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 MiamiHurricanes09:
Landfall might come sooner than previously anticipated.


I disagree, look at how the coastline is shaped in that area, I think a move further north would bring the center in sooner
Member Since: March 10, 2010 Posts: 1 Comments: 7397
Quoting Hurricanes101:


6-7 hours would be tonight lol


LOL, I meant OVERnight... :)
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Quoting JFLORIDA:


useful information - not how to smoke in a hurricane mind you.


Drinking in a hurricane would be more appropriate. Just use a straw to prevent waste.
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Quoting Drakoen:
Look like it has been moving almost due west over the past hour:

Landfall might come sooner than previously anticipated.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1392. Drakoen
Look like it has been moving almost due west over the past hour:

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Quoting winter123:
Link
Looks like landfall should be here. Looks like a completely unpopulated area.


I wish it were true, but zoom in on San Fernando ... 35 miles inland from likely landfall on the natural barrier.
Member Since: July 15, 2005 Posts: 3 Comments: 1262
Quoting VampyreGTX:
I'm using a different radar product (sorry WU, subscription through my FD) and based on the last 3 hours of radar returns, it looks like it's heading nearly due west, and at the distance it's covered in the last 3 hours, would put landfall in about 6-7 hours. I just don't see this waiting till tonight unless there is a large shift back to the N, which I don't see happening at the moment. Am I way off base here?


6-7 hours would be tonight lol
Member Since: March 10, 2010 Posts: 1 Comments: 7397
1389. NRAamy
Quoting Floodman:
Geez, guys...here it is:

Nut job in the rain



hahahahahahahahahaha!

:)
Member Since: Posts: Comments:
I'm using a different radar product (sorry WU, subscription through my FD) and based on the last 3 hours of radar returns, it looks like it's heading nearly due west, and at the distance it's covered in the last 3 hours, would put landfall in about 6-7 hours. I just don't see this waiting till tonight unless there is a large shift back to the N, which I don't see happening at the moment. Am I way off base here?
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Link

On the large visible looks like Alex is moving in a straight line but wobbling like an egg would rolling down a hill. Just an observation.. any thoughts?

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You can see the clouds and light rain in the eye on radar.

Radar

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Brownsville update - winds holding steady at between 15-22mph, highest gust in the past hour (that I measured) was only 25.
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I'm having fun watching CycloneOz (Brian Osburn) really entertaining and scary at times.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Floodman:
Geez, guys...here it is:

Nut job in the rain

THANKS!!!
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Quoting RecordSeason:
1350:

If the eye is open, why does composite radar show it closed and concentric?



It's picking up a thin layer of clouds in the eye, you can have a clear eye with clouds in it spinning and moving with the air motion.
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Quoting winter123:
Link
Looks like landfall should be here. Looks like a completely unpopulated area.


If I'm not mistaken, even Joe the Magnificent Bastardi called this one as a Tex-Mex event a week ago.

Some, I think, are still clinging to the "but the trough will take it to Florida!" wish-cast, but they are strangely silent now. ;)
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Quoting ncstorm:


didnt tampaspin get banned for linking his website on the blog?


He was linking to his own site and blowing his own horn...self aggrandizement is prohibited; linking to outside sites for information is different
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1376. IKE
Quoting CaneWarning:
Has anyone else noticed that we have a hurricane that will be making landfall within 12 hours?


Try within 4-6 hours...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1375. dmdhdms
NWS radar out of Brownsville is showing quite a picture. More importantly, the storm total precip is approx. seven inches so far. Not good in that flat land.

We have had approx. 5.5 inches in So. MS over the last two days from the banding.

As mentioned, the major threat seems to be the precip.

Still more to go.
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LOLZ! By tonight or tomorrow morning we will it may be Cat 2...UM..idiot on TWC...this will be over land by tonight or tomorrow..Unless it stalls..which...it could XD
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I wonder how big of a town San Fernando is? Looks like it is going to take a pretty good hit.
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Quoting HurricaneSwirl:


It's off air for me..


It's faeds in and out...be patient
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1371. 47n91w
Quoting 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?


If no one has yet answered your question, the purple is range folding. It's an unfortunate side-effect of radar technology. More information from NWS - JetStream - Online School for Weather.
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Quoting CaneWarning:
Oz is going for a swim?

I understand that people do not want his website linked on this blog, but I'm curious to see his video. Can someone WUmail me the link?
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 30th day of the month at 19:09Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Storm Number & Year: 01L in 2010
Storm Name: Alex (in the North Atlantic basin)
Mission Number: 12
Observation Number: 09
A. Time of Center Fix: 30th day of the month at 18:50:20Z
B. Center Fix Coordinates: 24°23'N 96°27'W (24.3833N 96.45W)
B. Center Fix Location: 125 miles (201 km) to the SSE (149°) from Brownsville, TX, USA.
C. Minimum Height at Standard Level: 1,103m (3,619ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 65kts (~ 74.8mph)
E. Location of the Estimated Maximum Surface Wind: 14 nautical miles (16 statute miles) to the E (97°) of center fix
F. Maximum Flight Level Wind Inbound: From 178° at 74kts (From the S at ~ 85.2mph)
G. Location of Maximum Flight Level Wind Inbound: 13 nautical miles (15 statute miles) to the E (95°) of center fix
H. Minimum Sea Level Pressure: 960mb (28.35 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,521m (4,990ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,523m (4,997ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 20°C (68°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southeast
M. Eye Shape & Diameter: Circular with a diameter of 9 nautical miles
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 96kts (~ 110.5mph) in the northeast quadrant at 16:51:20Z
Maximum Flight Level Wind Outbound: 87kts (~ 100.1mph) in the northwest quadrant at 18:55:20Z
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Quoting CaneWarning:
Has anyone else noticed that we have a hurricane that will be making landfall within 12 hours?


No, in general, nobody here notices such things. Thanks for the heads up.
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1367. beell
Quoting AstroHurricane001:


What's PW?


I see you got an answer.
On the skew-t, the red line represents the temperature profile up through the atmosphere. The green line is the dew point. Temp and dewpoint are very close to each other. A saturated column. No dry air on this model's guess.
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Quoting angiest:


I thought the EWRC was over.

well the pressure droping guess it hopped to the next level cat 2 or cat 3
Quoting Asta:
DVORAK- sure is takin' his time to go inland...


Thunderstorms from Alex heading for Mobile, AL
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Link
Looks like landfall should be here. Looks like a completely unpopulated area.
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1362. Asta
See ya later alligators!
Gotta take advantage of this break in the rains...
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1361. angiest
In the last few frams before this the northern and western eyewall fell apart and the eye started looking more ragged. Interestingly there are now decent echoes on the SE.

Photobucket
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Also, it's raining from Tampa to Naples. Flood Advisories are in effect for Sarasota.
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Current in Louisiana: 1.60" of Rain...Barometric pressure 29.15 inches or 987mb...Max wind speed 10mph...Average wind speed 3.0mph Temperature 76.2
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Not sure, but that's what HH recon had to say. The SE part of the eye is open.
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1357. JamesSA
Quoting CaneWarning:
Has anyone else noticed that we have a hurricane that will be making landfall within 12 hours?
LOL!.... Where? What hurricane? What IS a hurricane?

He looks to be about 5 hours ahead of the forecast point for 00z, just North of it now.
Member Since: August 17, 2009 Posts: 0 Comments: 579
1356. Asta
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The Salvation Army is up and operating a shelter in McAllen.

Link

Yesterday The Salvation Army opened the doors of its shelter in McAllen, TX to residents evacuating ahead of the storm. They housed 73 people, of which 23 were evacuees, and served 140 meals. They continue to remain on stand-by in case additional help is needed at any of the area designated shelters.
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1353. angiest
Quoting AlexEmmett:

no its a EWRC


I thought the EWRC was over.
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Has anyone else noticed that we have a hurricane that will be making landfall within 12 hours?
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1351. Asta
Lightning Strikes-N.A.
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Quoting homegirl:
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 30th day of the month at 19:09Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Storm Number & Year: 01L in 2010
Storm Name: Alex (flight in the North Atlantic basin)
Mission Number: 12
Observation Number: 09
A. Time of Center Fix: 30th day of the month at 18:50:20Z
B. Center Fix Coordinates: 24°23'N 96°27'W (24.3833N 96.45W)
B. Center Fix Location: 125 miles (201 km) to the SSE (149°) from Brownsville, TX, USA.
C. Minimum Height at Standard Level: 1,103m (3,619ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 65kts (~ 74.8mph)
E. Location of the Estimated Maximum Surface Wind: 14 nautical miles (16 statute miles) to the E (97°) of center fix
F. Maximum Flight Level Wind Inbound: From 178° at 74kts (From the S at ~ 85.2mph)
G. Location of Maximum Flight Level Wind Inbound: 13 nautical miles (15 statute miles) to the E (95°) of center fix
H. Minimum Sea Level Pressure: 960mb (28.35 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,521m (4,990ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 22°C (72°F) at a pressure alt. of 1,523m (4,997ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 20°C (68°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southeast
M. Eye Shape & Diameter: Circular with a diameter of 9 nautical miles
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 96kts (~ 110.5mph) in the northeast quadrant at 16:51:20Z
Maximum Flight Level Wind Outbound: 87kts (~ 100.1mph) in the northwest quadrant at 18:55:20Z


Eye is open on the SE side.
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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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