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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Quoting btwntx08:

?????
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Quoting Chicklit:

I'm sorry.


No need to be sorry...a very accurate and fitting image, dear
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Quoting Chicklit:

I'm sorry.


No problemo, I loved it....
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1567. angiest
Quoting Levi32:


It's out in the gulf so it must be an error lol. The 700mb-800mb pressures you see across Mexico are due to those weather stations being several thousand feet above sea-level where the air pressure is lower.


I was less concerned about those lower pressures in Mexico as they at least seem they could be plausible. But 263mb at sea level? The entire Gulf (at least) would be getting sucked into that!
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Quoting StormSurgeon:


He'll be back for the big ones, or he ran to Manitoba to get away from this tropical nonsense....


Historically when he's out for vacation something develops; it's sort of a running joke here that when the tropics are slow, Doc needs to go on vacation
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Quoting btwntx08:
im still tellin ya 96L still a shot at aleast being a ts nothing more imo


how many shots have you had? LOL
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Quoting StormSurgeon:


That's just plain gross...

I'm sorry.
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A
Quoting Baybuddy:
RIP NASA


I wish it wasn't so, but that's a true statement. We won't have Space Shuttles, won't have a way to really service the ISS, sure we'll have the Russians but personally I'm not a big fan of knowing our main enemy in space flight 40 years ago will take over American space flight.
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Quoting Floodman:


Such an image, chicklit...

BTW, you're right, the Doc is on vacation which is nearly always an indication that something nasty is on the way


He'll be back for the big ones, or he ran to Manitoba to get away from this tropical nonsense....
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Quoting Levi32:


It's out in the gulf so it must be an error lol. The 700mb-800mb pressures you see across Mexico are due to those weather stations being several thousand feet above sea-level where the air pressure is lower.
Maybe its the brother of the buoy we were watching a couple of days ago...Lol.
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1560. Levi32
Quoting angiest:


Who's reporting that 263mb pressure?


It's out in the gulf so it must be an error lol. The 700mb-800mb pressures you see across Mexico are due to those weather stations being several thousand feet above sea-level where the air pressure is lower.
Member Since: November 24, 2005 Posts: 635 Comments: 26686
Quoting notmaxmayfield:
96L's lower level circulation is easily seen on the last frame in the GOES visible floater. It's located at 20/89.5.




That's mid level, surface level is in the GOM already.
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Quoting Chicklit:
Africa just hawked a big one.
IRLoopEATL
Now if it keeps the vigorous convection after emerging off of the coast I will worry... Well not too much. Lol.
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Quoting Chicklit:

Schwee!


Such an image, chicklit...

BTW, you're right, the Doc is on vacation which is nearly always an indication that something nasty is on the way
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Quoting Levi32:


Well pressures are sitting pretty low across the Yucatan with 1006-1007mb readings over a wide area. We could very well see a broad area of low pressure develop near the NW Yucatan and SW gulf as this feature moves WNW.

Very interesting, didn't look at those reports.
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Quoting Floodman:



NIIIICE...

Schwee!
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Quoting Chicklit:
Africa just hawked a big one.
IRLoopEATL


That's just plain gross...
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Quoting msgambler:
Afternoon Flood


Hey, gambler!
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Quoting Baybuddy:
RIP NASA


???
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RIP NASA
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Quoting hydrus:
Look at the Bermuda High sprawled across the entire Atlantic. The southern periphery reminds me of a freeway made just for Cape Verde storms to come visit our part of the world. BTW I am not a doomcaster.:)


It is what it is...
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Afternoon Flood
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Dr. Masters is, after all, on vacation (need I say more?)
Interesting that the anticyclone over 96L disappeared for a while and now it's back.
And what's with the dual drive vorticity!
Curiouser and curiouser...
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1545. angiest
Quoting Levi32:


Well pressures are sitting pretty low across the Yucatan with 1006-1007mb readings over a wide area. We could very well see a broad area of low pressure develop near the NW Yucatan and SW gulf as this feature moves WNW.



Who's reporting that 263mb pressure?
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Quoting Chicklit:
Africa just hawked a big one.
IRLoopEATL



NIIIICE...
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1543. hydrus
Quoting CybrTeddy:
I got a feeling we're going to see a CV storm in the next 9-10 days.

ECMWF at 216 hours. 12z run.

Look at the Bermuda High sprawled across the entire Atlantic. The southern periphery reminds me of a freeway made just for Cape Verde storms to come visit our part of the world. BTW I am not a doomcaster.:)
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Quoting Stormchaser2007:


Why?

96L remains very disorganized and the potential trough split off of the East coast will take a while to unfold. Also most of the models (if not all) do not show development over the next 7 days.
96L although rather disorganized at the moment might not stay that way for long. Obviously it has a MLC nestled inside its convection but latest vorticity products and surface observations suggest that it might be on its way towards the surface if one is not already there, albeit broad. Several tropical waves in the Atlantic (especially the one at 40W) should be watched for development in the Caribbean. And the trough split by the Bahamas might not take as long as 5 to 7 days to organize, although I do think it will take some time.
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1541. Levi32
Quoting bayoubug:
will the ull in the gulf have any influence on 96l...


It is shearing the northern surface center, but if the mid-level low to the south remains slower, it may give time for the ULL to back away and actually ventilate it as it comes across, aiding in development. We're already starting to see the ULL move away to the northwest on water vapor loop, so I don't think it will be shearing 96L's southern center.
Member Since: November 24, 2005 Posts: 635 Comments: 26686
96L's lower level circulation is easily seen on the last frame in the GOES visible floater. It's located at 20/89.5.


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Africa just hawked a big one.
IRLoopEATL
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1538. Daveg
I think a lot of folks should wait a bit longer before calling 96L dead.

I'm not saying anything one way or the other as far as future development goes, but for one thing, 96L looks pretty much like Alex did before coming back into the gulf. So dead it is not.
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1537. RM706
Hurricane Haven w/Jeff Masters (without Jeff Masters)

http://www.wunderground.com/wxradio/wubroadcast.html
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1536. Levi32
Quoting msgambler:
Ohh hello Orca, Levi


Hey ms.
Member Since: November 24, 2005 Posts: 635 Comments: 26686
will the ull in the gulf have any influence on 96l...
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1533. Levi32
Quoting MiamiHurricanes09:
Interesting that they say "broad area of low pressure now over the northern Yucatan", they might be onto something we aren't although I don't see much pointing towards the fact of a low pressure already there.


Well pressures are sitting pretty low across the Yucatan with 1006-1007mb readings over a wide area. We could very well see a broad area of low pressure develop near the NW Yucatan and SW gulf as this feature moves WNW.

Member Since: November 24, 2005 Posts: 635 Comments: 26686
Ohh hello Orca, Levi
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1531. MTWX
Quoting jasoniscoolman2010x:
CV storm

pretty ugly wave coming off africa
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1530. JLPR2
The one near 10N, 40W


The one off the coast of Africa would need a day over water to get my attention
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Afternoon Pat. Looks like a typical day on WU.
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Quoting MiamiHurricanes09:
I wouldn't be so assured of that.


Why?

96L remains very disorganized and the potential trough split off of the East coast will take a while to unfold. Also most of the models (if not all) do not show development over the next 7 days.
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Quoting weatherman12345:
What do you think about the wave off africa
Looks like a full fledged AEW with somewhat of a vigorous mid level circulation. It definitely should be watched as it progresses along the Atlantic, especially when it reaches favorable conditions in the Caribbean.
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1526. Patrap
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another wave of rain coming for nola area...
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Quoting Stormchaser2007:
Looks like things have really quieted down.

Looks to stay that way for the next 5-7 days.
I wouldn't be so assured of that.
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Well, alrighty then, that's a big blob, for sure.
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1520. Levi32
Quoting KingofNewOrleans:
Seems like the N vorticity is being pulled up by 95L to SE LA while the S one is moving WNW across the Yucatan.


Well 95L is really too little to do any pulling. The high over the southeast U.S. is what is steering 96L's surface center straight northwest towards the north gulf coast. The mid-level feature will be pushed more to the south due to the high building southwestward over the southern states during the next couple days. This could possibly be another hit for Mexico if it develops, and at least another shot of heavy rainfall even if it doesn't.

Member Since: November 24, 2005 Posts: 635 Comments: 26686

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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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