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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Quoting IKE:


Who came up with the name Easy? As in Hurricane Easy in 1950?



And the names How and Dog. LOL
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646. IKE
Quoting nrtiwlnvragn:


LOL Opposed to a year like 1950 would really drive up WU page counts.... 11 huricanes, 8 of them major.


Who came up with the name Easy? As in Hurricane Easy in 1950?

Member Since: June 9, 2005 Posts: 23 Comments: 37858
bye yall...got to do my dang chores before it gets too hot
Member Since: April 26, 2006 Posts: 5 Comments: 3076
Quoting K8eCane:



wonder if this is an analog year to 1907 or 1914 but let me be clear..i realize the absense of activity right now means nothing


Indeed... as 456 stated before... (e.g. 2004 I love to use this year as examples... hehe) it started late and look with what we ended up.
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Quoting IKE:


Imagine the arguments that would cause on here....

Imagine what the NHC would be doing....throwing darts at a dart board, video games, playing poker...that would make for a boring job. Happily boring, but boring nonetheless.


LOL Opposed to a year like 1950 would really drive up WU page counts.... 11 huricanes, 8 of them major.
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Quoting IKE:


Imagine the arguments that would cause on here....

Imagine what the NHC would be doing....throwing darts at a dart board, video games, playing poker...that would make for a boring job. Happily boring, but boring nonetheless.



wonder if this is an analog year to 1907 or 1914 but let me be clear..i realize the absense of activity right now means nothing
Member Since: April 26, 2006 Posts: 5 Comments: 3076
Quoting IKE:


Imagine the arguments that would cause on here....

Imagine what the NHC would be doing....throwing darts at a dart board, video games, playing poker...that would make for a boring job. Happily boring, but boring nonetheless.


lol... quite true.
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640. IKE
Quoting WxLogic:
Interesting... that 1914 HURR Season definitely sucked. ;)


Imagine the arguments that would cause on here....

Imagine what the NHC would be doing....throwing darts at a dart board, video games, playing poker...that would make for a boring job. Happily boring, but boring nonetheless.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Interesting... that 1914 HURR Season definitely sucked. ;)
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ya i know

everyone suffering from tropical withdrawals

lol
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Good morning...
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Quoting KEEPEROFTHEGATE:
good morn orca


Morning KOG, not a lot out there to see...
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635. IKE
There it is...the entire season.....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
634. IKE
I remember back in the 1970's and I lived at south Walton county, Florida panhandle...on the beach during summer months, we rarely ever had a tropical system.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
well iam off to work see ya at noon when i take lunch
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting K8eCane:



back to the weather...has there ever been a year when NO tropical cyclones formed in the atlantic, or i guess my question is...when no hurricanes formed?


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These some of the best supercell photographs that I have never seen before, and they are the best never taken in Spain to me.

Mesocyclones were identified by Doppler in both structures. As I remember, one of them was an anticyclonic supercell.

Enjoy: http://www.cazatormentas.net/foro/reportajes-meteorolgicos/dos-supercelulas-posible-acoplamiento/msg 354763/#msg354763
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good morn orca
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Blog Update
Reflector site for those at work, which now also includes Weather456, daily updates


AOI

AOI
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Quoting K8eCane:



back to the weather...has there ever been a year when NO tropical cyclones formed in the atlantic, or i guess my question is...when no hurricanes formed?
1914 the year of no storms or none reported anyway
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting K8eCane:



back to the weather...has there ever been a year when NO tropical cyclones formed in the atlantic, or i guess my question is...when no hurricanes formed?

No.
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Quoting K8eCane:


ok but i dont know how to do that

Above the box where you enter comments, click, the link next to 'Weather Chat:'.
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back to the weather...has there ever been a year when NO tropical cyclones formed in the atlantic, or i guess my question is...when no hurricanes formed?
Member Since: April 26, 2006 Posts: 5 Comments: 3076
624. IKE
As Dr. Masters has said before, the real season begins August 1st.

Things will pick up and there will be more arguing on here. Best to just roll with the flow and move on. Don't get suckered in. Or use the ignore feature.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
What is this?? People getting slammed for inncorect punctuation and spelling? On a weather blog??
I admire Taz for his weather knowledge. If I wanted a Literary blog, I would go to one. You should do that, Pearlandaggie.
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622. IKE
Quoting KEEPEROFTHEGATE:
ct just stay out of it don't get suck in iam sure once admin reports in for work this am things will get taken care of quickly its sad that it has come to this really but iam sure before the end of this day there will be some that can no longer post here for a bit


For the most part, it's the same people.

If I was admin, I'd give someone 3 strikes and you're out...for good.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
ct just stay out of it don't get suck in iam sure once admin reports in for work this am things will get taken care of quickly its sad that it has come to this really but iam sure before the end of this day there will be some that can no longer post here for a bit
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Anyone that makes fun of Taz should get a swift kick to the ignore list. Taz is awesome, don't mess with him.
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well i see that there will be some empty space create today
a just reward for a just display

no fate but that
which we make for ourselves

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Quoting cg2916:
K8ECane, why don't we go on chat?


ok but i dont know how to do that
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K8ECane, why don't we go on chat?
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Quoting K8eCane:


well you have Ocean Isle just to the north of Sunset and then Holden just to the north of Ocean Isle...Holden is between Ocean Isle and Long Beach (or Oak Island)...there has been talk of replacing that little bridge for years but the residents of Sunset kicked up a fuss about it
Well I'm pretty sure the residents would be happier being a little more crowded then drowned from the bridge falling or stuck on the island. The state said "Look. Here's the money for a new bridge. We're gonna do it whether you like it or not." As a vacationer there, I'm happy with that new bridge.
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Quoting K8eCane:


well you have Ocean Isle just to the north of Sunset and then Holden just to the north of Ocean Isle...Holden is between Ocean Isle and Long Beach (or Oak Island)...there has been talk of replacing that little bridge for years but the residents of Sunset kicked up a fuss about it



Sunset is just a few miles form North Myrtle...maybe 10 miles?
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Quoting cg2916:

That rickety old swing-out? Yep. It's still there, but they're currently in the process of building a new bridge. It should be done early-mid 2010. I live in Greenville, SC, so I know cities like Greenville, Spartanburg, Anderson, and I'm not sure where Holden is. I only know Sunset, Ocean Isle, Wilmington, and Calabash in that area.


well you have Ocean Isle just to the north of Sunset and then Holden just to the north of Ocean Isle...Holden is between Ocean Isle and Long Beach (or Oak Island)...there has been talk of replacing that little bridge for years but the residents of Sunset kicked up a fuss about it
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Quoting K8eCane:


Yep
i know exactly where it is...i actually grew up at Holden Beach....have lived in wilmington the past 30 years...do they still have the little floating bridge there at Sunset?

That rickety old swing-out? Yep. It's still there, but they're currently in the process of building a new bridge. It should be done early-mid 2010. I live in Greenville, SC, so I know cities like Greenville, Spartanburg, Anderson, and I'm not sure where Holden is. I only know Sunset, Ocean Isle, Wilmington, and Calabash in that area.
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Quoting cg2916:

Wow... 65 in Greenville, SC, and if you live in WIlmington, NC, you probably know where Sunset Beach is, that's my vacation beach.


Yep
i know exactly where it is...i actually grew up at Holden Beach....have lived in wilmington the past 30 years...do they still have the little floating bridge there at Sunset?
Member Since: April 26, 2006 Posts: 5 Comments: 3076
Maxwell House Light? Who's watching their caffine intake?
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610. IKE
Long-term from Tallahassee,FL...

LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)...
EXTENDED BEGINS WITH A FAMILIAR PATTERN...TROUGH IN THE EAST AND
RIDGING IN THE WEST WITH A QUASI STATIONARY FRONT ON OUR DOORSTEP.
THE EXTENDED REMAINS SOMEWHAT DISTURBED AS A SERIES OF SHORT WAVES
MOVE OVER THE QUASI STATIONARY FRONT AT LEAST THROUGH WEDNESDAY. FOR
THE REMAINDER OF THE PERIOD...MOISTURE WILL CONTINUE TO FEED
AFTERNOON CONVECTION WITH A FAVORABLE UPPER AIR PATTERN AS THE
RIDGE IN THE WEST BUILDS BACK INTO THE SOUTHERN PLAINS PRODUCING A
TROUGH IN THE LOWER MISSISSIPPI VALLEY SEPARATING THE EAST-WEST
ATLANTIC RIDGE TO THE SOUTHEAST OF OUR AREA. HGTS WILL BE ON THE
RISE AGAIN ACROSS THE EASTERN HALF OF THE NATION DURING THE PERIOD.
SO...POPS WILL BE AT NORMAL VALUES FOR EARLY JULY. TEMPS WILL BE
VERY CLOSE TO NORMAL OR SLIGHTLY BELOW NORMAL...ESPECIALLY THE MAX
TEMPS. THIS WILL BE A WELCOMED CHANGE.
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Quoting IKE:


Good morning. Good coffee. Maxwell House light....


With a purple umbrella and a 50 cent hat....

Finally got some rain yesterday on the beach...
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608. IKE
Quoting K8eCane:
PEARLANDAGGIE

I have been on this blog since 2005 and i have seen a lot of folks rag Taz...I also know that i can be cantankerous as all get out...but I have never seen anyone be deliberately CRUEL as you were last nite...its one thing to give constructive criticism and quite another to be damn CRUEL.....you know nothing about Taz or the obstacles he may be facing...so PUT A LID ON IT


I have been on this blog since 2005 as well.

95% of the time I understand what TAZ is saying. I also don't condemn him on a blog. It's disrespectful.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting K8eCane:
Oh good morning everybody..its quite a bit cooler ...71..in wilmington this morning

Wow... 65 in Greenville, SC, and if you live in WIlmington, NC, you probably know where Sunset Beach is, that's my vacation beach.
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Oh good morning everybody..its quite a bit cooler ...71..in wilmington this morning
Member Since: April 26, 2006 Posts: 5 Comments: 3076
PEARLANDAGGIE

I have been on this blog since 2005 and i have seen a lot of folks rag Taz...I also know that i can be cantankerous as all get out...but I have never seen anyone be deliberately CRUEL as you were last nite...its one thing to give constructive criticism and quite another to be damn CRUEL.....you know nothing about Taz or the obstacles he may be facing...so PUT A LID ON IT
Member Since: April 26, 2006 Posts: 5 Comments: 3076
Quoting IKE:


Mine came about 5 pm. Looks like real good chances of rain early next week with a cold front stalling out along the gulf coast.
Got ours around 6:30
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603. IKE
Quoting ALCoastGambler:
Glad to hear you finally got some rainfall Ike. Saw it on radar last night. Looked as though we were going to get hit hard but it went to the bay. Made for a beautiful sunset though.


Mine came about 5 pm. Looks like real good chances of rain early next week with a cold front stalling out along the gulf coast.
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Still nothing going on in the world?!

Looks like I can enjoy my Twilight Zone marathon today.
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Glad to hear you finally got some rainfall Ike. Saw it on radar last night. Looked as though we were going to get hit hard but it went to the bay. Made for a beautiful sunset though.
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Quoting IKE:


Good morning. Good coffee. Maxwell House light....


LOL!!! yeah good coffee!! lol.. drinking Maxwell House... good to the last drop...LOL!!!
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599. IKE
Quoting ALCoastGambler:
Ike it started last night about 10:30-1100pm. And was all started by pearlandaggie putting political crap on a weather blog. And let me tell ya, it went haywire after that.


Yeah, politics is almost a no-no and sure to cause problems.

Best to avoid it.
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598. IKE
Quoting Joanie38:
Good morning IKE...:)


Good morning. Good coffee. Maxwell House light....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
I was reading too about the showdown....WOW...that was something....
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.