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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1820. Levi32
Quoting beell:
Wow! Where did the big-a surface trough come from? Just when you think you know everything!


What surface trough? The one in the central gulf has been there forever.
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1819. Patrap
Its a Tale Of 2 GOM's today..

The west,Dry..and the East wetts
Member Since: July 3, 2005 Posts: 420 Comments: 127541
Quoting Orcasystems:

check out Post 1806 and see what I see.
OMG, this isn't good, looks like trouble :)
Are you saying what I think your saying?
Member Since: February 27, 2010 Posts: 0 Comments: 1125
1817. Patrap
Quoting GetReal:


Now that 95L is history, and out of the way, the winds here in the NOLA area have switched back around to a easterly direction, in response to the new surface low in the central GOM. The winds are gusty, with the usual low flying cloud deck that is common with tropical systems.

IMO the surface low over the central GOM may very well bewcome the dominate feature, as it has recently begun to steal some of the energy to the south, over the Yucatan...


The sky Looks too August Like.

Itsa Creepy GR.
Member Since: July 3, 2005 Posts: 420 Comments: 127541
1816. beell
Wow! Where did the big-a surface trough come from? Just when you think you know everything!
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Joe Flynn was a great character actor.
Member Since: September 10, 2007 Posts: 0 Comments: 10972
Quoting DestinJeff:
for the benefit of the less clairvoyant, can we lay off the cryptic posts that allude to something of import without clarifying?

"check out X and see what I see"

"this isn't good"

"very interesting"

"looks like trouble"

"OMG!"

Lol, yes I understand. But Levi32 explained it clearly so you would think everyone would catch on.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1813. GetReal


Now that 95L is history, and out of the way, the winds here in the NOLA area have switched back around to a easterly direction, in response to the new surface low in the central GOM. The winds are gusty, with the usual low flying cloud deck that is common with tropical systems.

IMO the surface low over the central GOM may very well bewcome the dominate feature, as it has recently begun to steal some of the energy to the south, over the Yucatan...
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1812. Patrap
..or trending "west"
Member Since: July 3, 2005 Posts: 420 Comments: 127541
1811. JLPR2
Quoting DestinJeff:
for the benefit of the less clairvoyant, can we lay off the cryptic posts that allude to something of import without clarifying?

"check out X and see what I see"

"this isn't good"

"very interesting"

"looks like trouble"

"OMG!"



haha! LOl but can I still post them as long as it is accompanied by an image?


Look!

LOL!
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Quoting Tazmanian:



?????????????
Levi explained it clearly in post 1789.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting DestinJeff:
for the benefit of the less clairvoyant, can we lay off the cryptic posts that allude to something of import without clarifying?

"check out X and see what I see"

"this isn't good"

"very interesting"

"looks like trouble"

"OMG!"


check out Post 1806 and see what I see.
OMG, this isn't good, looks like trouble :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Good post Jeff. And you can add "Wow" to that list.
Member Since: September 10, 2007 Posts: 0 Comments: 10972
1807. Patrap
McCales Navy comes to mind.


hee,Hee...
Member Since: July 3, 2005 Posts: 420 Comments: 127541
Quoting MiamiHurricanes09:
Uh-oh.



?????????????
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AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
1803. Patrap
GOM 84 Hour Wave Forecast Model(using MIKE21)
Member Since: July 3, 2005 Posts: 420 Comments: 127541
1802. JLPR2
Quoting DestinJeff:


just one of those instances where you have to consider the perspective of the person making the comment, and understand they don't mean what they say in such an insensitive context.

the reverse argument doesn't hold water either ... "I hope it doesn't hit the islands, even though a more catastrophic landfall on the U.S. coast is likely."

it is natural to become myopic in our thoughts when faced with devastation.


yeah that's true, I know the person didn't meant it like that, its natural to think that if your area is affected it will be more important

Oh and in the reverse situation I would say well it didn't hit the islands so hurray for me and I wish for it to fall apart before reaching you guys, in other words the other way around doesn't work because only one part is involved.
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Quoting TexasHurricane:


what?
Post 1789 explains it clearly.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting JLPR2:


You mean this one?

its fading away :)

Yeah, i see it too, it's too early it seems for cape verde storms, however you may want to see what the GFS develops on July 17th.
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Quoting Patrap:
Note the Cyclonic structure developing off the La Coastline 240 Miles .

Sheesh.

Here we go again.


It doesn't bode well for hubby to make it in tomorrow, It they do it's going to be one hairy boat ride.
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Quoting MiamiHurricanes09:
Uh-oh.


what?
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1797. Patrap
Remember..95L left a weakness behind..so thats to be in the mix if the Mid Gulf trends to a Better developed system
Member Since: July 3, 2005 Posts: 420 Comments: 127541
1796. Levi32
Quoting Orcasystems:


Sorry my mistake, as a Nav, we use tactical, or nautical miles. Your using miles..
In miles, its correct.


Oh I see....yeah I figured people in general would be more familiar with thinking in statute miles.
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yes it has...
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Quoting nrtiwlnvragn:


Guess it depends on timing and data source.


I *think* that shows almost the same thing...with a little more around blob-east.
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1793. Patrap
Quoting bayoubug:
hey patrap maybe the viper model was picking up on that last night, the low you pointed out....


VIPER has done well with the Lows pass the Yucatan..yes indeed
Member Since: July 3, 2005 Posts: 420 Comments: 127541
.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
this is very interesting a trough and a wave attached to each other and no expected low forming



and with our African AOI nice look at wind barbs

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Quoting Levi32:


It's fine...check it with this. The distances are larger closer to the equator.


Sorry my mistake, as a Nav, we use tactical, or nautical miles. Your using miles..
In miles, its correct.

We would never measuring using Long, only Lat
Member Since: October 1, 2007 Posts: 81 Comments: 26511
1789. Levi32
Quoting MississippiWx:


Levi-

Go to the NASA satellite and zoom in "high" on 96L on visible. Look at the low clouds on the periphery of the system and see if you see what I see.


There is a very broad surface circulation around the entire area but the surface winds right near the mid-level low still appear to be southeasterly. We'll keep watching it for more signs of working down to the surface, but it's not there yet.
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1788. Patrap
The Mid Gulf is Much Larger Cyclonic signature.

And Proximity to the Better Uppers is gonna help her win I think.


Member Since: July 3, 2005 Posts: 420 Comments: 127541
hey patrap maybe the viper model was picking up on that last night, the low you pointed out....
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Quoting atmoaggie:
I find it interesting that the TPW for here (SE LA) is higher than the scary-wave...and much higher than either around the central GOM trough.



Guess it depends on timing and data source.


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Quoting Patrap:
We have a Mid Level ,,Mid Gulf.

And the 96L seed Cyclonic thing on the Yuc.

Phun,Phun,,phun!!!


a little exhust will help, you think?
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1783. Levi32
Quoting Orcasystems:




You might want to check your math, that doesn't look right.


It's fine...check it with this. The distances are larger closer to the equator.
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Quoting JLPR2:


You mean this one?

its fading away :)
And not surprisingly.
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1781. Skyepony (Mod)
The surface low or trough in the center of the gulf of Mexico looks to be stealing some blob from the midlevel over the Yucatan.. should slow development.

click pic for loop
rgb loop
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1780. hydrus
Quoting MississippiWx:


We got caught out in a large thunderstorm one time. Probably the most terrifying thing I've ever experienced. I had my eyes closed praying, but that still didn't keep me from seeing the flash of the lightning. It was striking very close to us and we were the tallest object for miles. Prayer might have done the trick for us...
I know where you are coming from. I have had a few bad experiences out on the water myself. Gulf, Atlantic, Great Lakes and some rivers...Extremely dangerous situations to say the least.
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Quoting Levi32:


67 miles.

Here's the list of longitude degree distances between each longitude point at different latitudes.


5N - 69 miles
10N - 68 miles
15N - 67 miles
20N - 65 miles
25N - 63 miles
30N - 60 miles
35N - 57 miles
40N - 53 miles


Thank you... that makes sense that closer to the equator that the distances grow larger.
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1778. Patrap
Quoting TexasHurricane:


I am no met here....what does that mean?


Neither am I..but it seems the one or the other will spin out..most like the Yucatan one or it may trend west away from the Mid Gulf energy.

Its a Big Wave axis for sure
Member Since: July 3, 2005 Posts: 420 Comments: 127541
1777. Patrap
Note the Cyclonic structure developing off the La Coastline 240 Miles .

Sheesh.

Here we go again.
Member Since: July 3, 2005 Posts: 420 Comments: 127541
Quoting Patrap:
We hava Mid Level ,,Mid Gulf.

And the 96L seed Cyclonic thing on the Yuc.

Phun,Phun,,phun!!!


I am no met here....what does that mean?
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1775. JLPR2
Quoting atmoaggie:
I find it interesting that the TPW for here (SE LA) is higher than the scary-wave...and much higher than either around the central GOM trough.



You mean this one?

its fading away :)
Member Since: September 4, 2007 Posts: 7 Comments: 8499
1774. Patrap
We have a Mid Level ,,Mid Gulf.

And the 96L seed Cyclonic thing on the Yuc.

Phun,Phun,,phun!!!
Member Since: July 3, 2005 Posts: 420 Comments: 127541


Quoting Levi32:


67 miles.

Here's the list of longitude degree distances between each longitude point at different latitudes.


5N - 69 miles
10N - 68 miles
15N - 67 miles
20N - 65 miles
25N - 63 miles
30N - 60 miles
35N - 57 miles
40N - 53 miles


You might want to check your math, that doesn't look right.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
1772. JLPR2
Quoting MiamiHurricanes09:
I was about to say the same thing. I give you a "+" for that one.


Thanks, yeah, I see that a lot, like: ''its better if it goes trough the islands because it will weaken before reaching the US'' ¬¬
Makes my blood boil LOL!
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Quoting Levi32:


67 miles.

Here's the list of longitude degree distances between each longitude point at different latitudes.


5N - 69 miles
10N - 68 miles
15N - 67 miles
20N - 65 miles
25N - 63 miles
30N - 60 miles
35N - 57 miles
40N - 53 miles


Levi-

Go to the NASA satellite and zoom in "high" on 96L on visible. Look at the low clouds on the periphery of the system and see if you see what I see.
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1770. Levi32
Quoting Patrap:
Look real closely atmo mid gulf at the surface..a Cyclonic rotation is there.





It never wasn't.
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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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