Invest 95L Brushes Louisiana Coastline

By: Dr. Jeff Masters , 12:42 AM GMT on July 06, 2010

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Hi all,

Dr. Rob Carver, filling in for Jeff this week.

Midnight CDT Update
The low known as Invest 95L stopped it's northward progression and is now moving west along the Louisiana coastline. This is the oddest mesoscale convective complex/tropical feature I've seen in awhile. It's still producing a lot of rain, 2+ inches inland and 6+ inches over the ocean.


Base reflectivity from Lake Charles, LA at 11PM July 5 showing a very nice comma head. Animated loop.


Invest 95L is making landfall now in southern Louisiana near Terrebonne Bay. A CMAN station in Terrebonne Bay is currently reporting winds from the SE at 21 mph and the pressure is 1009 mb. Looking at the radar data, Invest 95L never had convection around the center of circulation. Also, it was hard to see a distinct surface circulation in the different analyses available. I believe soaking rains for southern Lousisana are going to be Invest 95L's main legacy. It's already produced 5+ inches of rain in some offshore locations according to radar-derived rainfall estimates.


Fig. 1 Meteogram for TRBL1 in Terrebonne Bay, LA. Tabular data are here.


Fig. 2 Base reflectivity from New Orleans, LA at 706PM, July 5. Animated loop.

Invest 96L
430 AM Update
In sum, the 00Z model runs don't present a different picture. It is curious to note that the Canadian Global model does not intensify 96L at all in the 00Z run, while NOGAPS has shifted towards a SE Louisiana landfall. I think the following discussion is still valid.

96L is going to be an interesting feature to forecast. It's still on the edge of a strong wind shear gradient. 40+ knots of shear are on the NE side of 96L, and <10 knots are on the SW side. The "center" of 96L is under about 15 knots of shear. This is likely inhibiting 96L. Nearly all forecast models take 96L NW through the Yucatan peninsula and into the Gulf of Mexico. Near the Yucatan itself, sea-surface temperatures are relatively cool, not the best environment for intensification. However, at 25N, 87W there is a hotspot of SST's, which would promote rapid intensification. However, there's currently 20 knots of shear over the hotspot, so the thunderstorms that do form as a result will be well ventilated, and not cause 96L to intensify.

The dynamical models have different takes on how 96L intensifies in the next 120 hours. The 18Z operational GFS strongly intensifies 96L over the hotspot and takes 96L towards Grand Isle, LA. The parallel (for testing model configuration changes) GFS has a similar track, but does not strengthen 96L as much. This indicates uncertainty on how the models are handling the upper-level winds.

The 18Z HWRF solution is much like the parallel GFS solution. The 12Z Canadian global model has a more westerly track, pushing 96L towards Port Arthur, but it strengthens 96L right before it makes landfall, not when it's over open water. NOGAPS takes the "a little from column A, a little from column B" approach, with a spinup over the hotspot (op. GFS solution), but a westerly landfall (the Canadian solution). More data to initialize the models from synoptic reconnaissance flights will help reduce uncertainty.

The bottom line, 96L will move into the Gulf of Mexico and is then shrouded by the mists of uncertainty. I also think that it's a possibility (>50%) that it will become a tropical cyclone sometime in the next 48-72 hours (leaning towards sometime in day 2-3 based on the model runs.)


Fig. 3 Plot of maximum winds (mph) for the next 120 hours from the 18Z July 5 GFS model run.Parallel GFS version.


Fig. 4 Plot of maximum winds (mph) for the next 120 hours from the 18Z July 5 HWRF model run.


Fig. 5 Plot of maximum winds (mph) for the next 120 hours from the 12Z July 5 CMC global model run.NOGAPS wind swath.

Next update
I'll probably tweak this blog later tonight as new model runs come in. I'll have a full update tomorrow afternoon (Pacific time).

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Whoa!!!!!! Who are you and why are you trying to impose upon my name?
Member Since: Posts: Comments:
1719. Levi32
Quoting hydrus:
I have something worth mentioning. If 96L runs over the same real estate as Alex did. That region will suffer some of the worst flooding ever recorded there. It will be horrible.


For sure....they don't need anymore rain over there. Hopefully it will track by to the north and spare those regions. Texas can share some of the load this time.
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1718. Patrap
<
Member Since: July 3, 2005 Posts: 426 Comments: 128636
1717. at519
Is that a mid level low spinning to the north of 96l in the central GOM?
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2100 UTC image of the wave emerging off of Africa. Although it is making the transition between water and land, thus warming some cloud tops, it does have a pretty structure to look at.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
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1714. hydrus
Quoting Levi32:


That image is showing yesterday's 18z model runs....notice the initialization position.
I have something worth mentioning. If 96L runs over the same real estate as Alex did. That region will suffer some of the worst flooding ever recorded there. It will be horrible.
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1713. JLPR2
Quoting Chicklit:
Hi JLPR, yeah it's unusual for them to stay together like that upon leaving the coast.



yep, we got a suspicious one, D-max will make its intentions clearer :) so time for blob watching LOL
*forgot to say hi to you too so HI! XD*
Member Since: Posts: Comments:
Quoting Patrap:
A Lot of"healthy" waves come off looking organized.

We dont usually pay much attention to they until we them make the transition to the Water.

Most fade fast as they have a hard time developing just off the Coast.

And when a System that far out does Strengthen,,it can go more Poleward as a weaker system tends to track west.


Thanks for the reply. I am going to kinda keep an eye on it anyway. Really holding together better than the previous healthy looking impulses.
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Quoting MiamiHurricanes09:
The weak low level circulation is already moving towards the Louisiana/Texas border so it isn't going to have to deal with multiple vorticies.


Then it that's one less problem for it. I do think that 96L will become Bonnie in my opinion.. but I still give it 50-50% with all the barriers it has to overcome.
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Quoting mralagranny:
Where is my wife? Make me a sammich!
Well, she ain't here cuttin' my yard...LOL
Member Since: February 27, 2010 Posts: 0 Comments: 1125
Hi JLPR, yeah it's unusual for them to stay together like that upon leaving the coast.

Dr. Carver thinks 96L has a greater than 50% chance of becoming a tropical cyclone in the next 48 to 72 hours.

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Quoting HurricaneKyle:


It probably is, and needs to if this system wants to get organized at all past TD status even. It may not have time before it hits Texas remember this is another WPAC style system like Alex, with multiple centers battling it out. This will take as much time as Alex did to organize yet it has less room to work with.
The weak low level circulation is already moving towards the Louisiana/Texas border so it isn't going to have to deal with multiple vorticies.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1705. Patrap
A Lot of"healthy" waves come off looking organized.

We dont usually pay much attention to they until we them make the transition to the Water.

Most fade fast as they have a hard time developing just off the Coast.

And when a System that far out does Strengthen,,it can go more Poleward as a weaker system tends to track west.
Member Since: July 3, 2005 Posts: 426 Comments: 128636
1704. angiest
Quoting CitikatzSouthFL:
Not to discount the dangers of 96L developing and heading to Texas (although living FL, am Texas gal born and bred, with lots of friends and family in the projected path), but has anyone seen that VERY HEALTHY impulse coming off Africa right now??? Any models or thoughts on this one yet?


It's discussed earlier in the comments.

Other similarly impressive waves have moved off Africa in the last week or so but they aren't doing anything, at least significant, for quite awhile. At least, not yet.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1703. Levi32
Quoting TexasHurricane:


oh ok...so what are they showing now?


That particular map hasn't updated yet but the general trend at 18z continues to be south, which makes sense given the big ridge building southwest over the southern states during the next few days.

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Quoting IKE:
18Z NAM takes the LLC of 96L approaching the upper Texas coast in just 18 hours. Not saying the non-tropical NAM is correct, just showing it.....



Notice where the NAM starts it from, the weak circulation already in the GOM, not what most would consider to be 96L. Thats the area of lower pressure NHC was previously tracking, then went back to east of the Yucatan. Who knows, could get a two fer.


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Quoting MiamiHurricanes09:
I don't think there is much discussion of a closed LLC at the surface or else we would probably have a tropical depression, but what there is, is a MLC working down towards the surface. Lowering pressures at the surface and increasing vorticity at the 850mb level and 925mb level would all suggest that this MLC is working down towards the surface.


It probably is, and needs to if this system wants to get organized at all past TD status even. It may not have time before it hits Texas remember this is another WPAC style system like Alex, with multiple centers battling it out. This will take as much time as Alex did to organize yet it has less room to work with.
Member Since: Posts: Comments:
Not to discount the dangers of 96L developing and heading to Texas (although living FL, am Texas gal born and bred, with lots of friends and family in the projected path), but has anyone seen that VERY HEALTHY impulse coming off Africa right now??? Any models or thoughts on this one yet?
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Quoting Levi32:


That image is showing yesterday's 18z model runs....notice the initialization position.


oh ok...so what are they showing now?
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Quoting HurricaneKyle:
Afternoon everyone! I missed the Alex fiasco on here, but watched it on the NHC site instead. I see we have 96L, at its current state is highly disorganized. First of all, there is no ground obs to indicate any sort of closed LLC associated with 96L. 96L is also not vertically stacked as the broad and disorganized surface circulation has been ejected from the main body of convection and is in the middle of the Gulf of Mexico because all the heat wants to be over the MLC. Shear is also a minor problem for organization, but isn't a real issue. SST's have also been fairly cooled down by Alex in its path due to upwelling but there's a area of warm SST's and TCHP ahead and if it adapts to that we should will likely see anywhere from a TD to a moderate Tropical storm. I give this a 50%, a coin toss basically, of 96L becoming a named storm.

Towards the end of the ECMWF's run it develops a CV storm, GFS parallel also supports a CV storm last I checked which is more reliable than the regular GFS. Seeing as there is a high amount of warm SST's out there, I'm fairly confident when I say that we'll have a CV strong TS or maybe a Hurricane by the end of the month. We've already seen the highly impressive waves roll of the coast and 92L which nearly became a TD.
I don't think there is much discussion of a closed LLC at the surface or else we would probably have a tropical depression, but what there is, is a MLC working down towards the surface. Lowering pressures at the surface and increasing vorticity at the 850mb level and 925mb level would all suggest that this MLC is working down towards the surface. Yes I know I overused the word "surface", lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1696. JLPR2
Will be watching this closely, no concern of development yet, but if it manages to fire at D-max we might have something to watch


As of now it seems to be trying to fire some new convection but let see if it actually grows
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1695. Levi32
Quoting TexasHurricane:


I was thinking the Dynamic Models were showing more south earlier...now they are going more north?


That image is showing yesterday's 18z model runs....notice the initialization position.
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1694. Patrap
A good tip.

If one gets confused as to your local time vs UTC,..just go to your LocaL radar and the clock has it displayed to the Local

Member Since: July 3, 2005 Posts: 426 Comments: 128636
1693. angiest
Quoting Patrap:
18z Early Cycle NHC model tracks
Invest96
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts


I can't tell which they are but I love the two parallel tracks doing a doughnut in central Texas.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Afternoon everyone! I missed the Alex fiasco on here, but watched it on the NHC site instead. I see we have 96L, at its current state is highly disorganized. First of all, there is no ground obs to indicate any sort of closed LLC associated with 96L. 96L is also not vertically stacked as the broad and disorganized surface circulation has been ejected from the main body of convection and is in the middle of the Gulf of Mexico because all the heat wants to be over the MLC. Shear is also a minor problem for organization, but isn't a real issue. SST's have also been fairly cooled down by Alex in its path due to upwelling but there's a area of warm SST's and TCHP ahead and if it adapts to that we should will likely see anywhere from a TD to a moderate Tropical storm. I give this a 50%, a coin toss basically, of 96L becoming a named storm.

Towards the end of the ECMWF's run it develops a CV storm, GFS parallel also supports a CV storm last I checked which is more reliable than the regular GFS. Seeing as there is a high amount of warm SST's out there, I'm fairly confident when I say that we'll have a CV strong TS or maybe a Hurricane by the end of the month. We've already seen the highly impressive waves roll of the coast and 92L which nearly became a TD.
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Quoting Patrap:
18z Early Cycle NHC model tracks
Invest96
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts


I was thinking the Dynamic Models were showing more south earlier...now they are going more north?
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Quoting btwntx08:

those runs are old


18:00 UTC for July 6th is about as up-to-date as you can get for models...
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1688. angiest
Quoting btwntx08:

those runs are old


Noon? They aren't that old. It is also similar to what is on WU right now as well. If there's something newer I don't see it.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting angiest:
1545 forecast discussion from NWS Houston/Galveston still doesn't talk about 96L at all.
It definitely is worth mention but at the moment it is a little unlikely that it will make it that far north, but a possibility nonetheless.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1686. Patrap
18z Early Cycle NHC model tracks
Invest96
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts
Member Since: July 3, 2005 Posts: 426 Comments: 128636
1685. IKE
18Z NAM takes the LLC of 96L approaching the upper Texas coast in just 18 hours. Not saying the non-tropical NAM is correct, just showing it.....

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1683. angiest
1545 forecast discussion from NWS Houston/Galveston still doesn't talk about 96L at all.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting louisianaweatherguy:
am I seeing a LLC over the Yucatan??? wow did 96L work its way down to the surface over land?!?!?! Alex got better organizing over yucatan, too if I remember correctly


There are about 10 posts on this page of comments alone about this subject. Lol. Just read around. To answer your question, no.
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Quoting louisianaweatherguy:
am I seeing a LLC over the Yucatan??? wow did 96L work its way down to the surface over land?!?!?! Alex got better organizing over yucatan, too if I remember correctly
No, the spin you're seeing is in the mid levels, thus it looks more evident because its higher in the clouds basically. We are still waiting for that MLC to make its way to the surface.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
So if this 96L actually developes....does it have a chance of going to Mexico? I just can't imagine them getting another so close together...anything is possible I guess.
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Quoting MississippiWx:


I think it has a chance. If the upper high moves in tandem with it all the way across the Gulf, I'd give it a 50-60% chance. I think it's almost a certainty that it won't reach anywhere close to Alex's intensity since the waters have been upwelled. I wouldn't count out a minimal hurricane, especially if it goes farther north towards Central or Upper Texas coastline. The biggest thing is getting that spin all the way down to the surface.
Agree.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1678. IKE
Merida, MX (Airport)...@ 21.0N and 89.7W....
Updated: 26 min 17 sec ago
Overcast
82 °F
Overcast
Humidity: 94%
Dew Point: 81 °F
Wind: 9 mph from the South
Pressure: 29.74 in (Steady)
Heat Index: 94 °F
Visibility: 7.0 miles
UV: 3 out of 16
Clouds:
Mostly Cloudy 1500 ft
Overcast 7000 ft
(Above Ground Level)
Elevation: 33 ft
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am I seeing a LLC over the Yucatan??? wow did 96L work its way down to the surface over land?!?!?! Alex got better organizing over yucatan, too if I remember correctly
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1676. angiest
So, will Channel 2 in Houston use the latest CLP5 run in their news?

Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting Floodman:


Yeahhhh, but it's a dry heat!


Dry heat, something I'd like to have here once in a while...
Member Since: September 6, 2009 Posts: 2 Comments: 3757
Quoting Levi32:
The circulation seen in visible imagery with 96L over the NW Yucatan is mid-level, and is not a surface low. We will have to see if it can work down to the surface once it's over water.
Thank you Levi... as I said, I am using my untrained eye... folks like you are why I am here. Thanks again!
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Quoting CybrTeddy:


Do you think 96L will ever become Bonnie even?


I think it has a chance. If the upper high moves in tandem with it all the way across the Gulf, I'd give it a 50-60% chance. I think it's almost a certainty that it won't reach anywhere close to Alex's intensity since the waters have been upwelled. I wouldn't count out a minimal hurricane, especially if it goes farther north towards Central or Upper Texas coastline. The biggest thing is getting that spin all the way down to the surface.
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Quoting Levi32:


Yes, but all it takes is this one surface observation of southeast winds on the SW side of the swirl to show that there is absolutely no surface reflection yet. The NW winds on the southeast coast of the Bay of Campeche indicate the tendency for a broad low pressure to form in this area near the NW Yucatan, but current observations near the spin on visible imagery indicate that it is not working down to the surface yet. The increase in low-mid level vorticity indicates it may be working downward in the atmosphere slowly.

Maybe tomorrow. Meanwhile, looks like the east coast of the Yucatan is still taking a beating....
Member Since: October 25, 2005 Posts: 19 Comments: 22318
Quoting Floodman:


Yeahhhh, but it's a dry heat!
Yeah not here. The humidity is through the roof so not only is it hot but its sticky.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
hey patrap- where do you think 96l is going? should we be concerned? do you think viper is calling 96l like it did 95l? thanks in advance:)
Member Since: September 10, 2008 Posts: 0 Comments: 1294

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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.