Alex, strongest June hurricane in 44 years, is now a tropical storm

By: Dr. Jeff Masters , 2:20 PM GMT on July 01, 2010

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Hurricane Alex, the strongest June hurricane in 44 years, is Tropical Storm Alex, thanks to passage over the rugged terrain of Mexico. Alex made landfall at 9pm CDT last night, 110 miles south of Brownsville, Texas, as a Category 2 hurricane with 105 mph winds. Alex was the strongest June hurricane since Hurricane Alma of 1966, which had 125 mph winds as it skirted the west coast of Florida. Brownsville long-range radar shows that Alex's heavy rains continue to pound the Texas/Mexico border region, and satellite estimates of rainfall (Figure 1) show that some of Alex's spiral bands dumped rains in excess of five inches today, in addition to the 5+ inches that fell yesterday. The Brownsville airport received 6.46" of rain as of 8am CDT today from Alex. Alex is being blamed for at least thirteen deaths in Central America and Mexico due to flooding, though none of these deaths occurred in the region where the storm made landfall. Alex spawned two tornadoes that hit South Texas, and there were at least four other reports of tornado funnel clouds that did not touch ground. Alex may continue to spawn isolated tornadoes today over South Texas and northern Mexico.


Figure 1. Radar-estimated rainfall so far today for Alex.


Figure 2. Snapshot of the Brownsville long-range radar showing Hurricane Alex at landfall at 8pm CDT Wednesday June 30, 2010.


Figure 3. Alex nearing landfall in northeastern Mexico at 12:10 CDT June 30, 2010, as seen by the MODIS instrument on NASA's Terra satellite. Image credit: NASA.

Storm Surge
Alex's maximum storm surge occurred along a 50-mile stretch of the Mexican coast centered about 75 miles south of Brownsville, Texas. The National Hurricane Center Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model predicted that the maximum water depth at the coast reached about 5 - 6 feet above ground level (Figure 3.) A storm surge of 1 - 2 feet was predicted by SLOSH for the Brownsville, Texas region. A storm surge of about 2 feet was observed in South Texas at the South Padre Island Coast Guard Station and Port Isabel.


Figure 4. Hurricane Alex's 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 surge occurred to the right of where Alex's core made landfall, over a sparsely populated marshy area. This "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. For more information on storm surge, consult our detailed storm surge pages.

Alex in historical context
Alex is the first June hurricane since Hurricane Allison of 1995. There have been only eleven hurricanes in May or June since 1945; only four of these were major Category 3 or higher storms.

Alex's bizarre behavior
Alex had several rather remarkable features I've never seen in a hurricane. Firstly, it underwent an eyewall replacement cycle as a Category 1 hurricane with 80 mph winds. Usually, we don't see the inner eyewall collapse and an eyewall replacement cycle occur until a hurricane reaches Category 3 strength. I've seen it happen on occasion to a Category 2 storm, but never a Category 1. Secondly, after Alex's inner 9-mile diameter eyewall collapsed at 10am EDT yesterday morning, an outer spiral band began to become the new eyewall. Winds in this outer spiral band/new eywall increased as the day progressed, as typically happens in an eyewall replacement cycle. However, part way through that process, Alex suddenly reversed course, and was able to build a small inner eyewall with a 12-mile diameter that was completed by landfall. I've never seen a hurricane change its mind in the middle of an eyewall replacement cycle and build an inner eyewall so fast. Finally, Alex had an unusually weak winds, considering how low the pressure was. The pressure was more typical of a hurricane one Saffir-Simpson category stronger than what the surface winds suggested.

Elsewhere in the tropics
The latest run of the NOGAPS model predicts the formation of a tropical depression the Western Caribbean on Tuesday. None of the other models is showing tropical development worthy of concern over the coming seven days.

Wind and ocean current forecast for the BP oil disaster
Alex is continuing to generate very rough conditions over the Deepwater Horizon blowout location, with 5 - 9 foot waves and 3 - 4 foot swells. The wind and seas will gradually subside today, according to the latest marine forecast from NOAA. The resulting currents induced by Alex's strong winds will push oil to many protected bays and estuaries that haven't seen oil yet. The latest trajectory forecasts from NOAA and the State of Louisiana show oil will also move westward along the central Louisiana coast towards the Texas border. Winds will decrease to 5 - 15 knots Friday through Tuesday but remain mostly out of the southeast, keeping the pressure on the regions of coast in Louisiana, Alabama, and Mississippi that are seeing oil hit their shores this week.

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

Next post
I'll have an update Friday morning. Dr. Rob Carver plans on summarizing Alex in his blog later today.

Jeff Masters

Hurricane Alex (LRandyB)
Weather inbound to Hurricane Alex.
Hurricane Alex

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THere are many different kinds of lows. You can have an induced low or a heat low without precip. Both of those usually are dry and just cause in increase in the pressure gradient. the heat lows in the mid east tend to surprise some with duststorms.
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Quoting TexasHurricane:


so true....sometimes I wish I could go back to 13.... :)


NEVER NEVER NEVER

Now twice that......... :)
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Quoting IKE:
Watching Central Gulf Coast for Tropical Development


Maybe when the 2am advisory from the NHC comes out, they might hilight that area in yellow.
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Quoting Levi32:


LOL....I love how that doesn't actually define a low and give us criteria for analyzing one.

Hey man no L on the map no low..this way noaa is always right and first!!!

Gotta go have a good night all1
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting atmoaggie:
delta-T was huge further north. Lows in the upper 40s in the northern mid-west. (and they are none too happy about it...)

up north I buy...we were more in the shearline if there was a true front. I watched the temps all up and down MS and the whole state was in the 80s. If anything the coast was cooler which is expected with a south wind
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Quoting CybrTeddy:


Yep he is. I didn't even get an honorable mention. :-( ah well, don't matter to me. Just enjoy blogging, and enjoy learning.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting Baltimorebirds:
Yeah.I'm enjoying the blog.Really learning here in the process.


Me too. Nice to know I don't have everything figured out. (that's something you'll understand hen you're older) Lol
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better..but some kind of delta pressure over distance would be nice
Trough
An elongated area of relatively low atmospheric pressure, usually not associated with a closed circulation, and thus used to distinguish from a closed low. The opposite of ridge.
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting HaboobsRsweet:
It is not that rare to get a stationary boundary this far south...that trough was not a true cold front. There was no true seperation of air masses and the temperature difference was nonexistant.
delta-T was huge further north. Lows in the upper 40s in the northern mid-west. (and they are none too happy about it...)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
1332. Levi32
Quoting sailingallover:
Really Scientific
From NOAA defs
Low
A region of low pressure, marked as "L" on a weather map. A low center is usually accompanied by precipitation, extensive cloudiness, and moderate winds. See Cyclone.


LOL....I love how that doesn't actually define a low and give us criteria for analyzing one.
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you know stormpetrol I lernt over the years that one of the best ways to learn is to talk to the older people yeah it could be annoying for a kid to be asking like umm stormpetrol why did Ivan missed Jamaica and came here? stormpetrol why did Alex hit Mexico and not Texas? stormpetrol why did that tropical wave gave us nearly no rain? But this is there way of learning eventually they will end up reading and learning for them self at school but by telling them will help them grow any maybe be ahead of you. lol!. So I say that the Young one should stay atleast if you want so badly make it 10 and up ok
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Really Scientific
From NOAA defs
Low
A region of low pressure, marked as "L" on a weather map. A low center is usually accompanied by precipitation, extensive cloudiness, and moderate winds. See Cyclone.
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting StSimonsIslandGAGuy:
OK Levi.

But I still say that proclaiming a low's presence now is really, really reaching. ;)

The Aleutian low would pick its teeth with this thing.
LOL. I think there is a low present there. There was a buoy reporting west winds earlier in the 10 to 20 mph range so there has to be something cooking there.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting Baltimorebirds:
Lol.My mother told me to enjoy my childhood while It last.Becuase once your an adult you can never go back.


Smart Mama. :) And you could be doing worse things than hanging out on a weather blog. Hope you're enjoying it.
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Quoting Levi32:


Didn't say there was a COC, and again, the comparison can be made to the ITCZ or monsoon trough, which in this situation the vort max would likely be proclaimed a low, though of course it would be at a much lower pressure. The pressure field is indeed flat, which is the only thing I can see that doesn't justify this being a low. I think it's a very weak one, but it doesn't really matter right now. What matters is what happens over the water during the next 5-7 days in the NE gulf.
Sorry teasing a bit..
I agree with the rest 100% except I would use potential rather than weak..
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting Hurricane1956:
It's amazing with all this moisture over Florida, here in Miami we are not getting any rain at all!!!!!!,a rain that we desperatly need!,don't understand why the East coast of South Florida is free of rain??????,even with a ULL between Cuba and South Florida is not pushing any rain this way.

Where is the trigger? did you hit yoru convective temp today to help induce growth? Any convergent boundary near by or a sea breeze? If you are on the north side of the low you will probably just see a bunch of midlevel clouds.
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Quoting Baltimorebirds:
Lol.My mother told me to enjoy my childhood while It last.Becuase once your an adult you can never go back.


so true....sometimes I wish I could go back to 13.... :)
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Quoting sailingallover:


All frontal boundries have sections of vorticity.
They are very unstable..
and yes a low will try to form there..but it is not a low yet and the instability has a tendency to travel along the wave
and there is no COC!! :)
You're going against several graphs and maps. Just look at surface observations and satellite imagery. There is definitely an area of low pressure there, albeit it being ill-defined and weak. Anyways no one ever said anything about a COC.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting stormpetrol:


An example of " making pure fun" and yet someone defends you, I'm finsihed here for the night before I get banned!!!

Shouldn't there be a ban on banning when there is no AOI or better? What else are we gonna do beside try to have what fun we can? that might involved a bit of teasing or ridiculousness..
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting floridaT:
question to anyone who might know. how often are the water temps updated? all the rain in the gulf must have cooled it a bit?


Since that was a warm core system and the rain was fairly warm rain I doubt the temp dropped too much. maybe half a degree at most. Now the system itself could have mixed the cooler water under the surface and had an effect on the surface temps. I dont know how often they are updated.
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Quoting Baltimorebirds:
I'm 13 and I'm proud.Thank you.Moving on.


I've been 13 several times. :)
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1315. Levi32
Quoting sailingallover:


All frontal boundries have sections of vorticity.
They are very unstable..
and yes a low will try to form there..but it is not a low yet and the instability has a tendency to travel along the wave
and there is no COC!! :)


Didn't say there was a COC, and again, the comparison can be made to the ITCZ or monsoon trough, which in this situation the vort max would likely be proclaimed a low, though of course it would be at a much lower pressure. The pressure field is indeed rather flat, which is the only thing I can see that doesn't justify this being a low. I think it's a very weak one, but it doesn't really matter right now. What matters is what happens over the water during the next 5-7 days in the NE gulf.
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It's amazing with all this moisture over Florida, here in Miami we are not getting any rain at all!!!!!!,a rain that we desperatly need!,don't understand why the East coast of South Florida is free of rain??????,even with a ULL between Cuba and South Florida is not pushing any rain this way.
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1312. Levi32
Quoting StSimonsIslandGAGuy:


Actually that's not quite so. Our average pressure here runs between 1018/1019 mb. We are close to the subsidence at 30 N and to the subtropical Atlantic high. So pressures here are not unusually high.

In fact, the coast between Savannah and Cape Canaveral has the highest average annual barometric pressure in the country, I believe.


Hmm, perhaps I'm just used to the below-normal pressures in the SW Atlantic this year, but I was going by this:

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Quoting Levi32:


A distinguished spin and vorticity max that stands out from the rest of the frontal boundary is something more than just a regular section of the frontal boundary. I believe a low is forming there, but it should not be a concern for 3-4 days yet until pressures lower in the gulf. A 1018mb low isn't going to develop.


All frontal boundries have sections of vorticity.
They are very unstable..
and yes a low will try to form there..but it is not a low yet and the instability has a tendency to travel along the wave
and there is no COC!! :)
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting Baltimorebirds:
Do you think this will be a cat 5 Taz.


An example of " making pure fun" and yet someone defends you, I'm finsihed here for the night before I get banned!!!
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Quoting homelesswanderer:


Hi Tex. :) Finally stopped raining here.


yep....
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Quoting txalwaysprepared:
I asked for rain... didn't really mean this much!!


Right!!!
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question to anyone who might know. how often are the water temps updated? all the rain in the gulf must have cooled it a bit?
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Quoting TexasHurricane:


Hi Homeless.....


Hi Tex. :) Finally stopped raining here.
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Quoting StSimonsIslandGAGuy:


The dew point differences are quite existant.


Duh...you had a south wind for over 3 days...that is going to increase the dewpoint along the coast. that can happen with just a standard sea breeze...dont need a front for that.
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1300. Levi32
And atmo, you make some of the most useful posts when it comes to hard data and questioning validity of certain things. You're definitely an asset we would miss.
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Quoting atmoaggie:
??? Appears I missed something...

Aw, gee, CT, thanks. But, I'd gladly admit that there are quite a few that make more useful contributions.

(I simply haven't the spare time and some of the others listed are just so danged smart!)

Hey, did anyone list Drak? Should be there. And my short-name is moag.


Yep he is. I didn't even get an honorable mention. :-( ah well, don't matter to me. Just enjoy blogging, and enjoy learning.
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Quoting atmoaggie:
??? Appears I missed something...

Aw, gee, CT, thanks. But, I'd gladly admit that there are quite a few that make more useful contributions.

(I simply haven't the spare time and some of the others listed are just so danged smart!)

Hey, did anyone list Drak? Should be there. And my short-name is moag.

Was the statement who posts the most or the most useful? haha. atmoaggie does post less than the others but when he does it is usually correct and useful. Drak def a good one as well.
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Quoting WindynEYW:
storm please dont swear at herm she is only 13

I'm not swearing at anyone and as far as I'm concerned with all due respect I thought this blog was for 18 and over, if you can join a blog like this learn to take what you can dish out, I don't care if they have Einstein IQ at 13 and I realize one of the persons I named maybe under 18 but still I think this should be an 18 and over blog!!
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1296. Levi32
Quoting atmoaggie:
??? Appears I missed something...

Aw, gee, CT, thanks. But, I'd gladly admit that there are quite a few that make more useful contributions.

(I simply haven't the spare time and some of the others listed are just so danged smart!)

Hey, did anyone list Drak? Should be there. And my short-name is moag.


He was.
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Quoting homelesswanderer:


Lol. Me either. I've blob watched since 2008. There were a few even last year that were interesting.


Hi Homeless.....
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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.