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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4:00 PM CDT Wed Jun 30
Location: 24.5°N 96.8°W
Max sustained: 90 mph
Moving: W at 13 mph
Min pressure: 959 mb
Member Since: Posts: Comments:
Quoting gbreezegirl:
and all the way to Gulf Breeze/Pensacola


even IKE is getting in on this mess.....

Mobile Radar
Member Since: Posts: Comments:
1645. Titoxd
New advisory up


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...24.5N 96.8W
ABOUT 80 MI...130 KM NE OF LA PESCA MEXICO
ABOUT 105 MI...170 KM SSE OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 13 MPH...20 KM/HR
MINIMUM CENTRAL PRESSURE...959 MB...28.32 INCHES
Member Since: Posts: Comments:
4:00 PM CDT Wed Jun 30
Location: 24.5°N 96.8°W
Max sustained: 90 mph
Moving: W at 13 mph
Min pressure: 959 mb
Member Since: July 1, 2008 Posts: 13 Comments: 7340
1643. Patrap
NEXRAD Radar
Brownsville, Base Radial Velocity 0.50 Degree Elevation Range 124 NMI


Member Since: July 3, 2005 Posts: 421 Comments: 127592
...ALEX HEADING TOWARD NORTHEAST MEXICO WITH 90 MPH WINDS...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...24.5N 96.8W
ABOUT 80 MI...130 KM NE OF LA PESCA MEXICO
ABOUT 105 MI...170 KM SSE OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 13 MPH...20 KM/HR
MINIMUM CENTRAL PRESSURE...959 MB...28.32 INCHES

Member Since: September 23, 2005 Posts: 14 Comments: 10883
Quoting scott39:
I dont think its unrealistic. Isnt Cat 3 115mph?
It would need to intensify quite quickly for it to achieve category 3 intensity, although a possibility, it seems unlikely.
Member Since: September 2, 2009 Posts: 130 Comments: 21091


Quoting RickWPB:


Because Alex is so big it take time to wrap itself up. Thank goodness it's going run out of real-estate... or actually run into real-estate.

thanks!
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I think ADT likes Alex's eye.

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 30 JUN 2010 Time : 191500 UTC
Lat : 24:28:11 N Lon : 96:37:29 W


CI# /Pressure/ Vmax
4.3 / 982.1mb/ 72.2kt


Final T# Adj T# Raw T#
4.3 4.3 5.7

Latitude bias adjustment to MSLP : -0.1mb

Estimated radius of max. wind based on IR :N/A km

Center Temp : -42.9C Cloud Region Temp : -67.9C

Scene Type : EYE

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : MW HOLD
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
Member Since: Posts: Comments:
1637. Patrap
Member Since: July 3, 2005 Posts: 421 Comments: 127592
Quoting TheDawnAwakening2:
Atmos, that vortex message says closed eyewall, it is too late for intensification, he is out of time, out of water. Too bad.


Spoken like a true amnesiac that has forgotten a little system that came to be known as Humberto
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Thank you.The last I heard this morning was they were gonna see what the trough above us was gonna do.They say it may stall.Who knows.LOL!!!!!
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Quoting Tazmanian:
looks like are storm Alex is makeing land fall in the same spot this storm did





any commets
Member Since: May 21, 2006 Posts: 5091 Comments: 114751
Quoting StormSurgeon:


You're right. You getting rained on today? Can't believe Alex is throwing mess all the way up to Mobile.
and all the way to Gulf Breeze/Pensacola
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1631. SeALWx
Quoting StormSurgeon:


You're right. You getting rained on today? Can't believe Alex is throwing mess all the way up to Mobile.


Not much yet today. It's looking like we may get an isolated storm or two this afternoon/evening.
Member Since: April 2, 2010 Posts: 0 Comments: 196
1630. Jax82
Lets all be Thankful this hurricane did not directly hit Texas and is making landfall in a sparsely populated area in Mexico. It could have been a lot worse. And to think we still have July/August/Sept/Oct to go. I'm crossing my fingers we get a break for a while!
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Quoting MiamiHurricanes09:
It should have 95mph winds from what Recon is reporting. Lots of 93mph SFMR readings.


95mph is 82.6 Kt.Which would round to 85 kts,making alex a cat 2,which is reasonable considering this storm is very similar to Dolly in 2008.Right?
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1628. scott39
Quoting MiamiHurricanes09:
LOL, no. Landfall will likely come in 3-6 hours. The strongest Alex will get is category 2, imo.
I dont think its unrealistic. Isnt Cat 3 115mph?
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Quoting CaneWarning:
All I can say is if this is our first storm, I hate to see what the rest of the season will look like. Our little 93L overcame so much just to form. If he didn't cross the Yucatan we'd be dealing with a monster.


yeah, although we have a nice size and strength storm for our first, I'm still kinda surprised that their isn't at least an AOI out there to keep an eye on...not that I am aware of anyways...
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Quoting TheDawnAwakening2:
Atmos, that vortex message says closed eyewall, it is too late for intensification, he is out of time, out of water. Too bad.
Again, ??? There is still another 3-6 hours before landfall. Alex could easily become a category 2.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1625. SeALWx
Quoting mrsalagranny:
Has anyone heard anything else about the low that is suppose to be on the Alabama coast this weekend?


Still no good model agreements on this weekend's weather. Most of the local NWS AFD forecast authors are just pretty much throwing their hands in the air.
Member Since: April 2, 2010 Posts: 0 Comments: 196
1623. RickWPB
Quoting RavensFan:
this storm has the look and pressure of at least a cat 2. why are the winds still not gaining as fast as the pressure is dropping?


Because Alex is so big it takes time to wrap itself up. Thank goodness it's going run out of real-estate... or actually run into real-estate.
Member Since: Posts: Comments:
Quoting TheDawnAwakening2:
Atmos, that vortex message says closed eyewall, it is too late for intensification, he is out of time, out of water. Too bad.

Thank God. It is a very beautiful looking Hurricane :o)!!
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looks like are storm Alex is makeing land fall in the same spot this storm did

Member Since: May 21, 2006 Posts: 5091 Comments: 114751
Quoting Orcasystems:


I am assuming if your within 150 miles north of the landfall.. you might consider it a monster now .


Probably, but he's just a baby cane.
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Quoting StSimonsIslandGAGuy:
MiamiHurricanes09 is right---30 mins isn't old, Taz.



sorry my bad
Member Since: May 21, 2006 Posts: 5091 Comments: 114751
Quoting TheDawnAwakening2:
Atmos, that vortex message says closed eyewall, it is too late for intensification, he is out of time, out of water. Too bad.


I disagree, he still has a few hours and can continue to intensify until then

Charley intensified all the way up until the moment he made landfall
Member Since: March 10, 2010 Posts: 1 Comments: 7376
Quoting SeALWx:

No posts are truly worthless, it's just that some are worth less than others! :)


You're right. You getting rained on today? Can't believe Alex is throwing mess all the way up to Mobile.
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Quoting MILLERTIME1:
San Fernandos population is 29,171! Hope they are prepared!


I'm sure they've been following it all day on their iPhones.
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Quoting KORBIN:
Since we know what's going on with Alex,

What is our 4th of July going to look like for the rest of the Gulf Coast?

Any Spurious Lows? Blobs? Invests? Aoi?
Has anyone heard anything else about the low that is suppose to be on the Alabama coast this weekend?
Member Since: Posts: Comments:
Quoting CaneWarning:
All I can say is if this is our first storm, I hate to see what the rest of the season will look like. Our little 93L overcame so much just to form. If he didn't cross the Yucatan we'd be dealing with a monster.


I am assuming if your within 150 miles north of the landfall.. you might consider it a monster now .
Member Since: Posts: Comments:
Member Since: February 19, 2007 Posts: 0 Comments: 239
Atmos, that vortex message says closed eyewall, it is too late for intensification, he is out of time, out of water. Too bad.
Member Since: Posts: Comments:
Quoting scott39:
Alex has got at least 6 more hours over water. I say a Cat 3 at landfall easy!
LOL, no. Landfall will likely come in 3-6 hours. The strongest Alex will get is category 2, imo.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Ok then Alex (Alejandro). Just don't hurt anybody else, that's all I'm asking. Keep the flooding down to a bare minimum and get a handle on those tornadoes.
Photobucket
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San Fernandos population is 29,171! Hope they are prepared!
Member Since: Posts: Comments:
All I can say is if this is our first storm, I hate to see what the rest of the season will look like. Our little 93L overcame so much just to form. If he didn't cross the Yucatan we'd be dealing with a monster.
Member Since: Posts: Comments:
Straight west now and cranking along :)



AOI
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Quoting StSimonsIslandGAGuy:
I remember the talk about integrated kinetic energy index when Ike was in the Gulf---what is the integrated kinetic energy index for Alex?


TS force 67 TJ, HU force 3 TJ
Distructive Potential Rating wind = 2.2, surge/waves = 4.2



Click on image to view original size in a new window



Member Since: September 23, 2005 Posts: 14 Comments: 10883
1601. scott39
Alex has got at least 6 more hours over water. I say a Cat 3 at landfall easy!
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1600. SeALWx
Quoting Tazmanian:




old


It's really not that old, Taz. Lots of vortex posts are in the ~30min age range.
Member Since: April 2, 2010 Posts: 0 Comments: 196
Quoting HaboobsRsweet:
Alex is causing all kinds of issues in Southern MS. As I said we have had 5 inches in a short time, lots of flooding streets and winds did get up to 28kts (yes not that impress on the winds but good enough).
Thank goodness I cut the grass yesterday..I think I hear it growing...
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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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