Alex Becomes a Hurricane

By: Dr. Jeff Masters , 2:57 AM GMT on June 30, 2010

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Hi, Dr. Rob Carver filling in for Jeff on the late shift.

430AM EDT Update
The 400AM EDT advisory package has hit the wires. Alex' center of circulation is located at 23.3N, 95.1W, which is 175 miles east of La Pesca, MX and 235 miles southeast of Brownsville, TX. Alex is responding to a weakness in the ridge to it's north, the storm motion has shifted to WNW at 7 mph. The winds are unchanged from the 100AM advisory, they are still 80 mph. However, Alex continues to deepen it's pressure, the minimum central pressure is 961 mb. Hurricane force winds now extend to 30 miles away from the center, and tropical force winds extend to 200 miles from the center. Alex is currently over warm ocean waters and under weak vertical shear, so the winds are forecast to increase. However, given the strength of Alex's central pressure, there is a small possibility of a rapid intensification of an additional 35 mph.

I haven't changed my risk assessment with this advisory. Flooding from rain still remains the greatest hazard posed by Alex. Tropical storm force winds are expected to reach the coast later this morning. People should plan on finishing their outdoor preparations by this time.

150 AM Update As of the 100AM EDT advisory, Alex is at 23.1N, 94.8W. The minimum central pressure is 972 mb, and the winds have increased to 80 mph. Alex is slowly moving westwards at 5 mph in an "erratic" fashion.

As of the 11PM EDT advisory, NHC has upgraded Alex to a hurricane with maximum winds of 75 mph and a minimum central pressure of 973 mb. Alex's center is at 23.1N, 94.8W, which is 255 miles south of Brownsville, TX and 195 miles east-southeast of La Pesca, MX. Alex is moving westwards at 9 mph. Alex is expected to slightly alter it's course to the WNW before making landfall south of the Rio Grande. The winds are also forecast to pick up to 90 mph before landfall. In any event, mandatory evacuation orders have been issued for recreational vehicles and other high-profile vehicles in county parks on South Padre Island. A voluntary evacuation is in place for residents of South Padre Island and Port Isabel.

Threat from storm surge
NHC is forecasting a 3-5 foot storm surge north of the eye as Alex makes landfall.

Threat from wind
NWS forecasters expect that damage from Alex's winds will be limited to the southern counties of Cameron, Willacy, and Hidalgo. Hurricane force winds extend 15 miles from the storm center, but tropical storm force winds extend 175 miles from the center. This is a rather large circulation. The Storm Prediction Center is monitoring southern Texas for the threat of tornadoes in the outer rainbands as Alex makes landfall. I'd expect a tornado watch to be issued around noon CDT.

Threat from rain
This is the most significant impact from Alex. Rainfall totals of 6 to 12 inches are expected over northern Mexico/southern Texas with 20 inches possible in some locations. There will be flooding from this storm. If more than 5 inches fall in 6 hours, there will likely be flash flooding. The NWS office in Brownsville is advising people who were flooded out by Dolly in 2008 to evacuate to higher ground now.


Satellite-derived rainfall estimates for Alex's passage over the Yucatan peninsula on June 28, 2010. Data provided by the Climate Prediction Center.

Alex is the first Atlantic June hurricane since 1995's Allison. The storm tally for that season was 19 named storms, 11 hurricanes, and 5 major hurricanes. It will be interesting to see how this season compares to 1995.

Next update
I'll have an update Wednesday evening/night. Jeff will have an update sometime tomorrow morning.

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Quoting Skyepony:
Watching Alex on MIMIC it looks to have taken a small wobble north & back..looks west ho the last few frames.
Doesn't MIMIC do a bunch of interpolation in time between obs, though?
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Quoting OracleDeAtlantis:


Kind of scary looking, isn't it. It's almost as if something caused a sudden acceleration that moved much faster than the surrounding environment. What could it be?


All that Pressure Falling earlier and now the response as the Vort Max within the Column is in Warmer SST's is my best bet.





Member Since: July 3, 2005 Posts: 426 Comments: 128648
Quoting Xyrus2000:


The rotten egg smell is hydrogen sulfide, and it's no surprise you're smelling it around oil areas: H2S
great, another thing for me to worry about :( thanks for the info though.

Just took the dog out and the smell has returned. We must be about to get more rain... Night everyone :)
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138. Asta
wow
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"Thermal Structure and Composition of Jupiter’s Great Red Spot from High-Resolution Thermal Imaging", Preprint submitted to Icarus February 1, 2010 (2.6 MB pdf)

It is a warm-core system, or at least a hybrid system with a warm core. Way too many large pictures to post.
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Thanks Kman

This system looks to have a lot of moisture -- I'm very glad that I'm not going to have deal with that.

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Quoting Skyepony:
Watching Alex on MIMIC it looks to have taken a small wobble north & back..looks west ho the last few frames.


Yes MIMIC looks like it is moving again

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Quoting Patrap:
Note the Nose of the Newer Convective Blow up at 12Oclock and the vort associated with it.



Kind of scary looking, isn't it? It's almost as if something caused a sudden acceleration that moved much faster than the surrounding environment. What could it be? It's like it took a deep breath or something.
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Quoting SavannahStorm:


LOL

"I blew my forecast because the pseudo orographic advection was miscalculated or overlooked."



ROFLMAO
Member Since: October 1, 2007 Posts: 81 Comments: 26511
weatherunderground advisory has the movement as stationary on the tropical page.
Member Since: August 14, 2009 Posts: 0 Comments: 52
is it me or is Alex moveing vary slow too the N
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Quoting sarahjola:

so the 9mph thing is old? so if its stalled the nhc won't know for how long, or report for how long?
It isn't old it is just an average of motion over the past 12 hours. So average motion is 9mph, but actual current motion right now is stalled/stationary.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
Looks stalled to me right now, but previously there obviously was due west motion.
If a couple more frames come in with no motion, I'd agree. Tough to peg the center well enough in the last couple...with no relatively static feature like an eye.
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Alex spun out a CoC just Like were seeing 2 Days ago..

..as it Faded under a Convective Blow up to its North.

Member Since: July 3, 2005 Posts: 426 Comments: 128648
Quoting hurricaster:
"Enjoy" Alex. Looks like the only game in town for a while. The rest of the Atlantic Basin is quiet as a mouse. Entering a downward phase in the MJO.
Really? I'm not seeing any downward motion coming anytime soon.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
126. amd
Quoting StormJunkie:


CycloneOz is going to be in Carbonera if all goes the way he has it planned.


I think the NHC has landfall about 25 miles north of La Pesca. Since Alex today seems to be left of the forecast, La Pesca would seem to be a good chase location.
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125. Skyepony (Mod)
Watching Alex on MIMIC it looks to have taken a small wobble north & back..looks west ho the last few frames.
Member Since: August 10, 2005 Posts: 174 Comments: 38159
I'm still in awe of the convectie blowup in the NE quadrat.
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Hurricane Alex
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Quoting zoomiami:
As usual there are many opinions about whats going on. Is there any consensus on the stall?



This loop says stalled and intensifying.

AVN
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Carbonera? Where is that? I considered going into MX but my partner has to work and cant go with me... plus not as familiar/confident in the infrastructure and geography of the gulf coast in mx
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Does the models develop the wave in the African coast?
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Quoting truecajun:
We can all expect to gain at LEAST five pounds during the 2010 hurricane season due to stationary hineys.

--Forecaster truecajun
Good one!
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Quoting angiest:


I pulled it. It didn't seem like it was going to be that bad but it would never load for me once I embedded the image.
17 MB does that in here...
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116. Asta
Evening all-
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Quoting Patrap:
Note the Nose of the Newer Convective Blow up at 12Oclock and the vort associated with it.

It shows that area on the TC formation probability map.
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We can all expect to gain at LEAST five pounds during the 2010 hurricane season due to stationary hineys.

--Forecaster truecajun
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Quoting MiamiHurricanes09:
Current motion is stationary (seen on the WU main page) but the average over the past 12 hours (seen on the NHC main page) is 9mph, that's why there is such a large discrepancy between the NHC and Wunderground.

so the 9mph thing is old? so if its stalled the nhc won't know for how long, or report for how long?
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Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 426 Comments: 128648
"Enjoy" Alex. Looks like the only game in town for a while. The rest of the Atlantic Basin is quiet as a mouse. Entering a downward phase in the MJO.
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Quoting Xyrus2000:


WV loop still seems to show the center moving almost exactly due west, maybe just a touch south of west.

Use radar. In 3-4 hours it actually hasn't moved much...
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Quoting Xyrus2000:


WV loop still seems to show the center moving almost exactly due west, maybe just a touch south of west.
Looks stalled to me right now, but previously there obviously was due west motion.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting TexasHurricane:


so what does that mean or could mean?
Not much. Just stationary motion at the moment, that's it. But if this stalling persists for several more hours (which I find unlikely) then there will likely be a change in track.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
So what is the official track forecast now?
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If stalled it totally goes against expert opinion that ridge would build in and over time change more W even SW possible. While that looks correct in late day movement it does not forecast a stall. That indicates a weakness after ridge built in. Keep watching, there is a reason for cone.
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Quoting MiamiHurricanes09:
In the last few frames it seems like Alex is stalling/stationary as it just seems like he is spinning in place.



WV loop still seems to show the center moving almost exactly due west, maybe just a touch south of west.
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What would that mean if it has stalled?
Quoting DestinJeff:


check the relative IR imagery loop. looks stalled.

Link
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As usual there are many opinions about whats going on. Is there any consensus on the stall?
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Note the Nose of the Newer Convective Blow up at 12Oclock and the vort associated with it.

Member Since: July 3, 2005 Posts: 426 Comments: 128648
Quoting OracleDeAtlantis:
I think we can all remember systems that seemed to pause or stall, as they were in the process of deepening or rapid strengthening. I've been expecting just such a pause or stall, and if the system becomes powerful enough, it could begin to control the weather surrounding it. In which case, the models are out.
Systems begin to create their own environment when they're much stronger than Alex is right now. Like around upper cat 4 I believe. And even then they are still subject to most of their surroundings.
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.
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Quoting MiamiHurricanes09:
Current motion is stationary (seen on the WU main page) but the average over the past 12 hours (seen on the NHC main page) is 9mph, that's why there is such a large discrepancy between the NHC and Wunderground.


so what does that mean or could mean?
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Quoting DestinJeff:


check the relative IR imagery loop. looks stalled.

Link
Quoting nishinigami:
Every band we get, the smell is unusually strong just before it. This morning it was very strong, and then when it started raining it smelled like rotten eggs :( I refuse to let my kids outside when it smells like that, and my 10 year old is about to drive me bonkers about it.


The rotten egg smell is hydrogen sulfide, and it's no surprise you're smelling it around oil areas: H2S
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Quoting nishinigami:
Every band we get, the smell is unusually strong just before it. This morning it was very strong, and then when it started raining it smelled like rotten eggs :( I refuse to let my kids outside when it smells like that, and my 10 year old is about to drive me bonkers about it.


good call, but i know it's hard to "lock 'em in" they'll really be climbing the walls tomorrow and thursday since we are under a flood watch
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Quoting hurricaster:
Hmmm. Storm stalls. Hurricane Hunters forced home. Busted forecast Alibi? Where's Orca when you need him.

All in jest...


LOL

"I blew my forecast because the pseudo orographic advection was miscalculated or overlooked."

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Quoting kmanislander:


Winds lagging pressure, the story of Alex.


Alex's size and expanse is his Biggest detractor.

He always had a Huge circulation.

and still does.

And always has spun out a older CoC for a Newer one within the Envelope.
We may be seeing it again.

Member Since: July 3, 2005 Posts: 426 Comments: 128648
I think we can all remember systems that seemed to pause or stall, as they were in the process of deepening or rapid strengthening. I've been expecting just such a pause or stall, and if the system becomes powerful enough, it could begin to control the weather surrounding it. In which case, the models are out.
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Quoting TexasHurricane:


Now we have what? I'm confused....
Current motion is stationary (seen on the WU main page) but the average over the past 12 hours (seen on the NHC main page) is 9mph, that's why there is such a large discrepancy between the NHC and Wunderground.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
In the last few frames it seems like Alex is stalling/stationary as it just seems like he is spinning in place.


That is not good. Hopefully it won't be that way for long.
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Quoting c150flyer:
When Alex was forecasted to go further north, we had decided to chase near South Point (slightly SE of Brownsville) to avoid potential surge. Now that it looks to be going much further south, I'm tempted to go to SPI, since surge won't be quite as high.

Only thing hindering me is whether it'd be worth it to be 10 miles inland if i'm 15 miles further south (again, South Point).

Anybody else gonna be on SPI tomorrow?


CycloneOz is going to be in Carbonera if all goes the way he has it planned.
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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.