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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Quoting AstroHurricane001:


That's almost a cat. 3! Is that flight-level or surface winds?



Looks like some mesocyclones coming into Brownsville...tornado threat.



So the storm hasn't really strengthened in terms of pressure. But is that why NHC didn't update the winds either?


SAB gave out a 5.5, which is CAT3. And these are satellite estimates, not recon data so A: It has to be surface level and B: recon is more accurate because it actually goes inside it rather than looking at it and estimating the intensity based on its appearance.
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Quoting weathermanwannabe:
Too many folks second guessing NHC and Avila who is about the best in the business....NHC is the Official word a few wobbles aside and I am sure they will correct (if need be) later this afternoon but I would not expect any major changes....BBL

Ditto..and it scares people like the post at the end of the last blog "should New Orleans begin evacuating?" Answer: Absolutely not!!
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Quoting IKE:
Brownsville is going to get hammered. It's just too close to miss them.

That blogger that's been on here wishing for a storm. He's fixing to get it.

Good luck....hope everyone is out of harms way.


This is what I've been stressing the most on this storm, the northward trend. Unfortunately for him, he will only get TS force winds lol.
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Quoting AussieStorm:
Evening all... I see we have Hurricane Alex, Could become a Cat 2 just before landfall.
Storm surge of how many ft can be expected from Alex?


Forecast inundation surge






Link
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the original eyewall is trying to strengthen itself... has that ever happened an EWRC reverse itself halfway through and keep the smaller eye while the bigger one goes away
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webcams from Matamoros http://www.matamoros.com/puentes.php
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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)
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Quoting USSINS:



It just might be "significant" to the folks in Brownsville, or even a bit further north.


A hurricane is not a point on a map its affects extend miles away from the center of circulation. Concentric eyewalls are noted pretty clearly on BRO radar.
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Quoting extreme236:
TAFB gave out a T5.0/90kt estimate, so an average of the two agencies would be 95kts.


That's almost a cat. 3! Is that flight-level or surface winds?

Quoting IKE:


Looks like some mesocyclones coming into Brownsville...tornado threat.

Quoting nrtiwlnvragn:


A dropsonde in the eye measured 961mb.


So the storm hasn't really strengthened in terms of pressure. But is that why NHC didn't update the winds either?
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Re#168

Thanks Drak---that explains why NHC is sticking with their cone.
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00z ECMWF developed another Caribbean storm again at 216hr. Probably won't amount to anything. GFS shows an African wave developing 144-192hr range.
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183. IKE
Brownsville is going to get hammered. It's just too close to miss them.

That blogger that's been on here wishing for a storm. He's fixing to get it.

Good luck....hope everyone is out of harms way.
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My short-term, last track for Hurricane Alex based on it's movement and pattern...

Photobucket
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Evening all... I see we have Hurricane Alex, Could become a Cat 2 just before landfall.
Storm surge of how many ft can be expected from Alex?
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Member Since: September 2, 2009 Posts: 130 Comments: 21194
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178. amd
Latest dropsone information from NorthEast Quandrant

Part B: Data For Significant Levels...


Significant Wind Levels...
Level Wind Direction Wind Speed
975mb (Surface) 105° (from the ESE) 80 knots (92 mph)
972mb 105° (from the ESE) 80 knots (92 mph)
965mb 110° (from the ESE) 91 knots (105 mph)
958mb 110° (from the ESE) 88 knots (101 mph)
951mb 110° (from the ESE) 95 knots (109 mph)
941mb 125° (from the SE) 90 knots (104 mph)
932mb 125° (from the SE) 98 knots (113 mph)
915mb 130° (from the SE) 85 knots (98 mph)
882mb 135° (from the SE) 85 knots (98 mph)
842mb 140° (from the SE) 83 knots (96 mph)
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Too many folks second guessing NHC and Avila who is about the best in the business....NHC is the Official word a few wobbles aside and I am sure they will correct (if need be) later this afternoon but I would not expect any major changes....BBL
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Quoting Drakoen:
I see Alex has strengthened and is moving to the northwest. Alex is still feeling the effects of the 500mb longwave trough as seen on water vapor imagery. You can see the ridge behind the trough, the inverted U shape building into the Plains region that will turn the system more Westward.


The question is how far north does it get.
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Quoting reedzone:
Throw the NHC track out folks, this is moving NW and may probably make landfall just south of the borderline. I don't care what maps show, models show, look at the storm!

That's exactly like looking at the XTRAP and saying that will be the final track without taking other forces into consideration.
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174. IKE
Brownsville, Texas (Airport)
Updated: 6 min 43 sec ago
Heavy Rain
81 °F
Heavy Rain Mist
Humidity: 94%
Dew Point: 79 °F
Wind: 22 mph from the NE
Wind Gust: 29 mph
Pressure: 29.61 in (Falling)
Heat Index: 88 °F
Visibility: 2.5 miles
UV: 2 out of 16
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173. IMA
Quoting kmanislander:


IMO.

One of the many reasons to respect your opinion -- you don't speak in absolutes about things which aren't or can't be known :) Always appreciate your take on things, kman
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Thank u dr. Masters. Good morning everyone. Quick question: what is the difference between swells and waves?
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Once a storm gets less than 200 miles from shore, need to stop watching models and maps and watch radar and satellite
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Quoting MiamiHurricanes09:
Yes! Rapid-fire is working again.



I spy, with my little eye... an eye..
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They are probably waiting to see how Alex responds to the ridge later today as a WSW motion is indicated by some fairly reliable models. Although, none have been very reliable with Alex.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
I see Alex has strengthened and is moving to the northwest. Alex is still feeling the effects of the 500mb longwave trough as seen on water vapor imagery. You can see the ridge behind the trough, the inverted U shape building into the Plains region that will turn the system more Westward.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Quoting FLdewey:
My favorite part of this blog is the people who like to say what the NHC should be doing. Really?


I don't get it either, Avila has been forecasting cyclones longer than many on this blog have been alive, he has seen it all. Also, while many were forecasting earlier in the week movement to the north, NHC disregarded those models and stuck to their forecast, so to say they need to stop following the models doesn't make sense.

Off soapbox
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Yes! Rapid-fire is working again.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Good morning all. While the ridge over Texas is still holding strong, an unusual event in Texas considering the season, there are indications that it is beginning to break down. Water vapor imagery over west Texas is showing a return flow from the southwest. This is also confirmed by the shift in winds in Dalhart to a WSW component. The ridges' slow slide east combined with the slow forward motion of Alex suggests a more northerly landfall. This is being confirmed with the more northerly track that Alex has taken over the past 4 hours. Folks in south and central Texas should be alert to flooding conditions that are sure to develop later tonite into tomorrow. Let's all hope that there is no loss of life with this storm.
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My personal forecast. Might be proven wrong, might be proven right. Only time and that trough will determine.

Member Since: July 9, 2008 Posts: 8 Comments: 334
Quoting hurricane23:


There is not going to be any significant shift the subtropical ridge to its north will soon turn alex on a westerly course and possibly towards the sw.


I think it will get pushed SW also but not until it's already over land.
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I will check back later to see how this plays out. Bye for now.
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158. Daveg
He's definitely being stubborn on that NW track right now. He'll have to stall soon and turn directly west to meet the forecast track (or course there is some wiggle room in the cone).

Right now he has a bead dead on Brownsville, but I doubt he makes it that far north....

Then again, sometimes these storms love to defy all logic.
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Time: 14:19:00Z
Coordinates: 24.0667N 95.2167W
Acft. Static Air Press: 842.6 mb (~ 24.88 inHg)
Acft. Geopotential Hgt: 1,298 meters (~ 4,259 feet)
Extrap. Sfc. Press: 978.5 mb (~ 28.90 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 139° at 86 knots (From the SE at ~ 98.9 mph)
Air Temp: 17.0°C (~ 62.6°F)
Dew Pt: 17.0°C (~ 62.6°F)
Peak (10s) Flt. Lvl. Wind: 89 knots (~ 102.3 mph)
SFMR Peak (10s) Sfc. Wind: 65 knots (~ 74.8 mph)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting USSINS:



It just might be "significant" to the folks in Brownsville, or even a bit further north.


By significant shift he means large shift, not important shift..
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Throw the NHC track out folks, this is moving NW and may probably make landfall just south of the borderline. I don't care what maps show, models show, look at the storm!
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Also Alex is deeper pressure wise than all but two of last year's storms. If Alex can knock off a couple of mbs, it will be stronger than all but Bill. (Fred's minimum mb is 958 mb)
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Quoting hurricane23:


There is not going to be any significant shift the subtropical ridge to its north will soon turn alex on a westerly course and possibly towards the sw.



It just might be "significant" to the folks in Brownsville, or even a bit further north.
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NOAA tidal station Texas Coast

NOAA TIDAL STATIONS/CURRENTS
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lol...folks....please don't go by frames, especially off of radar...lol...or you'll be stating its shifted from nw to wnw to nnw every 20 minutes....its a hurricane, that center will wobble...
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TS force winds extend out 200 miles now
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PLEASE DO NOT POST ALTERED IMAGES

Member Since: July 3, 2005 Posts: 426 Comments: 129093
If I were in Brownsville Id be rushing my Preps to completion as the Storm is making headway NNW
Member Since: July 3, 2005 Posts: 426 Comments: 129093

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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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