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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Quoting HurricaneSwirl:


That's not what happened with 90L. You're still probably right.
True, 90L was warm secluded, but it also was subtropical at some point in its lifetime. Another thing I've noticed this year is that the NHC is giving out invest status more freely so I wouldn't be surprised to see 95L while it still is cold cored. But IMO, no invest until a couple more days.
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Right you are. English is a difficult language to decipher, taxq91met, and i've been practicing all my life :)
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Quoting Tazmanian:
when could we see 95L and when

soon I think

Ithink for the next 2 week or so we may have Invests 95L, 96L, 97L
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1440. xcool



There is no doubt that we have seen some much needed rain this week across Acadiana; some of us have seen too much rain. It looks as though the rain chances will go down some for the Fourth of July Weekend, then we will see the rain chances increase once again early next week. One computer model puts an area of low pressure to our east early next week, and it looks as though that area of low pressure will move west toward Acadiana. We’re not expecting this area of low pressure to be a tropical system, but it will give us a good chance of tropical showers and storms. We will watch it closely in case it starts developing tropical characteristics, but it looks as though it will be too close to land or on land. From the first to middle half of next week, some areas of Acadiana will see several more inches of rain. At least we won’t have to water our yards over the next week or so. There is no doubt that the first week of July looks wet.

Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting MiamiHurricanes09:
We likely won't see an invest until some sort of transition to a warm core low which could take another couple days.


That's not what happened with 90L. You're still probably right.
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Quoting Levi32:


By the time it shows up on the GFS yes it is, which is 60 hours from now on that phase diagram. Before that, like right now, it's not fully warm-core, and won't be until it's spent a couple days over water.


Does not that graph show when a low develops so if it has not developed yet it will be warm core when it starts .......You are probably correct tho.
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting mrsalagranny:
Oh my goodness.That is sad to hear.I myself live in Alabama.I wish this was all a bad dream.My prayers are with everyone on the Gulf Coast.

Yeah. I Live in Chickasaw. I hope it dosent get into the bayou's and estuaries here. That would be catastrophic
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Quoting tropicfreak:


Anyone?
We likely won't see an invest until some sort of transition to a warm core low which could take another couple days.
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1435. xcool
48hr ifif
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Tazmanian:
when could we see 95L and when


Anyone?
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Quoting SomeRandomTexan:


That is where the formation stats thing shows there being a low chance of tropical formation


Yeah just saw that. Weird.
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Quoting TampaSpin:


THAT is not so! Where did you get your information from....its warm core all the way!

Post 1431 explains what I'm seeing.
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1431. Levi32
Quoting TampaSpin:


THAT is not so! Where did you get your information from....its warm core all the way!



By the time it shows up on the GFS yes it is, which is 60 hours from now on that phase diagram. Before that, like right now, it's not fully warm-core, and won't be until it's spent a couple days over water.
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MiamiHurricanes09 yes you are right and if you also look to the west the wave at 60W has also been increasing it vort at that level and continue to so maybe the ECMWF is right or I think it was the ECMWF that if forecasting both waves to develop
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Im off for a few... catch back up with you guys in a few...
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Quoting KoritheMan:
Alex's cool wake is clearly evident in the Gulf:

The cool wake will be gone in a couple of weeks...should be at least. Latent heat of evaporation...
Quoting Progster:



Latent heat of evaporation creates cooling. What restores oceanic heat is circulation and sunshine.
Yes latent heat of evaporation caused it! I think you misunderstood what I was getting across.
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1427. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Thanks for the link Levi, very cool tool.
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Quoting MiamiHurricanes09:
According to the GFS it will likely start off extratropical and then slowly make the transition to a warm core tropical system, as SSTs will allow it to do so.


THAT is not so! Where did you get your information from....its warm core all the way!

Member Since: September 2, 2007 Posts: 178 Comments: 20443
1424. Levi32
Quoting HaboobsRsweet:

I guess but that circulation looks induced to me from the interaction of the flow from Alex throughout the Gulf and the ridge digging in from the east. Like a small eddy. Basically a COL near the shearline. I dunno not impressed yet. While I dont rule out it can happen I def do not think there is a true low there yet.


Well either way, a stalled out front in the Gulf of Mexico with a trough-split occurring in the mid-levels always means trouble, and should be watched. Development, if any, won't occur for 3-4 days.
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Quoting Progster:
this is probably nothing, but if you draw a line due east from Brownsville, and another due south of the LA/TX border right at the coast, at the point where those two lines intersect there looks like low level swirl (at least in from RGB imagery and you need to look underneath the cirrus)...any body else see that?


That is where the formation stats thing shows there being a low chance of tropical formation
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Quoting Levi32:


Key difference being that the wind flow near that 1016.4mb pressure reading is nearly universal with no significant wind shifts around it, and as far as I know that reading hasn't been there all day. The one east of Tallahassee has, and the wind regime showing cyclonic turning has been consistent.

I guess but that circulation looks induced to me from the interaction of the flow from Alex throughout the Gulf and the ridge digging in from the east. Like a small eddy. Basically a COL near the shearline. I dunno not impressed yet. While I dont rule out it can happen I def do not think there is a true low there yet.
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Quoting Levi32:


Early-season frontal lows in the Gulf of Mexico often start out baroclinically induced, and thus at least partially cold-core, but if this one were to deepen in several days, it would quickly become warm-core.


So most likely it probably wouldn't deepen as rapidly due to the cooling. If this is correct the MOST.. keyword being most anyone might see from this is an Extratropical storm.. is this correct?
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850mb vorticity beginning to strengthen in association with the tropical wave around 40˚W. Plus, it still has an anticyclone aloft which should help it possibly develop if and when it separates from the ITCZ.

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this is probably nothing, but if you draw a line due east from Brownsville, and another due south of the LA/TX border right at the coast, at the point where those two lines intersect there looks like low level swirl (at least in from RGB imagery and you need to look underneath the cirrus)...any body else see that?
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Quoting SomeRandomTexan:


Ed made me laugh.. listening to the newscasters saying it. It sounded so funny.. They were prepping us for a Tropical Storm and the stuff we got today was like 10 times worse...lol!


Yeah I think they were a lil gun shy after NOT talking up Humberto. OOPS! LOL
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Quoting MiamiHurricanes09:
According to the GFS it will likely start off extratropical and then slowly make the transition to a warm core tropical system, as SSTs will allow it to do so.


Thanks Miami, I figured so much being that it would be born from a frontal boundary.
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1414. xcool
Dirtleg yayy
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1413. Levi32
Quoting SomeRandomTexan:
Just speculating... but if this Low were to get in the gulf.. would it be a cold core or warm?


Early-season frontal lows in the Gulf of Mexico often start out baroclinically induced, and thus at least partially cold-core, but if this one were to deepen in several days, it would quickly become warm-core.
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Quoting SomeRandomTexan:
Just speculating... but if this Low were to get in the gulf.. would it be a cold core or warm?
According to the GFS it will likely start off extratropical and then slowly make the transition to a warm core tropical system, as SSTs will allow it to do so.
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1411. Dirtleg
Well I'm not banned..but this tropical moisture in Tampa is ridiculous. We have 3 inches in the gauge so far...I'm just east of Tampa. Brandon area...
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1410. Levi32
Quoting Kristina40:
Hey Levi, where do you get the pressure information map?


Nowcoast mapping portal
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1409. Levi32
Quoting HaboobsRsweet:

Look at the western panhandle...you have the same exact thing going on with the pressures. if you notice both places where that lower pressure is are areas where they saw the most rain today which would lead me to expect a pressure drop until it stops.


Key difference being that the wind flow near that 1016.4mb pressure reading is nearly universal with no significant wind shifts around it, and as far as I know that reading hasn't been there all day. The one east of Tallahassee has, and the wind regime showing cyclonic turning has been consistent.
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1408. xcool
48hr
Member Since: September 26, 2009 Posts: 2 Comments: 15684
when could we see 95L and when
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1406. xcool
Tazmanian /maybe
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting stormwatcherCI:
I think you and I are in the same boat. When I was 13 computers took up a whole room and there was no such thing as a PC much less lap top. LOL


Lol. Yeah I used to see the ones with the reel to reel tape on em. Big as a couple refrigerators in my dads office in the Pentagon. They would be very uncomfy on the lap. Lol.
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Hey Levi, where do you get the pressure information map?
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Just speculating... but if this Low were to get in the gulf.. would it be a cold core or warm?
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Quoting jpritch:
What is going on over Cuba?



Upper Level Low that might be making it to the surface
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1401. Levi32
Quoting portcharlotte:
That's interesting Levi32. I was 14 living in West Palm Beach, Fl. when I experienced Hurcn Cleo. I was able to fulfill my dream and I worked at PBI airport as a Met. Tech doing wx obs, pilot briefing, radar and upper air. I found it hard to leave and go home everyday. Unfortunately, I earned a degree but not in meteorology so I was always a tech. You are very talented and if given the oppportunity and maybe you are... you should pursue a weather career. I enjoyed mine for 14 years. >Quoting Levi32:


I've lived in Homer, Alaska my entire life. When I was little winter storms were my first love....watching it come down heavy outside the window at night with the outdoor lights on lol. I saw my first hurricane on satellite imagery 7 years ago and have loved them ever since. The tropics are now my favorite aspect of Meteorology.


Wow, that's great. I definitely want to pursue a career in Meteorology, somehow...
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looks like things re starting too pick up
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Quoting homelesswanderer:


Oh I didn't know that. Lets hope more Ed less Alli. :)


Ed made me laugh.. listening to the newscasters saying it. It sounded so funny.. They were prepping us for a Tropical Storm and the stuff we got today was like 10 times worse...lol!
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you think we could see 95L soon
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Quoting Levi32:
Perry, Florida reporting 1016.8mb....lower than every station around it. There has been a consistent point of lowest pressure near north Florida moving southward all day today, and yes of course the pressure gradient is weak, and overall pressures are high, but there is a clear point of low pressure. Also notice where the 1016.8 reading is located, right where the winds from different directions all around it converge. That's a weak low.

850mb vorticity would also support some type of spin there. If current southward motion continues it could be in the GOM as early as tomorrow early morning.
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Quoting Levi32:
Perry, Florida reporting 1016.8mb....lower than every station around it. There has been a consistent point of lowest pressure near north Florida moving southward all day today, and yes of course the pressure gradient is weak, and overall pressures are high, but there is a clear point of low pressure. Also notice where the 1016.8 reading is located, right where the winds from different directions all around it converge. That's a weak low.


Look at the western panhandle...you have the same exact thing going on with the pressures. if you notice both places where that lower pressure is are areas where they saw the most rain today which would lead me to expect a pressure drop until it stops.
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hey JRRP can you post the link to that wrf model thanks
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Quoting SomeRandomTexan:


Eduard?? Allison?? maybe... lol both of those if I recall correctly were born off of frontal boundaries and meandered over our way.


Oh I didn't know that. Lets hope more Ed less Alli. :)
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Sounds like post hurricane grumpies in here tonight.

Many people make great contributions to the blog - some in different ways. Wouldn't want those who contribute to get their feelings hurt!

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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.