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 AstroHurricane001:


Wow. I have NEVER seen a hurricane before that took up the entire Gulf of Mexico. The convection almost stops at the coast but its outer bands are too wide to do that. That means all the dry air over Texas is gone, but Alex has not yet absorbed ex-94L. This storm is going to alter the circulation patterns across the entire Western Hemisphere. If this storm stalls, even on land, terrible flooding could result. It's only the first storm of the season, and even a category one of this size could be devastating.

Meanwhile, flooding in Southern China leaves 382 dead. Link


I have... Hurricane Ike destroyed my house.
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Eyewall forming seen from visible

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Quoting galvestonhurricane:


What do you mean? I thought Alex was coming here. I guess I will just leave the boards there for the rest of hurricane season.


Did he supposedly say that today?
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Quoting MiamiHurricanes09:
Well he is lying, although I doubt he said that. Alex isn't going near Galveston and it isn't going to be a CAT.3. If you were being serious you just wasted a lot of time.


bastardi, on local media in S. Texas is forecasting landfall further South in Mexico than most of the current models. Like 125 miles South of the River.
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Recon on its way to Alex.
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Quoting galvestonhurricane:


What do you mean? I thought Alex was coming here. I guess I will just leave the boards there for the rest of hurricane season.
Tune into the NHC site and your local news for information, not me. But I am 99% sure you are not going to get much from Alex, except some rain.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Vented your spleen now that sounds a little bloody to me Flood.
Member Since: August 18, 2008 Posts: 0 Comments: 3112


Wow. I have NEVER seen a hurricane before that took up the entire Gulf of Mexico. The convection almost stops at the coast but its outer bands are too wide to do that. That means all the dry air over Texas is gone, but Alex has not yet absorbed ex-94L. This storm is going to alter the circulation patterns across the entire Western Hemisphere. If this storm stalls, even on land, terrible flooding could result. It's only the first storm of the season, and even a category one of this size could be devastating.

Meanwhile, flooding in Southern China leaves 382 dead. Link
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Quoting galvestonhurricane:


Why wouldn't I be? Joe Bastardi says that a category 3 storm is going to hit Galveston.


No he did not.
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Quoting will45:
I have sent Dr Masters and admin an email concerning him.
Admin already got angry about all the messages I've sent them concerning him, Lol.

Back to Alex.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting MiamiHurricanes09:
Well he is lying, although I doubt he said that. Alex isn't going near Galveston and it isn't going to be a CAT.3. If you were being serious you just wasted a lot of time.


What do you mean? I thought Alex was coming here. I guess I will just leave the boards there for the rest of hurricane season.
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Alex has mixed the dry air out of his core, eyewall is probably closed now. Should finally be able to get going.
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Quoting MiamiHurricanes09:
Oh I just started a little conversation off of what you said but it wasn't directed at you, I was just saying that in general.


Fair enough.
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Quoting galvestonhurricane:


Why wouldn't I be? Joe Bastardi says that a category 3 storm is going to hit Galveston.


Oh no! Another victinm of Bastardism
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Quoting MiamiHurricanes09:
I wonder how many e-mail addresses he has? You know how you have to put in a new address every time you create an account.
I have sent Dr Masters and admin an email concerning him.
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Quoting Floodman:


You noticed that too? It is going to be an interesting season at the very least...


Yes, It it interesting the appearant amount of energy (cloud cold tops) in the next wave that is about to emerge off the coast. Looks like it could be a bugger.
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Quoting galvestonhurricane:


Why wouldn't I be? Joe Bastardi says that a category 3 storm is going to hit Galveston.
Well he is lying, although I doubt he said that. Alex isn't going near Galveston and it isn't going to be a CAT.3. If you were being serious you just wasted a lot of time.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
This also showing 4.0..

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 29 JUN 2010 Time : 204500 UTC
Lat : 23:10:54 N Lon : 93:58:02 W


CI# /Pressure/ Vmax
4.0 / 987.3mb/ 65.0kt


Final T# Adj T# Raw T#
4.0 4.0 4.0

Latitude bias adjustment to MSLP : +0.3mb

Center Temp : -57.6C Cloud Region Temp : -63.0C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
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Quoting CyclonicVoyage:


Do you even read the blog? Or just look to start things?


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.


Yes I follow the blog very carefully. However, if you followed the track and the NHC you should have been fairly certain it was going to arrive sooner or later. You should been prepared when the first watches and warnings went up or sooner. . . For that matter, when June 1st rolled around. Love those that blame others for being unprepared and now have to rush.
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Quoting Orcasystems:


Now now Flood... meditate.. breath deep... think of your happy place... then go sight in the rifle :)


I'm much better now, bro for having vented my spleen
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Hurricane Emily 2005

Member Since: July 14, 2008 Posts: 1 Comments: 9628
Check this out!

29/1745 UTC 23.0N 93.6W T4.0/4.0
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Quoting weatherwart:
To clarify, I wouldn't wish a hurricane on anyone. I was echoing some of the comments I've heard over the years. A lot of peckerwood bravado, the "bring-it-on" mentalitly of those too stupid to get out of the way of a major hurricane. Lots of those folks around the Tampa Bay area, sad to say.

Y'all don't know me, and my sarcasm didn't translate well.

Oh I just started a little conversation off of what you said but it wasn't directed at you, I was just saying that in general.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting MiamiHurricanes09:
LOL!! Are you being serious?


Why wouldn't I be? Joe Bastardi says that a category 3 storm is going to hit Galveston.
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I think the dry air shows up pretty well on the IR-JSL loop at the NHC.
Member Since: August 18, 2008 Posts: 0 Comments: 3112
Quoting earthlydragonfly:
I know a bit off the topic of the closest storm in proximity ... But the West African Coast is looking alot like a nursery of waves...


You noticed that too? It is going to be an interesting season at the very least...
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To clarify, I wouldn't wish a hurricane on anyone. I was echoing some of the comments I've heard over the years. A lot of peckerwood bravado, the "bring-it-on" mentalitly of those too stupid to get out of the way of a major hurricane. Lots of those folks around the Tampa Bay area, sad to say.

Y'all don't know me, and my sarcasm didn't translate well.

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Quoting galvestonhurricane:
I am finished boarding up my house and am getting ready to evacuate...
LOL!! Are you being serious?
Member Since: September 2, 2009 Posts: 130 Comments: 21091
I know a bit off the topic of the closest storm in proximity ... But the West African Coast is looking alot like a nursery of waves...
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Quoting zoomiami:
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.


Well said; CAt1s can cause plenty of damage on their own ansd slow moving TS can wreak havoc...I believe some of us have been talking about Allison today?
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Quoting extreme236:
Looks like the eye could be visible soon. Continuing to get better organized.
Agreed.
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I am finished boarding up my house and am getting ready to evacuate...
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559. xcool
aol
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Looks like the eye could be visible soon. Continuing to get better organized.
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.
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Quoting MiamiHurricanes09:
I wonder how many e-mail addresses he has? You know how you have to put in a new address every time you create an account.


hotmail, gmail, yahoo.. etc etc.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Floodman:


I will repeat what I said earlier:

Strong words from a person whose greatest claim to fame here is the continuous circumvention of bans. You are a piteous and annoying little person who is loved most for his absence...


.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Floodman:


I will repeat what I said earlier:

Strong words from a person whose greatest claim to fame here is the continuous circumvention of bans. You are a piteous and annoying little person who is loved most for his absence...
I wonder how many e-mail addresses he has? You know how you have to put in a new address every time you create an account.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting WaterWitch11:
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


Wow, outstanding!
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Quoting cooldayr:


well that is slightly faster than i thought
any guesses to when we will have an eye
An eye? Probably by Wednesday morning.
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Hiya zoo,..
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Quoting StSimonsIslandGAGuy:


So would Draco. Crabbe. Goyle. Nicely evil.


I like them all.
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Even though it's not a first name I would like to suggest a write in campaign for Bueller we should all be able to have fun with that one from formation until the bitter end.
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Respect the Hurricane


Cuz it wont you.
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Hey Orca, Pat, Ike & all --- popping in and right back out. Still at the office on my home, finally!
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Quoting GlobalWarming:


Beep, if this doesn't do you in then IDk what will, viejo.


I will repeat what I said earlier:

Strong words from a person whose greatest claim to fame here is the continuous circumvention of bans. You are a piteous and annoying little person who is loved most for his absence...
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Quoting IKE:


I didn't see any in the next 10 days.

Both 00Z and 12Z show an area of enhanced vorticity starting at about 8 days out.


00Z at day 10.


12Z at day 9.
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.