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 Patrap:
NEXRAD Radar
Brownsville, Vertically Integrated Liquid Range 124 NMI



"Liquid" is not the same as Vapor...
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Quoting MarathonZiggy:
So, is it safe to say it'll cross the coast just north of 25 ???


Seems Alex has hit the ceiling. But, nothing is for sure with this one until it's inland.
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1245. Titoxd
Quoting Orcasystems:
Models Just updated :)


link plz :)
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Models Just updated :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
1242. Gorty
If the NOGAPS is correct with the Carribean system, do you think it could come up here where I am Southern New England?

I know we are just waiting on a hurricane to come any season.
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1240. tkeith
Quoting neonlazer:
We are getting some nice gusts here in central LA from some this first line of storms! I love tropical thunderstorms!!!!em>



I hate to admit it but so do I :)
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Any speculations on 5 pm advisory? I say 90 mph, the flight level winds support it as they're 110 mph.
Member Since: July 8, 2005 Posts: 259 Comments: 23619
1238. Patrap
NEXRAD Radar
Brownsville, Velocity Azimuth Display Wind Profile Range 124 NMI


Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting Jedkins01:



If you understood the process of convection a little more, the factors that favor it, and the factors that go against it, then maybe you would agree with me. Just because convection lacks in that part of its circulation does not mean there is dry air present there, its not that simple. Strong thunderstorms form in the plains in air masses that are relatively much drier then the driest quadrant of Alex. Yet, there's plenty enough moisture to unleash powerful thunderstorms with heavy rain.

While at the same time, we have a very deep tropical air mass over Florida, but yesterday convection lacked till the evening, because convective forcing was too weak and convergence was weak until evening, then convection fired big time.

Tropical cyclones organize lift and convergence in bands and segments throughout the system. There are also areas where the cyclones do not create lift and convergence, thus convection does not develop, this is a normal function of tropical cyclones, having nothing to do with dry air.

There are times where tropical cyclones move into dry air masses, temporarily causing dry air to wrap intro the circulation. However, this is far from the case with Alex, Alex is not surrounded by dry air, so there can't be dry air entrainment in the first place.


What bothers me though, is not people who are ignorant. There can be pure humility in ignorance, in other words, an ignorant person who is willing to actually listen.
However, what bothers me is someone who is ignorant and insists they actually know better.


I won't argue about this with you anymore, cause that's just stupid, and doesn't cause anything but trouble. Also I like keeping peace with others as best is I can.

I just hope you'll consider what I'm saying, and study convective processes a little further.

Ditto. For all the people that look at enhanced pictures and make statements based on those pictures about things those picture can't show. You can't tell PW values from radar if there is no percipitation. You can't see LLC or COC's looking at enhanced IR pics unless you already have a TD/TS/H, You can't tell PW values from Visible satellite either. My PW is 2+ on sunny days with no clouds often. Clouds can be over cool dryer air or warm moist air. Microwave imagery is the way to tell PW accurately in Sat Pics.
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1236. Titoxd
Quick question for anyone that knows the answer: Why is there a purple ring at a constant distance from the Doppler radar in the velocity views?
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Quoting RitaEvac:
45mph gust at a buoy near Sabine Pass (thats at the TX/LA border!)
We are getting some nice gusts here in central LA from some this first line of storms! I love tropical thunderstorms!!!!
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1234. jaseone
Recon missed the center on that pass through, could Alex be moving further to the N than they were expecting? Looks like they were expecting it to be close to due W from the last vortex message.
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So, is it safe to say it'll cross the coast just north of 25 ???
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Hail was included in the warnings for Tornadoes.
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1230. Patrap
NEXRAD Radar
Brownsville, Vertically Integrated Liquid Range 124 NMI


Member Since: July 3, 2005 Posts: 421 Comments: 127636
45mph gust at a buoy near Sabine Pass (thats at the TX/LA border!)
Member Since: July 14, 2008 Posts: 1 Comments: 9628
1225. Patrap
Quoting tkeith:
I thought I saw one flambeau...


LOL.. tkeith
Member Since: July 3, 2005 Posts: 421 Comments: 127636
1224. Patrap
Quoting medicroc:

I'm monitoring Cameron County Public Safety scanner feed. They are expecting to see "80 mph winds and heavy rain". I haven't heard them mention anything about a tornado as of yet


THats cuz they musnt have a NOAA weather radio.

College of DuPage Meteorology
Severe Weather and Flash Flood Warnings
.
Member Since: July 3, 2005 Posts: 421 Comments: 127636
1223. tkeith
Quoting Patrap:



No beads,doubloons or Clydesdale's neither.
I thought I saw one flambeau...
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1222. Levi32
Alex is likely finally committing to a movement west or WNW to a landfall in NE Mexico near 25N. It will still be a nasty day in Brownsville with possibly hurricane-force winds up to extreme south Texas.

Back later.
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Looks like Alex got his act together just in time for arrival.
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I agree Ike, looks like it's made that westward turn


Afternoon all
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1219. Patrap
Quoting JFLORIDA:
Mesocyclone parade pat !



No beads,doubloons or Clydesdale's neither.
Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting Patrap:

672
WFUS54 KBRO 301846
TORBRO
TXC061-301900-
/O.NEW.KBRO.TO.W.0012.100630T1846Z-100630T1900Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE BROWNSVILLE TX
146 PM CDT WED JUN 30 2010

THE NATIONAL WEATHER SERVICE IN BROWNSVILLE HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHERN CAMERON COUNTY IN DEEP SOUTH TEXAS.

* UNTIL 200 PM CDT

* AT 146 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 8 MILES NORTHEAST OF OLMITO...MOVING WEST AT 45 MPH.

* THE TORNADO WILL BE NEAR...
LOS FRESNOS.
RANCHO VIEJO.
LA PALOMA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT TORNADOES OR FUNNEL CLOUDS...WINDS OF 58 MPH OR
HIGHER...AND ANY WIND DAMAGE TO YOUR NATIONAL WEATHER SERVICE IN
BROWNSVILLE BY CALLING 956-504-1432.

I'm monitoring Cameron County Public Safety scanner feed. They are expecting to see "80 mph winds and heavy rain". I haven't heard them mention anything about a tornado as of yet
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1217. IKE
Moving just north of west now....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
1216. Patrap
oooofh...



NEXRAD Radar
Brownsville, Storm Total Surface Rainfall Accumulation Range 124 NMI

Member Since: July 3, 2005 Posts: 421 Comments: 127636
1215. angiest
Quoting homegirl:
HHunters should find a closed eyewall and dropping pressure as the EWRC has finished. They'll be flying through the COC in the next 15-30 mins.

Link


Eyewall on radar is looking very nice. Ring of yellows almost all the way around. The gap on the SE side could just as easily be signal attenuation.
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Member Since: June 9, 2007 Posts: 4 Comments: 15790
1211. Patrap
NEXRAD Radar
Brownsville, Storm Relative Mean Radial Velocity 1.45 Degree Elevation Range 124 NMI


Member Since: July 3, 2005 Posts: 421 Comments: 127636
Looks like a WSW bobble there on radar.
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HHunters should find a closed eyewall and dropping pressure as the EWRC has finished. They'll be flying through the COC in the next 15-30 mins.

Link
Member Since: Posts: Comments:
1207. Patrap

672
WFUS54 KBRO 301846
TORBRO
TXC061-301900-
/O.NEW.KBRO.TO.W.0012.100630T1846Z-100630T1900Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE BROWNSVILLE TX
146 PM CDT WED JUN 30 2010

THE NATIONAL WEATHER SERVICE IN BROWNSVILLE HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHERN CAMERON COUNTY IN DEEP SOUTH TEXAS.

* UNTIL 200 PM CDT

* AT 146 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
TORNADO 8 MILES NORTHEAST OF OLMITO...MOVING WEST AT 45 MPH.

* THE TORNADO WILL BE NEAR...
LOS FRESNOS.
RANCHO VIEJO.
LA PALOMA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT TORNADOES OR FUNNEL CLOUDS...WINDS OF 58 MPH OR
HIGHER...AND ANY WIND DAMAGE TO YOUR NATIONAL WEATHER SERVICE IN
BROWNSVILLE BY CALLING 956-504-1432.
Member Since: July 3, 2005 Posts: 421 Comments: 127636
1206. Patrap
Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting FLdewey:
Looks like it's about time for Reed to Photoshop a new map. :D


Actually, Hurricane Alex is right on my track, maybe slightly north, but if it's turning, it will be dead on.

Photobucket
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Quoting btwntx08:

based on radar nope i see nw/wnw


How are you doing? Things going ok in Brownsville?
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1203. Levi32
Alex may be a Cat 1 officially but with a pressure down at 962mb that means the core is going to tighten from frictional effects at landfall and winds will likely be up to Cat 2 force near the eyewall at landfall, and I wouldn't even be surprised to see winds approach Cat 3 force if the pressure remains steady up until landfall....Alex has the pressure of a typical low-end Cat 3.
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Say what you want... but the plots don't lie... its sped up and heading for the Tex/Mex border.



AOI

AOI

AOI

Hurricane Hunter Data

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
landfall in 4 hours..
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Quoting NRAamy:
GoodOleBudSir....always happy to see you on here....


:)


Always nice to see you on here as well. I can't contribute much, so I only poke my head out once and a while but I am almost always here.
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Quoting Stormchaser2007:

i spy an eye
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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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