23 20:54:26"
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Quoting StSimonsIslandGAGuy:
It appears I have an earlier join date than anyone else so far :)


Yep

Signed Up: 2005-07-23 23:29:32
Member Since: July 24, 2005 Posts: 407 Comments: 19076
thanks, pat and ms nadia!

have a great evening!
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Quoting StSimonsIslandGAGuy:
It appears I have an earlier join date than anyone else so far :)


Where do you find the join date? I lurked forever before joining. I've been here lurking since before Katrina but can't remember the exact date.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting firegirl:
hi guys! mind if i break in for a quick question?

i'm looking for a good weather radio. after katrina, rita, gustav and ike, i think it's past time to buy one.

i've looked on the NHC, NWC, TWC, and other weather websites and don't really get a sense of what i should be looking for in terms of functionality and quality.

thanks in advance for your help!


NOAA weather Radio Entry
Member Since: July 3, 2005 Posts: 421 Comments: 127679
Join date:
November-3-2005
Didnt post until:
June-6-2006

You have posted 7 entries in your own blog.

You have posted 9112 comments in all blogs.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
412 firegirl
Radio Shack has a good one.
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Here's the seasons experiences

2003

I nice year, did not had too much trouble, tracked Claudette during the July mornings, Fabian in August, Isabel in September and Juan.

2004

Beginning to think the season was a dud until July 31 when news come of a tropical wave over the Sw Atlantic. Track Alex up the Eastern Sea board. Actually thought that was it for a while, until TD 2 in the Caribbean. Then Charley shortly after. Remember TS Bonnie paved the way for big brother Charley on Friday the 13. We had Danielle then Earl and we went from 0 named storms to 5 in 2 weeks. A pause, then Frances broke the silence. TS warnings issued for us as it pass north of us. Then cross the Bahamas and Floirda. Had a few others but none was like longlived TD 9 or Ivan. Then a tropical wave caused flooding in the islands, soon became Jeanne.

2005

I track every storm during 2005 and it was cool at first in June, July and parts of August, but by the time Katrina had landed, I wanted the season to end because I also feared for my neck of the woods. By Rita I was fed up, By Wilma exhausted, By Epsilon drained and scratching my head, by Zeta relief.

2006

Slow year with Alberto formation, actually reminded me of 2005. Ernesto was the most notable storm of the season.

2007

Missed Andrea, was amazed by Barry. Most notable storms Dean, Felix and Humberto.

2008

Worst of all the years for me. Most active cape verde season since 2004. Most notable storms Bertha (my favorite), Gustav, Ike, Omar and Paloma.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting ChillinInTheKeys:
Been lurkin' since RandrewL was Randrewl. Maybe 2003. Hardly ever post. Keep up the good work all.


Those were the days of 2005.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
Quoting Tazmanian:



???


go back to like post number 380 about the azores storm.. the next 30 post since mine were completely unrelated to it
Member Since: July 29, 2006 Posts: 28 Comments: 1777
Quoting ChrisDcane:


they should be hesitant or else we would 2005 or worse hurricane season every year they try to not stir up the people with a little low like this


Well that's not true because the NHC's job is to identify tropical systems and name them accordingly. If what you say is true then you're saying the NHC hasn't done its job and named everything that should be named. If they have named what deserves to be named consistently since their operation began, then there is no problem with actually naming something that should be named!

I wish politics like that wouldn't influence their decisions. The NHC's job isn't to keep people calm it's to inform them about what's out there. They can't base every decision they make on whether it will hype people up or not. People are smart enough to know that when they hear of a sub-tropical storm over by SPAIN then we don't have to worry.
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The most well informed piece
I have read on the Air France flight so far is:

So what happened to Air France Flight 447?


by Miles O'Brien, a pilot, airplane owner,
and freelance journalist who lives in Manhattan.
His blog is located here:
http://trueslant.com/milesobrien/

"...here is what we do know for sure.
Keep this in mind as you process
the often inaccurate reporting on aviation that is so prevalent..."

-----------------
CRS

[edit] ...looks like O'Brien's blog server is overwhelmed...
text of his report can be read at:
http://www.reuters.com/article/idUSTRE5505BF20090602?virtualBrandChannel=10531
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Been lurkin' since RandrewL was Randrewl. Maybe 2003. Hardly ever post. Keep up the good work all.
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hi guys! mind if i break in for a quick question?

i'm looking for a good weather radio. after katrina, rita, gustav and ike, i think it's past time to buy one.

i've looked on the NHC, NWC, TWC, and other weather websites and don't really get a sense of what i should be looking for in terms of functionality and quality.

thanks in advance for your help!
Member Since: Posts: Comments:
welll FL dos need the rain



send them more oh wait send them snow
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Quoting winter123:


Great, as soon as i post, the thread goes horribly off topic and i get ignored. T_T /wrist etc..



???
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if we have an active season, I am going back into hibernation. Not ready to watch south florida become underwater.
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i here it snowed in new york city this AM
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Quoting Tazmanian:
i join on this date


Signed Up: 2006-05-21 12:35:40


Great, as soon as i post, the thread goes horribly off topic and i get ignored. T_T /wrist etc..
Member Since: July 29, 2006 Posts: 28 Comments: 1777
2006 2007 2008 2009



i have been on here for 4 years now
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Quoting Levi32:




I do not understand why the NHC delays naming these things. Pretty soon it will fizzle and they'll say it never was an STS, but it is, and has been already for the 6-hour minimum the NHC likes to see before naming something. They're inconsistent in this area so I can't say for sure why it is or what they'll do next. All I can say is that by all definition, this invest is a sub-tropical storm.


they should be hesitant or else we would 2005 or worse hurricane season every year they try to not stir up the people with a little low like this
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Quoting CaneWarning:


I bet you will, especially if we have an active season.



yup am on my way
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i join on this date


Signed Up: 2006-05-21 12:35:40
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Quoting Tazmanian:



thanks i hop too have 35,000 commets made by NOV


I bet you will, especially if we have an active season.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting CaneWarning:


Impessive taz. Seeing all of you post your numbers make mine seem small!



thanks i hop too have 35,000 commets made by NOV
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Quoting Weather456:
Taz that is amazing

Found the site in December 2004 but joined July 2005, became a paid member later the next year. started my first blog on Alberto 2006.


Found also in 2004 but I was too young to be allowed by my parents to post so I had to read-only through 2005 (and I was so mad to miss 2005!! lol)

Joined in November 2005 and posted for the 2006 hurricane season.
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Quoting Weather456:
Taz that is amazing

Found the site in December 2004 but joined July 2005, became a paid member later the next year. started my first blog on Alberto 2006.



thanks for 456
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Quoting Tazmanian:
here is my



You have posted 5071 entries in your own blog.

You have posted 33747 comments in all blogs.


Impessive taz. Seeing all of you post your numbers make mine seem small!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting WPBHurricane05:


You win. I think you have the most post on this site.



thanks but i think pat has the most post with overe 40,000 commets he made and they where all in links so if any one wins it sould be pat i will come in 2nd
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Taz that is amazing

Found the site in December 2004 but joined July 2005, became a paid member later the next year. started my first blog on Alberto 2006.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CaneWarning:


Wow, so they actually gave it a small chance of being a sub-tropical depression in the next couple of days.


But what if it already WAS a STS?? Personally I say it's a polar low but the fact that it looks exactly like Vince... there was clear outflow, well defined COC and of course this:

http://img15.imageshack.us/img15/4040/invest92l2.jpg

and this!

http://img25.imageshack.us/img25/6944/4phase1.png

Proving that it had a symmetric warm core. I understand why NHC hesitated because this is new ground in tropics they are stepping on... for all we know storms like this have been occuring for hundreds of years but we just didn't have the proper satellite and analytic data.. I'm ranting now but i hope that post made sense to someone.
Member Since: July 29, 2006 Posts: 28 Comments: 1777
Quoting Tazmanian:
here is my



You have posted 5071 entries in your own blog.

You have posted 33747 comments in all blogs.


You win. I think you have the most post on this site.
Member Since: Posts: Comments:

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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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