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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1148. Patrap
Quoting midgulfmom:
Pat.. Oh my...we had a camp(Katrina got) on the back bay of Pass Christian and I always begged my parents to stop at Louise's with the pile of shells. BTW we are the same age. Go figure.


Kewl stuff.



Love da beach and used to dine at Annie's a Lot in da summa.
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting Patrap:


Then you can follow along the learning cure..

Cuz a Blind Duck in Bangkok can easily see the dry air in the Systems envelope on the south side.


Picture color coded to show intensity of radar return on rain.. no way to know how much moisture is in the places it is NOT raining..
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Quoting hurricaster:
sarahjola - That's what wondering. Starting to get squeezed by the western high.

it was getting squeezed early this morning. still happening. anyone have a current steering map? thanks in advance:)
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1143. Levi32
The 1pm advisoroy updates position not track. The track won't look like that at 4pm CDT when they update it.
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1141. JamesSA
Quoting Floodman:


I will say he l;ooks to be moving a little W of NW; landfall looks to be south of the border, but not by much...again, this close in there can be any one of a number of last minute jogs in track. Let's just sauy that Brownsville isn't out of the woods for a direct hit...

Floodman, did you see this bizarre looking 1 PM advisory?
Member Since: August 17, 2009 Posts: 0 Comments: 579
1140. GBguy88
Quoting hurricaster:
Closed eye and poleward bound. This could get interesting.


I think the window for Alex to do anything *too* interesting is closing pretty quickly. Relatively shortly, the heat potential is going to drop quite a bit and land interaction will start to become a problem. I see category 2, but I think the eyewall showing such marked improvement could be a "last hurrah" situation. Just my opinion, which is generally not the right one :P
Member Since: August 22, 2008 Posts: 0 Comments: 483
Quoting Floodman:


Yeah, make sure you start that missive with "Long time listener, first time caller"


Thanks, Flood. Gotta go again. Will check back in to watch landfall with y'all.
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YES oz was banned
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Pat.. Oh my...we had a camp(Katrina got) on the back bay of Pass Christian and I always begged my parents to stop at Louise's with the pile of shells. BTW we are the same age. Go figure.
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WHATS THE LATEST
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What did Oz do to get banned?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Levi32:
Dry air is really wrapping around the core....the eyewall is nearly completely cut-off from the surrounding spiral bands.



Kinda groovy looking. Should stop it from strengthening significantly.
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thanks patrap, you guys are awesome, im a learning a little at a time.
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I want to leave and cant make myself leave the computer....... dang it!


The anticipation of every new pic of alex keeps me stuck to my sit. He is looking better and better on visible.....
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RE: 1113

I was wondering the same thing.

Looks like a Cat 2 now.
Member Since: May 17, 2007 Posts: 0 Comments: 631
Of course, but where do the remnants go?
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1128. angiest
MESOSCALE DISCUSSION 1166
NWS STORM PREDICTION CENTER NORMAN OK
0113 PM CDT WED JUN 30 2010

AREAS AFFECTED...MIDDLE TO UPPER TX COAST...SW LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 301813Z - 301945Z

AN ISOLATED TORNADO THREAT IS EXPECTED TO DEVELOP ALONG THE MIDDLE
TO UPPER TX COAST INTO SW LA EARLY THIS AFTERNOON. THE THREAT SHOULD
REMAIN TOO MARGINAL TO WARRANT WW ISSUANCE.

THE OUTER RAINBANDS ASSOCIATED WITH HURRICANE ALEX ARE CURRENTLY
LOCATED IN THE NW GULF OF MEXICO AND WILL MOVE ONSHORE INTO SE TX
AND SW LA THIS AFTERNOON. OBJECTIVE ANALYSIS SUGGESTS THAT LOW-LEVEL
SHEAR GRADUALLY STRENGTHENS WITH SWWD EXTENT FROM SW LA SWWD ALONG
THE TX COAST. THE WSR-88D VWPS ALONG THE UPPER TX COAST SHOW 0-1 KM
SHEAR AROUND 20 KT WHICH IS MARGINALLY SUFFICIENT FOR ROTATING
STORMS. LOW-LEVEL SHEAR MAY INCREASE SOME AS THE HURRICANE MOVES TO
THE WEST BRINGING THE STRONGER LOW-LEVEL WINDS FURTHER INLAND. IN
ADDITION...INSTABILITY MAY ALSO INCREASE ALONG THE COASTS AS SFC
TEMPS CONTINUE TO WARM. THESE TWO FACTORS MAY RESULT IN AN ISOLATED
TORNADO THREAT WITH THE MORE INTENSE CELLS EMBEDDED IN THE OUTER
RAINBANDS OF ALEX.

..BROYLES.. 06/30/2010

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT..
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1127. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting FLdewey:
LMAO... yeah please email the NHC and tell them you know better.


Yeah, make sure you start that missive with "Long time listener, first time caller"
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Quoting fire635:


They updated the current position on the last update, but they only update forecast tracks on the "major updates"... the next major update is at 5pm


Thanks, Fire.
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Expect at least one more pull to the north before land fall they always seem to do that,

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sarahjola - That's what wondering. Starting to get squeezed by the western high.
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1121. Patrap
Use the View/save this image on the Radar bottom
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting katadman:


Ju8st poked my head in for a minute to catch up from this morning. Why is the NHC track showing a SW movement before the WNW move to landfall? From what I've read in the last two pages of the blog, it appears that either that SW movement is already past or that the NHC was mistaken (which would alter the expected point of landfall). Fill me in, brudda.


I will say he l;ooks to be moving a little W of NW; landfall looks to be south of the border, but not by much...again, this close in there can be any one of a number of last minute jogs in track. Let's just sauy that Brownsville isn't out of the woods for a direct hit...
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1119. Levi32
Dry air is really wrapping around the core....the eyewall is nearly completely cut-off from the surrounding spiral bands.

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1118. guygee
Quoting JamesSA:
I was there over 20 years ago and there were many poor people living in makeshift shacks in the bottom of that dry arroyo for miles driving out of the city. When Gilbert came in and spent itself in that area of the Sierra Madres there were many deaths among those living in the dry wash. Most had been unaware anything was even coming.
That sounds really bad. The population has grown a lot since 20 years ago too, according to reliable sources, mostly from former subsistence farmers emigrating out of the countryside trying to scrape up a living in the city.
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1117. JDSmith
Quoting Patrap:


Then you can follow along the learning cure..

Cuz a Blind Duck in Bangkok can easily see the dry air in the Systems envelope on the south side.





What's that? Dry air? Where do you see that?
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1114. fire635
Quoting katadman:


Ju8st poked my head in for a minute to catch up from this morning. Why is the NHC track showing a SW movement before the WNW move to landfall? From what I've read in the last two pages of the blog, it appears that either that SW movement is already past or that the NHC was mistaken (which would alter the expected point of landfall). Fill me in, brudda.


They updated the current position on the last update, but they only update forecast tracks on the "major updates"... the next major update is at 5pm
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could alex ride the coast?
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1112. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Closed eye and poleward bound. This could get interesting.
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hey patrap, i tried posting the same radar you and ike posted. i right clicked the radar and copied the url and pasted it and it didnt come out. what am i doing wrong??
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Quoting Patrap:


Then you can follow along the learning cure..

Cuz a Blind Duck in Bangkok can easily see the dry air in the Systems envelope on the south side.



Looks like dry air is surrounding the eyewall. EWRC?
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On radar, Alex has suddenly become better organized with yellow and red storms appearing around the eye. Category 2 possible.

Member Since: July 8, 2005 Posts: 259 Comments: 24508
One Dropsonde Report a min. preassure of 962mb and the other sonde 81 kts (93mph)at sea level so its near to CAT2 hurricane.
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Don't trust NOGAPS on SW Caribbean storms within a week unless it's corrobated by another model. It often predicts that for most of the hurricane season. It was also predicting a storm trailing Alex since it approached the Yucatan.
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Looking at the Water Vapor, all of the outflow is being pulled northeast along the trough.
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change of direction???,he's moving NW and will not be making landfall north of the border...
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1101. Patrap
Quoting Jedkins01:



just because convection lacks there, doesn't mean its from dry air, the hurricane just isn't producing any lift or convergence there.

Somehow I doubt a PW reading between 2.5 and 3.00 inches throughout the storm has anything to do with dry air... Thats about as much moisture the air can possibly hold...


Then you can follow along the learning cure..

Cuz a Blind Duck in Bangkok can easily see the dry air in the Systems envelope on the south side.

Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting KingofNewOrleans:


I don't think the coast is particularly populated along there. As for flooding, both sides of the Rio Grande Valley could take it pretty hard.


It's going into a good area for landfall. Damage to property should be minimal.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
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Alex seems to have slowed down just a bit over the last hour...about 12mph down from 15.
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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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