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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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: 421 Comments: 127626
Is Oz broadcasting live now?
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2496. Asta
Water Vapor G.O.M
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Quoting jurakantaino:
They should stay there to check its intensity at land fall.


Can't fly into foreign airspace without permission ahead of time probably.
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962 mb and not even close to the center with 95 mph winds? Wow
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Quoting CybrTeddy:


That translates to roughly what? 110 mph or so?

wow allmost cat 3
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"With current motion and distance from land Alex will likely be making landfall at 9PM EDT tonight."

Still sticking with my forecast from earlier.

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BRO issues Flash Flood Warning for Cameron [TX] till 10:45 PM CDT
Member Since: January 24, 2010 Posts: 0 Comments: 529
2490. Patrap
Quoting InTheCone:


Thanks Pat, a bit of levity was definately needed!


In here..

Always
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Stadium effect next pass ?
Member Since: January 24, 2010 Posts: 0 Comments: 529
No good! Keep trying! You will not believe it when he is streaming live. Wow!!
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2486. Patrap

Note the Convective thing a ma bob near the Yucatan tip.






Member Since: July 3, 2005 Posts: 421 Comments: 127626
Quoting KatyTexasNewbee:


The Local Cell tower has been taken out. So we cant see him anymore.

hahaha nice
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Quoting Patrap:
Pinhole eye,Pinhole eye,Pinhole eye,Pinhole eye.





Thanks Pat, a bit of levity was definately needed!
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Quoting bappit:

It is a large storm. I'd like to see the Integrated Kinetic Energy--IKE, not to be confused with Ike which also was large. A Hurricane Hunter plane reported a secondary wind maximum, and it was thought by some that the small eye would disappear. This arrangement helped spread the energy around. A plot of pressure gradient across the storm would also be interesting to see.


IKE at the bottom of the image


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Quoting FloridaDweller:
Oh yes, that Oz video is really outrageous KatyTexasNewbee! A true must-see! :)


The Local Cell tower has been taken out. So we cant see him anymore.
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Quoting NRAamy:
Oz has a new sponsor....Depends....

;)


roflmao!!!
HI Amy, I see you are still being funny!
love it!
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2480. centex
It's moving slow but jog to W this afternoon has sped up landfall. While most watching landfall I'm more interested in post landfall track for personal reasons. Is it going to bury itself into mountains? The slow movement makes me wonder.
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Quoting Stormchaser2007:
Flight level

106 knots
(~ 121.9 mph)


That translates to roughly what? 110 mph or so?
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Quoting Hurricanejer95:


A cat. 2 with 100 mph winds


wow. he sure does look good. he's huge.
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Flight level

106 knots
(~ 121.9 mph)
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2476. bappit
An image of cloud tops does not show the eye well. Compare:



with



Of course, Patrap just posted both of these pics. Kudos to him for helping to clarify what's going on. :)
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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?

Member Since: August 30, 2008 Posts: 8 Comments: 2835
2474. Patrap
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 30th day of the month at 23:38Z
Date: June 30, 2010
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Storm Number: 01
Storm Name: Alex (flight in the North Atlantic basin)
Mission Number: 12
Observation Number: 54


23:38:00Z 24.467N 97.300W 842.4 mb

(~ 24.88 inHg) 1,148 meters

(~ 3,766 feet) 961.6 mb

(~ 28.40 inHg) - From 87° at 96 knots

(From the E at ~ 110.4 mph)
Member Since: July 3, 2005 Posts: 421 Comments: 127626
Recons getting some 105knot plus flight level winds.
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Pressure beginning to plummet and they are still far from the eye. Also notice the 106 knot flight level wind.

000
URNT15 KNHC 302338
AF304 1201A ALEX HDOB 54 20100630
232830 2457N 09718W 8432 01378 9869 192 179 085056 056 047 001 00
232900 2456N 09718W 8432 01373 9864 194 182 086056 056 046 002 00
232930 2454N 09718W 8434 01368 9858 195 186 087057 057 045 004 00
233000 2453N 09718W 8429 01369 9855 193 190 089058 059 046 003 00
233030 2451N 09718W 8432 01362 9848 194 193 088059 061 045 001 00
233100 2449N 09718W 8429 01361 9844 193 193 088061 062 045 002 00
233130 2448N 09718W 8432 01354 9840 192 192 088063 064 044 003 00
233200 2446N 09718W 8422 01356 9830 197 197 086065 065 046 002 00
233230 2445N 09718W 8430 01342 9821 201 199 085066 066 049 001 00
233300 2443N 09718W 8428 01336 9817 192 192 083068 069 048 002 00
233330 2442N 09718W 8431 01326 9808 195 195 082068 068 052 002 00
233400 2440N 09718W 8428 01325 9802 192 192 083072 073 056 001 00
233430 2438N 09718W 8425 01315 9791 190 190 083075 076 055 003 00
233500 2437N 09718W 8435 01293 9778 191 191 082078 080 057 006 00
233530 2435N 09718W 8430 01285 9764 189 189 081085 086 061 007 00
233600 2434N 09718W 8431 01265 9746 179 179 079087 087 065 010 05
233630 2432N 09718W 8428 01248 9724 182 182 080092 095 067 009 00
233700 2431N 09718W 8426 01220 9688 190 190 078098 100 073 005 00
233730 2429N 09718W 8428 01187 9650 196 189 083103 106 081 006 00
233800 2428N 09718W 8424 01148 9616 176 176 087096 104 083 011 00
$$
;

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2470. NRAamy
Oz has a new sponsor....Depends....

;)
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Down to 961.6..not to center yet
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Quoting truecajun:
hey everyone. so what category is he now? i've been out all day


A cat. 2 with 100 mph winds
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Oh yes, that Oz video is really outrageous KatyTexasNewbee! A true must-see! :)
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Quoting IKE:
NOGAPS keeping a Caribbean storm on the end of the run...


18Z GFS at 204 hrs....yeah, I know it's 8-9 days out...

what is that L by la.
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2465. Patrap
Quoting 1900hurricane:

He looks like he might be on the move again.



Seems so..

That eye has a lot of Radial Forces yanking on it as the Cyclones size is Big to say the least.

I think the tugs and forward mo get canceled out some maybe and reestablishes.
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Anybody think that we will hear them say nice stadium effect in the eye next pass ?
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2462. Asta
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hey everyone. so what category is he now? i've been out all day
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2460. angiest
Quoting 1900hurricane:

He looks like he might be on the move again.


Yeah it looks back to a slow SW drift.
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Quoting IKE:
NOGAPS keeping a Caribbean storm on the end of the run...


18Z GFS at 204 hrs....yeah, I know it's 8-9 days out...


ECMWF had one there yesterday in approximately the same timeframe.
Member Since: August 2, 2006 Posts: 46 Comments: 11666
Quoting 69Viking:
So where is this live Web Cam everyone is talking about seeing Oz on?
Link
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Quoting Patrap:

He looks like he might be on the move again.
Member Since: August 2, 2006 Posts: 46 Comments: 11666
Quoting Stormchaser2007:
RI


doe it jump directly to cat 4 or 5
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2454. Patrap
Member Since: July 3, 2005 Posts: 421 Comments: 127626
2453. IKE
NOGAPS keeping a Caribbean storm on the end of the run...


18Z GFS at 204 hrs....yeah, I know it's 8-9 days out...

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting angiest:


Two years ago...
Even with Ike its pretty rare.
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Quoting Hurricanes101:


probably due to his size

While the pressure is very low, the pressures are evenly distributed; there are no real huge pressure drops from one recon observation to the next

In other words we are seeing a ton of areas with pressures in the 980s, 970s and 960s with this storm; therefore the difference in pressure is not as impressive

In storms with stronger winds we see recon go from 981mb and then on their very next observation it shows 970mb or something like that; causing stronger winds


Storms with a little a eye usually have very strong winds.
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2450. xcool
AlexEmmett lol
Member Since: September 26, 2009 Posts: 2 Comments: 15625
2449. Daveg
Do storms tend to spin out (I know that's not the right way to say it...can't seem to think of a better way at the moment) more rain as they come inland?

It always seems to me the rain really increases away from the center of the storm a bit after the storm has come in.

If so, why is that?
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RI

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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.