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: 1843 - 1793

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 scott39:
What does that mean in reference to Alex?
Weaknesses tend to attract areas of low pressure. I'm sure Kman can explain better, I'm just stating the basics. :)
Member Since: September 2, 2009 Posts: 130 Comments: 21178
ritaevac, the radar is intersting. i'm not sure if that is the center, but if it is, i think that you and i are correct that it's moving south or southwest. it's probably not the center though??
Member Since: Posts: Comments:
Alex is now a Hurricane on the models
Check 1819 pic :)
Member Since: Posts: Comments:
Hurricane Alex is born, according to CNN's Anderson Cooper. Like we really needed someone to tell us that.
Member Since: Posts: Comments:
Quoting SavannahStorm:
Dominating an entire hemisphere...



"Red Storm" of Jupiter like. Huge Storm ideed.
Member Since: Posts: Comments:
1837. aquak9
msgambler- don't make me laugh any harder then I already am!

MH09- love the banner effect!

So do we have a cane yet? I can be very annoying, I've learned from the best!
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
My funny little image, lol. I'm eager to see if the 03:00 UTC graph shows a larger weakness, which seems more probable.


What does that mean?
Member Since: Posts: Comments:
000
WTNT31 KNHC 300231
TCPAT1
BULLETIN
HURRICANE ALEX ADVISORY NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010
1000 PM CDT TUE JUN 29 2010

...ALEX BECOMES THE FIRST HURRICANE OF THE 2010 SEASON AND THE FIRST
JUNE ATLANTIC HURRICANE SINCE 1995...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...23.1N 94.8W
ABOUT 195 MI...315 KM ESE OF LA PESCA MEXICO
ABOUT 255 MI...415 KM SE OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/HR
PRESENT MOVEMENT...W OR 280 DEGREES AT 9 MPH...15 KM/HR
MINIMUM CENTRAL PRESSURE...973 MB...28.73 INCHES
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Its officially a HURRICANE!!!
Member Since: May 27, 2009 Posts: 0 Comments: 4438
1833. Ossqss
Quoting atmoaggie:
My new fav for TC analysis. From here, sector 5, thermal infrared: http://rammb.cira.colostate.edu/ramsdis/online/rmtc.asp#Sector%205


Seems to me the folks on the northern side need to get ready in the extra mode. Just sayin, that is where the energy seems to be coming soon! That is at thick leg growin..........

Thanks also 09!
Member Since: Posts: Comments:
1832. centex
For those who post the best example of images or loops during the day. Keep it up, some of us access from work and getting it all looking through a few recent pages of blog really appreciates getting it all in a few minutes.
Member Since: Posts: Comments:
1831. Patrap
Evening to yas ms..
Welcome to the Premiere of the 2010 Season.

Pass the Napkins and theres a seat down up front nearer the screen.

The Previews are bout over.
Member Since: Posts: Comments:
Quoting NCHurricane2009:
Wow, Alex just won't be upgraded to a hurricane. I think it will at 11 PM because they said at 5 PM the satellite presentation (Dvorak numbers I believe) support a 65-knot (75 mph wind) hurricane, I think they are just waiting to get into the center with a recon plane to confirm winds have increased to 75 mph, which will happens shortly.

I mean, 980 mb is such a low pressure for a tropical storm, even for a broad circulation.


Pressure is 972.9mb
Member Since: May 27, 2009 Posts: 0 Comments: 4438
1829. angiest
Quoting Baltimorebirds:
alex is almost Ike's size.wow.


According to Wikipedia, Ike was ~900 miles across.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting atmoaggie:
FYI: A bunch of my company's data goes into the viper system...
And Omni, Mobile Threat Net, and WxWorx.
awesome!:)
Member Since: Posts: Comments:
Quoting SavannahStorm:
Dominating an entire hemisphere...



Impressive. Thanks.
Member Since: Posts: Comments:
Link

GOES-12 Low Cloud Product
Member Since: Posts: Comments:
1825. scott39
Quoting MiamiHurricanes09:
My funny little image, lol. I'm eager to see if the 03:00 UTC graph shows a larger weakness, which seems more probable.

What does that mean in reference to Alex?
Member Since: Posts: Comments:
Quoting aquak9:
elConando- we got over an inch here in Jacksonville today offa those bands!


In Jacksonville!! That just goes to show what an impact Alex can have on places far away.
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Wow, Alex just won't be upgraded to a hurricane. I think it will at 11 PM because they said at 5 PM the satellite presentation (Dvorak numbers I believe) support a 65-knot (75 mph wind) hurricane, I think they are just waiting to get into the center with a recon plane to confirm winds have increased to 75 mph, which will happens shortly.

I mean, 980 mb is such a low pressure for a tropical storm, even for a broad circulation.
Member Since: Posts: Comments:


Interesting facts about Hurricane Tip, 1900Hurricane. An amazing storm with an 870 sea level pressure and peak winds of 190mph. Thanks for sharing. I sure hope I never see anything like Tip in the Gulf!
Member Since: Posts: Comments:
Quoting 1900hurricane:

Never mind, found it!
Ok.
Member Since: September 2, 2009 Posts: 130 Comments: 21178
Hurricane Alex is alive :)



AOI

AOI

AOI

Hurricane Hunter Data

TS BUSTED FORECAST ALIBI
Member Since: Posts: Comments:
Just got settled in at my hotel room in McAllen. Was in the same Hotel for Dolly so I thought for this trip I would stay in the same place. Not much going on right now just some showers passing by from time to time, busy day tomorrow as I have to hook up three 100kw generators and make a plan to survive the night.

I always appreciate all of the quality information on Masters-Blog. And I always find it a little entertaining reading the comment section.

.
Member Since: Posts: Comments:
1817. guygee
Alex's pressure is lower that expected compared to its maximum winds due to the low pressure environment that surrounds it. The 1012 mb isobar arcs from Houston in a large southeasterly arc all the way down to Havana. The 1008 mb isobar encompasses the entire SW Gulf stretching down into the E. Pac and Western Mexico: 18Z Alex Surface Analysis from NWS-OPC.
Member Since: Posts: Comments:
1816. Patrap
Member Since: Posts: Comments:
Evening Pat, Aqua. ATMO, and of course Orca (sir). Let me see what senseless question I can ask....LOL
Member Since: Posts: Comments:
My funny little image, lol. I'm eager to see if the 03:00 UTC graph shows a larger weakness, which seems more probable.

Member Since: September 2, 2009 Posts: 130 Comments: 21178
1813. aquak9
elConando- we got over an inch here in Jacksonville today offa those bands!
Member Since: Posts: Comments:
Quoting 1900hurricane:

Would you mind posting the link where you got that from? Please and thank you! :)

Never mind, found it!
Member Since: Posts: Comments:
Tallahassee forcast is 90 percent rain tomorrow

Member Since: Posts: Comments:
1810. Patrap
.."Beware the Tail of the hurricane the next day"..
Member Since: Posts: Comments:
Alex is Huge, its causing some cloudiness and light rain in S Fla.
Member Since: Posts: Comments:
Truecajun - Beware of the tail as they always say.
Member Since: Posts: Comments:
Dominating an entire hemisphere...

Member Since: September 22, 2005 Posts: 18 Comments: 2337
Quoting MiamiHurricanes09:
Here's the same image but a little more zoomed-out. Another thing is that I'm using GOES-15, which I think is awesome.


Would you mind posting the link where you got that from? Please and thank you! :)
Member Since: Posts: Comments:
Without having to sift through all these post, can somebody post the link to the rainfall projections for this thing.
Member Since: Posts: Comments:
Wow Pat. You guys are pulling in some dry air right now.
Member Since: Posts: Comments:
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Quoting hurricaster:
Agreed. The banding on the eastern quadrant is out of hand. May pack a significant punch.


but the banding there always seems to break away from it. it never really wraps around.
Member Since: Posts: Comments:
1800. Patrap
NEXRAD Radar
Brownsville, Storm Relative Mean Radial Velocity 1.45 Degree Elevation Range 124 NMI


Member Since: Posts: Comments:
Quoting Ossqss:




That is an interesting image ATMO
My new fav for TC analysis. From here, sector 5, thermal infrared: http://rammb.cira.colostate.edu/ramsdis/online/rmtc.asp#Sector%205
Member Since: Posts: Comments:
1798. aquak9
do we have a cane yet or what? Jeeeez'm'neeez we been following this thing for like 3 WEEKS NOW!!!

and yes my dear this is for you- ♥
Member Since: Posts: Comments:
1797. Patrap
NEXRAD Radar
New Orleans, Storm Relative Mean Radial Velocity 1.45 Degree Elevation Range 124 NMI

Member Since: Posts: Comments:
Quoting Ossqss:




That is an interesting image ATMO
Here's the same image but a little more zoomed-out. Another thing is that I'm using GOES-15, which I think is awesome.

Member Since: September 2, 2009 Posts: 130 Comments: 21178
Under the hood:

Member Since: Posts: Comments:
Can you see the center at the 5'o clock angle on radar? looks to be moving SW and I know this would be way up in the top part of the clouds being so far off

Member Since: Posts: Comments:

Viewing: 1843 - 1793

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.