Alex building an eyewall, still not a hurricane

By: Dr. Jeff Masters , 07:34 PM GMT on iunie 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:


Things to beware this season:

Gulf Stream riders
Gulf of Mexico oilcanes
First storm of September
Any storm that kills the Bermuda high
Any storm that rounds the Bermuda high as a born-again Cape Verde storm

Also, three things I would not trust Bastardi with:

1. Life-or-death decisions
2. Exact landfall locations for tropical cyclones beyond 5 days
3. Any statements pertaining to GW

4. A Dentist
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Quoting HurricaneSwirl:


Yeah, he's losing his "cinnamon roll" look.



thanks my love
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting nrtiwlnvragn:


GHCC Infrared
Thanks! ;)
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Quoting victoriahurricane:


You can really see how much Alex has worked to fill in his gaps in that loop.


Yeah, he's losing his "cinnamon roll" look.
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Quoting Levi32:


SHIPS 85mph at 24 hours out looks alright, but if Alex mixes out the dry air you could see him rapidly deepen before landfall...I'll be holding onto my Cat 2 prediction for intensity at landfall.
Thanks. Now for a hard question: what will the surge be at marker 84 in the intercoastal waterway off Navarre Fl, say, Saturday morning 8AM?...LOL!
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Quoting Floodman:


Sorry, Taz...I know that the use of the tri-letter is pretty foul and I do apologize...
You have WU mail, omnipotent king of ubiquity.
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At 8 p.m we should have a 80-85 mph hurricane.
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Quoting Tazmanian:
can i have the google eath data from the HH link may be
Link
Member Since: septembrie 2, 2009 Posts: 130 Comments: 21032
This will be a non-event for the U.S... other than some squally weather.
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Quoting atmoaggie:
NAM initializes the first closed isobar off of Georgia and then south off of FL in the GS:



Things to beware this season:

Gulf Stream riders
Gulf of Mexico oilcanes
First storm of September
Any storm that kills the Bermuda high
Any storm that rounds the Bermuda high as a born-again Cape Verde storm

Also, three things I would not trust Bastardi with:

1. Life-or-death decisions
2. Exact landfall locations for tropical cyclones beyond 5 days
3. Any statements pertaining to GW
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MIMIC shows a very nice circulation
Member Since: iulie 18, 2009 Posts: 1 Comments: 994
Quoting KEEPEROFTHEGATE:
01L/H/A/C1
MARK
23.2N/94.4W


POINT OF IMPACT NEAR 23.6N 97.8W


You can really see how much Alex has worked to fill in his gaps in that loop.
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can i have the google eath data from the HH link may be
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting atmoaggie:

Okay, I was really in Nerdland.


Hope you meant Nederland. If not explains al lot!.LOL How are you atmo! Nailed this one, too.
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777. Daveg
Quoting KEEPEROFTHEGATE:
01L/H/A/C1
MARK
23.2N/94.4W


POINT OF LANDFALL 23.6N/97.8W


Wow... he's really slowed down... barely moving over that entire time frame.
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Quoting StSimonsIslandGAGuy:
For once, my forecast 8 days ago was largely correct. From my blog, Monday, June 21 in the evening:
[snip]
Not too bad from 8 days ago :) Even a broken clock is right twice a day. I think I did rather well. This once ;)


Just sayin.

(j/k, not bad.)
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Quoting TankHead93:
May someone please post a link of the GOES Rapid Scan Satellite (IR not VIS)... and another thing the Euro is spinning up something in the Caribbean in about 6-8 days from either the wave that just moved off of Africa this morning or the wave with a ton of convection getting ready to emerge. Are any of the other models showing this and are they being consistent on it?


GHCC Infrared
Member Since: septembrie 23, 2005 Posts: 13 Comments: 10464
01L/H/A/C1
MARK
23.2N/94.4W


POINT OF LANDFALL 23.6N/97.8W
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Okay kids, play nice...BBL
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oh all you firefox fans firefox 4.0 beta 1 is out any one want a link
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting GTcooliebai:
Alex is soo HUGE!!! Imagine if it were a Cat. 5, it sure would be quite the Perfect Storm!


Sorry, but the Perfect Storm was tiny. However we could easily get a storm this year that takes up 40% of the North Atlantic basin and that could alter ocean currents on a global scale (it's happened before recently).
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hi y'all quick check. glad to see alex is behaving.

Bright knots of glowing gas light up the arms of spiral galaxy M74, indicating a rich environment of star formation. Messier 74, also called NGC 628, is slightly smaller than our Milky Way. (From The Hubblesite.org)

HubbleSitePictureGallery
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768. Daveg
Quoting Hurricanes101:
Alex isn't going SW either

he continues to the WNW right now


Indeed, he's wobbling all around like a drunk sailor. Must of passed over an old sunken Spanish Galleon full of rum.....
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Quoting Floodman:


Sorry, Taz...I know that the use of the tri-letter is pretty foul and I do apologize...



ok
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting Tazmanian:
IS Alex going SW


Look at the latest imagery loops, it's going on a bit of a NW-W-SW wobble (counterclockwise).
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Quoting Tazmanian:
now now calling some one a name is not nic


Sorry, Taz...I know that the use of the tri-letter is pretty foul and I do apologize...
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can i have the link too the HH date for goole earth
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting Dakster:


Only if you are looking at it upside down.


LOL
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Quoting gator23:

the funny thing is he will deny it but the second you say something bad about JFV he reports you.


Also how he calls everyone by the same nicknames he called them with the previous handle.. For example: senior chief
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Quoting Dakster:


Only if you are looking at it upside down.



lol
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting StSimonsIslandGAGuy:
For once, my forecast 8 days ago was largely correct. From my blog, Monday, June 21 in the evening:


85. StSimonsIslandGAGuy 1:54 AM GMT on June 22, 2010
OK. It's time for my first tropical cyclone guess.

I think there is a 60% chance that 93L will be tropical storm Alex by Friday night. As in 11 pm. wrong. Saturday at 5 a.m.

I do not think we will see significant development before Wednesday night. Check

I do not have a good feel for its intensity. It is large, and may attain major intensity. But climatology says no. Check

I do believe the chances of whatever it becomes making landfall on the east coast or the Gulf Coast east of the Mississippi are very low. I think a westward track towards Mexico, and maybe Texas, is most likely. Check

I wouldn't call this a forecast. Only a guess!


Not too bad from 8 days ago :) Even a broken clock is right twice a day. I think I did rather well. This once ;)



actually....that is quite good SSG. The problem is
no one ever seem's to remember the good forecast's
on this Blog only the ones that were embarassingly
bad. something right now pretty much everyone can relate to.
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now now calling some one a name is not nic
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
would be something if alex stalled off the coast for 2 or 3 days.
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Quoting Tazmanian:
IS Alex going SW


Only if you are looking at it upside down.
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anyone hear about this:
WFTV Finds BP Operation Base On Small Island
http://www.wftv.com/news/24086095/detail.html
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Quoting salttube:
I hear ya! I live about 20 miles north of Beaumont and we had around 30.75" in three days from Allison!

Okay, I was really in Nerdland.
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Quoting Floodman:


Density, thy name is JFV

the funny thing is he will deny it but the second you say something bad about JFV he reports you.
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NAM initializes the first closed isobar off of Georgia and then south off of FL in the GS:

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Quoting atmoaggie:
How could a Houstonian not know Allison all that well?

Was in Beaumont for that one...

Allison (2001) formed from a wave that came from Africa, went to South America, to the Pacific, turned north across central America and developed in the Gulf just offshore from Galveston.
I hear ya! I live about 20 miles north of Beaumont and we had around 30.75" in three days from Allison!
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Alex is soo HUGE!!! Imagine if it were a Cat. 5, it sure would be quite the Perfect Storm!
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Quoting Baltimorebirds:
This means alex is intensifying.Your such a laughing stock on the blog.Geez what a moron.


Density, thy name is JFV
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Alex isn't going SW either

he continues to the WNW right now
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Issued by The National Weather Service
Lake Charles, LA
3:31 pm CDT, Tue., Jun. 29, 2010

... FLASH FLOOD WATCH IN EFFECT FROM 7 PM CDT THIS EVENING THROUGH THURSDAY MORNING...

THE NATIONAL WEATHER SERVICE IN LAKE CHARLES HAS ISSUED A

* FLASH FLOOD WATCH FOR PORTIONS OF LOUISIANA AND SOUTHEAST TEXAS... INCLUDING THE FOLLOWING AREAS... IN LOUISIANA... ACADIA... CALCASIEU... CAMERON... IBERIA... JEFFERSON DAVIS... LAFAYETTE... LOWER ST. MARTIN... ST. MARY... UPPER ST. MARTIN AND VERMILION. IN SOUTHEAST TEXAS... JEFFERSON AND ORANGE.

* FROM 7 PM CDT THIS EVENING THROUGH THURSDAY MORNING

* DEEP TROPICAL MOISTURE ASSOCIATED WITH TROPICAL STORM ALEX IN THE WESTERN GULF WILL CONTINUE TO SPREAD OVER THE AREA BRINGING THE POTENTIAL FOR HEAVY RAINFALL. OUTER RAIN BANDS FROM ALEX MOVING ACROSS THE REGION AND A WEAK FRONTAL BOUNDARY TO THE NORTH WILL HELP PRODUCE HEAVY SHOWERS AND THUNDERSTORMS. RAINFALL TOTALS WILL AVERAGE TWO TO THREE INCHES WITH ISOLATED AMOUNTS UP TO 5 INCHES THROUGH THURSDAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION. REMEMBER... TURN AROUND... DON'T DROWN... WHEN YOU SEE FLOODED ROADWAYS.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION SHOULD FLASH FLOOD WARNINGS BE ISSUED.
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Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

Afternoon everyone.
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Looks like my forecast was wrong I said SOMEWHERE IN THE GULF COAST SOMETIME BETWEEN 3 and 5 DAYS FROM NOW

this is hitting in the BAY OF CAMPECHE and therefore not the gulf. Sigh my perfect vauge forecast failed.
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Quoting Daveg:

Am I high (don't answer that) or has the forward motion really slowed over the past couple of hours?


It's wobbling away from its NW trajectory. Don't be surprised if it does a few loop-de-loops.
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IS Alex going SW
Member Since: mai 21, 2006 Posts: 5089 Comments: 114053
Quoting nrtiwlnvragn:


No support from the parallel GFS, which performed well with Alex.
I saw that too.
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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.

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