Alex building an eyewall, still not a hurricane

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

Share this Blog
3
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1593 - 1543

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40Blog Index

Quoting mtyweatherfan90:
Holy cow! Over 12 inches of rain and more than 11.3 at my spot! :O



We are feeling right now the first rain bands. Tommorrow I'll take some pics and post them as the day goes along.


are these maps pretty accurate?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting Xyrus2000:
On NHC's WV loop, seems like Alex is drifting WSW.

Of course, that's only eyeballing it. HH's give far more accurate locations.
Between the 8PM intermediate advisory and the last vortex center fix Alex just drifted to the SW so you could be right.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1591. Hhunter
let me introduce the greatest tropical storm ever in all creation
Member Since: Posts: Comments:
Quoting Patrap:


Saw the Viper Run with Bob and its not what we want to see.
forming so close to land it shouldn't do too much but cause alot of rain, right? nothing could really form that close to land could it?:)
Member Since: Posts: Comments:
Quoting will45:
They are at 16000 ft


You may be right.. wonder if they bent the bird again?
Member Since: Posts: Comments:
1588. SamTeam
Quoting Patrap:


Saw the Viper Run with Bob and its not what we want to see.


Could you explain further please?
Member Since: Posts: Comments:
when is the ridge to its north forecast to move out?
Member Since: Posts: Comments:
On NHC's WV loop, seems like Alex is drifting WSW.

Of course, that's only eyeballing it. HH's give far more accurate locations.
Member Since: Posts: Comments:
Quoting kmanislander:


Actually I didn't see that post but based upon the loop I am not seeing any motion at this time.
was this forecasted i think not but i expect a mexico landfall still.
Member Since: Posts: Comments:
Quoting kmanislander:


Actually I didn't see that post but based upon the loop I am not seeing any motion at this time.
I noticed the same thing too just after posting it, kind of scary. Let's hope he doesn't stall or else we could be in for a whole different ballgame.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting kmanislander:


Why not ??. After all it is 2010 right ?? LOL


;) Enjoying this blog.
Member Since: Posts: Comments:
Quoting angiest:


I'm up in the very northern tip of the county.


I am in the Southern part of the county, almost where it touches Wharton and Brazoria
Member Since: Posts: Comments:
Quoting Baltimorebirds:
It was some people asking why havn't they updated the status yet on the nhc page.The nch is still waiting to upgrade this.


oh, I thought maybe there had been some change in direction or something...
Member Since: July 2, 2009 Posts: 0 Comments: 2811
BreakingNews: Obama declares federal emergency in Texas as Tropical Storm Alex builds toward hurricane strength http://bit.ly/cJ5SMZ
Member Since: Posts: Comments:
Quoting StormW:


Thanks!


Wow that was fast! You must have been itching to get back in here. Nice job. I guess we may see a little break in the action after Alex.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
You just had to say that after post 1543, lol.


Actually I didn't see that post but based upon the loop I am not seeing any motion at this time.
Member Since: Posts: Comments:
Holy cow! Over 12 inches of rain and more than 11.3 at my spot! :O



We are feeling right now the first rain bands. Tommorrow I'll take some pics and post them as the day goes along.
Member Since: Posts: Comments:
1575. dearmas
I know that this is off the subject of the tropics but today in Tampa Fl we lost the lives of 2 police officers. One who was the dad of 4 boys ages 8mos to 9yrs old, the other officer was due to be a daddy next week. They got one scum bag and are still looking for the other... May the families find some kind of peace :(
Member Since: Posts: Comments:
Quoting sarahjola:
bob breck on fox 8 news said that too. but he said it will form off of our coast in new orleans. he said that viper indicated it, and he hopes it is not true because it will sit over us for days bringing lots of rain. he said that should happen on friday or sat.
p.s. hats off to the people who called the landfall of t.s. alex. good job. i only hope that the next storm we can all get along and realize that its ok to have different opinions. 1 question- why hasn't alex become a hurricane yet. isn't he in very hot water, and hasn't the conditions been right for further strengthening?
FYI: A bunch of my company's data goes into the viper system...
And Omni, Mobile Threat Net, and WxWorx.
Member Since: Posts: Comments:
Quoting Stormchaser2007:
As they approach the NE quad, SFMR fails.

Of course...
Oh man! Why does this happen every time.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1572. angiest
Quoting FortBendTX:


Good evening!


I'm up in the very northern tip of the county.
Member Since: Posts: Comments:
1570. will45
They are at 16000 ft
Member Since: Posts: Comments:
Great job StormW, good to finally hear from you :)
Member Since: July 1, 2008 Posts: 13 Comments: 7396
Inbound again :)


AOI
Member Since: Posts: Comments:
1567. Patrap
Quoting sarahjola:
bob breck on fox 8 news said that too. but he said it will form off of our coast in new orleans. he said that viper indicated it, and he hopes it is not true because it will sit over us for days bringing lots of rain. he said that should happen on friday or sat.
p.s. hats off to the people who called the landfall of t.s. alex. good job. i only hope that the next storm we can all get along and realize that its ok to have different opinions. 1 question- why hasn't alex become a hurricane yet. isn't he in very hot water, and hasn't the conditions been right for further strengthening?


Saw the Viper Run with Bob and its not what we want to see.
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting Stormchaser2007:
Looks like Alex has slowed a bit.
I wasnt expecting that maybe a more westward movement when it picks speed again
Member Since: Posts: Comments:
1565. will45
looks like HH heading home
Member Since: Posts: Comments:
Quoting thegoldenstrand:


Think he might be ready to pull a big surprise on all of us, but can he?


Why not ??. After all it is 2010 right ?? LOL
Member Since: Posts: Comments:
As they approach the NE quad, SFMR fails.

Of course...
Member Since: Posts: Comments:
Quoting angiest:


Howdy, neighbor!


Good evening!
Member Since: Posts: Comments:
slowing down and wanting to go S of due West, wants to maybe hang out little longer in BOC and this is skeptical but not entirely impossible
Member Since: Posts: Comments:
1560. txjac
was thinking the same thing hurricane hannah ..great job storm ...and I like Bob's kitty cat
Member Since: Posts: Comments:
Quoting kmanislander:
Has Alex stalled again ??
Quoting Stormchaser2007:
Looks like Alex has slowed a bit.
You just had to say that after post 1543, lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Orcasystems:


yes, the Docs blog... look up :)

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.
bob breck on fox 8 news said that too. but he said it will form off of our coast in new orleans. he said that viper indicated it, and he hopes it is not true because it will sit over us for days bringing lots of rain. he said that should happen on friday or sat.
p.s. hats off to the people who called the landfall of t.s. alex. good job. i only hope that the next storm we can all get along and realize that its ok to have different opinions. 1 question- why hasn't alex become a hurricane yet. isn't he in very hot water, and hasn't the conditions been right for further strengthening?
Member Since: Posts: Comments:
1557. angiest
Quoting FortBendTX:
how long is the ridge to the north scheduled to be in place?


Howdy, neighbor!
Member Since: Posts: Comments:
Alex just about a hurricane. Hurricanes in June farly rare. Over last 150 yrs. Average about 1 a decade. But first since 1986.
Member Since: Posts: Comments:
Quoting kmanislander:
Has Alex stalled again ??


Think he might be ready to pull a big surprise on all of us, but can he?
Member Since: Posts: Comments:
What direction is Alex moving?
Member Since: Posts: Comments:
every gulf state is getting a piece of alex
Member Since: Posts: Comments:
Quoting Baltimorebirds:
Pipe down folks they will eventually update it.Just...well WAIT!!!!.


what? did I miss something?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
how long is the ridge to the north scheduled to be in place?
Member Since: Posts: Comments:
Looks like Alex has slowed a bit.
Member Since: Posts: Comments:
Has Alex stalled again ??
Member Since: Posts: Comments:
Quoting StormW:


Thanks!


Great job Storm! Nice to finally have a voice to put with the face!
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Quoting Baltimorebirds:
Goodoldbudsir you must have gotten your username from that man correct?You know who...


yes. a couple of seasons ago. all in fun
Member Since: Posts: Comments:
If Alex slows down he could easily become a category 3 hurricane, let's hope he doesn't.

Member Since: September 2, 2009 Posts: 130 Comments: 21194

Viewing: 1593 - 1543

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40Blog Index

Top of Page

About

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