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

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

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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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Quoting 1900hurricane:
Anyone else think there might be an Eyewall Replacement Cycle going on in there?

I was saying it earlier, StormW just gave me the "???". Lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Raining hard in Corpus right now
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Anyone else think there might be an Eyewall Replacement Cycle going on in there?

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Quoting IKE:
Director of NHC...on TWC...."it's taken a jog NW"


Jog?? Why can't they just admit they were wrong on the initial movement? This is going to be a frustrating year.
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Finally can see the eye of Hurricane Alex.
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Quoting AussieStorm:

Link


Thank you!
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Quoting Daveg:

He sure is bouncing about quite a bit
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441. xcool
IKE yeah
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ESL by LSU with a Fresh new Look to the Home Page

Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting CaneWarning:
Where can I watch Oz?

Link
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438. IKE
Director of NHC...on TWC...."it's taken a jog NW"
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Dr Greg Forbes is going to raise his Torcon index..... shocker there
Member Since: January 24, 2010 Posts: 0 Comments: 529



3 things I notice here

1. the outflow around the eye is amazing
2. just north of the center we see another hot tower forming
3. the eye is really clearing out
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Nasa rapid-fire satellite imagery suggests that the eye and eyewall of Alex are becoming more-defined. I wouldn't be surprised to see a small transparent eye pop at any time.

Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting KORBIN:
So what happened to all those posts showing some things popping up near Florida late this weekend early next week?

What Model was that?
GFS. NAM says no. CMC says maybe. ECMWF says no.

And GFS has been trending more west, to SW LA, and weaker in every run for the last day.

Probably not going to happen.
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Quoting miguel617:
Here in Matmamoros at work. Our employer does not want to let us out until the end of shift at 5 PM. We were all hoping to leave at noon. Many people use public transportation and the streets are already flooded. It has been raining since early morning almost nonstop.

LEave..LEave now.

Ones safety is paramount.

A Job isnt.

The Law can deal with them.

Member Since: July 3, 2005 Posts: 414 Comments: 125418
Where can I watch Oz?
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ROfl i have a hard time watching OZ ... lol lol lol
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429. xcool
Recon fiy in
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Quoting NCHurricane2009:
Morning,

As Alex comes ashore, please feel free to comment on my blog (link) any impacts you are getting from Alex (trying to get a sense of what kind of impacts Alex is producing). To people in S Texas and N Mexico, stay safe!

You can also find the entire synoptic history of Alex on my blog as well.


We were on the NE side of Alex on the Yucatan and are STILL with VERY heavy seas and huge winds. I can't believe we are still experiencing weather related to Alex but it appears we are. This is VERY abnormal weather for us.
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427. ryang
.
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426. ryang
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Quoting btwntx08:
im here and yes im beginning to worry i will lose power if it gets real close


If you lose power, turn on the radio. Just in case they issue tornado warnings or the eyewall comes ashore or something.
Member Since: August 30, 2008 Posts: 8 Comments: 2834
Quoting AstroHurricane001:


NO XTRAP!
Current trajectory is one of the most reliable pieces of data we have at this moment. "An object in motion..."
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Here in Matmamoros at work. Our employer does not want to let us out until the end of shift at 5 PM. We were all hoping to leave at noon. Many people use public transportation and the streets are already flooded. It has been raining since early morning almost nonstop.
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Quoting StormW:
I just ain't buying this right now:



US landfall now is more likely.
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420. Daveg
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Biggest lesson from this storm:

Even if every single model is in close agreement as little as 24 hours from landfall, that doesn't mean they are guaranteed to be right. Looks like an incredible mis-hit from even the ECMWF on this one. A landfall near the border looks possible now. I was pretty much giving up on that idea yesterday afternoon after the due west turn.
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Quoting Hhunter:


ridge forecast to build and turn him west. anything possible. but that is forecast.
It wasn't supposed to be a forecast or track, it is just an extrapolation if Alex does keep moving NW. We'll know soon enough where it is going.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
On a side note related to the Air Force HH Planes per the picture posted at the end of Dr. M's Blog entry (Flight deck view from a WC-130J Hurricane Hunter aircraft), that is a "killer" digital upgrade in the cockpit of those older Hercs......God Bless Them and the jobs they do.

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416. IKE
Quoting KORBIN:
So what happened to all those posts showing some things popping up near Florida late this weekend early next week?

What Model was that?


GFS, vol. 1...it's about dropped that spurious low.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
.
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the outflow is expanding further around the center
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Quoting reedzone:


Exactly, now howd you do that? I certainly can't put a moving image on paint and draw on it. LOL


Here you go Reed

Member Since: January 24, 2010 Posts: 0 Comments: 529
How do you get the live images of the recon flights on Google Earth?
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Quoting Levi32:
The eye on radar imagery is rather small.



Impressive storm, continues to defy the odds. Looks like to me it's north of the models and NHC.
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Quoting btwntx08:
im here and yes im beginning to worry i will lose power if it gets real close
Extrapolation suggests a border landfall so I'm sure you'll get some effects. Right now you should be hoping for the system to either go over or north of you because the strongest quadrant of Alex is the NE side, so if Alex goes south of you, you'll get the worst of it. Stay tuned to Jeff Masters' blog, lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
So what happened to all those posts showing some things popping up near Florida late this weekend early next week?

What Model was that?
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Quoting Drakoen:
Short GOES visible Animation reveals a system moving to the NW prehaps making landfall just south of the border and potentially giving southern Texas the worst of this storm.


Agree Drak.
Member Since: August 14, 2007 Posts: 0 Comments: 435
Quoting MiamiHurricanes09:
If you extrapolate motion from the beginning of the loop Alex is likely to make landfall very near the Texas/Mexico border, but we all know that this motion can change in a heart beat.



NO XTRAP!
Member Since: August 30, 2008 Posts: 8 Comments: 2834
Quoting MiamiHurricanes09:
If you extrapolate motion from the beginning of the loop Alex is likely to make landfall very near the Texas/Mexico border, but we all know that this motion can change in a heart beat.



ridge forecast to build and turn him west. anything possible. but that is forecast.
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The eye on radar imagery is rather small.

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402. xcool
:( he lucky not at nigth .
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Storm... waiting for your next grand thought on this thing :)
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Quoting reedzone:


Exactly, now howd you do that? I certainly can't put a moving image on paint and draw on it. LOL
LOL. I use a combination of Lunapic and Tinypic.

Quoting mtyweatherfan90:


In the last position it might seem a little bit south of your extrapolated track. I no it's just a "what would happen if..." but I'm still thinking that soon it will feel the ridge and begin to curve to the wnw.
Yeah pretty much, wasn't supposed to be a track. Let's see what happens, though at the moment I'm leaning more towards a border landfall we'll know soon enough.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Morning,

As Alex comes ashore, please feel free to comment on my blog (link) any impacts you are getting from Alex (trying to get a sense of what kind of impacts Alex is producing). To people in S Texas and N Mexico, stay safe!

You can also find the entire synoptic history of Alex on my blog as well.
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About JeffMasters

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