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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Imo we'll see a 90 mph Category 1 at 2, dropsonde in the last recon found 90 mph surface winds. Wondering what the new recon will find.
Member Since: July 8, 2005 Posts: 259 Comments: 23892
The hurricane winds extend pretty far out from the center (especially to the north and east), and Brownsville will likely experience those.
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The Direction commentary isnt needed anymore as the Center is well tracked by radar.

The Storm is closing in on the COastal regions and the Hurricane begins to makes its presence felt in a LARGE way
Member Since: July 3, 2005 Posts: 423 Comments: 127810
494. MahFL
1010 AM TORNADO PORT ISABEL 26.07N 97.22W
06/30/2010 CAMERON TX PUBLIC

PUBLIC REPORTS FENCE IN THE MIDDLE OF THE STREET AND
TREES DOWN BEHIND CONVENIENCE STORE AT THE INTERSECTION
OF HIGHWAY 100 AND MESSINA STREET IN PORT ISABEL
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Quoting TampaTom:


Yeah, if you guys are under any evac orders, it's time to get out and start working your family plan. Seriously. 5 puts this storm much closer....
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I think Alex just got Oz.
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Quoting Levi32:
Radar shows about due NW motion (members who can view more than 6 frames can see it better...40-frame loop is nice for storm movement).

Unless that ridge builds in quickly Alex will make landfall very near the border.
Member Since: September 2, 2009 Posts: 130 Comments: 21122
Heavy rains are really starting to move in now. Keep in mind that radar always underestimates the rainfall from tropical cyclones, so that 3-4"/hr band is probably more than that!


Member Since: August 2, 2006 Posts: 46 Comments: 11666
Quoting txalwaysprepared:
Did Oz just flood out? He was driving thru flood water and the camera is out now.


I think you are right.
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up until 2am last night............argh...

what happen to rob carver? what is a beta effect?
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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.


Yeah, if you guys are under any evac orders, it's time to get out and start working your family plan. Seriously. 5 puts this storm much closer....
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yup NW motion over a 40 frame loop yet some want to say it is moving WNW now based on what 4 frames?

Alex is still moving NW
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Quoting 1900hurricane:
Anyone else think there might be an Eyewall Replacement Cycle going on in there?



Im no met but I believe that Eye wall replacement cycles are normally found in well developed hurricanes of cat 3 or higher..
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omg stream is off air now?
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Member Since: July 3, 2005 Posts: 423 Comments: 127810
Quoting IKE:
Director of NHC...on TWC...."it's taken a jog NW"
Quoting reedzone:


Jog?? Why can't they just admit they were wrong on the initial movement?

Hold a straight edge next to eye on the Brownsville radar...

It has been steady motion toward Port Isabel for the past 4 hours.

"XTRP" is your "model" until you can observe a change in direction on this radar.
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Did Oz just flood out? He was driving thru flood water and the camera is out now.
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Quoting Chucktown:


Ridge will continue to build in as we go on through the day. Alex should really begin to feel it in the next few hours. Already see a more westerly component to last few radar and sat images. Its gonna make landfall south of Brownsville, but they will be in the NE quadrant so expect some healthy storm surge and wind along with tornadoes.
The worst of the system is in the NE quadrant so if Alex goes south of Brownsville they will get the worst of the weather inside of Alex. Latest steering layer map (950-969mb layer) from CIMSS shows a rather weak ridge to the north and a large weakness so we'll have to see how this unfolds.

CIMSS 950-969mb steering layer - 12:00 UTC
Member Since: September 2, 2009 Posts: 130 Comments: 21122
Quoting IKE:
System is moving on...appears WNW....to slightly north of WNW, right now.


Yep, I just saw that on the radar. Appears it might finally be starting that turn. Unless that's a wobble, which it might just be.
Member Since: July 1, 2008 Posts: 13 Comments: 7362
WNW movement trying to start
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Quoting Hardcoreweather2010:
Corpus Christi NWS reporting 64mph gusts at Baffin Bay


What do you think the strongest gust in Brownsville will be when the fat lady sings? I say 101mph. Just a guess though.
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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.


I agree with your assessment. History shows that storms with this track also have the potential for very heavy flooding in central Texas because of the topography of the region. Also, the central Texas region has had rain recently, so the grounds are saturated, increasing run-off.
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Radar shows about due NW motion (members who can view more than 6 frames can see it better...40-frame loop is nice for storm movement).

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NEXRAD Radar
Corpus Christi, Composite Reflectivity Range 124 NM


Member Since: July 3, 2005 Posts: 423 Comments: 127810
Looking the lastest visible loop.......Alex is moving a little more NW, closer to Brownsville. With that said, looking at the Texas Coast line....that maybe he could parallel the coast which would not be a good thing.
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Quoting Hurricanes101:


??? NHC says it is moving NW

Nevermind, I misread the advisory, thought it said WNW.
Member Since: July 1, 2008 Posts: 13 Comments: 7362
there is a reason that NHC has not dropped the hurricane warning north of the border... it is because hurricane force winds are possible there as well
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468. jpsb
Quoting Patrap:

LEave..LEave now.

Ones safety is paramount.

A Job isnt.

The Law can deal with them.

Agreed
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The rains have come into downtown CC TX now. I fell for that person who is in Matamores because I know it's way worse there than it is here.
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Quoting IMA:
My thoughts exactly, Pat. Only essential personnel in essential jobs (doctors, nurses, police, fire, EMS, power companies, etc) should be expected to be at work in Matamoros!

Vaya y sea seguro



Definitely.

Member Since: July 3, 2005 Posts: 423 Comments: 127810
465. MahFL
* AT 1008 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A TORNADO OVER PORT ISABEL...MOVING SOUTHWEST AT 50 MPH.

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464. IKE
System is moving on...appears WNW....to slightly north of WNW, right now.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Oz is too funny.....7 Cops just passed him by and he is criticizing the "straggler"...
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Corpus Christi NWS reporting 64mph gusts at Baffin Bay
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The time to Hunker down in South Texas is rapidly approaching as the Effects are beginning in Ernest.

Member Since: July 3, 2005 Posts: 423 Comments: 127810
460. IMA
Quoting Patrap:

LEave..LEave now.

Ones safety is paramount.

A Job isnt.

The Law can deal with them.
My thoughts exactly, Pat. Only essential personnel in essential jobs (doctors, nurses, police, fire, EMS, power companies, etc) should be expected to be at work in Matamoros!

Vaya y sea seguro
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If the dry air mixes out we could potentially see an eyewall replacement cycle as well. Recon confirmed 2 wind maxima northeast of the center.
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With the pressure continuing to low and the slow change in direction. I would not be surprised if this thing decides it wants to be a coast hugger for a little while. Perhaps a jog up to north padre? Wouldn't that suck?


Looks like I may be spending a few hot ass days in South Texas.
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Looks like some dry air is affecting the western side of the CDO
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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.

Time to get out of there, my friend...you have a while until landfall, but things will only get worse from here on out until Alex passes
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Patrap,
Do you think there is a possibility of the trough pushing Alex back offshore after a first landfall?
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454. xcool
reedzone .no clue why.
Member Since: September 26, 2009 Posts: 2 Comments: 15648
Quoting reedzone:


Jog?? Why can't they just admit they were wrong on the initial movement?


??? NHC says it is moving NW
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452. MahFL
The WC130J's are not old Herc's, they are the lastest model and and new builds, with redisgned wing,engines/props and a new glass cockpit display. And fitted out with gear they need to be HH's.
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NEXRAD Radar
Corpus Christi, Storm Relative Mean Radial Velocity 1.45 Degree Elevation Range 124 NMI


Member Since: July 3, 2005 Posts: 423 Comments: 127810
Quoting JamesSA:
Current trajectory is one of the most reliable pieces of data we have at this moment. "An object in motion..."


Ridge will continue to build in as we go on through the day. Alex should really begin to feel it in the next few hours. Already see a more westerly component to last few radar and sat images. Its gonna make landfall south of Brownsville, but they will be in the NE quadrant so expect some healthy storm surge and wind along with tornadoes.
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Good afternoon,


Alex looks very strong and lively.......


Im still thinking that 115 mph winds are coming for the coast and everyone in the watch area should be prepared for that. I do believe that the winds were higher than 80 mph for a short time last night but fell when the eyewall collapsed. In any event Alex is still a formidable storm and cant be taken lightly.
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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: 21122

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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.

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