Large and intensifying Hurricane Alex bears down on northeastern Mexico, South Texas

By: Dr. Jeff Masters , 2:23 PM GMT on June 30, 2010

Hurricane Alex continues to intensify as it slowly bears down on the coast of northeastern Mexico. Brownsville long-range radar shows the spiral bands of Alex, which has dumped heavy rains of up to four inches in northeastern Mexico and near Brownsville, according to satellite estimates of rainfall. The Brownsville airport received 0.78" of rain in the hour ending at 8am CDT, and 0.61" in the hour ending at 9am CDT. Floods from Alex have already killed ten people--six in Nicaragua, and two each in El Salvador and Guatemala.

Figure 1. Snapshot of the Brownsville long-range radar showing Hurricane Alex approaching the coast.

The 7:12am CDT eye penetration of the Hurricane Hunters found a central pressure of 959 mb, a modest 2 mb drop from the reading four hours previous to that. They noted a very tiny eye, ten miles in diameter, with a gap in the northwest side. Tiny eyes like this tend to be unstable, and in the 9:05am CDT eye penetration, the Hurricane Hunters found that the inner eyewall had collapsed, and the pressure had risen 2 mb, to 961 mb. A new, much larger eye will form today as the day progresses. During these "eyewall replacement cycles", a hurricane will typically weaken a few millibars , and the strongest winds will spread out over a larger area as the hurricane conserves angular momentum. Thus, the hurricane still has about the same amount of destructive power, it is just spread out over a larger area. This tends to increase the hurricane's storm surge, but lessens the wind damage, since the extreme winds of the inner eyewall are no longer present. Satellite loops show a large, well-organized storm with increasing amounts of low-level spiral bands forming, and improving upper-level outflow. Data from last night's flight of the NOAA jet showed an unusually moist atmosphere surrounds Alex, so dry air is no longer a problem for it. It's a good thing Alex has less than a day before making landfall, or else is would be a large and very powerful major hurricane.

Figure 2. Visible light image of Tropical Storm Alex taken at 19:35 UTC (2:35 pm CDT) on June 29, 2010, by NASA's Aqua satellite. At the time, Alex was a tropical storm with 70 mph winds. Image credit: NASA.

Storm Surge
Traditionally, a storm's ranking on the Saffir-Simpson Scale--the familiar Category 1, 2, 3, 4, 5 rankings we always talk about--have also been used to quantify storm surge threat. However, large, weaker storms that cover a huge area of the Gulf of Mexico, like Alex, can generate a larger storm surge than a smaller but more intense hurricane with a higher Saffir-Simpson rating. Thus, the National Hurricane Center has formally discontinued use of the Saffir-Simpson scale to characterize storm surge, and is studying the possibility of issuing separate Storm Surge Warnings a few years from now. These would be in addition to their traditional Hurricane Warnings. To give us a better idea of a storm's surge potential, Dr. Mark Powell of NOAA's Hurricane Research Division has developed the Integrated Kinetic Energy scale to rank storms. The scale ranges from 0 to 6, and a parallel wind damage scale that runs from 0 to 6 is also generated. Alex had an Integrated Kinetic Energy of 2.6 on the 0 to 6 scale at 1:30pm CDT yesterday, and its destructive potential rating for winds was just 1.2. Thus, Alex's surge ranked alomst one-and-a-half categories higher in destructive potential than its wind. These numbers have probably increased by a full category since yesterday afternoon. NHC is giving a 40% - 60% chance of a storm surge of at least 3 feet affecting the Brownsville area, and 10% - 30% chance the surge will exceed 5 feet. In theory, a Category 2 hurricane moving WNW at 5 mph can bring a storm surge of up to 8 - 9 feet to the South Texas and northern Mexican coast.

Other Impacts
Alex is bringing bands of heavy rain to the coasts of Texas and Mexico, as seen on the Brownsville, Texas radar. Hurricane local statements with projections for how Alex will affect the coast are now being issued by the National Weather Service in Brownsville and Corpus Christi. Flooding damage from the expected 6 - 12 inches of rain from Alex will be the main concern. Wind damage is a lesser concern, since the core of Alex is making landfall in a swampy, sparsely populated region of Mexico. The combined wind, surge, and flooding damage from Alex may be similar to 2008's Hurricane Dolly, which hit near Brownsville. Dolly was a Category 2 hurricane offshore that weakened to a Category 1 hurricane with 85 mph winds when it made landfall, and did about $1 billion in damage. Dolly also generated two weak EF-0 tornadoes, and Alex is capable of generating a few tornadoes as well, according to the latest discussion from NOAA's Storm Prediction Center. The atmosphere is moderately unstable, there is plenty of moisture, and wind shear at low levels has been increasing this morning. The greatest threat for tornadoes will occur late this afternoon, on the right side of where the storm makes landfall.

Alex in historical context
Alex is the first June hurricane since Hurricane Allison of 1995. Allison briefly became a minimal 75 mph hurricane before weakening and hitting the Florida Panhandle as a tropical storm. Alex is the strongest June hurricane since Hurricane Bonnie of 1986, which had 85 mph winds. Bonnie was the first hurricane I flew into as a member of the Hurricane Hunters. Bonnie made landfall along the upper Texas coast, and caused less than $20 million in damage. If Alex strengthens to 90 mph winds, it will be the strongest June hurricane since Hurricane Alma of 1966, which had 125 mph winds as it skirted the Florida Keys. There have been only ten hurricanes in May or June since 1945; only four of these were major Category 3 or higher storms.

Track forecast for Alex
All of the models take Alex to the west or west-northwest into northern Mexico by early Thursday morning. However, the steering currents are fairly weak, and Alex could stall and move erratically at times today. I don't anticipate that this weakness in the steering currents will allow Alex to move northward and make landfall in Texas. After landfall, the ridge of high pressure forcing Alex westward should remain in place and strengthen, keeping Alex's remnants over northern Mexico for several days.

Intensity forecast for Alex
Alex is over a region of ocean with moderately high total ocean heat content . Wind shear has fallen to a low 5 knots, and is projected by the SHIPS model to remain in the low range, below 10 knots, through landfall. The combination of low wind shear, moderately high ocean heat content, and plenty of moisture should allow Alex to continue to intensify today. Alex's pressure is already characteristic of a Category 3 hurricane, but the storm is so large that it is taking time for the winds to catch up to the pressure falls. It is unlikely that Alex's winds will be at Category 3 strength at landfall, since the storm is undergoing an eyewall replacement cycle, and does not have time to build a tight inner eyewall with strong winds before landfall. A Category 2 storm at landfall looks more likely.

Elsewhere in the tropics
The latest run of the NOGAPS model predicts the formation of a tropical disturbance in the Western Caribbean on Monday. None of the other models is showing anything brewing over the coming seven days.

Wind and ocean current forecast for the BP oil disaster
Alex is generating very rough conditions over the Deepwater Horizon blowout location, with 6 - 8 foot waves and 3 - 4 foot swells. Strong southeast to south winds of 15 - 25 knots will blow over the oil slick region today through Thursday, according to the latest marine forecast from NOAA. The resulting currents will push oil to many protected bays and estuaries that haven't seen oil yet. In addition, the 1 - 2 foot storm surge Alex is generating along the Louisiana coast will act to push oil deep into some low-lying marshlands. While this oil will be diluted some by the wave action, the impact of the oil and accompanying toxic dispersants on the marshlands is of concern. 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 10 - 15 knots Friday through Monday but remain 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
Either Rob Carver or myself will do an update late this afternoon or this evening.

Jeff Masters

Hurricane Alex (LRandyB)
Weather inbound to Hurricane Alex.
Hurricane Alex
Hurricane Alex (LRandyB)
Weather inbound to Hurricane Alex.
Hurricane Alex
Hurricane Alex (LRandyB)
Flight deck view from a WC-130J Hurricane Hunter aircraft
Hurricane Alex

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Pretty impressive wave heights

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Member Since: September 22, 2005 Posts: 11 Comments: 2142
Quoting StormW:
I just ain't buying this right now:

I'm thinking a Texas/Mexico border landfall. I think Brownsville should be watching this very very closely.
Member Since: September 2, 2009 Posts: 131 Comments: 21689
Quoting 1900hurricane:
Dang, 3 inch PWs in Brownsville! I've never seen them that high before (although I haven't been observing PWs for all that long yet).

I can't remember the last time I saw a sounding completely saturated from the ground to the tropopause - brings me back to the old days of thermodynamics
Member Since: August 27, 2006 Posts: 0 Comments: 1817
75 people watching Oz right now!
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Member Since: July 8, 2005 Posts: 259 Comments: 26061
Quoting AussieStorm:

Let him know i am watching.

I just got in and out. Try it again. Seems to have opened up. :)
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CycloneOz live right now in Brownsville!
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Quoting Asta:

Roughly 8 x 8 deg in diameter (lat x lon) for the inner storm over water, and 28 x 20 deg for the entire storm including outer bands.
Member Since: August 30, 2008 Posts: 8 Comments: 2853
Not trying to be annoying, but people need to be aware that the NHC and models are already off on the storm. This is my latest forecast based on the trend and pattern of Alex. Yes, it will eventually turn westward, but I believe this will make landfall a bit south of the borderline. I'm very confident on this forecast.

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Crossed the causeway into South Padre Island but 1/2 mile up the road, the road was nearly impassable due to flooding. So, I turned back around. Am currently in Port Isabel - contemplating going down to Bville, near the airport. There have been some very hefty squalls with gusts easily near 40mph but presently is rather tranquil
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tornado threat coming to S. Texas
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Quoting reedzone:

Hmm.. you have a point there, Just saw the radar, clearly continues a NW motion. Wouldn't surprise me if the track is north of my track.

will the ridge build in before it hits the coast? that is the question...
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Mission 11 of the HH is over and mission 12 is already en route, they are keeping a very close eye on this one! Hopefully they approach the eye from the NE as their current flight path would dictate.
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Alex is clearly not moving due west, east, southeast, north or anything like that

only 2 movements it could be going is NW and WNW, right now it is mostly NW
Member Since: March 10, 2010 Posts: 4 Comments: 10798
BDG308 Post # 301 Thank you very much. Excellant analogy. I have a very clear picture of what angular momentum is now. Again thanks.
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Storm Prediction Center just issued a mesoscale discussion - tornado watch likely to be issued shortly for south Texas
Member Since: August 27, 2006 Posts: 0 Comments: 1817
looks like its moving due west now... mayby that was just a north wobble earlier
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Quoting Ossqss:

Probably has a cap on total number of participants and is full..

Let him know i am watching.
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Dang, 3 inch PWs in Brownsville! I've never seen them that high before (although I haven't been observing PWs for all that long yet).

Member Since: August 2, 2006 Posts: 61 Comments: 12279
It looks to be doing pretty close to the models in the next couple hrs. they all seem to point to a hard left.
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subtract the wobbles and its still on NW course
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Quoting IKE:
Definetly moving NW/NNW.
Member Since: September 2, 2009 Posts: 131 Comments: 21689

Sometimes they just dont display correctly. They know about it.

They are always doing something/upgradeing so if a glitch appears - wait - mine always comes back.

Thanks JFLorida - it used to appear normally with the animation in past years, but now the animation blurs over the picture for several seconds.

Where in Florida are you? I'm on a barrier island between Jax and St Augustine.
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Quoting AllStar17:
How do you change your avatar?

I don't remeber right off hand. You may want to contact support if no one chimes in.
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Quoting homelesswanderer:

Can't remember what storm but it hit the Rio Grand at just the wrong angle flooded a long way up stream.

Not to mention that the national flood insurance program has not been able to issue new policies for a while now, so if you were one of the individuals who tried to be responsible and inusre your home (as opposed to a handout afterwards), you are left twisting in the wind until it is reauthorized if your policy is expired.
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the sustained winds at the Port Isabel Arpt. just jumped up to 32 mph (gusting to 40). Tropical storm conditions are approaching for S. Padre Island.
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Quoting AstroHurricane001:

Are those actually 30-ft waves threatening to come ashore on the Texas-Mexico border?

The 30' swells will be breaking offshore depending on the depth of the water off of the beach. The deeper the water the closer the big swells will break, the shallower the water the more offshore they will break. This will contribute to the surge as alex approaches.
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313. Asta
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Quoting kmanislander:
Alex still well to the right of the revised forecast points as seen here. Check the L/L and pts. to on if not checked and watch the loop run.

I woudl point out..very carefully so as to not start the up/down casters singing...that where the "first" landfall is may not be the only question here. If that trough picks up Alex it will be immaterial as to whether or not it has hit Tx/Mex for LA and FL. There is a growing percent chance that Alex will be moved back offshore where re-intensification could occur. I hope that is a slight chance..but it needs to be considered and the possibility of a "second" landfall location considered with factoring for how far the trough could push Alex into the gulf after a "first" landfall...if one occurs before the trough arrives.
Member Since: June 26, 2008 Posts: 0 Comments: 393
Quoting twhcracker:

ok, we got w, nnw, nw, n, nne, s, and ne so far. whats left?
How about "up"?
(technically, more accurate than any of those...)
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Last update for awhile.. off to work (or at least fake it)

I suspect that Alex is not going to make a rapid turn towards the coast, and landfall will be around the border.. Brownsville is going to get the dirty end of it.




Hurricane Hunter Data

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Quoting btwntx08:

For the time being it seems like you are going to get the brunt of Alex. Some hurricane force winds and torrential downpours should be anticipated. Stay safe!
Member Since: September 2, 2009 Posts: 131 Comments: 21689
Quoting btwntx08:
man it is raining so hard right now

Take care BT.
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306. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 38327
Quoting Hurricanes101:

still looks NW to me

ok, we got w, nnw, nw, n, nne, s, and ne so far. whats left?
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The graphic was posted, here is the text from Storm Prediction Center on the tornado threat:

1017 AM CDT WED JUN 30 2010



VALID 301517Z - 301645Z



..BROYLES.. 06/30/2010

Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting truecajun:
Oil being pushed into these bays and estuaries is killing me. These places are so quiet and sleepy. When you r there it's as if the rest of the world is nonexistent. It's so still and very quiet. The birds and fish etc are going to be rudely interupted. It's Extremely sad.

T'as beaucoup de raison, Truecajun. Ca casse notre coeur! (You're absolutely right, Truecajun. This breaks our heart!) As happy as we'll be to see Alex exit stage left, who knows what tropical demon will enter stage right in a few days or weeks?

Just like BP can't stop the onslaught of oil, neither can we stop the onslaught of the worst part of hurricane season. These are stressful days.
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Quoting RidingTheStormOut:
In the Dr.'s blog "and the strongest winds will spread out over a larger area as the hurricane conserves angular momentum" Thank you kind Dr. for the update. Could one of these fine folks please explain to me what is angular momentum. Thanks in advance.

Google or Wikipedia.

Think of an ice skater doing a spin. The spread their arms out and begin to slow down. Pull them in and speed up. In this case, The ice skater is Alex, and the arms are rain bands
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How do you change your avatar?
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Glad Alex lost that huge area of deep convection to the north before it go onto heavily populated areas. That thing was monstrous.

Now much weaker and smaller:

Good loop for it: 404
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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