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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Quoting MiamiHurricanes09:
About 80%.


well that is slightly faster than i thought
any guesses to when we will have an eye
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Quoting CosmicEvents:
I think that the wishcasters are about equally split into 2 camps...those that want to have the hurricane experience, as if it's a 5 ticket ride at Disney...and those who want a hit on some heavily populated US area, anywhere. Just so we get plenty of CNN coverage. Katrina, though it was and continues to be a calamity for the central gulf coast, was a perfect example of the wishcasters "perfect storm". Sad.
I don't find it sad but rather disgusting to have a person basically wish for a lost of life.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Checking in - first time today - and whats up? Storms now have ranks, crow has become a delicacy -- and some are still arguing Texas or Mexcio...hmm interesting place

On a more serious note -- people refer to "only" a cat 1 -- Katrina didn't become a cat 1 until it reached shore in Miami Dade. The only storm that caused more roofs to be replaced in my area was Hurricane Andrew. The moral being - Cat 1's won't destroy your house, but geez will it cause some trouble.
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537. Daveg
Still amazed at how BIG a storm this is...pretty or not. No wonder our rain chances are through the roof the next 3 days.

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OMG, this thing is getting bigger....



AOI

AOI

AOI

Hurricane Hunter Data

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26493


tropicalatlantic.com
Member Since: July 3, 2005 Posts: 414 Comments: 125560
My reason for watching gulf storms so close is one.. been thru several (Katrina,Ike) but I have elderly family that live in GAlveston and need as much warning as I can get if I need to get them out of dodge.
I would never wish a major hurricane on anyone. well...... maybe a couple of people.. but nobody on here :o)
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Quoting MiamiHurricanes09:
Not all of us. Some prefer the location they live in, which doesn't have any logic to it. Why would you like to be hit by a disaster?


But... but, it's Tampa. You know. They get all excited and stuff. ;)
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ALEX Graphics Archive

3-Day Track Forecast, Uncertainty Cone, and Watch/Warning

3-Day Cone and Watch/Warning (no track line)

5-Day Track Forecast, Uncertainty Cone, and Watch/Warning

5-Day Cone and Watch/Warning (no track line)

Surface Wind Field and Watch/Warning

Wind History

Maximum 1-minute Wind Speed Forecast Table

34-kt Surface Wind Speed Probabilities (120 Hours)

50-kt Surface Wind Speed Probabilities (120 Hours)

64-kt Surface Wind Speed Probabilities (120 Hours)
Member Since: July 3, 2005 Posts: 414 Comments: 125560
Quoting cooldayr:
How completed is the eye wall now (percentage wise)
About 80%.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Dumbledore would be an awesome name for a storm...
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It's got a good eye if you like the letter G.
Member Since: August 18, 2008 Posts: 0 Comments: 3109
Quoting MiamiHurricanes09:
Not all of us. Some prefer the location they live in, which doesn't have any logic to it. Why would you like to be hit by a disaster?
I think that the wishcasters are about equally split into 2 camps...those that want to have the hurricane experience, as if it's a 5 ticket ride at Disney...and those who want a hit on some heavily populated US area, anywhere. Just so we get plenty of CNN coverage. Katrina, though it was and continues to be a calamity for the central gulf coast, was a perfect example of the wishcasters "perfect storm". Sad.
Member Since: August 3, 2005 Posts: 10 Comments: 5458
He might not make a direct hit on Texas, but if he lingers around and dumps massive quantities of rain, it is going to be a mess with serious flooding. Don't forget what TS Allison did when it parked itself over Houston. Not saying Alex is going to sit there and dump, but it is going to have a serious impact on the State of Texas either way. So, everyone serving crow to those who were calling a Texas hit best leave that dish unserved for the time being, at least until we see what this storm dishes out.

And, it is not ashore yet. Keep that in mind.
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How completed is the eye wall now (percentage wise)
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Hermione Jean Granger (pronounced /hərˈmaɪ.əni ˈdʒiːn ˈɡreɪndʒər/) is a fictional character and one of the three protagonists (the other two being Harry Potter and Ron Weasley) in J. K. Rowling's Harry Potter series.

Sorry, just had to post it :o) done now
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Quoting Patrap:
:
Hermione?? really? someone has been watching way to much Harry Potter.



Its Hermine.

Stop fidgeting and you can focus.



Harry Potter is the best. Especially the new Land at Universal Studios Orlando. We really need to keep the Canes away from here.
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Quoting weatherwart:
I think Alex will make a u-turn, head all the way across the GOMEX and hit Tampa. Because, you know, we all want the big storms to hit Tampa.
:)
well i can always firer up the tractor beam
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519. IKE
Quoting GlobalWarming:
Ike, any activity seeked out on the long range ECm outlook?


I didn't see any in the next 10 days.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting earthlydragonfly:


Hope we dont make it another Greek Year!!


yeah.... that was just crazy. Starting the year out pretty good so far though...
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Member Since: July 3, 2005 Posts: 414 Comments: 125560
At kids swim practice. Clouds and extremely breezy!! But no rain. Out south galveston. Still hoping Alex brings us rain.
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514. IKE
Quoting GlobalWarming:
I see them being discontinued, Ike.


Ain't happening...Alex is fixing to be a cane and make landfall tomorrow.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Feminie form of Hermes, a name of uncertain etymology borne by the messenger god. The name Hermione is borne in Greek legend by the daughter of King Menelaus of Sparta and his wife, Helene of Troy
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Quoting TexasHurricane:


I wonder how many names we will go through this year......


Hope we dont make it another Greek Year!!
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Eye trying to pop; not succeeding.

Member Since: September 2, 2009 Posts: 130 Comments: 21032
g2g, bye.
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:
Hermione?? really? someone has been watching way to much Harry Potter.



Its Hermine.

Stop fidgeting and you can focus.

Member Since: July 3, 2005 Posts: 414 Comments: 125560
Quoting RecordSeason:
I'm pretty sure Alex is going to manage to close off the eye wall within the next hour or two, but hey, I haven't been right about anything at all so far...
well, at least you were right about admitting your misplaced exuberance. That's something most never do. It's to be commended.
Member Since: August 3, 2005 Posts: 10 Comments: 5458
Jim Cantori is riding down to South Padre from Venice LA on the short bus so it will take him till at least monday to get there.
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Cantore can take a ride to Brownsville and hang for the SPI weekend.

Woo Hooo


I think he's still in Venice...Billy wont let him off that backhoe.
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Quoting weatherwart:
I think Alex will make a u-turn, head all the way across the GOMEX and hit Tampa. Because, you know, we all want the big storms to hit Tampa.
:)
Not all of us. Some prefer the location they live in, which doesn't have any logic to it. Why would you like to be hit by a disaster?
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting HoustonTxGal:
The way he has been all over the place I think Alex has had more than a shot or two/=. I think he sucked back the entire bottle! lol

Looks like he's on his way. Gonna call him "Alejandro" once he crosses the border. ROFLOL
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500. xcool
lmao
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Hermione?? really? someone has been watching way to much Harry Potter.
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Quoting Patrap:
Bonnie
Colin
Danielle
Earl
Fiona
Gaston
Hermine
Igor
Julia
Karl
Lisa
Matthew
Nicole
Otto
Paula
Richard
Shary
Tomas
Virginie
Walter

Hopefully we will not get into the Greeks again.
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497. IKE
Quoting gordydunnot:
I don't think its going to much further north than 23.5 if that were to be the case, anyone want to speculate on the criticism for the NHC hurricane warning area.Old dammed if you do dammed if you don't.


If it comes in at 23.5N, it probably is too far north on the hurricane warnings. Maybe they trim it back some if it comes in near 23.5N....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
496. Daveg

Really slowed down don't y'all think? Might give him more time to organize.....
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A

alex will stay a TS
Quoting Patrap:
Cantore can take a ride to Brownsville and hang for the SPI weekend.

Woo Hooo


Mike Sidel is in South Padre Island, because he knows the storm aint gonna hit there! :o
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I think Alex will make a u-turn, head all the way across the GOMEX and hit Tampa. Because, you know, we all want the big storms to hit Tampa.
:)
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.