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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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.

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I got a feeling we're going to see a CV storm in the next 9-10 days.

ECMWF at 216 hours. 12z run.

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Quoting btwntx08:
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
146 PM CDT TUE JUL 6 2010

.SHORT TERM /TONIGHT THROUGH 7 AM THURSDAY/...WHILE THE GFS WENT
HEAVILY BULLISH ON RAIN CHANCES IN THE SHORT TERM...OTHER MODELS
LIKE THE NAM AND SREF WERE A LITTLE DRIER. USED A BLEND FOR THIS
FORECAST...BUT THE OVERALL TREND IS DEFINITELY UP. CONVECTION IN
NORTHERN MEXICO WILL REPEAT AGAIN TONIGHT...AND THEN LOOK FOR MORE
WIDESPREAD RAIN ACTIVITY OVER DEEP SOUTH TEXAS ON WEDNESDAY.

TROPICAL MOISTURE WILL BE ARRIVING FROM THE GULF WITH ONSHORE
FLOW...AND COASTAL LOW PRESSURE WILL PROVIDE FORCING FOR MORE
UNSETTLED WEATHER ALONG THE COAST WEDNESDAY. TWENTY-FOUR MORE HOURS
WILL ALSO GIVE US MORE INFORMATION ABOUT THE POTENTIAL IMPACT OF THE
BROAD AREA OF LOW PRESSURE NOW OVER THE NORTHERN YUCATAN PENINSULA.
DEEP TROPICAL MOISTURE HEADING THIS WAY MAY PROMPT FLASH FLOOD
WATCHES.

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.
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Looks like things have really quieted down.

Looks to stay that way for the next 5-7 days.
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Seems like the N vorticity is being pulled up by 95L to SE LA while the S one is moving WNW across the Yucatan.
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1514. hydrus
Quoting Asta:
Just got 1 inch of rain in 15 minutes of a gusty downpour north of Covington, LA
Sure felt like a tropical band...
1 inch of rain in 15 minutes? I bet it did.
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A more updated vorticy map.... Link
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Quoting nrtiwlnvragn:


Invest:
A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g., microwave imagery) and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic web sites, including the Naval Research Laboratory (NRL) and the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS). The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone; operational products such as the Tropical Weather Outlook or the JTWC/TCFA should be consulted for this purpose.


Link


Thanks NRT. I'm quoting because you answered with the true definition and I want many to read it again. I know what an invest is as many on the blog do also. It's an area of tropical activity that warrants attention...or investigation. There is no such thing as a landfall location for an invest. It's impossible to model an invest and any attempt to do so is (for all practical purposes)is meaningless. Until a tropical low, depression, storm or huricane exists, all predictions and forcast are simply null and void. Blast me if I'm wrong.
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1509. Levi32
Quoting TexasHurricane:


meaning??


Meaning that the mid-level center may be trying to work down to the surface and form a 2nd surface low center to the south of the one that's currently over the central gulf.
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I've been checking out the vis. sat on 96L and to my untrained eye it appears the coc (at least where I see it) is about 1/3 into the boc. JMO
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If it is just an investigation going on then it makes no sense to me whatsoever why the public would be scared for no reason by drawing colored circles willy-nilly.
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1506. Halyn
Quoting miamiamiga:


wow. can we keep the partisan attacks out of this blog? I am a Democrat and proud of it and give plenty of money to organizations...this type of stereotyping does not belong here!
Right on, miamiamiga !!!
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AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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Quoting TexasHurricane:


meaning??
Meaning that the mid level center currently nestled within 96L's deepest convection might be trying to work its way down to the surface.
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Quoting Levi32:
Low-level vorticity is increasing underneath 96L's mid-level center near the Yucatan.



It's definitely a start, at the moment it's very elongated and poorly defined but we'll have to see if the increasing trend continues and consolidates.
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Quoting StormSurgeon:


Only if the salt in the water is kosher...


lol
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Quoting Levi32:
Low-level vorticity is increasing underneath 96L's mid-level center near the Yucatan.





meaning??
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Wheeeeeee 30 mph winds and sideways blinding rain for 10 minutes...thanks 95L
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Quoting PtownBryan:


A friend and I used to call it the commerical channel in the 90's. Now it is the new lifetime. More stories than actual weather coverage!
It is bad no, I did not have cable for the last 5 years and after getting a few months ago, I was shocked on how bad they have gotten.
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.
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1496. Levi32
Low-level vorticity is increasing underneath 96L's mid-level center near the Yucatan.



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Quoting StormSurgeon:
I hate to sound ignorant, but would somebody please define "invest" for me....I need reaffirmation.


Something worthy of Invest..igation
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Quoting jasoniscoolman2010x:
wow update watching 40 west wave..
Hefty looking wave with strong vorticy there! We'll have to see how well it holds together once away from land.
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Quoting Hurricanes101:


"Invest" is short of Investigation and is labeled for an area of interest that the NHC would like to look into further for chances of possible development

Thanks, I didn't know the reason for the name either.
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Quoting StormSurgeon:
I hate to sound ignorant, but would somebody please define "invest" for me....I need reaffirmation.


Invest:
A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g., microwave imagery) and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic web sites, including the Naval Research Laboratory (NRL) and the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS). The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone; operational products such as the Tropical Weather Outlook or the JTWC/TCFA should be consulted for this purpose.


Link
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Quoting StormSurgeon:
I hate to sound ignorant, but would somebody please define "invest" for me....I need reaffirmation.


"Invest" is short of Investigation and is labeled for an area of interest that the NHC would like to look into further for chances of possible development
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Quoting StormSurgeon:
I hate to sound ignorant, but would somebody please define "invest" for me....I need reaffirmation.
I believe it is short for investigation. Just a guess.
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1487. angiest
Quoting superweatherman:


I think more like 2008 just the pattern of most of them wanting to go to Texas...


I concur, seems likely to be a bad year for the western Gulf.
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1486. Levi32
Quoting frecklespugsley:


I'm in MD and am curious about what people think about this system off the east coast. At what point does NHC classify something as an AOI or invest?


The designation of an invest is completely subjective and has no criteria required for declaring one. The hurricane forecasters can label a disturbance an invest whenever they feel that it has potential to develop and they want to run model forecasts on it.

The area off the southeast coast could turn out to be interesting, but high pressures in the area may make it difficult to get anything going. There is a lot of energy trying to bundle in that area though, so there is potential. Any low that does form will likely miss the southeast coast and head north towards New England or the Canadian Maritimes. The system may even start off subtropical in nature. I wouldn't worry about a significant system, but you might get some stormy weather from it if it comes close to the eastern seaboard on its way north.
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I hate to sound ignorant, but would somebody please define "invest" for me....I need reaffirmation.
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Quoting jaseone:
Recon currently out on a non tasked mission to drop dropsondes to help seed the models for 96L it would seem.


Primary intention is not for the models although they will use the data. That GIV flight along with the soon to take off P3 is focusing on genesis and 3D doppler radar. If their plans don't change, the P3 will fly a "lawnmower" pattern instead of the traditional X.
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I think more like 2008 just the pattern of most of them wanting to go to Texas...
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Quoting Levi32:


That warm water off the east coast is bad news for them if any hurricanes come calling up the eastern seaboard. That Gulf Stream is boiling this year with the warm AMO.


I'm in MD and am curious about what people think about this system off the east coast. At what point does NHC classify something as an AOI or invest?
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Quoting StormW:


Well, I am preferring a blend, really...I'm partial to 1995, 1998, and 2004.

In fact, I know some are doubting the total numbers, and I'll try to put it in perspective...Those 3 years...1995 had a total of 19 storms...2 in July, and 10 forming in AUG and SEP.

1998 had 14 storms...1 in JUL, 10 in AUG and SEP.

2004 had 15 storms, 1 in JUL, 11 in AUG and SEP.

This season has conditions that are more favorable than those 3 years mentioned, and I don't see any change. We've already seen what type of developments are taking place now, and I personally have not seen a typhoon type development situation in the Atlantic before, or at least I haven't noticed.


Also people need to realize how the numbers add up

If we go through July with say 3 named storms; we can still very easily get to 20

Heart of the season we can easily get 17 storms out of the months of August, September and October.
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1479. IKE
Quoting Daveg:


Center is almost back over water, then we shall see.


Agree that it will be back over water in 4-6 hours.
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Quoting Daveg:


Center is almost back over water, then we shall see.
Unless you're talking about the low level center, it seems to me that 96L is still over the Yucatan.
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1476. RM706
Time to talk about the ACTIVE tropics http://www.wunderground.com/wxradio/wubroadcast.html

C'mon over ...

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1475. Daveg
Quoting IKE:
Looks like 96L is headed for a lower pct. on the next TWO if it doesn't improve....



Center is almost back over water, then we shall see.
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1474. Levi32
Quoting winter123:
The most above average part of the atlantic is now off the NJ/DE coast. I was there just over a week ago, I did think it felt unusually warm. Also note the western gulf is below average where Alex went and will inhibit development of 96L slightly.


That warm water off the east coast is bad news for them if any hurricanes come calling up the eastern seaboard. That Gulf Stream is boiling this year with the warm AMO.
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Quoting Hurricanes101:


personally I think the area off the Eastern coast of the US has the best shot to become the next system
It's definitely going to be a complicated scenario, and after all the system might turn out subtropical.
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1471. IKE
Looks like 96L is headed for a lower pct. on the next TWO if it doesn't improve....

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The most above average part of the atlantic is now off the NJ/DE coast. I was there just over a week ago, I did think it felt unusually warm. Also note the western gulf is below average where Alex went and will inhibit development of 96L slightly.
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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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