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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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: http://rammb.cira.colostate.edu/ramsdis/online/loop_timestamp_640.asp?data_folder=rmtc/rmtcsasec5ir 404
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting MiamiHurricanes09:
The city of Brownsville might receive some hurricane force winds if Alex does move through the northern portion of the NHC cone.



I estimate that Brownsville will receive max. winds of 85 mph (135 km/h) and gusts up to 110 mph (175 km/h).
Member Since: August 30, 2008 Posts: 8 Comments: 2835
296. Asta
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Quoting AussieStorm:

I am using firefox, just tried chrome, still nothing


Probably has a cap on total number of participants and is full..
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294. IKE
Quoting MiamiHurricanes09:
Location?


Brownsville,TX.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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.
Looks to be moving between NW and NNW. Looking more and more likely that we're in for a Mexico/Texas border landfall, for the time being.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
If long range radar is picking up those yellows and organges on the NE quad of the eyewall, you know there is some serious rain and wind going on in there
Member Since: July 14, 2008 Posts: 1 Comments: 9630
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.
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Quoting btwntx08:
man it is raining so hard right now
Location?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting WPBHurricane05:


Only took me a minute or two. Maybe try a different web browser (Internet Explorer or Firefox)?

I am using firefox, just tried chrome, still nothing
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Texas a state of Extremes, we are either in severe drought or big time flooded.
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Quoting AstroHurricane001:


The models that move the storm WSW also leave behind a stable ULL in the BOC, which would cause flooding in NOLA.



If Alex can pull itself together and strengthen to a high-end cat. 2, I wouldn't be surprised to see 20+ ft surge.

And the Chances of this????
Don't forget it's all fun and games for the people on the board who think hurricanes are cool..it the people who lives their lives and property that are affected and they have to plan and madly prepare if something like this did happen..
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Quoting AussieStorm:

I updated my flash but still nothing.
How long does it take for the chat room to appear?


Only took me a minute or two. Maybe try a different web browser (Internet Explorer or Firefox)?
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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.
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I hope the storm not stalls again or wobbles NE
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Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting btwntx08:
man it is raining so hard right now
It's only just begun for you....Good Luck!
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Quoting Ossqss:


Are those actually 30-ft waves threatening to come ashore on the Texas-Mexico border?
Member Since: August 30, 2008 Posts: 8 Comments: 2835
How do you change your avatar?
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TOrnado warning 1

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1022 AM CDT WED JUN 30 2010

TXC061-301545-
/O.CON.KBRO.TO.W.0007.000000T0000Z-100630T1545Z/
CAMERON-
1022 AM CDT WED JUN 30 2010

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1045 AM CDT FOR
SOUTHEASTERN CAMERON COUNTY...

AT 1021 AM CDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 9 MILES WEST OF PORT ISABEL...MOVING SOUTHWEST AT 50 MPH.

THE TORNADO WILL BE NEAR...
DEL MAR HEIGHTS.
BROWNSVILLE.
RANCHO VIEJO.

Member Since: January 24, 2010 Posts: 0 Comments: 529
Quoting WPBHurricane05:


I had to refresh it before it worked for me. Make sure your flash is up to date too.

I updated my flash but still nothing.
How long does it take for the chat room to appear?
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270. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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.
At least it looks like the extra-tropical low that GFS has been forecasting will prolly be weaker than it was calling for or non-existent. Other models do not have it and the GFS trend, run to run, has been weaker for every run in the last day.

Was calling for days of 30 knots winds from the SE, which would push more oil into places it hasn't been seen yet and would generate big waves to thwart any remediation efforts, too.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
267. IMA
Great pics, Randy. That must be a hell of an experience! Thanks for sharing :)
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try www.7674u.com
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Quoting AussieStorm:

I can't get into the chat room.


I had to refresh it before it worked for me. Make sure your flash is up to date too.
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Quoting btwntx08:
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1008 AM CDT WED JUN 30 2010

THE NATIONAL WEATHER SERVICE IN BROWNSVILLE HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHEASTERN CAMERON COUNTY IN DEEP SOUTH TEXAS


How are conditions in Brownsville?
Member Since: August 30, 2008 Posts: 8 Comments: 2835
The city of Brownsville might receive some hurricane force winds if Alex does move through the northern portion of the NHC cone.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting JamesSA:
The motion of the eye on radar is steady, not wobble.

And, if you extrapolate the movement it goes ashore right near the mouth of the Rio Grande at a disturbing angle.

I liked yesterday's track into La Pesca much better! This is trouble if this trend continues.


Can't remember what storm but it hit the Rio Grand at just the wrong angle flooded a long way up stream.
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Guys, the models were hinting that Alex could reach 24N before passing through 96W. Maybe they were expecting this to happen.

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Quoting PensacolaDoug:
Yea I'm watching him along with 51 others.



xtremehurricanes.com

I can't get into the chat room.
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Quoting SouthDadeFish:
Not sure if this has been posted but recon found 80 knots in the NE eyewall from a dropsonde:

975mb (28.79 inHg) Sea Level (Surface) 26.2°C (79.2°F) 26.1°C (79.0°F) 105° (from the ESE) 80 knots (92 mph)


Likely to be what the 2 pm is going to be imo. A 90 mph hurricane is what recon is showing.
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I am sure I'm a late adopter but the iphone option Wunderground added is awesome. Thanks guys.
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Quoting mtyweatherfan90:
Wow! Over 15 inches of rain!



HOLY COW, Alex's 3 inch rain swath extends from Mexico to the Florida Panhandle, and it looks to dump 7 inches of rain at the Texas-Louisiana border at the coast ALL THE WHILE it makes landfall in Mexico! By contrast, Alex's rain swath is 7 times wider than Ike's in terms of rainfall over 3 inches. Also, Ike only dropped 5 inches of rain at the coast on the Texas-LA border, but it made landfall much closer to that location.

Member Since: August 30, 2008 Posts: 8 Comments: 2835
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Yea I'm watching him along with 51 others.



xtremehurricanes.com
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248. IKE
Quoting JamesSA:
The motion of the eye on radar is steady, not wobble.

And, if you extrapolate the movement it goes ashore right near the mouth of the Rio Grande at a disturbing angle.

I liked yesterday's track into La Pesca much better! This is trouble if this trend continues.


Looks headed right near the Mexico/Texas border, for now. It's almost to the point it doesn't matter if it bends back west.
Member Since: June 9, 2005 Posts: 23 Comments: 37858

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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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