Alex building an eyewall, still not a hurricane

By: Dr. Jeff Masters , 7:34 PM GMT on June 29, 2010

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Tropical Storm Alex is slowly building an eyewall, which is now more than 50% complete, according to recent satellite imagery and microwave images (Figure 1.) Satellite loops show a slot of dry air is spiraling into the center of the storm, and until this dry slot gets closed off, Alex will not be able to intensify significantly. Alex's heavy thunderstorms and low level spiral bands continue to slowly increase, but upper-level outflow is mediocre to the north and east, and absent elsewhere. The Hurricane Hunters are in the storm and have not found any hurricane-force winds at the surface yet.


Figure 1. Microwave "radar in space" image taken at 10:11 am CDT Tuesday June 28, 2010, showing that Alex had built an eyewall a little more than 50% complete. Image credit: Navy Research Lab.

Impacts
Alex is already 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. Since Alex is a large storm, it will have a storm surge that will affect most of the South Texas coast. 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 coast (Figure 2.) However, Alex is now unlikely to get that strong, and the surge should be less. Flooding damage from the expected 6 - 12 inches of rain from Alex will also be a major concern, as will wind damage. The combined wind, surge, and flooding damage from 2008's Hurricane Dolly, which hit near Brownsville, were about $1.05 billion. Dolly was a Category 2 hurricane offshore that weakened to a Category 1 hurricane with 85 mph winds when it made landfall. I expect Alex will be similar in its impacts to Dolly, though Alex's storm surge damage is likely to be greater. If Alex hits more than 50 miles south of the Texas border, as currently appears likely, the damage will be far less, since this region of the coast is relatively sparsely populated.


Figure 2. Maximum Water Depth (storm tide minus the elevation of the land it is passing over) computed using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. The "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of five feet above mean sea level, and the combined storm surge and tide (the "storm tide") is ten feet at your location, the water depth image will show five feet of inundation. This Maximum of the "Maximum Envelope of Waters" (MOM) image was generated for high tide, and thus shows the worst-case inundation scenarios for a mid-strength Category 2 hurricane moving WNW at 5 mph. For more information on storm surge, consult our detailed storm surge pages.

Track forecast for Alex
The latest 12 UTC (7am CDT) runs of our most reliable computer models confirm the faster movement of Alex to the coast, and residents in the affected areas now have 12 hours less to prepare for Alex's arrival than it seemed with yesterday's forecasts. Conditions will begin to deteriorate along the coast late tonight, so today is the day to finish preparations if you live near the Texas/Mexico border! The ridge that is steering Alex to the northwest is expected to strengthen today and Wednesday, which should push Alex on a more west-northwest and then westerly track on Wednesday. A few models even have Alex moving west-southwest by the time it makes landfall. The most northerly landfall location, near Brownsville, is predicted by the HWRF model.

To get the probability of receiving tropical storm force winds or hurricane force winds for your location, I recommend the NHC wind probability forecasts. The 4am CDT (9 UTC) wind probability product predicted that Brownsville, Texas had the highest odds of getting a direct hit from Alex:

Brownsville, TX: 88% chance of tropical storm conditions (winds 39+ mph), 23% chance of hurricane force winds (74+ mph). This is the cumulative probability through Saturday morning. The wind probability forecasts also include separate probabilities for each 12-hour period between now and three days from now, and each 24 hours for the period 4 - 5 days from now.

Corpus Christi, TX: 42% tropical storm, 1% hurricane.

La Pesco, MX: 37% tropical storm, 3% hurricane.

Freeport, TX: 18% tropical storm, 0% hurricane.

Tampico, MX: 14% tropical storm, 0% hurricane.

Galveston, TX: 13% tropical storm, 0% hurricane.

Intensity forecast for Alex
Alex is over a region of ocean with a warm, clockwise rotating Loop Current eddy that broke off from the Loop Current in July 2009 and moved west-southwest over the past 11 months. This eddy has 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, this afternoon and Wednesday. The combination of low wind shear and moderately high ocean heat content should allow Alex to intensify into a Category 1 hurricane, but time is running out for it to be a Category 2 hurricane. NHC is giving Alex a 79% chance of being a hurricane on Wednesday morning, and a 4% chance it will be a major hurricane at that time. Water vapor satellite images show the amount of dry air over the western Gulf of Mexico has decreased over the past day, though as I noted above, the dry slot wrapping into Alex's core is currently keeping the storm from closing off an eyewall. Dry air may turn out to be an increasing detriment to Alex on Wednesday as the storm approaches land. Another factor limiting Alex's intensification may be that the atmosphere is more stable than usual right now--temperatures at 200 mb are a rather warm -50°C, and are expected to warm an additional 1 - 2 degrees by Wednesday. I don't expect Alex to stall out again, so slow motion leading to upwelling of cold water will probably not be a problem for Alex. The main issue limiting intensification will be the fact that Alex is so large, and it takes more time for a large storm to organize. Thus, I think Alex has only a 10% chance of intensifying into a major hurricane before landfall.

Elsewhere in the tropics
The last few runs of the NOGAPS model have been predicting the formation of a tropical disturbance off the coast of Nicaragua on Friday or Saturday that will move northwestward towards western Cuba. The GFS model, and the two models that use it for starting conditions, the GFDL and HWRF, are indicating the possibility that a weak extratropical storm may form along coastal Alabama this weekend. It is unlikely that such a storm would be over water long enough to transition to a tropical storm.

Wind and ocean current forecast for the BP oil disaster
It currently appears that Alex's winds will not directly affect the oil slick location. However, because Alex is such a deep low pressure region, strong southeast to south winds of 10 - 20 knots will blow over the oil slick region today through Thursday, according to the latest marine forecast from NOAA. The resulting currents should act to push oil to the west and northwest onto portions of the Louisiana, Mississippi, and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Oil will also move westward along the central Louisiana coast towards the Texas border. Alex is currently bringing swells of 3 - 4 feet to the coastal regions impacted by the oil slick, and these swells will increase to 6 - 8 feet on Wednesday. Wave heights will increase to 5 - 7 feet on Wednesday. Alex is expected to bring a storm surge of 1 - 2 feet along the coast in the oil spill region. The swells and waves that will accompany these high water levels will act to push oil deep into the marshlands in some locations. The long range forecast for the oil slick region is uncertain, due to the possibility a weak area of low pressure might develop late this week along the remains of a cold front draped across the region.

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

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Alex
2) A look ahead at what may happen the rest of hurricane season

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Next post
I'll have an update Wednesday morning by 9:30am CDT. Rob Carver is planning on doing a late-night update tonight.

Jeff Masters

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i think it will be a hurricane at 11pm
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Did a blog on Alex.
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My take on it (and pardon me if I'm repeating what somewhat else said) is that the satellite estimates say hurricane, but the HH haven't been able to find that windspeed.
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1490. Patrap
Quoting angiest:


Haven't been that far east (Anahuac) in a year, since my grandmother's funeral. Tons of blue tarps still up everywhere. How is it now?

I have been hoping the NHC would re-evaluate how they assign category numbers to account for systems like Ike (or Katrina), where the storm behaved more like something a lot stronger than it officially was. Go look at what they have done with the Fujita Scale (which is no longer in use in the US, but was replaced with the Enhanced Fujita Scale).


Rural..and Still in the throes of recovery
Member Since: July 3, 2005 Posts: 427 Comments: 129419
Last time that I try explaining this...
FULL IMAGE


SOURCE
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1487. angiest
Quoting Patrap:


I'll relay that to the Folks In Crystal Beach as well as those In Anahuac when I visit next Month.


Haven't been that far east (Anahuac) in a year, since my grandmother's funeral. Tons of blue tarps still up everywhere. How is it now?

I have been hoping the NHC would re-evaluate how they assign category numbers to account for systems like Ike (or Katrina), where the storm behaved more like something a lot stronger than it officially was. Go look at what they have done with the Fujita Scale (which is no longer in use in the US, but was replaced with the Enhanced Fujita Scale).
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Quoting scott39:
Is there any potiential developement for TC in NE Gulf Coast this weekend?



I've seen that some of the models are forecasting possible development off the Alabama coast this weekend. Since I live on the Alabama coast (Mobile), that kinda has me a little concerned. Hopefully nothing will form.
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Or509 that was funny.
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1484. scott39
Quoting IKE:


There is some. Not great, but a chance.
I expect if it does it wont be anything more than a TD or TS?
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1483. Patrap
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 30th day of the month at 01:06Z
Date: June 30, 2010
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Storm Number: 01
Storm Name: Alex (flight in the North Atlantic basin)
Mission Number: 10
Observation Number: 21



INBOUND

01:06:30Z 22.617N 93.033W 842.5 mb

(~ 24.88 inHg) 1,471 meters

(~ 4,826 feet) 997.1 mb

(~ 29.44 inHg) - From 185° at 45 knots

(From the S at ~ 51.7 mph)
Member Since: July 3, 2005 Posts: 427 Comments: 129419
Quoting CybrTeddy:


I'm really tired of having to explain this each year. The data IS from the National Hurricane Center to the models, this has shown us what the next advisory is going to be each time Alex gained strength, weakened, or stayed the same and with every other storm the past few years.
Agreed, thanks for clearing it up for the 5000th time.

Quoting Stormchaser2007:
For all the people who are looking at the NHC site and not seeing anything...

They will not issue a special advisory until recon does a NE quad pass.

Simple.
Exactly! They want to see what are the strongest winds before issuance.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting CybrTeddy:


I'm really tired of having to explain this each year. The data IS from the National Hurricane Center to the models, this has shown us what the next advisory is going to be each time Alex gained strength, weakened, or stayed the same and with every other storm the past few years.

Then why doesn't the NHC change the post?
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Why doesn't the ssd site make some mirror sites or something? This has become completely terrible how hard it is to get up to date information about the storms, even with all the universities and other agencies offering it too. Takes up to two minutes to download a couple frames of a satellite video.
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Quoting ShenValleyFlyFish:


browser?


Or.... did he forget to log in?
Member Since: October 1, 2007 Posts: 81 Comments: 26512
Pretty pointless at this point but quite impressive nonetheless.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Could this be Alex's calling card ( Alex building an eyewall, still not a hurricane)? And the way off GFDL & HWRF yesterday has been right all along about not intensifying past a TS. Dry air is still evident.

Just sayin :-/

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1476. JLPR2
Quoting gordydunnot:
I don't really want to go here, but anybody criticizing someone pronunciation of Spanish words on this blog, I find comical.


I find that you guys speak Spanish funny. XD
As you would think we speak English funny. LOL!
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1475. IKE
Quoting scott39:
Is there any potiential developement for TC in NE Gulf Coast this weekend?


There is some. Not great, but a chance.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
For all the people who are looking at the NHC site and not seeing anything...

They will not issue a special advisory until recon does a NE quad pass.

Simple.
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Quoting IKE:


Looks just south of west to me.


I hope to GOD he isn't trying to bury himself down in the BOC, if he does, he's hanging around waiting for that next trough.
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Quoting JLPR2:


Closeup:

Looks nicer than the last one, lets see how it reacts to the land/sea change
I'm telling ya one of these waves are going to do a sneak attack on us one day.Anyway Alex is the distraction right now. Watch this season start getting active.
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Okay Atmo: Yes my chain has been yanked, all in good fun. I deserved it too after last nights pop-quiz in physics.

Seriously I must eat a bit of crow. I thought for certain this thing was going further north, maybe Corpus Christi.

For the record I was the only answer that included the definition of Knot as a "nautical MPH" for Balto. I thought that was what she was asking for anyway.
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Quoting hurricanehanna:
For those of you who THINK it was upgraded, go look at the NHC website and READ the information - IT AINT a Hurricane


I'm really tired of having to explain this each year. The data IS from the National Hurricane Center to the models, this has shown us what the next advisory is going to be each time Alex gained strength, weakened, or stayed the same and with every other storm the past few years.
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Or4590... I know they will, but it is not official yet... aint a doubt in my mind that they will. Check the NHC site
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1468. Patrap
Is it just me or does this Narrator sound Like Dr. Phil ?

A hurricane's "hot towers" can increase its intensity by adding power to boost the storm's heat engine. For the first time, research meteorologists have run complex simulations of these phenomena using a very fine temporal resolution. They have combined this new simulation data with satellite observations to study the innerworking of the "hot towers" in never-before-seen detail.


Member Since: July 3, 2005 Posts: 427 Comments: 129419
1467. Hhunter
Quoting angiest:


Yes, that is well-known. Ike was a ridiculously huge storm (hurricane wind radius larger than many system's tropical storm radius) with the pressure of at least a cat 3, possibly a 4. And a surge in that range as well. Alex looks a lot like Ike in many ways, including pressure that does not correlate with wind the way an "average" system would. But what kind of surge will it produce?


i fear think ike ish....
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I don't really want to go here, but anybody criticizing someone pronunciation of Spanish words on this blog, I find comical.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
Quoting hurricanehanna:
For those of you who THINK it was upgraded, go look at the NHC website and READ the information - IT AINT a Hurricane
For those of us that do think it was upgraded read this:

AL, 01, 2010063000, , BEST, 0, 230N, 944W, 65, 973, HU,
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1464. scott39
Is there any potiential developement for TC in NE Gulf Coast this weekend?
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Quoting ecflweatherfan:
Sorry about the all caps Stormchaser... these people just dont get it that it is not official until the NHC says so! I figured shouting might help them, but probably not! But its all good :-)


Well "these people" must not get it either.
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1462. JLPR2
Quoting MiamiHurricanes09:
Awesome! It would be pretty freaky if the pressure is less than 973mb.


I would have to serve myself something if that happens, haha! >:D
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Quoting aspectre:
Have the Quote, Ignore, ModifyComment, and Filter buttons been disabled?
Or was there an JAVA/etc update that I haven't heard of?


browser?
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1459. angiest
Quoting StSimonsIslandGAGuy:


Ike was never a major hurricane after he finished with Cuba. Cat 1 and Cat 2 in the Gulf the whole way across.


Yes, that is well-known. Ike was a ridiculously huge storm (hurricane wind radius larger than many system's tropical storm radius) with the pressure of at least a cat 3, possibly a 4. And a surge in that range as well. Alex looks a lot like Ike in many ways, including pressure that does not correlate with wind the way an "average" system would. But what kind of surge will it produce?
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1458. JRRP
Quoting lopaka001:
Last visible image filtered with UV and IR filters..



hot towers
impressive
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Barometer Bob brought up a good point about the tornadoes in the NE quadrant....we had a lot of damage from Lily with those little suckers
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Sorry about the all caps Stormchaser... these people just dont get it that it is not official until the NHC says so! I figured shouting might help them, but probably not! But its all good :-)
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1455. IKE
Quoting RitaEvac:
IKE looks like SW to ya?


Looks just south of west to me.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
For those of you who THINK it was upgraded, go look at the NHC website and READ the information - IT AINT a Hurricane
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In terms of pressure, Alex is the strongest hurricane in June since Hurricane Alma in 1966.
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1452. Or4590
Quoting ecflweatherfan:
NHC HAS NOT UPGRADED ALEX YET!!! NO ADVISORY OF UPGRADE HAS BEEN ISSUED, THEY WILL DO SO WHEN IT IS OFFICIAL!


they will...you're annoying poof!
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1451. JLPR2
Quoting AllStar17:
Watch this wave at is moves across the Atlantic:


Closeup:

Looks nicer than the last one, lets see how it reacts to the land/sea change
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1450. Patrap
Quoting StSimonsIslandGAGuy:


Ike was never a major hurricane after he finished with Cuba. Cat 1 and Cat 2 in the Gulf the whole way across.


I'll relay that to the Folks In Crystal Beach as well as those In Anahuac when I visit next Month.
Member Since: July 3, 2005 Posts: 427 Comments: 129419
I see hot towers in the eye......
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Quoting ecflweatherfan:
NHC HAS NOT UPGRADED ALEX YET!!! NO ADVISORY OF UPGRADE HAS BEEN ISSUED, THEY WILL DO SO WHEN IT IS OFFICIAL!


I think my ears are bleeding.
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if anything. the cloud cover has certainly cooled things down a bit here or did the front do it? either way, it's nice to be able to breath outdoors.
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Just because it is in the tropics doesn't necessarily mean you have to call it a hurricane based on it's bp, there have been lower bp on low pressure systems which don't have hurricane force winds. It's the dry air to the west that has been messing with this system for awhile.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
1443. bappit
1328

Tell Barometer Bob if you see him:

Laguna Madre is pronounced

Lah-goo-nah

not

Lah-gua-na

That's the mother of all lizards? Don't know Spanish.
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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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