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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2548. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
Check this link out:

Link
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The NHC had Alex pegged pretty good since day one on June 25.

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Quoting Patrap:
Folks worry about Cat Numbers like Nannies do children.



Its the "Impact" that counts always.

Not some tired old SSS thats so outmoded it creates more havoc than it does good half the time.

And nothing magical Happens at "landfall" save for someone saying.."I called it", too.

Come Landfall, Half the storm has impacted the coast.

Focus on what the Storm is doing..not where its been as well.

WooooHoooo Can't help but LOVE this post. Pat is my new HERO.....LOL
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2544. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting victoriahurricane:


105%? *wink*

yah well its covering the pacific basin too
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thanks for telling me where i can see Oz, katy and Geoffery too. LOL! i'll check him out later. gotta get the fam fed.
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Quoting AlexEmmett:

while 60% is still over water it just that big


105%? ;)
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the pressure is so low becuase Cyclone oz lets pressure out of his tires earlyer
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Quoting victoriahurricane:
Only 97 mph winds? I don't get it. Btw how much fuel does the recon plane have? Does it have to return to base, was that it's final pass?


I think. They're probably running low now.

Been out there for a while.
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Only 97 mph winds? I don't get it. Btw how much fuel does the recon plane have? Does it have to return to base, was that it's final pass?
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alright guys, what is causing the pressure to be so low?
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Quoting leo305:
45% of the storm is now over land..

while 60% is still over water it just that big
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Quoting Unfriendly:
so btw... Oz somehow found a tornado in the hurricane, and is looking to chase it... looks like his stream died...

One of the comments on his ustream chat made me squirt some coffee...

"7:51 ustreamer-73341: Driving your car into a tornado during a hurricane is counterproductive."


that's awesome! LOL!
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2532. Patrap
Folks worry about Cat Numbers like Nannies do children.



Its the "Impact" that counts always.

Not some tired old SSS thats so outmoded it creates more havoc than it does good half the time.

And nothing magical Happens at "landfall" save for someone saying.."I called it", too.

Come Landfall, Half the storm has impacted the coast.

Focus on what the Storm is doing..not where its been as well.

Member Since: July 3, 2005 Posts: 428 Comments: 129903
2531. Asta
DVORAK- G.O.M.
Member Since: Posts: Comments:
Quoting Clearwater1:
Any insurance agents care to field this question?
If a storm is labeled a "Tropical storm" when it hits your home, does your deductible fall under the category of simply wind damage? Conversely if it is labeled a "hurricane" will you be forced to use the "hurricane" deductible. Big cost difference. (at least in FL) The reason I ask, is because if what I mention is true, then it is very important in marginal storms as to how they are labeled coming inland. Anyone?


IDK answer to that one, but how crazy is this? my mom told me that her insurance company just recently sent out a letter that if there is oil in the water/hurricane damage on your home, then it won't be covered by flood insurance or wind and hail. so basically, any hurricane or hurricane related flood damage will not be covered in Louisiana. I forgot which company she said they are with, but it's a big "fancy" one. I told her she must have misunderstood, but she swears that's what it said.
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2529. leo305
45% of the storm is now over land..
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97 mph winds
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2527. centex
No one noticed radar on outer band convection in afternoon does not match Sat convection? This is SAT anomaly on land falling cane. New to me, no one explained this before.
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so btw... Oz somehow found a tornado in the hurricane, and is looking to chase it... looks like his stream died...

One of the comments on his ustream chat made me squirt some coffee...

"7:51 ustreamer-73341: Driving your car into a tornado during a hurricane is counterproductive."
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2525. DirtDan
Winds and storm surge will be a little worse than most people think. Pressure dumping fast on it. Alex is freaking massive......
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Surface winds were a bit high on that center pass, may see the pressure on the vortex message down to 947-949
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Quoting neonlazer:
234030 2420N 09717W 8433 01046 9497 +214 +202 105011 019 033 004 00

949.7mb!!!!

Didn't beat the record..sad..
First of all no vortex message. Second of all we are still 70 minutes from landfall.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
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23:40:30Z 24.333N 97.283W 843.3 mb
(~ 24.90 inHg) 1,046 meters
(~ 3,432 feet) 949.7 mb
(~ 28.04 inHg) - From 105° at 11 knots
(From the ESE at ~ 12.6 mph) 21.4°C
(~ 70.5°F) 20.2°C
(~ 68.4°F) 19 knots
(~ 21.8 mph) 33 knots
(~ 37.9 mph) 4 mm/hr
(~ 0.16 in/hr) 19.1 knots (~ 22.0 mph)
173.7%

WOW
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Alex looking immpressive and moving as forecast.NHC has done a great job so far!
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Quoting neonlazer:
234030 2420N 09717W 8433 01046 9497 +214 +202 105011 019 033 004 00

949.7mb!!!!

Didn't beat the record..sad..


Wait for the Vortex Data Message. Might be a tad lower.
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Quoting neonlazer:
234030 2420N 09717W 8433 01046 9497 +214 +202 105011 019 033 004 00

949.7mb!!!!

Didn't beat the record..sad..

by 3 mbs
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Quoting KatyTexasNewbee:
Link


Thank you!
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949.7mb.

000
URNT15 KNHC 302348
AF304 1201A ALEX HDOB 55 20100630
233830 2426N 09718W 8442 01101 9571 199 188 083069 077 078 010 03
233900 2425N 09718W 8430 01091 9543 211 188 079050 056 055 003 03
233930 2423N 09718W 8429 01075 9523 214 192 079042 044 042 004 00
234000 2421N 09718W 8423 01065 9507 213 197 078031 036 036 003 00
234030 2420N 09717W 8433 01046 9497 214 202 105011 019 033 004 00
234100 2418N 09717W 8423 01061 9501 215 207 214010 012 030 003 00
234130 2417N 09716W 8438 01050 9505 222 210 240015 020 028 003 03
234200 2415N 09716W 8434 01063 9515 218 213 260035 043 044 005 03
234230 2414N 09716W 8434 01091 9542 222 217 260055 059 062 007 03
234300 2413N 09716W 8434 01117 9990 190 999 258070 074 085 019 05
234330 2411N 09716W 8424 01173 9990 174 999 266077 083 085 028 01
234400 2410N 09716W 8431 01194 9990 174 999 271081 083 079 035 05
234430 2408N 09716W 8424 01239 9990 168 999 269080 082 075 026 05
234500 2407N 09716W 8426 01259 9990 168 999 268072 075 066 015 01
234530 2405N 09716W 8433 01270 9762 171 171 268069 070 063 012 01
234600 2404N 09716W 8431 01287 9771 182 182 269064 065 061 008 00
234630 2402N 09716W 8431 01298 9784 180 180 271062 062 060 009 00
234700 2401N 09716W 8428 01311 9796 180 180 272059 060 060 008 00
234730 2359N 09716W 8433 01318 9806 182 179 274057 057 057 007 00
234800 2358N 09716W 8434 01324 9816 182 179 274055 056 056 008 00
$$
;


Member Since: September 2, 2009 Posts: 130 Comments: 21194
2515. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting KatyTexasNewbee:

Cell tower is out..


Katy...I think he fell asleep as he has been up for 40 hours...that's what they said.
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234030 2420N 09717W 8433 01046 9497 +214 +202 105011 019 033 004 00

949.7mb!!!!

Didn't beat the record..sad..
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ike was pushing a category 4 storm surge... big difference.
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Quoting GeoffreyWPB:


The Emerald City :)

hahaha good one
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2510. Patrap
Quoting Asta:
2486. Patrap
Do ya' think,
that there Convective
thing a ma bob
will make it up here to S.E. LA tonight?


Thats a hard thing to say..its a LONG way down there.

Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting truecajun:
where do i go to see Oz?


The Emerald City :)
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2508. Asta
2486. Patrap
Do ya' think,
that there Convective
thing a ma bob
will make it up here to S.E. LA tonight?
Member Since: Posts: Comments:
Quoting PcolaDan:


Can't fly into foreign airspace without permission ahead of time probably.

Screw that theyll be to afraid to fly into a cane with a fighter jet
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Any insurance agents care to field this question?
If a storm is labeled a "Tropical storm" when it hits your home, does your deductible fall under the category of simply wind damage? Conversely if it is labeled a "hurricane" will you be forced to use the "hurricane" deductible. Big cost difference. (at least in FL) The reason I ask, is because if what I mention is true, then it is very important in marginal storms as to how they are labeled coming inland. Anyone?
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where do i go to see Oz?
Member Since: Posts: Comments:
2503. leo305
Quoting neonlazer:

This next punch might be a record breaker...


Quoting WPBHurricane05:
Whats the lowest pressure for a June hurricane? 946 mb?


yes, Alex as of the last update (a little over an hour ago) had a pressure of 950MB
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2502. xcool
yeah 946 June hurricane
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting GeoffreyWPB:
Is Oz broadcasting live now?

Cell tower is out..
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2500. bappit
Quoting AstroHurricane001:
Let's take a look at a hurricane size comparison.

Emily, cat. 3:



Ike, cat. 2:



Alex, TS (outdated, I know):



So, given that Hurricane Ike was about the same size of Alex, had a higher central pressure at landfall, had about the same windspeed, and end up with a 22-ft maximum storm surge, the question is why is Alex expected to deliver what appears to only be a 5-ft maximum surge prediction in south Texas?



Ike had time to build a wave of water that traveled across the northern Gulf Coast from the Florida panhandle to the Texas coast. That wave of water was 6 to 8 feet above sea level if I remember correctly in Lousiana. Also, the coast off of Galveston is quite shallow. The energy of the storm was not expended stirring up water at any great depth as it made landfall. The Gulf from Corpus on south drops off much more sharply.
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Whats the lowest pressure for a June hurricane? 946 mb?
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2498. Patrap

012
WGUS54 KBRO 302345
FFWBRO
TXC061-010345-
/O.NEW.KBRO.FF.W.0022.100630T2345Z-100701T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BROWNSVILLE TX
645 PM CDT WED JUN 30 2010

THE NATIONAL WEATHER SERVICE IN BROWNSVILLE HAS ISSUED A

* FLASH FLOOD WARNING FOR...
SOUTHERN CAMERON COUNTY IN DEEP SOUTH TEXAS.

LOCATIONS AFFECTED INCLUDE...
OLMITO.
PORT ISABEL.
SAN BENITO.
BROWNSVILLE.

* UNTIL 1045 PM CDT

* AT 638 PM CDT...SEVERAL AREAS OF BROWNSVILLE AND SOUTHERN CAMERON
COUNTY WERE REPORTING ROADWAYS UNDER WATER. RAINFALL AMOUNTS OF 4 TO
6 INCHES WITH ISOLATED AMOUNTS NEAR 8 INCHES HAVE OCCURRED TODAY. AN
ADDITIONAL 2 TO 4 INCHES OF RAIN CAN BE EXPECTED THIS EVENING OVER
THE WARNED AREA AS RAIN BANDS ASSOCIATED WITH HURRICANE ALEX
CONTINUE TO AFFECT THE AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE ROAD.
THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY.
MOVE TO HIGHER GROUND.

DON'T BECOME A STATISTIC. TURN AROUND...DON'T DROWN!
Member Since: July 3, 2005 Posts: 428 Comments: 129903

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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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