Gulf of Mexico disturbance 93L a Lousiana flood threat; Katia a hurricane

By: Dr. Jeff Masters , 3:28 PM GMT on September 01, 2011

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Surface winds over the northern Gulf of Mexico are rising, pressures are falling, and heavy thunderstorms are building today thanks to a tropical disturbance (Invest 93L) that is the product of a tropical wave interacting with an upper-level low pressure system. At 8:35 am CDT, winds at the Mississippi Canyon 711 oil rig were south-southeast at 38 mph. This is just 1 mph below tropical storm force, but the wind instrument was 348 feet (106 m) above the ocean surface, and winds near the surface were probably considerably lower, near 30 mph. Long range radar out of Mobile, Alabama shows heavy rain showers building along the northern Gulf Coast, but these rain showers are not organized into spiral bands and show no signs of rotation. Strong upper-level winds out of the west-northwest are creating 30 knots of wind shear over 93L, keeping the storm's heavy thunderstorms disorganized. Strong onshore winds raising tides to 1 - 2 feet above normal are likely along the northern Gulf Coast through the weekend, and coastal flood statements have been issued for the region.


Figure 1. Predicted rainfall for the 5-day period ending at 8am EDT Sep 6, 2011. A large region of rains in excess of 15 inches is expected over Southeast Louisiana. Image credit: NOAA/HPC.


Figure 2. U.S. drought conditions on August 30. The rains from 93L have the potential to bring major drought relief to drought-stricken portions of the coast. Image Credit: U.S. Drought Monitor.

By late tonight, wind shear is expected to drop to the moderate range, below 20 knots, and 93L should begin to organize into a tropical depression. Wind shear is expected to remain moderate, 10 - 20 knots, into Monday. There is some cold, dry air aloft that will retard this process, and I think the earliest we would see a tropical depression is Friday afternoon. NHC is giving 93L a 70% chance of developing into a tropical depression by Saturday morning. All of the major models develop 93L near the Louisiana coast, and show a slow and erratic movement due to weak steering currents. Coastal Louisiana, Mississippi, Alabama, and the extreme western Panhandle of Florida will likely receive very heavy flooding rains beginning this afternoon and intensifying Friday and Saturday. The latest rainfall forecast from NOAA Hydrological Prediction Center (Figure 1) shows that a large area of 15+ inches of rain is expected over Southeast Louisiana. The region is under moderate drought, so flooding problems will be delayed compared to what we'd normally expect from heavy rains of over a foot. Nevertheless, minor to moderate freshwater flooding is likely from 93L, and flash flood watches are posted for New Orleans and surrounding areas, and rainfall amounts of 1 - 3 inches per hour are possible in some of the heavier rain squalls. Ocean temperatures are near record warmth, 88°F (31.3°C), which will provide plenty of moisture for heavy rains, and plenty of energy to help 93L strengthen into a tropical storm. Most of the models predict 93L will have some motion to the west by Saturday, which would bring rains to the Texas coast near the Louisiana border. Steering currents will be weak in the Gulf this weekend and early next week, making it difficult to predict where the storm might go. If 93L stays over water through Tuesday, like the ECMWF model is predicting, the storm would be a threat to intensify into a hurricane. Most of the other models predict 93L will move ashore over Louisiana by Sunday, limiting the storm's development to just tropical storm strength. I think it at least 50% likely 93L will be a tropical storm with 40 - 60 mph winds along the coast of Louisiana by Sunday.

Hurricane Katia
Hurricane Katia intensified into the 2nd hurricane of the 2011 season last night, and continues its long trek across the Atlantic Ocean today. Katia is expected to arrive at a position several hundred miles north of the Northern Lesser Antilles Islands by Monday. The islands are not in the cone of uncertainty, and it appears unlikely that they will receive tropical storm-force winds from Katia. Satellite images show that Katia is a well-organized storm with plenty of heavy thunderstorms, but the storm has been struggling with dry air and moderate wind shear of 10 -20 knots, and is looking less organized than it did last night. These problems will likely diminish by Friday night, as the upper low bringing the wind shear moves away. It is still unclear how much of a threat Katia may post to the U.S. Dr. Bob Hart's Historical Tropical Cyclone Probability web page suggests shows that tropical storms in Katia's current position have an 16% chance of hitting North Carolina, a 21% chance of hitting Canada, a 12% chance of hitting Florida, and a 54% chance of never hitting land. I suspect that Katia will turn north before reaching the U.S. and potentially threaten Bermuda and Canada, based on what past storms in similar situations have done, and assuming the jet stream maintains its current pattern of bringing frequent troughs of low pressure off the coast of the U.S. It will be another day or two before the models will begin to have a handle on the long-term fate of Katia, though.


Figure 3. Morning satellite image of Katia.

94L
A well-organized low pressure system with a surface circulation and limited heavy thunderstorm activity has developed between Bermuda and the Canadian Maritimes. This disturbance, (94L), is headed out to sea, and is being given a 10% chance of developing into a tropical depression by NHC. 94L is under a very high 30 - 40 knots of wind shear, and will not be able to intensify very much. However, Tropical Storm Jose formed from a similar type of system, and we might get surprised by 94L.

I'll have more on Irene in tomorrow's post.

Jeff Masters

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2545. Delsol
When should we expect HH missions into Katia?
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Maybe Dr. Masters will do a blog tomorrow on why TD #13 needed to be classified or not...yipee.

lol.
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2543. KEEPEROFTHEGATE (Mod)
Quoting kmanislander:


Not a signature one would have expected from a system that was a hurricane this morning. No classic closed center.

The Northern Leewards need to pay attention to this, as do the central Bahamas IMO
i call this a loose cannon who to say right now wait watch and see
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check back later...
Member Since: July 2, 2009 Posts: 0 Comments: 2811
2541. Drakoen
Quoting Skyepony:
Fresh ASCAT of Katia. Tightened up a bit from the WINDSAT one.


LOL. Good for her.
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Quoting MississippiWx:
Next Scheduled Mission:

FLIGHT TWO --TEAL 71
A. 02/0600Z ,1200Z
B. AFXXX 0213A CYCLONE
C. 02/0430Z
D. 25.5N AND 95.5W
E. 02/0530Z TO 02/1200Z
F. SFC TO 15,000FT



What's up with those coordinates?
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To add to my last post, could the reason they haven't classed 94L a TD yet either, be that they haven't sent HH into there and they don't have the # of bouys and other data in the area to determine a closed circulation intensity etc. except for just satellite views? I'm sure they have many more 'tools' in the Gulf to properly classify that system quicker than one in the northern atlantic. (or am I just reaching for straws here?!) lol
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2535. emcf30
This maybe a better way for some of you to voice your dissatisfaction with the NHC. For questions and comments about National Hurricane Center forecasts and operations,
nhc.public.affairs@noaa.gov
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2533. DFWjc
Quoting nolacane2009:


The way I learned to live is that the government care about themselves and not the people atleast where I am at. I have voiced my opinion time and time again does not work lol.


like i said, it took me 6 months...the look on the council's faces every month when i came to the podium to speak... for a hole no bigger than 2 DVD cases...
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2532. Dennis8
MAYBE SOME OF US HAVE THIS EDUCAITON AND EXPERIENCE SO WHEN THEY HAVE OPENINGS WE CAN APPLY:

John Cangialosi

How did you find your way to NHC?

While I was doing graduate work at UM in 2005, I was involved in a project called RAINEX (Hurricane Rainband and Intensity Change Experiment). It was a multimillion dollar project that involved the University of Miami, University of Washington, NCAR (National Center for Atmospheric Research) and several other agencies. I had many jobs with it, but I was the lead forecaster, my first real taste of forecasting. I had to provide briefings every day at 11 AM and give the possibility of tropical cyclone formation. What they really wanted to know was there going to be any rapid intensity changes, because that's what the project was targeting. It put me to the test, the biggest challenge of my professional life up to that point. It was my first taste of hurricane forecasting.

What came next?

Since being in graduate school, I was into numerical modeling. So for the RAINEX project, I was able to conduct a team of models, similar to the GFDL used here at NHC, but custom-made for the project. I would present some of our model simulations during the briefings. But the project only lasted three months, then after that it was all research.

You didn't want to do research?

I wanted to be an operational forecaster, so I began to bid on (National) Weather Service jobs. I got to the interview stage on a job in Maine. But at the same time, I had bid on a job with NHC's Tropical Analysis and Forecast Branch (TAFB). I decided to go with that one and stay in Miami.

So you were definitely staying with hurricanes?

Oh yes! One of the coolest things I got to do that year was flying on a hurricane hunter P-3 plane into Hurricane Rita. That's the research plane, so we penetrated the core and the eye. What was real cool was we got there at maximum intensity, 897 millibars. Once I saw the beauty of the hurricane, I was just blown away. I decided there was no way I was going to forecast snow and frost events in Maine.

Now you're the newest hurricane specialist.

Yes, I had done the HSM (Hurricane Support Meteorologist) for a couple of years and had a little bit of experience with it, and it came through.
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2531. Skyepony (Mod)
Quoting mrjr101:
proximity to land should not be one of the NHC's tickler to classify a storm. I agree 100% with those who clearly stated their case that right now, TD13 is just a bad call by the NHC.


They flew a plane through it, it had a closed low. We could clearly see it from the data. It weakened since.
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Quoting kmanislander:


Sometimes it pays to come in late Lol.

TD 13 has been classified by the NHC. Period.


Good enough for me.

They flew the thing, they looked at the data.

They're smart folks, and until someone demonstrates to the contrary, I'll take their word for it.
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Quoting Dennis8:


Su

Thank you...


I hope that doesn't mean Shut Up...
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Quoting DFWjc:



A troll is a guy that thinks he's fly
And is also known as a buster (busta, busta...)
Always talkin' about what he wants
And just sits on his broke....

(stolen from TLC, LOL!)


Lol!!
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Interesting
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Quoting wxguesser:


You must not be from round here..we all say anything more than an inch an hour will overwhelm the pumps and the streets will flood... (lol) :-)


One acre of land collects 27,143 gallons of water. So, if it rains 3 inches in one hour, then 81,429 gallons per hour, per acre . . . and it has to go somewhere. How many acres of land is there in your area?
Member Since: August 26, 2006 Posts: 0 Comments: 1548
Quoting Skyepony:


I posted that when it happened..should elaborate the core has issues by that pass.. Not expecting it to bomb tonight. Models maybe trying to strengthen it faster than it may. Little nudge west.


Not a signature one would have expected from a system that was a hurricane this morning. No classic closed center.

The Northern Leewards need to pay attention to this, as do the central Bahamas IMO
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Enough bickering over classification with this storm. It is over the Gulf, with smoking hot water. There are hundreds of oil rigs beneath it, there are cities full of people just North of it...cities that are prone to flooding. Do not forget that the NHC sometimes has to make a political decision. This may be one of those times. This is sitting below me, so I am grateful for the NHC's actions. I am very concerned about flooding this weekend.
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Quoting scott39:
Agree to disagree and move on please.


I think you are onto something...
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2520. Bijou
Cleaning catchbasins is vitally important for NOLA neighborhoods to reduce the risk of flooding. Sure, the "authorities" should be responsible for this elementary flood preventive measure but I'm not above digging out the leaves and garbage myself. If it saves my car, my home, hell yes, I'll pitch in and clean catchbasins.

And guilt all my neighbors into joining me. A couple of beers, what's some sweat and debris between friends?

Quoting FLdewey:
Cantore has his smart glasses on... can't be good.

The Orleans Parish Sewerage & Water Board's director said there are back up generators at its power plant to try and ensure pumping operations don't go offline during a critical time.
"The pumping capacity is at 100 percent. We will close gates as necessary, but most importantly, it's important that citizens clean their catch basins, clean their drains," said Marcia St. Martin, executive director of the S&WB.


Good idea living in a bowl... DIY Public Works. :-o
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Quoting LBAR:


Because the goal is to up the number of storms to correlate with the premise of "climate change" and all of its speculated DOOM. There can be no other explanation. If there is, I want to know it.
Well the only DOOM I have seen this year is the river flooding caused by Hurricane Irene...By this time in 2005 Dennis, Emily, and Katrina had already left its mark.
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might get the school off to, if this baby strengthens come on you can do it
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Next Scheduled Mission:

FLIGHT TWO --TEAL 71
A. 02/0600Z ,1200Z
B. AFXXX 0213A CYCLONE
C. 02/0430Z
D. 25.5N AND 95.5W
E. 02/0530Z TO 02/1200Z
F. SFC TO 15,000FT

Member Since: Posts: Comments:
2516. Skyepony (Mod)
Fresh ASCAT of Katia. Tightened up a bit from the WINDSAT one.
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2515. mrjr101
proximity to land should not be one of the NHC's tickler to classify a storm. I agree 100% with those who clearly stated their case that right now, TD13 is just a bad call by the NHC.
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Quoting kmanislander:


Sometimes it pays to come in late Lol.

TD 13 has been classified by the NHC. Period.


Good to see ya, Kman.

We're just having a good natured debate. These debates are much easier when the debaters have respect for one another.
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2513. scott39
Agree to disagree and move on please.
Member Since: June 13, 2009 Posts: 0 Comments: 6912
Quoting DFWjc:


Glad i'm not there, i'd be all over city council... We've had a pot hole cause by running water for 6 months now and i told them i could save the city $2800/month if they would arch the black top so the water wouldn't run over and "wash" it out..sure enough they did that and no more potholes. Maybe your city government should hear a word from you....


The way I learned to live is that the government care about themselves and not the people atleast where I am at. I have voiced my opinion time and time again does not work lol.
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Quoting hurricanehunter27:
Looks to be trying to form an eye. Anybody got a recent Micro pass?
The most recent is a little less than 4 hours old, but at the time it had a pretty solid CDO with no sign of an eyewall developing (from what I can see from this partial pass).

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Guys, I'd say the discussion clearly states why they view it as a TD:

'SATELLITE...SURFACE...AND NOAA RECONNAISSANCE AIRCRAFT DATA INDICATE THAT THE LOW PRESSURE AREA OVER THE CENTRAL GULF OF MEXICO HAS ACQUIRED A CLOSED CIRCULATION THAT IS DEFINED ENOUGH TO BE CONSIDERED A TROPICAL DEPRESSION. HOWEVER...THE CENTRAL REGION STILL CONSISTS OF A LARGE AREA OF LIGHT WINDS. THE AIRCRAFT DATA AND BUOY OBSERVATIONS SUPPORT AN INITIAL INTENSITY OF 30 KT.'

It may not look pretty, but all their tools showed the closed circulation and observations supporting an intensity of 30 kts. Isn't that a TD?! They have more tools and data at their disposal then any of us on this blog.
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2507. xcool
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2506. DFWjc
Quoting Jasonsapology:


PATHETIC, your so powerful and have determined I'm a troll because I don't agree with your opinion or someone bashing the NHC.


I think your a troll



A troll is a guy that thinks he's fly
And is also known as a buster (busta, busta...)
Always talkin' about what he wants
And just sits on his broke....

(stolen from TLC, LOL!)
Member Since: Posts: Comments:
Quoting kmanislander:


Sometimes it pays to come in late Lol.

TD 13 has been classified by the NHC. Period.


Thank You! Thank You! Thank You!!!
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2504. STSUCKS
For the folks on here that say 13 is not a tropical depression deal with it..the "experts" at the national hurricane center classified it after the hurricane hunters found a closed circulation...you guys don't work for the nhc and I don't see anyone posting their bachelors in meteorology on here to tell the people on here who are in the affected area that are looking for information exactly why it shouldnt be...quit sending mixed messages and just accept it and move on and help use what knowledge you folks have on helping answer peoples questions who's in the affected area!
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Quoting DFWjc:


oh and the NWS can't be ever wrong? HA!
they. Can be and this blog is wrong much much more often
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Quoting Neapolitan:

Did you know:

--Only two storms this year have failed to accumulate at least 1 whole ACE unit (Jose and Franklin). 2005 had six such storms.

--Hurricane Irene was more powerful from an ACE perspective than 25 of 2005's 28 storms (including Katrina).

--Katia has already accumulated more ACE than 12 of 2005's storms.

--Even this year's lightweight Gert managed to gather more ACE than nine of 2005's storms.

My point being that, while 2005 was a spectacular oddity, to be sure, it wasn't as if every storm that year was a long-lived monster; 2005 had its share of "pip squeaks". It had twelve TSs, an unnamed subtropical storm, and an additional three TDs that never became TSs. (And, for the record, seven Cat 1s.)


Cool, didn't know those facts. Thanks, Nea! You are always loaded with good info!
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2501. bwi
Well, we'll see what happens in the gulf and the atlantic. Both the 12z ECMWF and 18z GFS bring Katia too close to the east coast for my liking. Would be interested to see if any ensemble members show landfall on both models tomorrow.
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2500. KEEPEROFTHEGATE (Mod)
Tropical.Cyclone.Formation.WARNING
013/TD/L/CX
MARK
25.95N/89.91W


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Quoting MiamiHurricanes09:
I'm thinking it's pretty close to becoming a hurricane again...probably at 5a.m.

Looks to be trying to form an eye. Anybody got a recent Micro pass?
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Quoting whepton3:


Thanks for that kman... If you had just tuned in to tonight's discussion... one would have forgotten Katia is out there.

In light of tonight's debate though, it's worth pointing out that Katia is indeed a bona fide tropical storm.

Don't think that's much of a stretch.


Sometimes it pays to come in late Lol.

TD 13 has been classified by the NHC. Period.
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i've noticed how some of the models show td13 going into la then coming back into the gom and riding the coast eastward..being that it would be over marshes, could it still stay the same strength?? but for anyone living along the beaches watch for extra high tides fri and sat..not too mention there is 1 hech of a rip-tide out there also..
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2496. Skyepony (Mod)
Quoting kmanislander:
Katia 4 hours ago



I posted that when it happened..should elaborate the core has issues by that pass.. Not expecting it to bomb tonight. Models maybe trying to strengthen it faster than it may. Little nudge west.
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2495. Dennis8
Quoting TropicalAnalystwx13:


(nods)
Quoting TropicalAnalystwx13:


A tropical depression by tomorrow? We have one now ;)


Su
Quoting Joshfsu123:
NHC makes the decision - they know what they are doing. Deal with it.


Thank you...
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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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