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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I only blog and forecast the Atlantic.......does not mean i don't care what happens in the Pacific. I worry more about the Atlantic as that is what will effect me. I think that is ok....if i lived on the West Coast my interest would turn toward the Pacific im sure.
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Quoting Tazmanian:



i do care the pacific has land when hurricane pop up they do too hit land this like when they hit FL they it MX and CA way S CA that is so yes we do care and will and we have the right too talk about if we want too post maps like wind shear map and so on and so on so if you dont care and olny want too talk about the storm that hit the east coast then may weather under ground is not the site for you then
Punctuation my man, punctuation, please :)
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Quoting Chicklit:
Lacking humor and being completely serious has its good qualities. I am officially naming that area a threat. And no, I am not the NHC so follow your own methods of finding intelligence out there somewhere.


I send cuotos out to chicklit... she just stated what most people on this blog think.
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.
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
care about yourself first for you are the only one who sustains you.
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Quoting SomeRandomTexan:
I have never had Grouper but I hear the meat is excellent...
If you truly like snapper, as you mentioned, I would stay clear from Grouper. As grouper tend to be large and thick, the meat taste and texture are not all that desirable. A small strawberry grouper can be good but the bigger they get, the lesser they are. For the local white flesh fish, stick with mangrove, hog and queen snapper. Small mutton and lane can be good as TRUE red snapper. Stay away from big eye snapper (the "fake" red snapper you usually see) and yellowtail.
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Quoting beell:
From my blog (such as it is) this morning.
Thanks, Homelesswanderer.

44. beell 11:45 AM GMT on July 02, 2009
Next good chance of rain for SE TX may come on Tuesday/Wednesday of next week. An upper level shortwave dipping down over the gulf coast with a few ripples in the mid level NW flow down the front (east) side of the death ridge. It would help quite a bit if the weak front associated with this set up can get just a little farther south than modeled to take advantage of fair southerly flow at the low levels. At the very least, maybe the seabreeze will become a little more active.



Your Welcome. Good call this morning. :)
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Quoting SomeRandomTexan:


i know exactly what you are saying... so much of language hinges on body expressions and tone and pitch of voice to relay a message in the correct manner. Words can be taken many ways... A piece of advice don't try to use texting as a main way of communicating with a girl over long distances... she will read every message the wrong way..haha!


True.. True...
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Quoting Levi32:


LOL....well fortunately nobody has ever fallen for me yet, long-distance or otherwise! lol


one day my friend... one day
Member Since: August 30, 2007 Posts: 0 Comments: 1857
Quoting SomeRandomTexan:


i know exactly what you are saying... so much of language hinges on body expressions and tone and pitch of voice to relay a message in the correct manner. Words can be taken many ways... A piece of advice don't try to use texting as a main way of communicating with a girl over long distances... she will read every message the wrong way..haha!


LOL....well fortunately nobody has ever fallen for me yet, long-distance or otherwise! lol
Member Since: November 24, 2005 Posts: 635 Comments: 26695
Quoting Chicklit:
Lacking humor and being completely serious has its good qualities. I am officially naming that area a threat. And no, I am not the NHC so follow your own methods of finding intelligence out there somewhere.


yes ma'am it does have its good qualities but lacking compassion also has its bad qualities...

I must say i tend to watch the areas that will effect me the most but still care about other places on this planet i share
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Quoting Chicklit:
Lacking humor and being completely serious has its good qualities. I am officially naming that area a threat. And no, I am not the NHC so follow your own methods of finding intelligence out there somewhere.



your jumping the gune
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
Quoting Chicklit:

Aussie Storm we don't care about the pacific or the azores. We only want to hear about the east coast of florida, the caribbean, the gulf of mexico, north and south carolina and possibly newfoundland. oh yeah, and the beautiful bahamas, haiti and its neighboring islands. hello. portugal seems quite far away!



i do care the pacific has land when hurricane pop up they do too hit land this like when they hit FL they it MX and CA way S CA that is so yes we do care and will and we have the right too talk about if we want too post maps like wind shear map and so on and so on so if you dont care and olny want too talk about the storm that hit the east coast then may weather under ground is not the site for you then
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
Quoting Levi32:


Well with it being text an' all it would help it people used exclamation marks or smileys or "lol"s or something...otherwise it looks completely serious.


i know exactly what you are saying... so much of language hinges on body expressions and tone and pitch of voice to relay a message in the correct manner. Words can be taken many ways... A piece of advice don't try to use texting as a main way of communicating with a girl over long distances... she will read every message the wrong way..haha!
Member Since: August 30, 2007 Posts: 0 Comments: 1857
Lacking humor and being completely serious has its good qualities. I am officially naming that area a threat. And no, I am not the NHC so follow your own methods of finding intelligence out there somewhere.
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i no guys whats all this go too bed the blog the mode runs well all be here in the AM and so will you so whats all hit the hey and i see you in the AM




or do you look forword on being ban overe the 3 day weekend


no fighting evere one play nic

now evere one most go too bed
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480. beell
From my blog (such as it is) this morning.
Thanks, Homelesswanderer.

44. beell 11:45 AM GMT on July 02, 2009
Next good chance of rain for SE TX may come on Tuesday/Wednesday of next week. An upper level shortwave dipping down over the gulf coast with a few ripples in the mid level NW flow down the front (east) side of the death ridge. It would help quite a bit if the weak front associated with this set up can get just a little farther south than modeled to take advantage of fair southerly flow at the low levels. At the very least, maybe the seabreeze will become a little more active.

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471. in reference to what???
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Quoting SomeRandomTexan:


ok I thought i was leaving but Levi my friend I think she was being sarcastic...


Well with it being text an' all it would help it people used exclamation marks or smileys or "lol"s or something...otherwise it looks completely serious, which I guess it was.
Member Since: November 24, 2005 Posts: 635 Comments: 26695
I think that system at about 40 has some potential and we need to keep an eye on it.
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Don't worry... For me the having people act the opposite of normal extends beyond the blog today.

Really I'm just looking to see if that non-tropical low tries to get its act together... It's really our only Atlantic area at the moment.
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Quoting Levi32:


Um ok.....everyone is acting opposite of normal tonight or something??

Since when do we ignore the rest of the world being threatened by hurricanes!? Geez.


ok I thought i was leaving but Levi my friend I think she was being sarcastic...
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Quoting Chicklit:

Hello Very Good Boy. I amended my statement to include as many areas in the Atlantic Basin and Gulf of Mexico as possible with my limited geographical skills due to being educated in the American Public School System, 1958-1971.


Um ok.....everyone is acting opposite of normal tonight or something??

Since when do we ignore the rest of the world being threatened by hurricanes!? Geez.
Member Since: November 24, 2005 Posts: 635 Comments: 26695
Guess you could consider me one of the Blog Fish...
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Quoting Levi32:


I hope you're not serious...

Hello Very Good Boy. I amended my statement to include as many areas in the Atlantic Basin and Gulf of Mexico as possible with my limited geographical skills due to being educated in the American Public School System, 1958-1971.
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1042 PM CDT THU JUL 2 2009


FOR MONDAY THROUGH WEDNESDAY...AS THE UPPER RIDGE WEAKENS...A MID
AND UPPER LEVEL SHORTWAVE TROUGH WILL DROP SOUTH INTO THE GULF COAST
STATES. THE NWRLY FLOW ALOFT WILL HELP TO PUSH A SFC FRONT INTO
CNTRL LA AND EAST TX. THE COMBINATION OF FEATURES WILL PROVIDE THE
AREA WITH OUR NEXT CHANCE FOR RAIN. SHOWER AND THUNDERSTORM
CHANCES WILL INCREASE ON MONDAY...CONTINUING THROUGH THURSDAY AS
THE FRONTAL BOUNDARY STALLS OVER THE AREA
. THE INCREASE IN CLOUDS
AND SHOWER ACTIVITY WILL ALSO HELP TO MODERATE TEMPERATURES CLOSER
TO SEASONAL NORMS.

... Hmmmm? Imagine that
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it's hard to beat a good yellowfin tuna steak though... lightly seared on both sides... makes me wanna crank up the grill right now!

I'm off for now... keep it real guys/gals
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Quoting SomeRandomTexan:
I have never had Grouper but I hear the meat is excellent...


WoW ! Love blackened Grouper sandwich....i wonder if PETA will be after me now......LOL
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463. top shelf! LOL
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Quoting Chicklit:

Aussie Storm we don't care about the pacific or the azores. We only want to hear about the east coast of florida.


I hope you're not serious...
Member Since: November 24, 2005 Posts: 635 Comments: 26695
I have never had Grouper but I hear the meat is excellent...
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Quoting AussieStorm:

Wind Shear in EPAC

Shear Tendency

850mb Vorticity


Aussie Storm we don't care about the pacific or the azores. We only want to hear about the east coast of florida, the caribbean, the gulf of mexico, north and south carolina and possibly newfoundland. oh yeah, and the beautiful bahamas, haiti and its neighboring islands. hello. portugal seems quite far away!
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459. never been to the gardens, but hope to some day. snapper rocks! i can't wait to get a grouper! :)
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460. beell
Member Since: September 11, 2007 Posts: 145 Comments: 16918
HAHA! so u do the real fishing... lot of my friends go out to the gardens and go scuba diving.. i can't dive but love the rewards of all the snapper!
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Glad to see the blog stressing, that means I don't have to stress over my boat and its weather.
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Quoting singlehander:
So nice map of everything in the Atlantic, can we assume there there was nothing happening in the Pacific? Or did the weather not reach the west coast of Mexico?

Wind Shear in EPAC

Shear Tendency

850mb Vorticity

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454. i gotta be honest with ya, bud. we DO fish the bay, but not often. we usually run 30-40 miles out or more in the GoM to go fishing. given the right boat ramp, SURE we can go in the bay :)
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Quoting pearlandaggie:
450. Goodnite, Atmo. Let me know if you want to go fishing!
Do yall fish the bay?
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453. beell
Member Since: September 11, 2007 Posts: 145 Comments: 16918
Quoting atmoaggie:
G'Nite, all.

2-year-old not up to putting himself to sleep tonight, apparently.


gotta love when that happens..lol
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450. Goodnite, Atmo. Let me know if you want to go fishing!
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G'Nite, all.

2-year-old not up to putting himself to sleep tonight, apparently.
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Quoting pearlandaggie:
440. i haven't heard from my buddy in a LONG time. in fact, it would be difficult for me to remember his last name. the funny thing is, he graduated from the College of Less Conservative Arts (as he called it) with a degree in Journalism, I believe, before they eliminated that college, I believe.


LMAO at the College of Less Conservative Arts..hahaha!
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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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