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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The long term motion however is NW
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Quoting Patrap:


Belay the OZ factor.

Its not important to the Scheme of things.

Its a distraction




Its entertaining



Hes back on




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Quoting stoormfury:
it appears that Alex is now moving NNW and could now threaten the southern part of Texas with hurricane force winds


Really? Wow! Look out Galveston.....sheesh come on man, get real!!
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545. xcool
BAD Alex
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Good burst of intensification. Maybe up to 100mph by 2pm update
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Member Since: July 3, 2005 Posts: 421 Comments: 127566
Quoting AstroHurricane001:


Maybe, but a hurricane is a complex co-interactive teleconnected "object" that has plenty of influences in a fluid atmosphere.
Sure. Lots of data points to feed complex speculation, but 'where it is presently going' shouldn't be dismissed just because it is simple. That is just arrogance.
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Looks like it wants to turn more towards the WNW
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Quoting NRAamy:
This is when the monkey starts to freak out... Life safety always trumps other concerns...

exactly...like Pat said, work your plan if you haven't already done so....


This person with the issue of being at work until 5...maybe they aren't able to leave at will due to the potential loss of a job. Yes, it's a bad situation to be in, but consider the employer when someone says "You're making a bad call, I'm leaving." That warrants a termination from a lot of bosses. Not really worth it for a less than major hurricane if you don't have another job on hand.
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Question:

Should I worry that this line of storms headed right for me has a mesocyclone mark on it? (R9)
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Quoting MiamiHurricanes09:
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


That high is still building down and moving SE. NHC is right on this - expect a sharp turn to the west as we go through the day. Northern fringe of the eyewall make scrape Brownsville.
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Quoting WaterWitch11:
up until 2am last night............argh...

what happen to rob carver? what is a beta effect?
A write up from NOAA about hurricane motion and some description of the beta effect: http://www.aoml.noaa.gov/hrd/hrd_sub/motion.html
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Belay the OZ factor.

Its not important to the Scheme of things.

Its a distraction
Member Since: July 3, 2005 Posts: 421 Comments: 127566
Quoting watchingnva:
i cant get oz reloaded...says hes on air....but it just keeps spinning and buffering...


I have the same issue. I think Alex got him.
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534. IKE
Heading on in....WNW to NW movement....still...

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i cant get oz reloaded...says hes on air....but it just keeps spinning and buffering...
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Quoting TampaTom:


You know that... I know that...

You know there are a lot of folks who are just making the connection.

The window is closing... move quickly or forever hold your peace...


YEppars....
Member Since: July 3, 2005 Posts: 421 Comments: 127566
Quoting GBguy88:


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


I already made an estimate of 110 mph.
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Quoting CaneWarning:
Has anybody been able to get Oz back up?

Nope
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it appears that Alex is now moving NNW and could now threaten the southern part of Texas with hurricane force winds
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Tryin to call OZ.
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Quoting 1900hurricane:

Typically this is the case, but Alex already had multiple radii of wind maxima prior to the development of eyewall(s), so the development of multiple eyewalls and then replacement cycles as they battled against each other isn't too far fetched. Alex also does have a pressure more typically found in a major hurricane as well.
Good point.. Pressure is pretty low for the wind speed.
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Quoting Patrap:
Folks should have been working their Hurricane Plan 36 Hours ago.


You know that... I know that...

You know there are a lot of folks who are just making the connection.

The window is closing... move quickly or forever hold your peace...
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Member Since: July 3, 2005 Posts: 421 Comments: 127566
Im still here
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523. xcool
he did take a wnw back to NW
Member Since: September 26, 2009 Posts: 2 Comments: 15620
ALEX ADDS rapid Scan loop
Member Since: July 3, 2005 Posts: 421 Comments: 127566
This is when the monkey starts to freak out... Life safety always trumps other concerns...

exactly...like Pat said, work your plan if you haven't already done so....
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Has anybody been able to get Oz back up?
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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....


Quoting KingofNewOrleans:


Brownsville is actually about 15 miles inland. I don't know know what the closest coastal station in NE Mexico is.


I've been keeping an eye on Port Isabel.
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That is a pretty big weakness in the Highs... why isn't the storm feeling this more... if the storm continues to deepen would it feel the weakness and pull to the North Northeast?
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Quoting Hardcoreweather2010:


horrible data issues down there so just try back a little later

dramatic he drove into the flodded road said this is itchy and oh oh ... but now on air again and still no image. someone should update him on the storm track so he can take cover.
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Quoting JamesSA:
Current trajectory is one of the most reliable pieces of data we have at this moment. "An object in motion..."


Maybe, but a hurricane is a complex co-interactive teleconnected "object" that has plenty of influences in a fluid atmosphere.
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Quoting earthlydragonfly:


Im no met but I believe that Eye wall replacement cycles are normally found in well developed hurricanes of cat 3 or higher..

Typically this is the case, but Alex already had multiple radii of wind maxima prior to the development of eyewall(s), so the development of multiple eyewalls and then replacement cycles as they battled against each other isn't too far fetched. Alex also does have a pressure more typically found in a major hurricane as well.
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514. FLMom
My sister is in Los Fresnos and said it's already starting to flood.
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Quoting NRAamy:
TT's crazy monkey is on it....


This is when the monkey starts to freak out... Life safety always trumps other concerns...
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Pat there is serious flooding in the lakeview area right now and all across metro New Orleans..I just received 1.23 inches of rain in about 33 minutes..incredible
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Quoting GBguy88:


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


Brownsville is actually about 15 miles inland. I don't know know what the closest coastal station in NE Mexico is.
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Folks should have been working their Hurricane Plan 36 Hours ago.
Member Since: July 3, 2005 Posts: 421 Comments: 127566
I swear Alex has taken a northward movement again!
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Quoting Thundercloud01221991:
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


Covering the royal hiney, from the NHC. Just in case Alex pulls some more tricks.

THIS TRACK SHOULD
BRING THE CORE OF THE HURRICANE TO THE COAST WITHIN THE WARNING
AREA
LATE TONIGHT OR EARLY THURSDAY.
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Quoting drg0dOwnCountry:
omg stream is off air now?


horrible data issues down there so just try back a little later
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Quoting 1900hurricane:
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!


Here we go. Now is when the weather will begin to deteriorate along Texas and Mexico.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Somewhere over the Rainbow is appropriate Id say..

Member Since: July 3, 2005 Posts: 421 Comments: 127566
503. xcool
still nw
Member Since: September 26, 2009 Posts: 2 Comments: 15620
TT's crazy monkey is on it....
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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....


yea he needs to tell his boss that it is very possible if he makes them stay til 5pm, they could be stranded there; conditions are already bad there, imagine what they will be like in another 5 h ours
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Quoting Hurricanes101:
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


Last couple of frames it has been. Looking for any indication that the ridge is taking over.
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my god brownsville going to get slammed
Member Since: August 11, 2008 Posts: 3 Comments: 1570
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.
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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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