July hurricane outlook

By: Dr. Jeff Masters , 7:26 PM GMT on July 02, 2009

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Atlantic tropical cyclone activity typically picks up a bit during the first half of July. Since the current active hurricane period began in 1995, seven of 14 years (50%) have had a named storm form during the first half of July. The busiest first half of July occurred in 2005, when three hurricanes formed. These included Hurricane Dennis and Hurricane Emily--the strongest hurricanes ever observed so early in the season. As seen in Figure 1, most of the early July activity occurs in the Gulf of Mexico, Western Caribbean, and Carolina waters. However, a few long-track "Cape Verdes" hurricanes begin to occur. These are spawned by tropical waves that come off the coast of Africa. Tropical waves serve as the instigators of about 85% of all major hurricanes. Last year's Hurricane Bertha was one such rare early July Cape Verdes hurricane. Bertha's 120 mph winds made it the sixth strongest early-season Atlantic hurricane on record. Bertha also set the record for farthest east formation as a tropical storm, hurricane, and major hurricane, so early in the season.


Figure 1. Tracks of all tropical storms and hurricanes 1851 - 2006 that formed July 1-15. North Carolina and the Gulf of Mexico coast from the Florida Panhandle to Texas are the preferred strike locations. Oddly, the Florida Peninsula has been struck by only two storms that formed in the first half of July.

Sea Surface Temperatures
Sea Surface Temperatures (SST) anomalies have warmed slightly over the past two weeks, but are close to average over the tropical Atlantic between Africa and Central America (Figure 2). These are the are the coolest SST anomalies we've seen since 1994. The strength of the Azores-Bermuda high has been near average over the past two weeks, driving near-average trade winds. Stronger-than-average trade winds were observed through most of the period November 2008 - May 2009, which helped cool the tropical Atlantic substantially. Strong winds mix up colder water from the depths and cause greater evaporative cooling. The latest 2-week run of the GFS model predicts continued average-strength trade winds through mid-July, so SSTs should remain near average during this period.

Typically, July tropical storms form over the Gulf of Mexico, Western Caribbean, and Gulf Stream waters just offshore Florida. SSTs are about 1.0°C above average for this time of year in the Gulf of Mexico, but near average elsewhere. July 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. There will be one or two fronts moving off the U.S. coast over the next two weeks, and we will need to watch these for development. Wind shear is too high and SSTs are usually too cold in July to allow African tropical waves to develop into tropical storms. African tropical waves serve as the instigators of about 85% of all major hurricanes,

Figure 2. Sea Surface Temperature (SST) departure from average for July 2, 2009. SSTs were near average over the tropical Atlantic's Main Development region for hurricanes, from Africa to Central America between 10° and 20° North Latitude. Note the large region of above average SSTs along the Equatorial Pacific off the coast of South America, the hallmark of a developing El Niño episode. Image credit: NOAA/NESDIS

El Niño
El Niño conditions continue to amplify over the tropical Eastern Pacific. Ocean temperatures there rose 0.5°C over the past two weeks, and are now 0.45°C above the threshold for El Niño, according to the Australian Bureau of Meteorology (Figure 3). NOAA's Climate Prediction Center issued an El Niño Watch in early June, saying "that conditions are favorable for a transition from neutral to El Niño conditions during June - August 2009". The pattern of changes in surface winds, upper-level winds, sea surface temperatures, and deeper water heat content are all consistent with what has been observed during previous developing El Niños, and latest set of mid-June runs of the El Niño computer models are almost universally calling for El Niño conditions to become well-established for the peak months of hurricane season, August - October. It is likely that Atlantic hurricane activity will be suppressed in 2009 due to the strong upper-level winds and resulting wind shear an El Niño event usually brings to the tropical Atlantic.


Figure 3. Sea Surface Temperature (SST) departure from average for the the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region"). El Niño conditions exist when the SST in this region rises 0.5°C above average. As of June 28, 2009, SSTs in the Niño 3.4 region had risen to 0.95°C above average. To be considered an "El Niño episode", El Niño conditions must occur for five consecutive months, using 3-month averages. Image credit: Australian Bureau of Meteorology.

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 July 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 two months 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 often leaves a "hole" of low shear between the two branches off the coast of North Carolina, which is where Tropical Depression One formed at the end of May.

The jet stream is forecast (Figure 4) to maintain this two-branch pattern over the coming two weeks. This means that the waters offshore of the Carolinas are the most likely place for a tropical storm to form during this period.


Figure 4. Wind shear in m/s between 200 mb and 850 mb, as forecast by the 06Z July 02, 2009 run of the GFS model. The position and strength of the subtropical jet stream is forecast to change little over the next two weeks, and this jet will bring high wind shear to the Caribbean and Gulf of Mexico into mid-July. There will at times be a region of low shear between the polar jet (northern set of arrows on the plots) and the subtropical jet, allowing for possible tropical development off the coast of North Carolina. 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
June and July are the peak months for dust coming off the coast of Africa, and the Saharan dust storms have been quite active over the past month. Expect dust from Africa to be a major deterrent to any storms that try to form between Africa and the Lesser Antilles Islands in July.

Steering currents
The steering current pattern over the past few weeks has not changed much, and is typical for June and July. We have 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 July pattern, bringing many troughs of low pressure off the East Coast capable of recurving any July 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 50% chance of a named storm occurring in the first half of July. Given that none of the computer models are forecasting tropical storm formation in the coming seven days, and SST and wind shear patterns look pretty average, I'll go with a 20% chance of a named storm forming during the first half of July.

Vote for Mike Theiss as an Antarctica blogger
Extreme weather photographer Mike Theiss, who wrote our Ultimate Chase photography blog for two years until a new job took him to South America, wants your help. He's entering a Quark Expeditions competition to receive an expense-paid 2-week trip to Antarctica, where he will do some intensive photography and blogging. In order to go, he needs the votes to show that he's a popular blogger. So, if you liked his posts while he was blogging for wunderground, and want to see him blog for wunderground during this potential Antarctica voyage, go to http://www.blogyourwaytoantarctica.com/blogs/view /220 and cast a vote. It takes about 3 minutes navigate through the registration and voting process. Mike will be back chasing hurricanes this August, and has promised to post his excellent storm photos on wunderground should we help him secure the Antarctica gig.

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

Jeff Masters

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cycloone

yeah, I can't but think though, we will wake up one morning and be like wow - where did all theses stomes come from..... They will just forming out of the blue.
Member Since: July 2, 2009 Posts: 0 Comments: 2811
'Cause you're the storm that I've been needing
And all this peace has been deceiving
I like the sweet life
and the silence
But it's the storm that I believe in



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895. JRRP
Quoting homelesswanderer:


Kinda looks that way doesn't it.

yeah
just looks interesting i do not expect development
Member Since: August 16, 2007 Posts: 0 Comments: 5081
i'm bored with the tropics; somthing needs to form!

Maby if I go out over the ocean and blow that might help things a bit... LOL
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This area in the middle of nowhere is shaded yellow but the AOI in the Caribbean area is not shaded, WTF?
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Quoting JRRP:
rotation 11n 61w???
Link


Kinda looks that way doesn't it.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
890. JRRP
rotation 11n 61w???
Link
Member Since: August 16, 2007 Posts: 0 Comments: 5081

AOI

AOI

Member Since: October 1, 2007 Posts: 81 Comments: 26493
Quoting messageinabottle:

you might have quite a long boring night my friend...well, there are always the "smart" people who set them off anyway. my best hope is illegal viewing! hope its better for you at work


ya well im not looking forward to doing it... may skip out..lol!
Member Since: August 30, 2007 Posts: 0 Comments: 1837
HEATHER CASPI
Firehouse.com News
On July 5, 2002, 44-year-old volunteer firefighter Barry Dockter of the Anamoose, North Dakota Fire Department was killed while loading shells into mortars at a public fireworks display. Approximately 40 minutes into the show, he suddenly yelled and ran from the mortar, covered with sparks and trying to brush something from his clothing, the report says. Seconds later, a shell exploded, and he fell. He was transported to a local hospital where he was pronounced dead later that night.
_____________________________________________
NIOSH investigators concluded that to minimize the risk of similar incidents, fire departments should:

Ensure that safety caps protecting the fuse on fireworks shells are not removed until immediately before the shell is to be fired and are removed only by the shooter
Ensure that all fire fighters participating in public fireworks displays are fully trained in the proper performance of their assigned tasks and that they are educated with regard to safety hazards
Ensure that mortars are not reloaded/fired more than seven times during a performance to prevent mortar disintegration
Develop, implement and enforce standard operating guidelines (SOGs) for the operation of fireworks displays
________________________________________________
Among the local events this year:
Edgewater, FL:
The day will begin with
a 5K walk/run, co-sponsored by the Southeast Volusia YMCA, along South Riverside Drive. At 9:00 AM there will be a dedication ceremony at the recently upgraded George R. Kennedy Park. The park is named after Edgewater Fire Chief George Kennedy who perished on the 4th of July in 1986 while launching the annual fireworks display. There will be live entertainment, food, kids games and local vendors at Menard-May Park and George R. Kennedy Park beginning at 4:00 PM. The day will culminate with a spectacular fireworks show by Zambelli Fireworks that is guaranteed to be a crowd pleaser.
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ESL By LSU
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Quoting scott39:
Why is no tropical developement expected out of the wave at about 60w?


Shear.
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Quoting futuremet:
For those of you who want more access to the ECMWF--click here


Bookmarked!!! Thx very much... excellent ECMWF that I've been able to see so far.
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Quoting TexasHurricane:
"Scientists have known for some time that El Niño, the warm spell that turns up every four or five years in the waters of the eastern Pacific Ocean, reduces hurricane activity in the Atlantic. But in a new study, researchers at the Georgia Institute of Technology have linked a variant of that pattern — periodic warming in the central Pacific — to more frequent hurricanes in the Atlantic, particularly on the Gulf Coast and in the Caribbean"

Hmmmm, wonder if this would refer to this year....I guess all us SE Texans need to keep an eye on the Gulf this year. Well, all who live on the Texas Gulf....


Yes, very interesting. Something to watch, especially when a few have mentioned the chance of close forming storms...??
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For those of you who want more access to the ECMWF--click here
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting scott39:
Why is no tropical developement expected out of the wave at about 60w?


Long story short, too much wind shear. The sub-tropical jet is still screaming through the Caribbean and even as it weakens over the next week there will be upper lows and TUTTs dancing around everywhere. Also the trade winds from the east have picked up in speed substancially, and that greatly limits surface convergence. Tropical waves find it extremely hard to amplify in that kind of a situation. All that impressive-looking convection is mainly due to diffluence aloft.
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Why is no tropical developement expected out of the wave at about 60w?
Member Since: June 13, 2009 Posts: 0 Comments: 6706
Quoting SomeRandomTexan:


I gotta work the firework stand tonight...

you might have quite a long boring night my friend...well, there are always the "smart" people who set them off anyway. my best hope is illegal viewing! hope its better for you at work
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"Scientists have known for some time that El Niño, the warm spell that turns up every four or five years in the waters of the eastern Pacific Ocean, reduces hurricane activity in the Atlantic. But in a new study, researchers at the Georgia Institute of Technology have linked a variant of that pattern — periodic warming in the central Pacific — to more frequent hurricanes in the Atlantic, particularly on the Gulf Coast and in the Caribbean"

Hmmmm, wonder if this would refer to this year....I guess all us SE Texans need to keep an eye on the Gulf this year. Well, all who live on the Texas Gulf....
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting kmanislander:
Good afternoon

I came across this article on the Cayman News Service web site and thought you all might find it of interest in relation to the El Nino debate this year.

El Nino Variant


Good afternoon... indeed read it this AM was an interesting article... so basically having El Nino is not quite an inhibitor for HURR depending on it's "variation".
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Good afternoon

I came across this article on the Cayman News Service web site and thought you all might find it of interest in relation to the El Nino debate this year.

El Nino Variant
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Quoting messageinabottle:

I know HW, I too, live in Se Tx and no fireworks for us tomorrow!! grr


I gotta work the firework stand tonight...
Member Since: August 30, 2007 Posts: 0 Comments: 1837
Quoting homelesswanderer:
Burn Ban Is Killing Fireworks Sales

Burn bans are in effect all across the Golden Triangle.

And that about says it all for our holiday weekend. :(

Have a happy and safe 4th of July everyone.

I know HW, I too, live in Se Tx and no fireworks for us tomorrow!! grr
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This in my 2009 hurricane season prediction. POOF it's done August and September get a break this year, No hurricanes, 1 week tropical storm and 2 depressions. No significant ocean cooling and the 2010 season, 35 named storms.

If this does not happen, so what? I would rather read foolish (and lot of educated) post about weather than highly opinionated political things that are best said elsewhere.
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Quoting extreme236:


They used to not be named until they decided to start naming them in 2002. I believe there was one season a few decades ago where they had a separate list of names for subtropical storms, but that didn't last.


Then that season must have been 1972.. Because
that season had 2 A storms. It had subtropical storm alpha and hurricane agnes
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oh ok. Seems as it would rain there it would hinder the dust and therefore wouldn't drag alot with it off into the atlantic. But then, what do I know....
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Masters had a blog on the dust just a little while back. Dust is forecast to not be as plentiful this year as in other years.
Member Since: May 18, 2006 Posts: 10 Comments: 5561
Kind of random....but every time I see Billy Mays' infomercials it makes me sad
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Quoting TexasHurricane:
So, this dust or whatever coming off of Africa to hinder these storms from forming - Is it expected to weaken or stop over a period of time? If so about when? or is it going to stay that way this whole season?


It is SAL (Saharan Air Layer) Dust. Tropical waves drag bouts of dust off the coast. All of the outbreaks are different in terms of the amount of dust. It never stops coming off the coast, the outbreaks just vary.
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Burn Ban Is Killing Fireworks Sales

Burn bans are in effect all across the Golden Triangle.

And that about says it all for our holiday weekend. :(

Have a happy and safe 4th of July everyone.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
So, this dust or whatever coming off of Africa to hinder these storms from forming - Is it expected to weaken or stop over a period of time? If so about when? or is it going to stay that way this whole season?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
They called them neutercanes back in '72. Yep. Me and gramma used to watch the satellites on the evening news.
Member Since: May 18, 2006 Posts: 10 Comments: 5561
Quoting gordydunnot:
I hope the shear keeps up because i dont like the swirl at 12n 48w large area.


What swirl, I do not believe that is a swirl, I think it is just a tropical wave wo/ convection.
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Quoting HurricaneSwirl:
i was looking back and can anybody tell me why
they used to name subtropical storms differently?
i was looking at the 1972 season and I saw
"subtropical storm Alpha" "subtropical storm Charlie" "subtropical storm delta" while the
"real" names were used for the tropical storms.


They used to not be named until they decided to start naming them in 2002. I believe there was one season a few decades ago where they had a separate list of names for subtropical storms, but that didn't last.
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The nhc gives it a less than 30% chance. See the map at www.nhc.noaa.gov. In this case they identified it before the Navy did. Seems like there is too much shear though.
Member Since: May 18, 2006 Posts: 10 Comments: 5561
AOI in North Central Atlantic firing some convection as close to the center as it can. I wonder if they will ever declare it an invest (I say that because the NAVY has been so bored lately).



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lol bappit...it's the tropics anything is possible.
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I hope the shear keeps up because i dont like the swirl at 12n 48w large area.
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i was looking back and can anybody tell me why
they used to name subtropical storms differently?
i was looking at the 1972 season and I saw
"subtropical storm Alpha" "subtropical storm Charlie" "subtropical storm delta" while the
"real" names were used for the tropical storms.
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Its pre 2005. There was a tight Florida community on here holding on from 2004. It left with a surge in adolescent back biting late in the spring of 2005.

The blog I mean, not the latest a storm.
Member Since: May 18, 2006 Posts: 10 Comments: 5561
Quoting muddertracker:
The older I get the faster the years go by..I forget how long ago 1992 was. I guess you could say this blog started off with a bang. Does anyone know the latest A-Storm?


I think it was Anita. It formed on 8-29-77

Unless you count other systems in seasons back
then when there were no names. In 1914 the first storm was on 9/15, but since there were no names it wasn't really an "A" storm lol.
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The older I get the faster the years go by..I forget how long ago 1992 was. I guess you could say this blog started off with a bang. Does anyone know the latest A-Storm?
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Quoting muddertracker:
Was this blog around in 1992 when the first A storm didn't form until August 17th? I bet it was crazy in here...oh, by the way, that storm was Andrew...Be careful what you pine for...


No, I believe the blog started in 2005
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Was this blog around in 1992 when the first A storm didn't form until August 17th? I bet it was crazy in here...oh, by the way, that storm was Andrew...Be careful what you pine for...
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Quoting WPBHurricane05:
..

It doesn't matter.
Quoting CybrTeddy:
Just stay calm folks, yall will get your Ana. And most likely this month too.


And, like Weather456 said, the later it forms the stronger it will likely be.
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Feel the buoy, be the buoy.

Here's some info on atmospheric tides.

You can see the tidal changes on the graph of pressure for each buoy.
Member Since: May 18, 2006 Posts: 10 Comments: 5561
..
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Quoting Acemmett90:

winds and presure is falling even with the shear at a bouy aleast 200 miles away
Station 42060
NDBC
Location: 16.500N 63.5W
Conditions as of:
Fri, 3 Jul 2009 17:50:00 UTC
Winds: ENE (60) at 17.5 kt gusting to 21.4 kt
Significant Wave Height: 5.9 ft
Dominant Wave Period: 5 sec
Atmospheric Pressure: 30.02 in and falling
Air Temperature: 83.5 F
Dew Point: 75.7 F
Water Temperature: 83.7 F


Pressures fall diurnally in the tropics at this time of day. That pressure reading is very high.
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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.