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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Daddy always warned about watchin the tail.
Lotsa trouble there.
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Quoting Patrap:
The 95L Swirly thing a ma bob with trailing fetch is goona influence the 96L track if those GOM Mid Gulf pressures continue to fall.

The NHC iz gonna have to be on their collective toes this week,..

Cuz we sure will.


...the combo effect of Chiklit's point on the peaceful Western GOM and Patrap's tail of the dog..er..95L could mean a stronger storm forming in the SW gulf being pulled more Northward towards the bayous of LA me thinks...messing with my beigner snacking...
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SuperInvestigation 95L.

Nice, but a bit concerning for anyone on the GOM!
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NOGAPS at 180 hrs would truly suck.
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What is with that vorticity just east of the bahamas?
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Quoting muddertracker:
I hope so...I dont' know Press personally, but I've always liked what he has to contribute on the blog. Good guy, Press.

He was a personal friend of the late, great Lewis Grizzard. I think Lewis left Paul with some of his ability to write one-liners.
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1213. hydrus
Quoting PensacolaDoug:
Its like god hates the gom these days. I live on a bayou just north of the Pensacola Pass. So far no oil in my bayou that I'm aware of anyway. Big storm in the gom could change that.
This NOGAPS model is a bit interesting....Link
Member Since: September 27, 2007 Posts: 1 Comments: 21734
1212. Patrap
The 95L Swirly thing a ma bob with trailing fetch is gonna influence the 96L track if those GOM Mid Gulf pressures continue to fall.

The NHC iz gonna have to be on their collective toes this week,..

Cuz we sure will.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Accuweather (lol yes I know it's accuweather) says that while 96L is currently disorganized it could become a tropical depression or Bonnie in the Gulf as soon as Wednesday.
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Quoting SiestaCpl:


...disturbing would be more correct to us here in NOLA...that vorticity could herald a sudden jump of a COC to the gulf side..making the Yucatan crossing a piece of cake...

Indeed. If you look at the shear map though, conditions are pretty wicked on the eastern half of the GOM. Much friendlier out west.
Link
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Quoting hydrus:
I was wondering if The Pressolina,s post would be sufficient for at least a brief but poignant post from Pressman. He may may post this year if it turns out to be a catastrophic season.
I hope so...I dont' know Press personally, but I've always liked what he has to contribute on the blog. Good guy, Press.
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Its like god hates the gom these days. I live on a bayou just north of the Pensacola Pass. So far no oil in my bayou that I'm aware of anyway. Big storm in the gom could change that.
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1206. Patrap
SuperInvestigation 95L.

oooh..I like dat un.

Im gonna send it to Avila
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Is 96L just now going over the Yucatan or is it almost into the GOM?
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I keep seeing that current conditions regarding the future path of 96L are very complex. Given the uncertainties, one cannot rule out a meandering or stalling in the GOM.

everyone understands what that means...lol
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Quoting Chicklit:
Personally, I'm glad it's not too busy.
Gives me more opportunity to get work done.

Interesting that the 850 mb vorticity associated with 96L is now in the middle of the Gulf.



96L doesn't really exist anymore. It's become a feeder band of SuperInvestigation 95L.


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Even though the vorticity max is over the Gulf there is some vorticity over the Yucatan and adjacent waters to the east.
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1201. Patrap
The Daily Downpour at 3 p.m. Eastern, 12 noon p.m. PT Tuesday! Hurricane Haven after

Posted by: shauntanner, 12:04 PM CDT on July 06, 2010
Listen to the Weather Underground Broadcast Network here!

Join Weather Underground Meteorologists Shaun and Tim for The Daily Downpour today, Tuesday, at 3 p.m. ET, 12 noon PT!
Listen here!

Weather Underground Meteorologists Shaun and Tim will talk about any new updates on the oil spill in the Gulf, the hurricane season, and any weather related topics that are going on around the world.

Dr. Jeff Masters' show Hurricane Haven will be on the air 4 p.m. ET, 1 p.m. PT to discuss the latest on the tropical activity in the Atlantic. Listen here

Both shows will be taking your phone calls at 415-983-2634
Member Since: July 3, 2005 Posts: 426 Comments: 129089
96L is still over the peninsula so looks better for it once it finally sticks its toes into the warm waters of the low-shear western half of the GOM. Though it is dry...
AN ELONGATED UPPER LOW IS OVER THE W GULF EXTENDING FROM THE LOUISIANA/TEXAS BORDER TO VERA CRUZ MEXICO AND DOMINATED BY STRONG SUBSIDENCE AND DRY STABLE AIR THUS LEAVING THE MOST OF THE W GULF UNDER CLEAR SKIES THIS MORNING.
...so who knows.
KmanIslander pointed out a wave that's just come off the African coast as an AOI down the road.
Anyway, back to work!
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Quoting SiestaCpl:


...disturbing would be more correct to us here in NOLA...that vorticity could herald a sudden jump of a COC to the gulf side..making the Yucatan crossing a piece of cake...


Here in SW MS too!
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Quoting Daveg:
Still a tropical system noob here... so question..

What would stop 96L from developing once it is back over water (here in a bit)? Seems all the reports look favorable for development at that point.


It could develop, but slowly. Factors like shear and its very unorganized.
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1197. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting Daveg:
Still a tropical system noob here... so question..

What would stop 96L from developing once it is back over water (here in a bit)? Seems all the reports look favorable for development at that point.


Nothing will. Just time.
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Looking good...
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Quoting Chicklit:
Personally, I'm glad it's not too busy.
Gives me more opportunity to get work done.

Interesting that the 850 mb vorticity associated with 96L is now in the middle of the Gulf.



...disturbing would be more correct to us here in NOLA...that vorticity could herald a sudden jump of a COC to the gulf side..making the Yucatan crossing a piece of cake...
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1193. Daveg
Still a tropical system noob here... so question..

What would stop 96L from developing once it is back over water (here in a bit)? Seems all the reports look favorable for development at that point.
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1192. Patrap
Special Weather Statement

Statement as of 11:57 AM CDT on July 06, 2010

... Line of strong thunderstorms moving northwest affecting Hancock
County... St. Bernard Parish... Orleans Parish... St. Tammany Parish...

At 1156 am CDT... National Weather Service Doppler radar indicated a
line of strong thunderstorms from Chalmette to 28 miles southeast of
Slidell... moving northwest at 25 mph.

The line of strong thunderstorms will affect areas in and around...
Lakefront Airport... east New Orleans... Lake
Catherine... Pearlington... Eden Isle... Slidell... and Lacombe

The primary threat from these storms is wind gusts to near 40 mph...
which could down tree limbs and blow around unsecured small objects.
Seek shelter in a safe home or building until these storms have
passed.

These storms could produce rainfall amounts of one to two inches in a
short period of time... resulting in ponding of water around low lying
roadways. Remember... do not drive your vehicle into water covered
roadways. The depth may be too great to allow a safe crossing.

Member Since: July 3, 2005 Posts: 426 Comments: 129089
The LSU site is driving my computer nuts again

And I dont even see any pics from there and my browser is still trying to load it
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Quoting Patrap:


me facetious?

Why never.


And I would ask you where the best beignet can be found in New Orleans if it would not get me banned...or cause me to fall over a railing in the French Quarter while I zoom in to see that radar loop on the 96L...
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Floodman...... you have WU-mail.
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1187. Patrap
Quoting StormSurgeon:



.....and his humor.....cheers Pat!


Hi,,dozo

Skoal!

ahhhhhhhh
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1186. hydrus
............... ...........VERY quiet in the Western Pacific....
Member Since: September 27, 2007 Posts: 1 Comments: 21734
Quoting Patrap:


me facetious?

Why never.



.....and his humor.....cheers Pat!
Member Since: September 1, 2007 Posts: 0 Comments: 1793
1184. Patrap
Vary interesting chicklit
Member Since: July 3, 2005 Posts: 426 Comments: 129089
1183. FLdewey
I am serious... and stop calling me Shirley.
Member Since: August 19, 2008 Posts: 42 Comments: 6269
Personally, I'm glad it's not too busy.
Gives me more opportunity to get work done.

Interesting that the 850 mb vorticity associated with 96L is now in the middle of the Gulf.

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1181. Patrap
Quoting StormSurgeon:


I sure hope Pat was being facetious quoting the rules of the road.......this blog would become really dull without his snappiness and wittiness....


me facetious?

Why never.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Thanks nrtiwlnvragn!
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Quoting NttyGrtty:
You mean like plugging the Dr. Phil show Pat? Sorry, couldn't resist...


I sure hope Pat was being facetious quoting the rules of the road.......this blog would become really dull without his snappiness and wittiness....
Member Since: September 1, 2007 Posts: 0 Comments: 1793
1178. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129089
maybe next invest97L
Member Since: July 4, 2010 Posts: 4 Comments: 965
Quoting nrtiwlnvragn:


Mets at the International Desk believe we are favorable now.

Preliminary Caribbean Forecast Discussion

Excerpt:

LATEST ANALYSIS OF 200 HPA VELOCITY POTENTIAL ANOMALIES AND
OUTGOING LONG WAVE RADIATION SHOWS FAVORABLE MJO CONDITIONS ACROSS
THE BASIN. THE CLIMATOLOGICAL MODELS HAVE BEEN HAVING A HARD TIME
FORECASTING THE EVOLVING PATTERN...WITH THE LATEST AVAILABLE CYCLE
FAILING TO REACH A CONSENSUS. LOOKS LIKE THE CFS CONTINUES TO
OUTPERFORM THE EWP...WITH THE FORMER SHOWING MOSTLY FAVORABLE
CONDITIONS TO PERSIST WHILE THE LATTER TRIES TO TREND AGAIN
TOWARDS UNFAVORABLE ENVIRONMENT. UNDER COLD ENSO CONDITIONS WE
EXPECT THE CFS PATTERN TO DOMINATE.


appreciated... :-)
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By the looks of this picture it doesn't seem like it would have a problem developing...but then what do I know...

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Quoting SiestaCpl:
MJO upward trend arrives at end of this week..correct?


Mets at the International Desk believe we are favorable now.

Preliminary Caribbean Forecast Discussion

Excerpt:

LATEST ANALYSIS OF 200 HPA VELOCITY POTENTIAL ANOMALIES AND
OUTGOING LONG WAVE RADIATION SHOWS FAVORABLE MJO CONDITIONS ACROSS
THE BASIN. THE CLIMATOLOGICAL MODELS HAVE BEEN HAVING A HARD TIME
FORECASTING THE EVOLVING PATTERN...WITH THE LATEST AVAILABLE CYCLE
FAILING TO REACH A CONSENSUS. LOOKS LIKE THE CFS CONTINUES TO
OUTPERFORM THE EWP...WITH THE FORMER SHOWING MOSTLY FAVORABLE
CONDITIONS TO PERSIST WHILE THE LATTER TRIES TO TREND AGAIN
TOWARDS UNFAVORABLE ENVIRONMENT. UNDER COLD ENSO CONDITIONS WE
EXPECT THE CFS PATTERN TO DOMINATE.
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1173. Patrap
..anytime
Member Since: July 3, 2005 Posts: 426 Comments: 129089
1172. hydrus
Quoting muddertracker:
I miss Press...and his dress...lol..Press, if you are out there, please come home!
I was wondering if The Pressolina,s post would be sufficient for at least a brief but poignant post from Pressman. He may may post this year if it turns out to be a catastrophic season.
Member Since: September 27, 2007 Posts: 1 Comments: 21734
Member Since: July 4, 2010 Posts: 4 Comments: 965
1165, Thanks, I knew I could count on you.
Member Since: July 25, 2008 Posts: 0 Comments: 626

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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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