Invest 96L: Organizing in the Gulf

By: Dr. Jeff Masters , 1:17 AM GMT on July 08, 2010

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Hi everybody, Dr. Rob Carver filling in for Jeff while he's on vacation.

Invest 96L appears to be in the process of developing into a tropical cyclone. The strength and extent of it's thunderstorms is much improved from yesterday (I used CIMMS tropical storm page for my analysis). It's under an upper-level anticyclone which promotes development because it efficiently removes "exhaust" from the thunderstorms. Shear is relatively low (~10 knots), and SST's are adequate for supporting a tropical cyclone (~28 deg. C). In the most recent Tropical Weather Outlook, NHC mentioned that research flights found that upper-level conditions were promising for storm development, so they assess the chances of 96L of becoming a tropical cyclone at 80%. My take is that 96L has an 80% chance of becoming TD #2, and about a 40% chance of being named Bonnie. My reasoning is that 96L has about 24 hours to intensify before interactions with land start interfering with intensification processes. Also, model intensity forecasts are not very supportive of 96L attaining tropical storm force winds. The model track forecast aids have 96L's center of circulation making landfall somewhere between Brownsville and Corpus Christi.

Impacts
The 12Z operational GFS, HWRF, NOGAPS, and 18Z NAM tell a similar story about the surface winds. Near tropical-storm force winds affect the Texas coast from Corpus Christi to Matagorda Bay. A broad area of 30+ mph winds also affects the Deepwater Horizon oil spill recovery efforts. The 12Z Canadian global model downplays the wind strengths, and the 12Z parallel GFS fails to develop any significant surface wind (> 20 mph). That said, I believe that 96L's greatest impact will be in the form of rain.

The Rio Grande from Del Rio to Laredo is either at major flood stage or is forecast to reach major flood stage in the next 24 hours. This is due to Alex and the moisture he brought to the high terrain of northern Mexico. Nearly all of the forecast models I've looked at forecast 2-3 inches of rain over the Rio Grande Valley in the next 5 days. That will only encourage more flooding. The main forecast problem is how much rain will fall along the Gulf Coast. The parallel GFS and HWRF suggest that 4.5 to 6.5 inches of rain will fall in the Galveston/Houston area in the next 5 days. In my opinion, people living in this area should be prepared for flooding.


Fig. 1. 120 hr accumulated precipitation (mm) for 12Z parallel GFS. Operational GFS


Fig. 2. 120 hr accumulated precipitation (mm) for 12Z HWRF.


Fig. 3. 120 hr accumulated precipitation (mm) for 12Z Canadian global model. NOGAPS

Emergency Preparations
People living along the Gulf coast from south of the Rio Grande to the Texas/Louisiana border should review their emergency preparations (hurricane preparations also make for good flood preparations). Jeff has put together a guide to hurricane preparedness with plenty of links for more information.

Next Update
If 96L becomes TD2 or Bonnie, I'll have an update tonight. Shaun Tanner may post something in the morning if that's when the naming occurs. Otherwise, I'll post a tropical update tomorrow afternoon.

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Hard to make a clear determination, but I believe the LLC will come ashore north of where Alex did....... looks like Brownsville to me! maybe even north of Brownsville towards Chorpus Christie.

But it will be a weak TS at best...... lucky it does not have another day...... much like lucky for Alex.
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I keep thinking of this band over the Yucatan coming around and slamming us later...

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Quoting StSimonsIslandGAGuy:
Thanks for the update Dr. Carver!

I am worried that if 96L takes a path too close to Alex's path that heavy rains on saturated ground could cause catastrophic flooding in northeastern Mexico. Especially if the people there don't take it as seriously because it is not a strong storm.


Pretty much anyone that was affected by Alex needs to be on the lookout. We were so far from Alex here in Houston, yet around 5-15 inches of rain fell in parts of my county alone. I feel bad for the people of Mexico though because they are not as prepared as we are here in Texas. I pray they and everyone affected by 96L are all ok after 96L passes on through!
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Too much emphasis is being put on what Alex did to the GOM waters. According to the SHIPS text the system is over 28.4C sea-surface temperatures which is plenty enough warmth for a tropical depression to get going. Invest and Tropical depressions don't need a deep pool of water to intensify.
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Which means more time for 96L to intensify.
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Quoting SouthDadeFish:
Wonder if the proximity to land will affect if the NHC starts issuing advisories on 96L.


SAB T number was 1.5. If TAFB's was also 1.5 that would be just enough to allow for classification if they so wish.
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Quoting caneswatch:


G' evening Hawk


Hey, Canes, thought you left the blog. Looks like a healthy little system forming.
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Looks like 96L is starting to take a more northerly curve.
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Quoting GeoffreyWPB:
You doing okay caneswatch?


Not so bad, yourself?
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Wonder if the proximity to land will affect if the NHC starts issuing advisories on 96L.
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Quoting BahaHurican:
I'm interested to see what's going to happen at 11 p.m. .....

I hope it's worth it; for me, will have to see what happens in the morning :)
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Quoting hunkerdown:
just messing with you, looks perfect in both blogs...


It is not nice to tease old people. It took me a half hour to find the CIMSS site, and sure enough they mention it in the blog. Missed it by one minute. Looks healthy
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You doing okay caneswatch?
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Quoting Patrap:


Semper Fi Big dog


Air Wing 80-88


Me too... VMFP-3 at El Toro LOL
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76. IKE
Brownsville radar...

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Quoting hunkerdown:
sorry, never mind, thought you said TS strength.


It's ok.
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There is currently 2 Recon missions going on, and it is not "top secret"! LOL

And from what I can see, you can make a good argument to classify 96L now!



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Quoting nrtiwlnvragn:


On Tropical Atlantic somehow the mission got split up, there is a continuation as another mission that shows them closing in on the center in that box pattern.


Yeah I realized that too late. It happened yesterday too where it got split into two missions...not sure why. Took me a while to figure out that it wasn't a data transmission delay in Google Earth.

The latest obs from the recon show the mid-level center (remember these winds are up at 640mb) becoming closer to vertically stacked over the surface center. The doors are now open for 96L to strengthen into a tropical cyclone, but Alex's cold wake is severely limiting convection at the moment. We'll see if diurnal max tonight helps it try to burst before landfall.



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Quoting tropicfreak:


????
sorry, never mind, thought you said TS strength.
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Quoting Grothar:


Evening Geoff!


G' evening Hawk
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Thanks DRC from SE TX.
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Quoting Headindaclouds:
Hey Patrap... I really enjoy your posts and consider you one of the most entertaining to say the least. Also respect your knowledge. Just wanted to say Semper Fi! I was in from 79 to 87. How about you?

Jeff


Semper Fi Big dog


Air Wing 80-88
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Quoting Grothar:


It is the letter I. LOL
just messing with you, looks perfect in both blogs...
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Quoting GeoffreyWPB:
Evening Grothar


Evening Geoff!
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I'm interested to see what's going to happen at 11 p.m. .....
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Quoting hunkerdown:
nope, if it were all about the wind speeds and nothing else, its 4 mph shy


????
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63. IKE
Quoting Levi32:


Alex's cold wake....does a lot more than some might think.


Apparently so>>>Link
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Quoting MiamiHurricanes09:
It basically meets all the requirements for a tropical cyclone except for the fact of weak convection. This I think won't have too much of an effect on the final outcome because the NHC knows why the convection is lacking and that is because of the upwelled waters left by Alex.

A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere.


Thanks!!!!! Appreciate it.I just keep learning on this blog.
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Quoting Baltimorebirds:
You mean like danny and erika from last year?.Those were horrable.


Exactly.
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Quoting tropicfreak:


Well we've got the winds covered. Max sustained winds are at 35 mph, which of course is TD strength. As for convection, well........
nope, if it were all about the wind speeds and nothing else, its 4 mph shy
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Quoting MiamiHurricanes09:
You are just looking at satellite appearance and presentation. ASCAT shows a closed surface circulation, CIMSS vorticity product show a vertically aligned system through the 850mb-500mb levels. Convergence and Divergence are good. I could just keep going...


great, but its not much time until it gets to land, and convection is waning not building.
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Quoting hunkerdown:
nope still don;t see anything (remember, I'm blind)..but I'll tell yo that picture I don;t see sure looks like an actual human eye in the center of the system.


It is the letter I. LOL
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Quoting tropicfreak:


Well we've got the winds covered. Max sustained winds are at 35 mph, which of course is TD strength. As for convection, well........


Exactly.
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Quoting Levi32:


Nah...it's up on the NHC site for the public to see the high-density obs.







On Tropical Atlantic somehow the mission got split up, there is a continuation as another mission that shows them closing in on the center in that box pattern.
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Quoting Levi32:


Closed circulation doesn't give you a TD. You also need decent winds and organized deep convection near the center of the system.


Well we've got the winds covered. Max sustained winds are at 35 mph, which of course is TD strength. As for convection, well........
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Quoting Grothar:
Can you see it now hunker. I was posting when the new blog came out.

Upload the image to imageshack or tinypic.
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Evening Grothar
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Quoting IKE:


I'd rather be under 96L then what Merida, Mexico has experienced today.

96L looks horrible. I'm not including structure. I'm talking convection.


Alex's cold wake....does a lot more than some might think.
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Quoting wxvoyeur:
Question:

If 96L makes landfall classified as a TD and upon later analysis is upgraded to TS status. What name does it get if something else has been Bonnie by that time?


it will be named TS NoName
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Like other things when it comes to a tropical systems looks can be deceiving, future Bonnie imo, TD2, 96 L whatever you what to call it might yet be a surprise!
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The convective cloud pattern is organized. It's just weak.
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Quoting tropicfreak:


So it is unofficially a TD, since it has a closed surface circulation?
It basically meets all the requirements for a tropical cyclone except for the fact of weak convection. This I think won't have too much of an effect on the final outcome because the NHC knows why the convection is lacking and that is because of the upwelled waters left by Alex.

A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Grothar:
Can you see it now hunker. I was posting when the new blog came out.

nope still don't see anything (remember, I'm blind)..but I'll tell you that picture I don't see sure looks like an actual human eye in the center of the system.
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Question:

If 96L makes landfall classified as a TD and upon later analysis is upgraded to TS status. What name does it get if something else has been Bonnie by that time?
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Quoting tropicfreak:


So it is unofficially a TD, since it has a closed surface circulation?


Closed circulation doesn't give you a TD. You also need decent winds and organized deep convection near the center of the system.
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41. IKE
Quoting txalwaysprepared:


You need glasses... remember? ;)


I got em...but apparently I need an upgrade...lol.
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About JeffMasters

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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