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 btwntx08:
holly man wow!! whew talk about unbelieveable damn
Hearne, Texas (Airport)
Updated: 13 min 21 sec ago
118 °F
Clear
Humidity: 37%
Dew Point: 85 °F
Wind: 6 mph from the South
Pressure: 29.88 in (Steady)
Heat Index: 154 °F
Visibility: 10.0 miles
UV: 6 out of 16



...dayum! Whew! Sweatin' just reading that! UGH!
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1391. bappit
That must be a mistake. Lists heat index of 154.
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1389. bappit
Hearne, Tx 117 F currently with a high of 118.

That's just northwest of College Station which is only at 101.
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lol gotta love the Navy NRL's humor:

NOTE: The Atlantic wins the contest...
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Quoting SSideBrac:
Whilst I admire this site, and most of the bloggers, immensely - I do wish that some bloggers would cease from apparently "wishing for a Hurricane!!

Living throughy and recovering from (and many of u know this)is a frightening, humbling, exhausting and expensive process - it is not a "wanabee adventure" by any means.

So for me personally - and I am sure I echo the thoughts of many people in the Caribbean - I do not care a whit if it is a boring, quiet season - I would prefer it that way.

I would hate to live my live based on the remoted, vicarious thrills of "that looks dramatic, that looks exciting - wish I was there" - it is dramatic, it is exciting,but trust me once tasted always hoping it never happens again.


I stayed in Beaumont, Tx for Rita... experienced a lot of tornados and downed trees... a really intense Hurricane. I stayed in Humble, Texas for Ike, played guitar on the front porch during the eyewall despite my wife's protests.

I made about $60-$65,000 from October 1st - Dec 31st on Hurricane Ike recovery. Several refineries and chemical plants in SE Texas got damaged and had to be repaired.

Thousands of contractors had good paying jobs, after Ike, for at least 3-months. Hurricanes can be good and bad for the local economy... but I was working 12-hour days 7-days/week for several months plus per-dium and hotel stay. Hurricanes are a real shot in the arm for some professions.

Also, they help neighbors get to know each other. We never hardly met the neighbors in Beaumont until Rita. Afterward, we all sort of banded together to protect the neighborhood.

Wishcasters aren't evil... they probably just don't know what they are asking for and will get far more than they bargained for.
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Hello again everyone!! Happy 4th!!! I was just reading through the blog here a minute ago... wow..you guys are somethin else..lol..I love reading this blog!!!! I am on here reading everday! ESPECIALLY, if there is a storm brewing... can't get off the blog...LOL!! I hope everyone is having a great day!
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1382. Gotcha, Kori. Agreed, mostly. :)
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Invest 94L

Invest 94L
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the t-wave over the antillies will have to be watched for TC development as it heads west over the next 72hrs.....conditions should be favorable!!!!!!
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Quoting moonlightcowboy:


Kori, I didn't say there was a coorelation to nGOM landfalls with Nino. My comment was more suggestive of nGOM landfalling storms during neutral conditions and a more active season. History shows that.

Nino storms tend to find FL-the eCoast or become fish storms as conditions for development become more suppressed.


Of course you didn't say that, but I did. As I said, I doubt there is an official correlation between Nino events and northern Gulf Coast landfalls, but from what I've studied on the subject, there does appear to be a weak correlation.

I do agree with you, however, in that during Nino years, Florida and the east coast are at the greatest risk of a major hurricane. But the weaker systems of the year tend to strike the northern Gulf Coast, likely in part due to following the low-level easterlies as weak tropical waves in unfavorable atmopsheric environments until they reach the Caribbean or Gulf of Mexico, when they find favorable conditions and subsequently begin to organize.

Just my thoughts.
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1380. KEEPEROFTHEGATE (Mod)


epac storm soon
Member Since: July 15, 2006 Posts: 169 Comments: 53308
Quoting KoritheMan:


I'm not sure if there is an official correlation to El Nino events and northern Gulf Coast landfalls, but I've found through studying that there does appear to be a correlation between hurricane landfalls along the northern Gulf Coast during El Nino years.

So even if we were to experience a below average season, owing to a weak to moderate El Nino event, then there would still be a risk of northern Gulf Coast landfalls.


Kori, I didn't say there was a coorelation to nGOM landfalls with Nino. My comment was more suggestive of nGOM landfalling storms during neutral conditions and a more active season. History shows that.

Nino storms tend to find FL-the eCoast or become fish storms as conditions for development become more suppressed.
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Quoting moonlightcowboy:
I'm not buying into a full-blown nino in the heart of the season yet. Atmospheric conditions tend to lag and it's difficult to conceive that we'd go almost immediately, as quickly as is being made to sound, from nina almost directly into nino. I believe we'll still see the lag and subsequent more neutral conditions through much of the season.

A couple of points: if condtions lag, we'll still see some nGOM storms; and if, nino is more prelavent then FL and the eCoast become more vulnerable. Either way, even with "suppressed" conditions we're still quite apt to have at least one potentially major, land-falling CONUS hurricane. Afterall, it does only take ONE to cause death and destruction. Slow starting season, extra speculation of nino almost dictates that we'll see a season less respected, people with their guard down, less prepared and potentially more dangerous. I'd much rather see the NHC continue to talk about the seriousness of even a less than average season.

I just don't think we've got it figured out yet! Obviously, our leadership doesn't when we can tag $50,000,000 worth of pork for an un-needed new hurricane research center. I'd much rather see that kind of money spent on additional shelters and storm education! :(


I'm not sure if there is an official correlation to El Nino events and northern Gulf Coast landfalls, but I've found through studying that there does appear to be a correlation between hurricane landfalls along the northern Gulf Coast during El Nino years.

So even if we were to experience a below average season, owing to a weak to moderate El Nino event, then there would still be a risk of northern Gulf Coast landfalls.
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1377. KEEPEROFTHEGATE (Mod)


cen fix
15n/73w
Member Since: July 15, 2006 Posts: 169 Comments: 53308
Quoting atmoaggie:
Can you imagine being stuck in traffic while it approaches? What fun.



That would be a fitting ending to a crappy day at work.
Member Since: July 8, 2005 Posts: 259 Comments: 23656
1375. beell
Thanks for pasting the links atmo. Not good coverage on the high seas or around 94L-the small point I was raising.

A great product, though!
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We had a waterspout on the 41 bridge between Punta Gorda and Port Charlotte in '95 I think... It picked up a pick up truck with a guy inside it and threw it 50' down below into the water. He had to cling to a bridge piling until help arrived. It also flipped over a few other cars on the bridge.

Quoting atmoaggie:
Can you imagine being stuck in traffic while it approaches? What fun.

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I'm not buying into a full-blown nino in the heart of the season yet. Atmospheric conditions tend to lag and it's difficult to conceive that we'd go almost immediately, as quickly as is being made to sound, from nina almost directly into nino. I believe we'll still see the lag and subsequent more neutral conditions through much of the season.

A couple of points: if condtions lag, we'll still see some nGOM storms; and if, nino is more prelavent then FL and the eCoast become more vulnerable. Either way, even with "suppressed" conditions we're still quite apt to have at least one potentially major, land-falling CONUS hurricane. Afterall, it does only take ONE to cause death and destruction. Slow starting season, extra speculation of nino almost dictates that we'll see a season less respected, people with their guard down, less prepared and potentially more dangerous. I'd much rather see the NHC continue to talk about the seriousness of even a less than average season.

I just don't think we've got it figured out yet! Obviously, our leadership doesn't when we can tag $50,000,000 worth of pork for an un-needed new hurricane research center. I'd much rather see that kind of money spent on additional shelters and storm education! :(
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Quoting beell:
Anybody ever checked out availability of XM Weather? CONUS and 100 miles off the coast...


I can tell ya, Gulf of Alaska to Hispaniola, Nova Scotia to Baha (and beyond). Obviously some products, such as land-based radar data are limited in coverage. Others, such as wave model forecasts and satellite mosaics are not.

The radar coverage looks like this. The full spatial coverage is a little bit larger.

EDIT: I guess WU doesn't want to link the pics at xmwxweather.com, interesting.

Radar coverage
http://www.xmwxweather.com/images/data-products/Radar-Coverage.jpg

Wave height example:
http://www.xmwxweather.com/images/data-products/Wave-Heights.jpg

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No mention of Steve McNair on Yahoo.News,still talking about Michael Jackson
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1369. Ossqss
After doing extensive research, perhaps a case study or 2, I have found there are actually benefits to Beer :)

10-Health-Benefits-of-Drinking-Beer
Member Since: June 12, 2005 Posts: 6 Comments: 8185
94E is looking better organized, and the circulation is gradually consolidating as well. With upper winds forecast to become more favorable for tropical cyclogenesis, I think this system has a shot at becoming a tropical cyclone.
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1366. beell
Anybody ever checked out availability of XM Weather? CONUS and 100 miles off the coast...
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1365. KEEPEROFTHEGATE (Mod)
just reading back

interesting
Member Since: July 15, 2006 Posts: 169 Comments: 53308
Quoting stormwatcherCI:
A lot of uncool people on here I think. Including me. Too many bad "memories."


No bad memories, but I usually have one drink a month. Just not motivated, I guess.
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Nice picture, put a little spice in your ride home. At least pottery will get a little more rain from the wave. That's the same wave that came off Africa, an everyone was talking about last week. Well everyone have a nice holiday weekend. Get a designated driver if you must.
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McNair was a great quarterback, a Mt. Olive, MS native. His son played at Oak Grove and was a standout there. Double homicide? Murder sucicide? Either way is tragic, but I hope we don't find out that it was a murder suicide - he absolutely seemed to have so much going for himself, opening new restaurants, hosting camps, wanting to teach children, etc.
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1361. KEEPEROFTHEGATE (Mod)
Quoting presslord:


I apparently haven't been cool since my kids became teenagers...
naw he's not at that phase yet only 9
Member Since: July 15, 2006 Posts: 169 Comments: 53308
Quoting KEEPEROFTHEGATE:
guess iam not cool i dont touch the stuff myself
A lot of uncool people on here I think. Including me. Too many bad "memories."
Member Since: October 9, 2008 Posts: 0 Comments: 8288
1358 Wow!
Member Since: August 13, 2007 Posts: 0 Comments: 10479
Can you imagine being stuck in traffic while it approaches? What fun.

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Quoting KEEPEROFTHEGATE:
guess iam not cool i dont touch the stuff myself


I apparently haven't been cool since my kids became teenagers...
Member Since: August 13, 2007 Posts: 0 Comments: 10479
1356. KEEPEROFTHEGATE (Mod)
Quoting presslord:


...but...All the cool kids are doin' it!!!!!!!!!!!!
guess iam not cool i dont touch the stuff myself
Member Since: July 15, 2006 Posts: 169 Comments: 53308
1355. auburn (Mod)
Report: Steve McNair Slain
Posted by Mike Florio on July 4, 2009 4:18 PM
According to NewsChannel5.com in Nashville, long-time NFL quarterback Steve McNair has been found dead.

McNair reportedly suffered a gunshot wound in an apparent murder-suicide.

Further details currently are not available; check back for more developments.

He was a first-round pick of the Houston Oilers in 1995, and he played for the franchise through the 2005 season. McNair was then traded to the Ravens, and he spent two seasons in Baltimore before retiring.

UPDATE: The report from NewsChanel5.com has been revised to describe the situation as a "double homicide.
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1354. hahaguy
Quoting presslord:


...but...All the cool kids are doin' it!!!!!!!!!!!!


I guess you'll be uncool then LOL
Member Since: August 12, 2007 Posts: 2 Comments: 2838
Quoting Makoto1:


Oh that really is sad... Is anyone allowed to live anymore?

I really enjoyed watching McNair play when he was on the Titans. Looks like there was another victim. One report says double homicide one report say murder suicide.
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Quoting Patrap:
#1330

Bull Sharks are nasty critters..


Me too! (So am I)
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1351. Makoto1
Quoting HaboobsRsweet:
On a side note...report Steve McNair was shot to death. He was a underated QB in the NFL. Sad.


Oh that really is sad... Is anyone allowed to live anymore?
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Quoting hahaguy:


Don't let anyone peer pressure you into drinking LOL.


...but...All the cool kids are doin' it!!!!!!!!!!!!
Member Since: August 13, 2007 Posts: 0 Comments: 10479
The last 14 day percent of normal shows how sporadic the rain has been...and how consistently it has been raining at the same spots.

No dead grass here, in Covington, under one of the blue spots getting 150 - 200% of normal rainfall (against a 1971 - 2000 average). Lots of dry areas around, though.

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That wave at 55w 11n looks to be firing up. And moving wnw. Any thoghts.
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1347. hahaguy
Quoting presslord:
Going to Mass @ 6P...then fireworks at the beach...might be some alcohol involved in the mix...


Don't let anyone peer pressure you into drinking LOL.
Member Since: August 12, 2007 Posts: 2 Comments: 2838

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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.