Alex, strongest June hurricane in 44 years, is now a tropical storm

By: Dr. Jeff Masters , 2:20 PM GMT on July 01, 2010

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Hurricane Alex, the strongest June hurricane in 44 years, is Tropical Storm Alex, thanks to passage over the rugged terrain of Mexico. Alex made landfall at 9pm CDT last night, 110 miles south of Brownsville, Texas, as a Category 2 hurricane with 105 mph winds. Alex was the strongest June hurricane since Hurricane Alma of 1966, which had 125 mph winds as it skirted the west coast of Florida. Brownsville long-range radar shows that Alex's heavy rains continue to pound the Texas/Mexico border region, and satellite estimates of rainfall (Figure 1) show that some of Alex's spiral bands dumped rains in excess of five inches today, in addition to the 5+ inches that fell yesterday. The Brownsville airport received 6.46" of rain as of 8am CDT today from Alex. Alex is being blamed for at least thirteen deaths in Central America and Mexico due to flooding, though none of these deaths occurred in the region where the storm made landfall. Alex spawned two tornadoes that hit South Texas, and there were at least four other reports of tornado funnel clouds that did not touch ground. Alex may continue to spawn isolated tornadoes today over South Texas and northern Mexico.


Figure 1. Radar-estimated rainfall so far today for Alex.


Figure 2. Snapshot of the Brownsville long-range radar showing Hurricane Alex at landfall at 8pm CDT Wednesday June 30, 2010.


Figure 3. Alex nearing landfall in northeastern Mexico at 12:10 CDT June 30, 2010, as seen by the MODIS instrument on NASA's Terra satellite. Image credit: NASA.

Storm Surge
Alex's maximum storm surge occurred along a 50-mile stretch of the Mexican coast centered about 75 miles south of Brownsville, Texas. The National Hurricane Center Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model predicted that the maximum water depth at the coast reached about 5 - 6 feet above ground level (Figure 3.) A storm surge of 1 - 2 feet was predicted by SLOSH for the Brownsville, Texas region. A storm surge of about 2 feet was observed in South Texas at the South Padre Island Coast Guard Station and Port Isabel.


Figure 4. Hurricane Alex's Maximum Water Depth (storm tide minus the elevation of the land it is passing over) computed using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. The maximum surge occurred to the right of where Alex's core made landfall, over a sparsely populated marshy area. This "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of five feet above mean sea level, and the combined storm surge and tide (the "storm tide") is ten feet at your location, the water depth image will show five feet of inundation. For more information on storm surge, consult our detailed storm surge pages.

Alex in historical context
Alex is the first June hurricane since Hurricane Allison of 1995. There have been only eleven hurricanes in May or June since 1945; only four of these were major Category 3 or higher storms.

Alex's bizarre behavior
Alex had several rather remarkable features I've never seen in a hurricane. Firstly, it underwent an eyewall replacement cycle as a Category 1 hurricane with 80 mph winds. Usually, we don't see the inner eyewall collapse and an eyewall replacement cycle occur until a hurricane reaches Category 3 strength. I've seen it happen on occasion to a Category 2 storm, but never a Category 1. Secondly, after Alex's inner 9-mile diameter eyewall collapsed at 10am EDT yesterday morning, an outer spiral band began to become the new eyewall. Winds in this outer spiral band/new eywall increased as the day progressed, as typically happens in an eyewall replacement cycle. However, part way through that process, Alex suddenly reversed course, and was able to build a small inner eyewall with a 12-mile diameter that was completed by landfall. I've never seen a hurricane change its mind in the middle of an eyewall replacement cycle and build an inner eyewall so fast. Finally, Alex had an unusually weak winds, considering how low the pressure was. The pressure was more typical of a hurricane one Saffir-Simpson category stronger than what the surface winds suggested.

Elsewhere in the tropics
The latest run of the NOGAPS model predicts the formation of a tropical depression the Western Caribbean on Tuesday. None of the other models is showing tropical development worthy of concern over the coming seven days.

Wind and ocean current forecast for the BP oil disaster
Alex is continuing to generate very rough conditions over the Deepwater Horizon blowout location, with 5 - 9 foot waves and 3 - 4 foot swells. The wind and seas will gradually subside today, according to the latest marine forecast from NOAA. The resulting currents induced by Alex's strong winds will push oil to many protected bays and estuaries that haven't seen oil yet. The latest trajectory forecasts from NOAA and the State of Louisiana show oil will also move westward along the central Louisiana coast towards the Texas border. Winds will decrease to 5 - 15 knots Friday through Tuesday but remain mostly out of the southeast, keeping the pressure on the regions of coast in Louisiana, Alabama, and Mississippi that are seeing oil hit their shores this week.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next post
I'll have an update Friday morning. Dr. Rob Carver plans on summarizing Alex in his blog later today.

Jeff Masters

Hurricane Alex (LRandyB)
Weather inbound to Hurricane Alex.
Hurricane Alex

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Quoting TexasHurricane:


what is the 1008 milibar?
Actually I'll send you an e-mail, because what I posted is not even half of the article.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Baltimorebirds:
I see a 1008 milibar low in the gulf.Could that be boonie.


what is the 1008 milibar?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting wunderkidcayman:
stormpetrol glad we can call out to those who do great jobs at forecasting and analysis on thos blog I would also like to add another to that list and that would be MiamiHurricanes09 and as young as he is he is doing very good WELL DONE KIDO

Agreed he's excellent for a young man 13, hell he and I even think the same wave at 10/60 needs to be watched :) and I'm usually wrong :(
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Link
How sad for Mobile Bay and the surrounding beaches.
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Quoting MiamiHurricanes09:
29.04 inches translate to about 983.4 millibars.
This is basically the "Bible" for translation of inches to millibars or vice versa. I would write it down if I were you Baltimorebirds.

To convert inches of mercury to millibars, multiply the inches value by 33.8637526.

To convert millibars to inches of mercury, multiply the millibar value by 0.0295301.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
I've never really made a list, but the bloggers I pay attention the most to is Levi, hurricane23, extreme, StormW, Pat, atmomaggie, stormchaser2007 and miamihurricanes09. They are the one's who I can have a discussion with and learn a lot of very valuable information.

In regards to tropical cyclone development in the GOMEX, it could happen. Trough splits are very common for the month of July and can bring sudden homegrown threats. However, I want to emphasis although the models are in good agreement that something will eventually pop up next week.. we want to see consistency on intensity and track. I want to note that the ECMWF did great with the genesis, track and intensity with Alex. ECMWF caught Alex first, a week in advance right after it was obvious 92L wasn't going to develop. ECMWF develops a Bret like system and a Alex like system. So we'll have to watch that closely.
Member Since: July 8, 2005 Posts: 259 Comments: 23494
Quoting Baltimorebirds:
What does 2904 inches mean.As in pressure.
29.04 inches translate to about 983.4 millibars.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1233. Levi32
Quoting atmoaggie:
If that low has any depth along the gulf, it could be vary bad news.


Indeed....that's a big reason why we should monitor the situation very closely even if the threat for development looks minimal during the next few days. Any low at all could reak havoc with the oil.
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Quoting txjac:



Stop ...he'll blush!

I feel the same, enjoy his posts and immense knowledge ...kudos kiddo!
LOL! Thanks.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting CaneWarning:


It's amazing that at one point in that graph, Alex actually went through the mountain.


?
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1229. txjac
Quoting wunderkidcayman:
stormpetrol glad we can call out to those who do great jobs at forecasting and analysis on thos blog I would also like to add another to that list and that would be MiamiHurricanes09 and as young as he is he is doing very good WELL DONE KIDO



Stop ...he'll blush!

I feel the same, enjoy his posts and immense knowledge ...kudos kiddo!
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Quoting AllStar17:
Alex has some rather flat land ahead:


It's amazing that at one point in that graph, Alex actually went through the mountain.
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stormpetrol glad we can call out to those who do great jobs at forecasting and analysis on thos blog I would also like to add another to that list and that would be MiamiHurricanes09 and as young as he is he is doing very good WELL DONE KIDO
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Quoting IKE:
Watching Central Gulf Coast for Tropical Development
I think one already developed, albeit it being weak and broad. I think that that's the area that needs to be watched in the short term for some cyclonegenesis to occur.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting MiamiHurricanes09:
Not necessarily. The TUTT basically can kill a developed system but can also develop a system.

Depends on the angle of the dangle I guess.
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Quoting Levi32:
The nature of the blocking ridge to the north could push any low that tries to form in the NE gulf westward right along the coast, and the 18z GFS is picking up on that. The 12z CMC ensembles also show a west movement towards Texas in the ensemble mean.

Day 6:

If that low has any depth along the gulf, it could be vary bad news.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Alex has some rather flat land ahead:
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Quoting stormpetrol:

Let's put it this Ike and Patrap are in class of their own, Ike with the models forecast(looks like he never sleeps during hurricane season):) and Patrap with the reminders, graphics and excellent links, what can I say we have it all on this blog!!!
We have everything on here and much faster than the NHC. This is where I come for my weather info.
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1221. EricSFL
Good night fellow wunderbloggers!
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Terry Hershey park off of I-10 and the beltway is another nice trail.
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Quoting Baltimorebirds:
That means increased shear which there for means no tropical development.
Not necessarily. The TUTT basically can kill a developed system but can also develop a system.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting IKE:
Watching Central Gulf Coast for Tropical Development


Our local Tampa met said it was possible something would develop over the weekend.
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Quoting Grecojdw:


ditto but I would also include Ike and Patrap to the mix:)

Let's put it this way Ike and Patrap are in class of their own, Ike with the models forecast(looks like he never sleeps during hurricane season):) and Patrap with the reminders, graphics and excellent links, what can I say we have it all on this blog!!!
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I think we are going to flood in Tampa if this rain storm doesn't die or move. It's crazy. Has anybody seen the radar?
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1214. IKE
Watching Central Gulf Coast for Tropical Development
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Evening Analysis

Link
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Quoting stormpetrol:
Not to discredit anyone but I'm going to name the 5 people on this blog that I really pay attention to , StormW, weather456,Drakoen, Levi32, and kmanislander(Kman) and few others also. BTW W456 was accurate with his forcast track on Alex.


ditto but I would also include Ike and Patrap to the mix:)
Member Since: January 6, 2010 Posts: 0 Comments: 339
Quoting stormpetrol:
Not to discredit anyone but I'm going to name the 5 people on this blog that I really pay attention to , StormW, weather456,Drakoen, Levi32, and kmanislander(Kman) and few others also. BTW W456 was accurate with his forcast track on Alex.


Id say that is a pretty good list

not only the most knowledgeable but also the 5 bloggers that explain and answer questions from others while RESPECTING them at the same time

something I think some other "experts" need to learn how to do.
Member Since: March 10, 2010 Posts: 1 Comments: 7337
Quoting Levi32:
The nature of the blocking ridge to the north could push any low that tries to form in the NE gulf westward right along the coast, and the 18z GFS is picking up on that. The 12z CMC ensembles also show a west movement towards Texas in the ensemble mean.

Day 6:



I was wondering if that could happen....I guess we will see.
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Not to discredit anyone but I'm going to name the 5 people on this blog that I really pay attention to , StormW, weather456,Drakoen, Levi32, and kmanislander(Kman) and few others also. BTW W456 was accurate with his forcast track on Alex.
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Quoting stayaway:
Very nice but a work in progress. Saw a flock of Canadian snow geese. The five year plan creates a bird sanctuary/flood prevention zone if funding stays in tact which i imagine it will. Ultimate plan is to create a bike trail linking UH on the bayou to the waterhole.


I didn't even know that was there - it's on my list of places to visit now. There's a mini-waterhole/flood plane very close to where I live - between Bellaire and Beechnut, west of the Tollroad. It's tiny, but used a lot and surprisingly peaceful, even though it sits right on the feeder road. We need lots more of them!
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1206. Levi32
Classic trough-split right over Florida in 5 days.

18z GFS ensembles 500mb day 5:

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Well, with all this model support next week, could get real interesting.
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1203. Levi32
Quoting Baltimorebirds:
I didn't see you on the blog earlier,and usually your around.


I was for a little bit after I posted today's tropical tidbit. Had to head off to work.
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Quoting stayaway:
Link to a great flood prevention and environmental recreation zone in Houston. Redeveloping a blighted area and great for migratory birds.
http://www.wwgc.org/


Fantastic! Thanks for the link!
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McQ at Blackfive posted on riding on the WC-130 during Alex

http://www.blackfive.net/main/2010/07/chasing-alex-with-the-hurricane-hunters.html

George
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1197. Levi32
Quoting Baltimorebirds:
Levie I was asking about you earlier.


About me? That doesn't sound good...lol.
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1196. Levi32
The nature of the blocking ridge to the north could push any low that tries to form in the NE gulf westward right along the coast, and the 18z GFS is picking up on that. The 12z CMC ensembles also show a west movement towards Texas in the ensemble mean.

Day 6:

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Quoting TexasHurricane:


what does that mean?

I'll take a guess at that one, it doesn't have strong effect at inhibiting tropical cyclone development like a strong TUTT does.
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1193. EricSFL
Quoting StormSurgeon:
Good lord, what's an Atlantic Sea Breeze?


Simply put, during daytime (especially summer) humid sea breezes from both sides of the Florida penninsula collide over the state creating thunderstorms.
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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.