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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Floater - Rainbow Color Infrared Loop
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Charley
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Quoting RecordSeason:
The storm is still struggling with the same problem it has always had: scale.

Due to the ridiculous size, the individual convection patches are so far apart from one part of the system to another that they keep attempting to establish their own local CoC. It truly is at or near the maximum possible limit of a surface low's size.

This is the only thing keeping Alex from RI at this point. If it ever gets the convection problem corrected we will have a major hurricane in short order.


I agree!
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Quoting zoomiami:
that's some picture Pat

Drak - if you're still around -- what do you think about that weakness in the ridge?


Not much. The slower Alex moves the more time it is giving for the ridge to build in the from west and guide the storm into Northern Mexico. Main reason why we have seen the models turn away from a Texas landfall is Alex's somewhat unexpected slow speed.
You can look at water vapor imagery and monitor the upper level features steering Alex.
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Quoting atmoaggie:
Only that I hope that they aren't showing motion when there isn't any...
Well if the center was moving in a loop back to its original position, and the obs sampled at the extremes of the loop, it could show false movement. Just for an example.
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I just logged on and I usually lurk, but I couldn't help notice that it looks like Alex spit out a kid to it's north.. is this simply a feeder band?
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Quoting SavannahStorm:
Oh my....

explain more :)
Member Since: September 22, 2005 Posts: 11 Comments: 2032
Wish we had recon on pressure last few hours. It was just getting interesting.
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Quoting Tazmanian:
i send JFV in and he can tell us


JFV preparing to launch his surface data collection vehicle.

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For all you hurricane trivia fiends out there -- what was the last storm that missed the NHC 3 day cone?
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Alex starting to gel now. COC almost completely surrounded in purple, 23N 94.8W.

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How about Gilbert in '88. Anyone remember him?
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Quoting RitaEvac:
That huge feeder band that took off from the Yucatan and jet rocket NW is one hellva moisture surge if you ask me...

by the way check out this zoom in of long range from Brownsville...aint moving much pals, where is that friggin ridge...


Posting the 40 image of that radar so it's easier to see movement.
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226. Asta
Lots of electricity inthe NE quadrant and the East quadrant.. wow look at hit
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I'm wondering if the blob of convection north of the COC will affect Houston or stay more to the south. Any ideas?
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Some person with the name "stillwaiting" predicted in his blog that it would get to this point where it is now and make a turn back to the north....between houston and SW La. any thoughts on this? i don't know him and don't know a thing about predicting hurricane landfalls...just watching and trusting the NHC.
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Bye Taco!
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Quoting WaterWitch11:
how many will lose sleep tonight?

I always lose sleep when a storm nears the coast. Even more so now that it's stalling near the coast... even if it turns out to be temporary.
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i send JFV in and he can tell us
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rel="nofollow" >Link..........MIMIC loop.Link....
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OK I'm off for the Night....

Thanks for all the Info from everybody....

Taco :o)
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That huge feeder band that took off from the Yucatan and jet rocket NW is one hellva moisture surge if you ask me...

by the way check out this zoom in of long range from Brownsville...aint moving much pals, where is that friggin ridge...

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Oh my....
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Quoting atmoaggie:
Ehh, it's a barely-thing, anyway.
Let's see if this stalling persists before making any calls, but it looks stationary to me.
Member Since: September 2, 2009 Posts: 130 Comments: 21122

..Lets Play HardBlog


Hah!
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Quoting guygee:
LOL to answer myself I guess at the interpolated points the true position is unknown so there would be reasonably small errors there, which would potentially become larger as the observation rate decreased(especially for an erratically moving system).
At the very least, we now know that you're less tired than I...
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Pat, you've seen quite a bit, where does Alex rank when it comes to the largest ATL basin storms?
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how many will lose sleep tonight?
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Quoting MiamiHurricanes09:
After 00:15 UTC I just see stationary "movement".
Ehh, it's a barely-thing, anyway.
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Quoting guygee:
So that would smooth out wobbles that take place in times smaller than the observation rate, but if there are no observations at specific times we wouldn't know anyways. The interpolation shouldn't introduce any false motion if they are doing it correctly, which I assume they are...Am I missing something?
LOL to answer myself I guess at the interpolated points the true position is unknown so there would be reasonably small errors there, which would potentially become larger as the observation rate decreased(especially for an erratically moving system).
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208. amd
Where's Taz to confirm that Alex has indeed a Pinhole Eye?

:)
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that's some picture Pat

Drak - if you're still around -- what do you think about that weakness in the ridge?
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Quoting Patrap:
I've been stressing for 4 days about this Size thingee.

Rare are these types...rare indeed.


That what *** said
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Wow! Lets hope Alex doesn't start to tighten his core and get those wrapped it closer to the center
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Quoting guygee:
So that would smooth out wobbles that take place in times smaller than the observation rate, but if there are no observations at specific times we wouldn't know anyways. The interpolation shouldn't introduce any false motion if they are doing it correctly, which I assume they are...Am I missing something?
Only that I hope that they aren't showing motion when there isn't any...
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Thanks Dr.Carver for the additional details. Have a good evening in San Francisco.
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201. JRRP
Link
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Juan in 85


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199. Asta
LINK SSEC
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Quoting atmoaggie:
Guess I had a link failure...

http://rammb.cira.colostate.edu/ramsdis/online/loop_timestamp_640.asp?data_folder=rmtc/rmtcsasec5ir 404
After 00:15 UTC I just see stationary "movement".
Member Since: September 2, 2009 Posts: 130 Comments: 21122
Quoting ElConando:


Evening Zoo! hope you got my mail!


Yep -- working on the new images
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It looks like Alex is moving just north of due west.
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I've been stressing for 4 days about this Size thingee.

Rare are these types...rare indeed.
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Quoting Patrap:



Wooof..



don't like that. i'm off to bed. y'all have fun
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It's called a cold front, or a trough. Draws moisture from the gulf and provides lift. Where Alex's rains end and those associated with the approaching trough is very debatable.

And the trough isn't of weak amplitude, either. Big difference in temps. 40s tonight in the upper midwest.
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Quoting HurricaneLovr75:


The deep convection in those feeder bands bands are getting impressive!


An AMSUB pass indicated rain rates in the bands anywhere from 1in-1.5in/hr.

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Quoting kmanislander:
The eye can be seen in this image as the small red circle in the white CDO. Very cold cloud tops out there.



THE DREADED PINHOLE EYE!!!!!!!!!!!!
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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.

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