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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1491. IMA
Quoting DestinJeff:


Good job, Grissom. You got me. I am the real JFV, I give up.


You must have had lots of therapy 'cause you've come a long way towards "normal"!
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1490. QMiami
Quoting DestinJeff:
Might be hard to see, but check out the last two available images of relative IR imagery ...

1225: Click to enlarge


1245: Click to enlarge


Find the center yellow dot and notice its positioning relative to 95W in the two images.


a little north and slightly east hmmm
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Quoting firematt255:
hope your wrong that would bring it into louisiana worst case senerio for oil spill.
Doesn't seem likely that it is going to Louisiana, it actually seems very unlikely. But the question that remains is, why isn't Alex gravitating towards the weakness?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting txalwaysprepared:
Orca's maps help me see the direction of the storm the best.


TY :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Skyepony:


Just about to fix center..


Thanks Skye. How are things?
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Quoting MiamiHurricanes09:
There has to be something at play that is basically forcing Alex to move towards the W/WNW instead of just plain N motion. With a set-up like that Alex is more likely to hit Texas or Louisiana instead of Mexico.

There is.. the Dark blue is deep layer High pressure that building..as that air sinks it will push Alex away. High Pressure pushes much more slowly the a low pressure trough pulls but it will push. Picture a bunch of mud being poured right next to the spinning top that is Alex
https://www.fnmoc.navy.mil/wxmap_cgi/cgi-bin/wxmap_single.cgi?area=gfs_troplant&dtg=2010063006&prod =gdlm&tau=030&set=Tropical
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1485. hercj
Quoting CyclonicVoyage:


Surely looks like a NWerly component, temporary maybe. When is recon going to be there again?

They are on their way back into the ctr now.
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1484. jpsb
Quoting Patrap:
Very nice thanks.
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1483. Skyepony (Mod)
Quoting CyclonicVoyage:


Surely looks like a NWerly component, temporary maybe. When is recon going to be there again?


Just about to fix center..
Member Since: August 10, 2005 Posts: 191 Comments: 38624
1482. 7544
thanks man if this thing does decide to turn nne this blog will go nuts i see only a few here are in the ne croud others say its impossible time will tell . alex has been weird so far can he slip thru the open door and pull a fast one .
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Quoting StormW:
Current RGB Imagery with forecast point overlay indicates the center is about 60nm east of the forecast point.


I know this is the million dollar question.. and you may not be able to answer it. Given current timing and if the steering weakens, what is the further up the coast you think Alex could/had time to make landfall? Just curious.
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1480. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting Thundercloud01221991:
when do you think a tornado watch will be issued for south Texas???


You'd think one would already be issued considering the feeder bands are coming ashore now.
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Quoting StormW:
Current RGB Imagery with forecast point overlay indicates the center is about 60nm east of the forecast point.
Wow pretty slow motion there. I'm starting to think more towards a landfall tomorrow morning/afternoon opposed to a landfall late tonight.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StormW:
Current RGB Imagery with forecast point overlay indicates the center is about 60nm east of the forecast point.


Surely looks like a NWerly component, temporary maybe. When is recon going to be there again?
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Quoting MiamiHurricanes09:
Yeah I've been thinking the same thing. Also if you look on water vapor you'll notice some distance between highs, meaning a larger weakness. I'm still surprised Alex is moving W/WNW opposed to NNE or NE.
hope your wrong that would bring it into louisiana worst case senerio for oil spill.
Member Since: August 14, 2009 Posts: 0 Comments: 52
1474. Max1023
1469 - That means 5-8 extra hours over water at the NHC speed.

OUCH.
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Orca's maps help me see the direction of the storm the best.
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1472. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129089
i know jeff but any movement alex has will be erratic to say the least..alex has nothing in play for him right now so i would say a very slow drift at 2mph to the north until the other influence comes in later..
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95.5/ 23.8 right now...has wobbled slightly nw...still going to mexico..
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1468. hercj
Quoting ncforecaster:


Here is the blog entry I just posted on why "H. Alex's winds aren't stronger". In it, I also posted the link to a blog entry I wrote a little more than two years ago on the six main TC components that influence the typical wind-pressure relationship.

I hope this helps and all of you have a great and safe rest of the day.:)

Most sincerely,
Tony

Thank You, I think I have a handle on it now.
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1467. angiest
Quoting Thundercloud01221991:
when do you think a tornado watch will be issued for south Texas???


Dunno but I was surprised to find I am on the edge of the 2% tornado risk.
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1466. Max1023
1464 - When Doppler radar picks up mesocyclones in the convective bands.
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1465. angiest
Quoting MiamiHurricanes09:
Lol, that still wouldn't explain the more westerly component in motion.


He has to stop all of that stuff that's moving west now and then shift gears and move it somewhere else. :)
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when do you think a tornado watch will be issued for south Texas???
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Quoting angiest:


Well, he's a large storm, there's a lot of momentum there. :)
Lol, that still wouldn't explain the more westerly component in motion.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1462. Max1023
1452- I would consider the fact that despite its size Alex has deepened from ~980mb to 958mb in 24 hours quite concerning. Until August the gulf will continue to warm, if a smaller system, say Felix 2007 size, moves over the loop current combined with near 32deg water we could see explosive strengthening over a whole day. Everywhere in a rectangle from 50W to the Mexico coast up to 30N is a time bomb with heat.

PS: Anyone notice the 2+ degree temp anomalies NNW of the bahamas?? That is where a Carolinas hit would track through.
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1461. angiest
Quoting MiamiHurricanes09:
Yeah I've been thinking the same thing. Also if you look on water vapor you'll notice some distance between highs, meaning a larger weakness. I'm still surprised Alex is moving W/WNW opposed to NNE or NE.


Well, he's a large storm, there's a lot of momentum there. :)
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sorry aquak i only can go by what the steering currents say and that says it all a north movement then ne...
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Quoting DestinJeff:


Good job, Grissom. You got me. I am the real JFV, I give up.
LOL.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1435:

The winds "should" be much higher in an average sized storm, but Alex is so large in diameter that it is difficult for the winds to be fast, even with a ridiculously low pressure.

A typical sized hurricane would be sustained around 115 to 120mph if it had Alex' current pressure of 959mb.

The storm is not "weak" by any stretch of the imagination. It has taken it this long to "Spin up" and it will take it that long to die, longer if it keeps intensifying.

There is going to be rain and wind for days and days along the land falling location, depending on exact track and speed.
Member Since: June 13, 2010 Posts: 0 Comments: 2336
7544 ALEX will move very little not much past 96w before this trough starts to influence him he cant go west nothing to steer him there the steering currents in that part of the gom are always weak this time of the year...one good thing once alex does start to move ne it will be quick..this trough in the sw will gradually take him out..alex will dump copious amounts of rain on the se us..
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Quoting Max1023:
1437 - The weakness is situated to the west of the storm center, I believe the combined effect of the A/B high (320deg) and the Midwest high (240deg) smooths out to 280deg WNW motion. The weakness is as of yet too close to the coast. However, if it moves eastward then the primary steering flow would cause a move to maybe 330deg-340deg, which besides shifting the landfall location would likely double Alex's time over water. This may be happening now as steering conditions evolve.
Yeah I've been thinking the same thing. Also if you look on water vapor you'll notice some distance between highs, meaning a larger weakness. I'm still surprised Alex is moving W/WNW opposed to NNE or NE.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Morning All.

Looking at visible, it seems Alex has taken on a more NWerly component.
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Quoting hercj:
Senior Chief, why is the pressure so low and the winds not coming down. The other day you said you felt like this system was more of a Typhoon than Hurricane can you explain if this has something to do with the winds not dropping?


Here is the blog entry I just posted on why "H. Alex's winds aren't stronger". In it, I also posted the link to a blog entry I wrote a little more than two years ago on the six main TC components that influence the typical wind-pressure relationship.

I hope this helps and all of you have a great and safe rest of the day.:)

Most sincerely,
Tony
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1451. aquak9
Quoting hurrkat05:
austin i can tell you this uch when alex starts to be influeneced by the strong deepening trough in the 750mb level it will move to the north then shoot off pretty fast to the ne...this will happen in the next 36-48 hours..


will you please wait till at least the D or E storm to be right? I want inland, I want torn up over the mountains, I want this OVER!! ♥♥
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All this north talk. No models say north of border so y all the talk?
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not going to texas...
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1447. 7544
thanks storm w great update as always
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Quoting leo305:
ITS SHOCKING to me hat Alex has a 958mb pressure and the winds are only 80mph ...


Reminds of of Florence 2006, just refused to strengthen to NHC's predictions because of its size.
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1445. Max1023
1437 - The weakness is situated to the west of the storm center, I believe the combined effect of the A/B high (320deg) and the Midwest high (240deg) smooths out to 280deg WNW motion. The weakness is as of yet too close to the coast. However, if it moves eastward then the primary steering flow would cause a move to maybe 330deg-340deg, which besides shifting the landfall location would likely double Alex's time over water. This may be happening now as steering conditions evolve.
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1444. swlavp
Quoting MiamiHurricanes09:
Teh? LOL, J/k.

I agree. That stalling off the coast of the Yucatan messed timing up which then messed all of us up. A Mexico landfall still seems more likely, but my question is, why is it making landfall in Mexico opposed to moving towards the weakness?
Let him keep heading to Mexico....That weakness leads to me!!! LOL
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Quoting Thundercloud01221991:
at the current rate of strengthening this will be the steering shortly



that deep layer ridge to Alexs' north is forecast to really build over the next few days. That makes the chances of Alex going north very slim and should push it more westward southward even as time goes on..
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1442. 7544
Quoting hurrkat05:
austin i can tell you this uch when alex starts to be influeneced by the strong deepening trough in the 750mb level it will move to the north then shoot off pretty fast to the ne...this will happen in the next 36-48 hours..

hat
hmm lets say if you are right what lat are predicting this could happen and if it does a big if are conditions better there for further strenghthing looks like the trof is moving faster than alex right
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It's my understanding that because of the size of the storm it takes longer for the winds to catch up to the pressure (like Ike).. or am I totally off base?
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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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