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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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: 1291
Quoting BaltOCane:
105 in Baltimore today. No heat index, as dew points were in the 30s.

Soooo much fun.


Yeahhhh, but it's a dry heat!
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Buoy's
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1667. Levi32
Quoting MississippiWx:


With such low surface pressures across the Yucatan, I think it's already trying to work its way down to the surface. I know it's not completely surface yet, but a 1006mb reading is relatively low.


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, but not to the surface yet.

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Quoting TxMarc71:



UH OH ...psst hey Pat.. OFFFF TOPIC...??

TROPICAL WEATHER BLOG!!... TROPICAL WEATHER BLOG!!



LOL... man you set me up well for that and I drove it straight down the fairway!! LOL THANKS!!
Be very careful now the blog patolice might push that button on you!!!
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Quoting HurricaneSwirl:
I see on CIMSS 850mb vorticity that the vort max in the central GOM has weakened some and the mid level circulation's vorticity has strengthened slightly over the Yucatan. No need to post the graphic as Levi and Miami have that covered.. but that does interest me and maybe the 8PM TWO will be the last TWO where the percent remains at 30% because of this possible consolidation and/or mid level circulation working down to the surface?
I do believe that the percentage will remain the same at 8PM, but slow increments will likely be seen at 2AM etc....
Member Since: September 2, 2009 Posts: 130 Comments: 21091
For those interested in research, Kermit just took off. This is a research flight so it will be at a higher altitude and not specifically looking for a center or highest winds. Tropical Atlantic Recon site
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low level swirl east of Bermuda
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I see on CIMSS 850mb vorticity that the vort max in the central GOM has weakened some and the mid level circulation's vorticity has strengthened slightly over the Yucatan. No need to post the graphic as Levi and Miami have that covered.. but that does interest me and maybe the 8PM TWO will be the last TWO where the percent remains at 30% because of this possible consolidation and/or mid level circulation working down to the surface?
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Quoting Patrap:


I may use dat,El..

with permission?



Of course, you are the guy who did a two verse rendition off of Kesha's song. Now if you can expand on my first line and create another gem, LOL!
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Quoting Levi32:
NAEFS Week 2 continuing to call for heat in the east...always a beast.



That would be correct, at least through the mid-range. Our highs are supposed to be up around 95 through the period. Have you ever experienced heat like that, Levi? And before you ask, yes, I have experienced sub-zero temps like you get in Alaska. LOL.
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Quoting MississippiWx:


With such low surface pressures across the Yucatan, I think it's already trying to work its way down to the surface. I know it's not completely surface yet, but a 1006mb reading is relatively low.


Do you think 96L will ever become Bonnie even?
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105 in Baltimore today. No heat index, as dew points were in the 30s.

Soooo much fun.
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Quoting Patrap:
pstt, Al..

yer fly iz Open



UH OH ...psst hey Pat.. OFFFF TOPIC...??

TROPICAL WEATHER BLOG!!... TROPICAL WEATHER BLOG!!



LOL... man you set me up well for that and I drove it straight down the fairway!! LOL THANKS!!
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Quoting btwntx08:
woah the 850 mb vitocity really picked up now over the yuactan
Hmmm... still looking at the vorticity near / over the Bahamas. If that thing sticks around long enough, we may get something out of it after all. Every day when I look I keep thinking it'll be gone, but it's just hanging around....
Member Since: October 25, 2005 Posts: 19 Comments: 21470
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.


With such low surface pressures across the Yucatan, I think it's already trying to work its way down to the surface. I know it's not completely surface yet, but a 1006mb reading is relatively low.
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1651. Levi32
NAEFS Week 2 continuing to call for heat in the east...always a beast.

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Yes it is......LOL
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Quoting MississippiWx:
Afternoon, everyone.

Looks like 96L is finally consolidating a circulation. Doesn't really surprise me that it's trying to do it over land. Nothing surprises me anymore in the tropics because anything can happen. Once it moves out over water, I think we have a decent chance of getting a tropical storm out of it. Haven't looked at observations of the upper levels yet, but it appears to have an upper high over it on visible as the clouds seem to be fanning out in all directions quite nicely at the moment.

Indeed. The anticyclone has strengthened some, but is still west of the circulation. Also, CIMSS vorticity product and surface observations suggest that the MLC might be trying to work its way down to the surface, if there isn't an LLC there yet, albeit broad. I'm still holding my opinion that we'll see Bonnie out of 96L, but one thing is for certain, and that is that 96L will probably not match Alex in intensity.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting TexasHurricane:
Think the % of development will go up on the next update? What % you think?


Pretty sure they'll keep it at 30%. They won't drop it lower due to model support, nor will they raise it due to lack of organization.
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Quoting muddertracker:
What is it with the Yucatan Pen.? I thought land was supposed to disrupt storms...all it seems to be doing now is helping them "pick a center and run with it."

Wow , I just wrote something similar and never even read your comment, glad some else noticed this , thought I might have been imagining things.
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Quoting Patrap:
Dont worry,..TWC has Al Roker on 96L..Right after Bkfst



Wake up in the morning feelin' like Al Roker.
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.
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1641. angiest
Quoting StormSurgeon:


C'mon....what is that? A lesson in Climatology?


I assume you are referring to the Hurricane Agnes graphic? People (including the one I quoted) are expressing some amount of shock at the thought of 96L (and previously Alex) possibly doing some development while over the Yucatan. I am showing that it is not unprecedented.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1640. IKE
Quoting Patrap:
pstt, Al..

yer fly iz Open


LMAO!
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Think the % of development will go up on the next update? What % you think?
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Quoting mrsalagranny:
Hey gambler.How are you?
Yeah, jsut fine, thank you. And hope you are good as well. Typical day on WU again.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
1637. 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.
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Quoting jamnkats:
Here on the Caribbean coast of the Yucatan peninsula we're on our 2nd day of no power and over 24 hours of constant rain. 96L is kicking our asses. We've had more beach damage than after hurricane Dean of 2007. Wicked weather (but wicked COLD also at 24C!)
Hey, kats! Was wondering if we'd hear from u guys... looks like the Yucatan is going to keep getting it for another 24 hours, too...
Member Since: October 25, 2005 Posts: 19 Comments: 21470
1634. Levi32
It wouldn't surprise me to get our first Cape Verde storm in the eastern Atlantic after the 15th.
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1633. IKE
"Hello WU Bloggers! 96L gettin' to ya?"

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1632. Patrap
wunderground Apollo Space Blog July 09
Member Since: July 3, 2005 Posts: 420 Comments: 127543
96L reminds alot of Alex, center is becoming more defined over land actually than over water, definitely a Bonnie to be once it enters the GOM in my opinion, Probably Thursday afternoon.
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Quoting Patrap:
Dont worry,..TWC has Al Roker on 96L..Right after Bkfst
What is he gonna do...bore the cyclone to death?
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Afternoon, everyone.

Looks like 96L is finally consolidating a circulation. Doesn't really surprise me that it's trying to do it over land. Nothing surprises me anymore in the tropics because anything can happen. Once it moves out over water, I think we have a decent chance of getting a tropical storm out of it. Haven't looked at observations of the upper levels yet, but it appears to have an upper high over it on visible as the clouds seem to be fanning out in all directions quite nicely at the moment.

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Hey gambler.How are you?
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1624. Patrap
Dont worry,..TWC has Al Roker on 96L..Right after Bkfst
Member Since: July 3, 2005 Posts: 420 Comments: 127543
Quoting DestinJeff:


C'mon, there is a partnership between space and tropical weather analysis. That's not a stretch.


Thats right. Maybe Nasa thinks IRAN can improve OUR weather sats....JEESH.
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Here on the Caribbean coast of the Yucatan peninsula we're on our 2nd day of no power and over 24 hours of constant rain. 96L is kicking our asses. We've had more beach damage than after hurricane Dean of 2007. Wicked weather (but wicked COLD also at 24C!)
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Quoting angiest:




C'mon....what is that? A lesson in Climatology?
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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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