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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RI

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2447. angiest
Quoting SouthDadeFish:
950 millibar category two hurricane. Thats not something you see everyday.


Two years ago...
Member Since: August 26, 2006 Posts: 16 Comments: 4766
BRO issues Tornado Warning for Cameron [TX] till 6:45 PM CDT ...* AT 632 PM CDT...EMERGENCY MANAGEMENT OFFICIALS REPORTED A TORNADO NEAR THE INTERSECTION OF ROBIN HOOD AND BOCA CHICA IN BROWNSVILLE...MOVING WEST AT 35 MPH.
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oh dear! that is serious!
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Impressive eye for any category.

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Xcool
a wake up call my butt this is truelly a monster
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950 millibar category two hurricane. Thats not something you see everyday.
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So where is this live Web Cam everyone is talking about seeing Oz on?
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2439. centex
Is it going to bury itself like many do into mexican mountains? If so a lot less rain in Texas, especially central or NE.
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Quoting Stormchaser2007:
Looks like recons going home.
They should stay there to check its intensity at land fall.
Member Since: July 31, 2008 Posts: 0 Comments: 730
2437. Asta
Goes G.O.M. Rainbow..
Alex has a far reach
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2435. Patrap
Pinhole eye,Pinhole eye,Pinhole eye,Pinhole eye.



Member Since: July 3, 2005 Posts: 426 Comments: 128667
Are my peeps seeing this correctly? Is Alex a Cat 2?
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At this point start the countdown till a possible cat 3 record
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2432. angiest
I'm having a hard time seeing any real movement in the last few radar frames.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Alex is probably the best looking Category 2 storm I've ever seen, simply beautiful to look on the visible!
Member Since: July 1, 2008 Posts: 13 Comments: 7396
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Quoting TampaSpin:
I have 6 live feeds on my site if anyone is wanting! I can't post the link for getting banned but, you can follow it from my WU blog.


Nice, Tampa.
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2428. xcool
Alex just Wake-Up Call
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Quoting bappit:

It is a large storm. I'd like to see the Integrated Kinetic Energy--IKE, not to be confused with Ike which also was large. A Hurricane Hunter plane reported a secondary wind maximum, and it was thought by some that the small eye would disappear. This arrangement helped spread the energy around. A plot of pressure gradient across the storm would also be interesting to see.
thanks for the info:)
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2426. BDAwx
looks a little bit like Alex is trying to form concentric eyewalls
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2425. bappit
Quoting AstroHurricane001:
Um, I think we should take a closer look at the surge expected. Like I said the surge could be worse than Ike's. Not sure if this is a glitch, but the NHC SLOSH model shows a 90% chance of storm surge higher than 2 feet from the Texas-Mexico border to the Texas-Louisiana border!!

We have a coastal flood warning for the Galveston area.
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2424. xcool
we go see more gulf storm .i have that feel..
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2423. Asta
Wow- look at the clouds that Alex is spinning off the Yucatan...
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2422. bappit
Quoting Levi32:


Pinhole eye is a very special term reserved for eyewalls 5nm across or less. An eyewall of 10 miles across is pretty common for intense Atlantic hurricanes. Don't overuse the term.

Good advice.
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Um, I think we should take a closer look at the surge expected. Like I said the surge could be worse than Ike's. Not sure if this is a glitch, but the NHC SLOSH model shows a 90% chance of storm surge higher than 2 feet from the Texas-Mexico border to the Texas-Louisiana border!!
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting Weather456:
What is puzzling is that Alex's pressure kept dropping yet winds increasing very slowly.


probably due to his size

While the pressure is very low, the pressures are evenly distributed; there are no real huge pressure drops from one recon observation to the next

In other words we are seeing a ton of areas with pressures in the 980s, 970s and 960s with this storm; therefore the difference in pressure is not as impressive

In storms with stronger winds we see recon go from 981mb and then on their very next observation it shows 970mb or something like that; causing stronger winds
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Hello WU,
Always lurking and listening. Went to the live Web Cam, which I believe is Oz? It is a kewl adventure he is on, and a passion he obviously has. However, the most discouraging aspect I saw/read were all the people making jokes and crude statements about his trip. Just saddens me, how people rip apart others when they are probably stuck to their chairs/computers and do not follow their passion, whatever they may be! Sad Sad Sad
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BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
622 PM CDT WED JUN 30 2010

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHERN GALVESTON COUNTY IN SOUTHEAST TEXAS...

* UNTIL 645 PM CDT

* AT 612 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS TORNADO JUST OFF
THE COASTLINE WEST OF 61ST STREET. POLICE DEPARTMENT REPORTED A WATERSPOUT
WITH THIS STORM. IT IS MOVING WEST NORTHWEST AT 15 MPH.

* LOCATIONS IN THE TORNADO WARNING INCLUDE BUT ARE NOT LIMITED TO
TIKI ISLAND...MOODY GARDENS...GALVESTON STATE PARK...JAMAICA
BEACH...HITCHCOCK GALVESTON ISLAND AND BAYOU VISTA.
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Quoting Weather456:
What is puzzling is that Alex's pressure kept dropping yet winds increasing very slowly.

its CDO is so big that the wind has trouble catching up with the pressure drops
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Absolutely beautiful.

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More hot towers:

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2413. bappit
Quoting sarahjola:
well, the fact is that everybody thought that if Alex sat over water for a long time that he would be a cat. 3, also the pressure drop says different than the winds. while i have been reading for the past 24 hrs. that this should be a cat.2 with the pressure it has. plain and simple that Alex is not as strong as everyone thought it could be given the conditions. my statement was based on what i have read on this blog. as my comment stands it was opinion. i didn't say anything was a fact. i also asked a question. can you talk about why it didn't get stronger than it is right now? thanks in advance:)

It is a large storm. I'd like to see the Integrated Kinetic Energy--IKE, not to be confused with Ike which also was large. A Hurricane Hunter plane reported a secondary wind maximum, and it was thought by some that the small eye would disappear. This arrangement helped spread the energy around. A plot of pressure gradient across the storm would also be interesting to see.
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2410. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128667
Quoting AlexEmmett:
Saffir-Simpson
Hurricane Scale
Category
Pressure
mb
Winds
mph
Depression -- <39
T. Storm -- 39-73
Hurricane 1 > 980 74-95
Hurricane 2 965-980 96-110
Hurricane 3 945-965 111-130
Hurricane 4 920-945 131-155
Hurricane 5 155
Effects and Damage Estimates.


The Saffir-Simpson Hurricane Wind Scale

Excerpt:

Earlier versions of this scale – known as the Saffir-Simpson Hurricane Scale – incorporated central pressure and storm surge as components of the categories. The central pressure was used during the 1970s and 1980s as a proxy for the winds as accurate wind speed intensity measurements from aircraft reconnaissance were not routinely available for hurricanes until 1990.
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if this hurricane had 12-24 hours more over water we would have been dealing with a major hurricane
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Quoting Weather456:
What is puzzling is that Alex's pressure kept dropping yet winds increasing very slowly.


It's been that way with Alex all along. Just a large system taking a long time to spin up in response to pressure falls.
Member Since: August 19, 2006 Posts: 0 Comments: 15842
2406. xcool
look stalla to me on damm rader
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Quoting Stormchaser2007:
Just maxed out my photobucket account
lol
Lol, really? I've only saved a few. What I did do is save this blog and when I want to look back at them I just come back here.
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Alex on June 12th

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2403. xcool
angiest lol .
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Alex not stalling is he? like someone said last night"its like he's taking a deep breathe." is it still unlikely that Alex will ride the coast?tia:)
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2401. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128667
Quoting Stormchaser2007:


Man, this storm just keeps shedding its inner eyewalls, layer upon layer.

Quoting Stormchaser2007:
Slowing a bit.



It's in the process of performing a retrograde loop smaller than its eye.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting 1900hurricane:
Recon is going in AGAIN?! How many center passes is this going to be???
Probably one more just so they can break the record :P
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2398. centex
It's been interesting watching sat versus radar on the outer bands in TX and LA. The Sat and Radar do not match like they normally do.
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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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