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: 1093 - 1043

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

1093. Patrap
23:46:30Z 24.300N 95.383W 842.9 mb

(~ 24.89 inHg) 1,479 meters
(~ 4,852 feet) 998.8 mb
(~ 29.49 inHg) - From 65 at 36 knots
(From the ENE at ~ 41.4 mph)
Member Since: Posts: Comments:
Barometer Bob playing some old time Boston music..
Good stuff!
Member Since: Posts: Comments:
Quoting atmoaggie:
Finally went back to having a reasonable wind speed...was looking goofy earlier with a weak TS.
Agreed. I am thinking category 2 strength before landfall, let's see if the NHC concurs with me.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
1087. Ossqss
Quoting StormW:
Barometer Bob is having another broadcast tonight at 8:00 pm. He has asked me to call in again at 8:30.


Have your cordless phone ready. We just got whacked by a Meso that is heading your direction :)

http://www.baynews9.com/weather/klystron9?animate=7county
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
GFDL 18z 30 hours

Finally went back to having a reasonable wind speed...was looking goofy earlier with a weak TS.
Member Since: Posts: Comments:
1084. Patrap
Member Since: Posts: Comments:
1083. CJC111
Even with the due west movement of late, the official track is still a bit further north isn't it?
i hate you ALEX
Member Since: Posts: Comments:
TWC just said a special NHC update may come in about an hour.
Member Since: Posts: Comments:
Quoting Orcasystems:


That part I know.. it was what you said that confused me :)

Sorry. I don't usually go back a check my typo. I just post it.
Member Since: Posts: Comments:
Quoting atmoaggie:
LOL! Must be from his mother...


LOL
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting whipster:


Yes a form of Ag, Fish Farming :) Studied the Mexican catfish and shrimp farms between Matamoros and Veracruz. Lived in La Pesca. Hope to go back and get an Organic Tilapia farm going sometime soon, after the drug wars wind down.


Tilapia are great tasting. Enjoy them when short on time to go out and catch some Tuna, Mahi and maybe Wahoo.

Wish you great success once the crime subsides, hopefully.

To my untrained eye, we are lucky Alex is so close to land. This storm in its current state just south of Cuba would have been an entirely different story. It's affecting weather all the way from the Pacific to the Florida Straits and beyond. Hope it makes landfall as soon as possible, and causes as little damage as possible.
Member Since: Posts: Comments:
Quoting SunnyDaysFla:
Re #1065

Good DNA
LOL! Must be from his mother...
Member Since: Posts: Comments:
Alex has moved due west over the past 3 hours.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
1074. xcool
Tazmanian .lmao.
Member Since: September 26, 2009 Posts: 2 Comments: 15669
Quoting Patrap:


All the Way to the wu-server in SF seems Ike.

LOL


LOL, here come the "Reintesification in the Gulf of California" theories...
Member Since: Posts: Comments:
Re #1065

Good DNA
Member Since: Posts: Comments:
1071. Patrap
TS Alex has not dropped the Chalupa..
Member Since: Posts: Comments:
Yep. Still a tropical storm. NHC might give a special advisory if the recon finds that it's a hurricane.
Member Since: Posts: Comments:
Quoting Tazmanian:
oh well there olny post season


here what i see in post season this year

Alex upgrade too hurricane

92L up grade too TD


This isn't the last advisory before it hits land.. it'll still be upped to hurricane status at 11PM tonight.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
mb 980mbs with a 70mph TS lol
Member Since: Posts: Comments:
GFDL 18z 30 hours

Member Since: September 2, 2009 Posts: 130 Comments: 21193
1066. Patrap
Quoting IKE:
GFDL 18Z on Alex....


All the Way to the wu-server in SF seems Ike.

LOL
Member Since: Posts: Comments:
Seems that some folks never noticed that rain commonly happens ahead of a cold front...something my 5 year old has noted.
Member Since: Posts: Comments:
Quoting spathy:


Jeff M mentioned that above in this update.
I thought I was imagining things. I knew I read it but couldn't remember where. Thanks.
Member Since: Posts: Comments:
1063. IKE
LOCATION...23.2N 94.5W

Moved due west .5 and zero north/south. This is getting closer to land....about 200 miles away.

Who said a hurricane at 7?
Member Since: Posts: Comments:
1062. will45
...ALEX NEAR HURRICANE STRENGTH...HURRICANE HUNTER PLANE APPROACHING
THE CENTER...
Member Since: July 18, 2009 Posts: 1 Comments: 994
1061. xcool
i'm back
Member Since: September 26, 2009 Posts: 2 Comments: 15669


Looks due west with a slight southern component to me
Member Since: Posts: Comments:
1059. Patrap
Member Since: Posts: Comments:
1058. bassis
Quoting StormW:
Barometer Bob is having another broadcast tonight at 8:00 pm. He has asked me to call in again at 8:30.

thank you storm, I look forward to it
Member Since: Posts: Comments:
8:00 is out, and he's still a TS...
Member Since: Posts: Comments:
oh well there olny post season


here what i see in post season this year

Alex upgrade too hurricane

92L up grade too TD
Member Since: Posts: Comments:
Quoting Ameister12:

The NHC probably won't upgrade it to a hurricane until the recon can prove it is. The recon isn't in the center yet.


That part I know.. it was what you said that confused me :)
Member Since: Posts: Comments:
MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/HR...WITH HIGHER
GUSTS. SATELLITE IMAGERY SUGGESTS THAT ALEX IS STRENGTHENING AND AN
AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT WILL REACH THE
CENTER SHORTLY. SOME STRENGTHENING IS EXPECTED PRIOR TO LANDFALL.

Member Since: July 8, 2005 Posts: 259 Comments: 24015
Winds are playing catch up, its a big storm going to take a little while for it to consolidate and push the dry air out. It's doing that right now.

Almost the whole southeast has done this and it's working on the northeast quad.
Member Since: Posts: Comments:
Still a TS per NHC... Xcool, who is this phony met???
Member Since: March 19, 2010 Posts: 0 Comments: 1147
000
WTNT31 KNHC 292349
TCPAT1
BULLETIN
TROPICAL STORM ALEX INTERMEDIATE ADVISORY NUMBER 17A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010
700 PM CDT TUE JUN 29 2010

...ALEX NEAR HURRICANE STRENGTH...HURRICANE HUNTER PLANE APPROACHING
THE CENTER...


SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...23.2N 94.5W
ABOUT 215 MI...345 KM E OF LA PESCA MEXICO
ABOUT 265 MI...425 KM SE OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/HR
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 12 MPH...19 KM/HR
MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES
Member Since: May 27, 2009 Posts: 0 Comments: 4438
1048. IKE
GFDL 18Z on Alex....
Member Since: Posts: Comments:
000
WTNT31 KNHC 292349
TCPAT1
BULLETIN
TROPICAL STORM ALEX INTERMEDIATE ADVISORY NUMBER 17A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010
700 PM CDT TUE JUN 29 2010

...ALEX NEAR HURRICANE STRENGTH...HURRICANE HUNTER PLANE APPROACHING
THE CENTER...

SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...23.2N 94.5W
ABOUT 215 MI...345 KM E OF LA PESCA MEXICO
ABOUT 265 MI...425 KM SE OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/HR
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 12 MPH...19 KM/HR
MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* THE COAST OF TEXAS SOUTH OF BAFFIN BAY TO THE MOUTH OF THE RIO
GRANDE
* THE COAST OF MEXICO FROM THE MOUTH OF THE RIO GRANDE TO LA CRUZ

A TROPICAL STORM WARNING IN IN EFFECT FOR...
* THE COAST OF TEXAS FROM BAFFIN BAY TO PORT OCONNOR
* THE COAST OF MEXICO SOUTH OF LA CRUZ TO CABO ROJO

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 700 PM CDT...0000 UTC...THE CENTER OF TROPICAL STORM ALEX WAS
LOCATED NEAR LATITUDE 23.2 NORTH...LONGITUDE 94.5 WEST. ALEX IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 12 MPH...19 KM/HR. THIS
GENERAL MOTION IS EXPECTED THROUGH WEDNESDAY. ON THE FORECAST
TRACK...THE CENTER OF ALEX WILL APPROACH THE COAST OF NORTHEASTERN
MEXICO AND SOUTHERN TEXAS ON WEDNESDAY AND MAKE LANDFALL IN THE
HURRICANE WARNING AREA LATE WEDNESDAY OR WEDNESDAY NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/HR...WITH HIGHER
GUSTS. SATELLITE IMAGERY SUGGESTS THAT ALEX IS STRENGTHENING AND AN
AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT WILL REACH THE
CENTER SHORTLY. SOME STRENGTHENING IS EXPECTED PRIOR TO LANDFALL.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM
FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB...28.94 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...ALEX IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS
OF 6 TO 12 INCHES OVER PORTIONS OF NORTHEASTERN MEXICO AND SOUTHERN
TEXAS...WITH ISOLATED MAXIMUM AMOUNTS OF 20 INCHES. THESE RAINS
COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES...
ESPECIALLY IN MOUNTAINOUS TERRAIN. RAINBANDS ASSOCIATED WITH ALEX
ARE SPREADING ONSHORE IN NORTHEASTERN MEXICO AND SOUTHERN TEXAS.

WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE COAST
WITHIN THE HURRICANE AND TROPICAL STORM WARNING AREAS BEGINNING LATE
TONIGHT OR EARLY WEDNESDAY...MAKING OUTSIDE PREPARATIONS DIFFICULT
OR DANGEROUS.

STORM SURGE...A DANGEROUS STORM SURGE WILL RAISE WATER LEVELS BY
AS MUCH AS 3 TO 5 FEET ABOVE GROUND LEVEL ALONG THE IMMEDIATE
COAST NEAR AND TO THE NORTH OF WHERE THE CENTER MAKES LANDFALL. THE
SURGE COULD PENETRATE INLAND AS FAR AS SEVERAL MILES FROM THE SHORE
WITH DEPTH GENERALLY DECREASING AS THE WATER MOVES INLAND. NEAR
THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DESTRUCTIVE
WAVES.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1000 PM CDT.

$$
FORECASTER PASCH/BERG



Member Since: September 2, 2009 Posts: 130 Comments: 21193
I don't see an advisory out yet, don't jump to conclusions.
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Link

Alex really squashed whatever dry air was around him out and continues to moisten it up.
Member Since: October 16, 2008 Posts: 0 Comments: 544
Quoting nrtiwlnvragn:


Probably because the cloud temperature in the center region is warming, went from ~ -57 to ~ -53.


Ah, alright. Thanks.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1043. Patrap
Member Since: Posts: Comments:

Viewing: 1093 - 1043

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.

Local Weather

Overcast
67 °F
Overcast