Isaac pounding Louisiana, Mississippi, Alabama, and Florida

By: Dr. Jeff Masters , 4:01 PM GMT on August 29, 2012

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Hurricane Isaac continues to lumber slowly northwestwards at 6 mph, as it pounds Louisiana, Mississippi, Alabama, and Florida's Panhandle with torrential rains, high winds, and a damaging storm surge. The eye was partially over water for most of the 15 hours after Isaac's official landfall at 7:45 pm EDT Tuesday night, but New Orleans radar shows the eye of the storm is now fully ashore near Houma. The radar echoes show some weakening on the west side of the eyewall, where dry air has infiltrated the storm. Wind shear remains light, and upper level outflow over Isaac is as impressive as we've seen so far, with a strong outflow channel to the north, and a respectable one to the south, as well. Infrared and visible satellite loops show a very large, symmetric, and well organized storm, and Isaac is going to be able to stay near Category 1 hurricane strength all day today. This will allow Isaac to drop rainfall amounts of 15 - 20" in some areas of Louisiana before the storm is over. A few rainfall totals from Isaac through 11 am EDT:

9.26" New Orleans Lakefront Airport
5.59" Belle Chasse, LA
5.21" Mobile, AL
3.65" Hattiesburg, MS
3.42" Gulfport, MS
2.81" Biloxi, MS


Figure 1. Morning radar reflectivity image from New Orleans.

A dangerous storm surge event underway
Isaac is bringing a large and dangerous storm surge to the coast from Central Louisiana to the Panhandle of Florida. Late this morning was high tide along much of the coast, and the highest water levels of Isaac are likely being experienced at many locations. At 11:30 am EDT, here were some of the storm surge values being recorded at NOAA tide gauges:

8.0' Waveland, MS
8.2' Shell Beach, LA
2.0' Pensacola, FL
4.6' Pascagoula, MS
3.4' Mobile, AL

The peak 11.06' storm surge at 1:30 am EDT this morning at Shell Beach, which is in Lake Borgne, 20 miles southeast of New Orleans, exceeded the 9.5' surge recorded there during Category 2 Hurricane Gustav of 2008. In general, the storm surge heights from Isaac have been more characteristic of a strong Category 2 hurricane, rather than the weak Category 1 hurricane one might suppose Isaac is, based on its top sustained winds of 75 - 80 mph. The Saffir-Simpson Scale for ranking hurricanes is only a crude measure of their potential impacts.

A storm surge estimated at 12' moved up the Mississippi in Plaquemines Parish near Port Sulphur, LA, near 8:30 pm EDT Tuesday, causing overtopping of the levees and flooding of homes in the mandatory evacuation areas behind the levees. These levees were not part of the $14.5 billion levee upgrade New Orleans got after Hurricane Katrina, and were not rated to Category 3 hurricane strength, like the levees protecting New Orleans are. The surge continued upriver, elevating the water levels 10' in New Orleans (103 miles upstream from the mouth of the Mississippi), 8' in Baton Rouge (228 miles upstream), and 1.4' at Knox Landing, an amazing 314 miles upstream. The river was 7' low due to the great 2012 U.S. drought, and I suspect the near-record low flow rate of the river allowed the storm surge to propagate so far upstream. The salt water from the storm surge will be slow to leave the river, due to the continued winds of Isaac keeping the surge going, plus the very low flow rates of the river. One benefit of the heavy rains of 10 - 20 inches expected to fall over Louisiana over the next two days will be to increase the flow rate of the Mississippi River, helping flush the salt water out of the river. The low flow rates of the Mississippi had allowed salt water to move upriver to just south of New Orleans over the past few weeks, threatening the drinking water supply of Plaquemines Parish.


Figure 2. Tide gauge data from Waveland, Mississippi. The green line shows the storm surge. The red line is the storm tide, the height of the water above Mean Sea Level (MSL.) The storm tide at Waveland currently (9') is 2' higher than that of Category 2 Hurricane Gustav of 2008. Image credit: NOAA Tides and Currents.

Tropical Storm Kirk in the Central Atlantic
Tropical Storm Kirk formed Tuesday night in the Central Atlantic. Kirk's formation at 03 UTC on August 29 puts 2012 in 4th place for earliest formation date of the season's 11th storm. Only 2005, 1995, and 1933 had an earlier formation date of the season's 11th storm. Kirk should stay well out to sea and not trouble any land areas.


Figure 3. Morning satellite image of Tropical Storm Kirk.

Invest 98L in the Eastern Atlantic
A tropical wave (Invest 98L) is about 750 miles west-southwest of the Cape Verde Islands, and is moving west to west-northwest at about 15 mph. In their 8 am EDT Tropical Weather Outlook, NHC gave 98L a 50% chance of developing by Friday morning. Several of the models develop 98L into a tropical depression by this weekend, but none of the reliable models foresee that 98L will be a threat to the Lesser Antilles. The storm may be a threat to Bermuda next week, but it is too early to say if it may threaten the U.S.

Jeff Masters

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Quoting JLPR2:


Actually a bit to the south of where the NHC has it, which is 13.3N.


Really JLPR2? Where do you see it?
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LOL Not a possibility here
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Quoting WhoDatRR:
This is one heck of a Cat-1. One of my cousins just lost her home, in LaPlace. And another is worried about her house. Is anyone posting a real-time flooding map?


Hope everything is fine with your family. hope this help:
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Lol.TWA13 all ways vanish when I get on.Anyway it's been a beautiful warm sunny day up hear in D.C.Couldn't ask for anything better in terms of weather!.I saw the butterflies fluttering in the wind and the birds still chirping.Getting in their last minute of summer before fall comes.The squirrels are all ready starting.Nice breezes to go along with the warmth outside as well.
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Quoting WhoDatRR:
This is one heck of a Cat-1. One of my cousins just lost her home, in LaPlace. And another is worried about her house. Is anyone posting a real-time flooding map?
Oh No................I'm so sorry....
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Quoting HurricaneHunterJoe:
And our eyes turn to the east already.


They are other systems out there that you gotta keep a close eye on. Don't want a system to creep up on you.
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This is one heck of a Cat-1. One of my cousins just lost her home, in LaPlace. And another is worried about her house. Is anyone posting a real-time flooding map?
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Quoting dhcoop59:
It's hard to wade through the political crap to get info on affected areas. I have a friend that's desperately trying to get some info out of Slidell. Does anyone have a report from that area about conditions?


just the most recent from TWC - initial flooding bc of the lake inflow. expect winds to begin pushing the water from the lake, north in a few hours. the combination does not look good. leaving probably a good idea if you can.
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Quoting AnthonyJKenn:

Brees and the entire Saints organization moved their operations to Tennessee to prepare for the Redskins game, so he's probably OK...his family probably evacuated with him.

Im sure they are, just hope there home is ok. People in the north shore rarely evacuate because they usually never flood...so I hope Mrs. Brees packed up.
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And our eyes turn to the east already.
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Quoting KatyMan:


I'm a 70 yr old man and not computer literate. Thank you for putting up with me. Will be there until the 6th. Hope you have a great camping trip.


You're very welcome. St. John is a beautiful island and I do hope that you have a wonderful time!
Member Since: July 30, 2011 Posts: 3 Comments: 699
Quoting groundedpilot:
Just got power back in New Iberia ! Anybody hear about a levee break around Madisonville ?
levee break... search and rescue underway...

"Hurricane Isaac has caused the levee to break at Port Louis/Guste Island near Madisonville, prompting St. Tammany Parish officials to start search and rescue operations in the area. In addition, search and rescue is under way in the Indian Village area south of Slidell."
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Quoting NoNamePub:
Alaina...you be careful!
Keep the info coming...
Hope Drew Brees is ok,,,,Just drafted hiim in my fantasy league!
Brees and the entire Saints organization moved their operations to Tennessee to prepare for the Redskins game, so he's probably OK...his family probably evacuated with him.
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Quoting LurkyMcLurkerson:


It is slowish. A lot of regular posters are probably busy dealing with weather or don't have power right now, though I'm glad to see folks checking in as they can.

I am _nothing like_ terribly knowledgeable on this stuff, but I suspect that people who are would say "the track is really hard to judge, probably a slow drift NW for the next day or two."

There's a ridge sitting right above isaac that stretches from the top of TX all the way to the east coast. It's hard for the storm to move much at the moment, there's some weakness in it to his W but it's not a lot and there's a weak trough going NE but it's not a lot either.

I'd expect that he'll meander NW or WNW but move very slowly, probably for the next day at least, and maybe wander around a bit unless something changes in that ridge soon. At the moment, he is seriously barely moving at all.


The models been pretty good on track the last few days and they are saying NW slowly.
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I wonder if it possible for Isaac to move back over the sea and restrengthen...
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681. JLPR2
Quoting stormpetrol:


Posted before , but I'll post it again, 98L center is still at a low latitude , if it's below 15N at 45 -50W , it will usually make it in to the Eastern Caribbean.


Actually a bit to the south of where the NHC has it, which is 13.3N.
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Quoting kidd5433:


More like a belly-button now

true dat. but was... over land, for quite a while... even as a TS, an eye. go figger.

i know a lot of the more experienced folks (i, myself am here to learn and usually fall into the lurker cat) are out of power or in the thick of it, but i hope when things dry out there is some reflection on the whole storm — there is so much that was unexpected, and it seems a lot for everyone to learn.
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Quoting padirescu:
While I really feel for those in the Central gulf coast that are getting the brunt of Isaac right now, please don't forget that there are 1000's of families who have been stranded in their homes since Sunday like myself. We also still have the threat of further flooding based on the new story below.

Palm Beach County Levee Concerns

It's been 48 hours since the last rains from Isaac and almost every home in our area has become an Island for the residents living in them. I can't even imagine what the aftermath for those in the gulf coast is going to look like. We ended up with 19" locally from Sunday night through Monday.


I watched that pounding that you guys took a few days ago -- that was serious crazy. And really unexpected, so I'm sure nobody was prepared for it -- there was no way to see it coming, that blob of huge convection Isaac lobbed over and then having it hang out stuck in the steering pattern all day -- I've never seen anything quite like it.

Thanks for the report. Indeed, serious stuff all over the place -- still worsening in a lot of places. Levees are going to be staying under an incredible amount of pressure for a while yet, and I think the damage when it's cleared out enough for more broad reporting is going to be pretty bad at this point. Fingers are crossed into knots that it is only to people's stuff.


Stay safe over there.
Member Since: August 26, 2012 Posts: 0 Comments: 368
Quoting LurkyMcLurkerson:


It is slowish. A lot of regular posters are probably busy dealing with weather or don't have power right now, though I'm glad to see folks checking in as they can.

I am _nothing like_ terribly knowledgeable on this stuff, but I suspect that people who are would say "the track is really hard to judge, probably a slow drift NW for the next day or two."

There's a ridge sitting right above isaac that stretches from the top of TX all the way to the east coast. It's hard for the storm to move much at the moment, there's some weakness in it to his W but it's not a lot and there's a weak trough going NE but it's not a lot either.

I'd expect that he'll meander NW or WNW but move very slowly, probably for the next day at least, and maybe wander around a bit unless something changes in that ridge soon. At the moment, he is seriously barely moving at all.


Thank you, Lurky. The ridge and any weakness with it is what I was wondering about. I'm hoping Isaac will go north and not more west, nothing against those in it's way going north, but not wanting anything more than I have to have with Isaac.
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Quoting padirescu:
While I really feel for those in the Central gulf coast that are getting the brunt of Isaac right now, please don't forget that there are 1000's of families who have been stranded in their homes since Sunday like myself. We also still have the threat of further flooding based on the new story below.

Palm Beach County Levee Concerns

It's been 48 hours since the last rains from Isaac and almost every home in our area has become an Island for the residents living in them. I can't even imagine what the aftermath for those in the gulf coast is going to look like. We ended up with 19" locally from Sunday night through Monday.
padirescu....I really feel you pain...I do...........But there are people struggling for their lives on rooftops and attics.... I'm sorry for you pain
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I am just wondering if he is going to turn or move further west?
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We are having some major drainage issues... Lake Ponchatrain and Lake Maurpas are being blown out of the west side and our water drains into lake maurpas but the wind is coming in the opposite direction of the way our water drains. Its a mess.
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I live an hour north of New Orleans: No flooding worries since I am 84 feet above sea level and by no bodies of water. The wind and rain have really picked up here in the last couple of hours. We lost power at 1:15PM and have been running a generator since that point. So far only 2 trees lost and the ground nearly covered in smaller branches (have nearly 7 acres and can see about 4 of it).
St. Tammany parish has instituted a parish-wide curfew of 6 PM to 6 AM tomorrow. The worst of the storm is supposed to be affection our area during that time frame. Right now local authorities are saying that the water in some areas has exceeded what was seen in 2005 during the "K" storm.
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Posted before , but I'll post it again, 98L center is still at a low latitude , if it's below 15N at 45 -50W , it will usually make it in to the Eastern Caribbean.
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Weather Channel just mentioned strong High Pressure to north of Isaac (100 degree Temp) -blocking N. Movement
Watch for S.W. Jogs
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It's hard to wade through the political crap to get info on affected areas. I have a friend that's desperately trying to get some info out of Slidell. Does anyone have a report from that area about conditions?
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Quoting VirginIslandsVisitor:


That's a yes on the earthquake.

Your guess is as good as anyone's at this point. We're supposed to go to Water Island for a long weekend camping trip and we're on hold too. We're giving it until tomorrow night before we make the decision.

I'll keep my fingers crossed for you though!

Keep an eye on Link as it has updated info on all the islands and can be a very big help in seeing the big picture when there's a storm coming in.

Lindy


I'm a 70 yr old man and not computer literate. Thank you for putting up with me. Will be there until the 6th. Hope you have a great camping trip.
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Here in Central Ms starting to get some strong wind gusts. Looks like Isaac will be swinging on in momentarily. Everyone stay safe out there. I am new here, so wanted to express my appreciation for the great info I am seeing here.
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Serious flooding in Laplace near I-10.
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Quoting GTcooliebai:
nice avatar
Thanks.I'm just amazed how for the past three hurricane seasons we have had a record amount of activity.Someone posted a chart and showed that the sst off of south america were cooling except for warming.If that trend continues then expect the activity in the Atlantic to continue.Wouldn't be something to have 19 storms all three season's in a row?.Not likely to happen this year.But would be interesting none the less.
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While I really feel for those in the Central gulf coast that are getting the brunt of Isaac right now, please don't forget that there are 1000's of families who have been stranded in their homes since Sunday like myself. We also still have the threat of further flooding based on the new story below.

Palm Beach County Levee Concerns

It's been 48 hours since the last rains from Isaac and almost every home in our area has become an Island for the residents living in them. I can't even imagine what the aftermath for those in the gulf coast is going to look like. We ended up with 19" locally from Sunday night through Monday.

Edit: Ironic that my post was number 666 in the thread.
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Quoting ncstorm:


I was the one who made the statement about the hurricane party and I only posted on what I saw on Good Morning America this morning which is national news..I never said everyone chose to party..I specifically said in New Orleans that they were having hurricane parties..if anyone want to gripe about that, then take it up with ABC news as its online on their website by reporter Bill Weir..I also posted in defense of those who didnt evacuate and even stated that the economy is bad and people are living from pay check to pay check and not everyone can up and leave to ride out a storm in a hotel/shelter due to financial and health reasons..as much as people here want to defend some, Im sure there were some who just thought it was a Cat 1 storm and refused to leave even with the means to do so..did they deserve to lose their homes..heck no! Also to state people are possibly dying is premature as I havent read or seen anything like that and I pray it dosent happen..we need to be more optomistic and stop making things appear worse than they really are..yes property has been lost but there is always living another day and able to hug your love ones..I will take that any day over materalistic possessions..Im sure Haiti islanders will disagree about people staying in mandatory evacuations when they had a choice to leave..remember, there is always someone who has it harder than all of us..blessings to all in the path of Isaac


Media, politics, blame, etc. have been exhausted here today and have exhausted me ... I'm not blaming anyone I just think the timing of those discussions leave a lot to be desired...Also, I do not feel I am hyping anything when houses are up to their roofs with water, a search and rescue is under way after the levee break, and numerous rescues have already occurred...Sorry I'm through now.
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Quoting NoNamePub:
Alaina...you be careful!
Keep the info coming...
Hope Drew Brees is ok,,,,Just drafted hiim in my fantasy league!

You chose wisely! And Thanks!
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Flooding will be a huge problem today and tomorrow.....the worst from Isaac is far from over
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662. Skyepony (Mod)
I know gone off on a tangent.. Radiation network.. Looks like most those areas in the dry air there in the jet stream north of Isaac has had a bit higher radiation lately. Not sure if it's local or drifted in. I hadn't really been keeping up with the Fukushima explosions/debri burning & such since that one a few months ago.. Seems like something is drifting over..(link for US cities)
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OSCAT SHOWING A WEAK AREA OF LOW PRESSURE WITH 98L NEAR 13.2N 37.5 W MOVING WEST ABOUT 15 MPH
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Quoting yoboi:



wow is it slacking up any???

Not at all... they are saying we can expect 50mph winds and rain till 9 pm but rain and 35 mph winds through 4pm tomorrow afternoon!
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It seems like Louisiana can't get a break in recent years. Looking back on it, when I saw the models shifting west I couldn't believe they would be accurate. Well, so much for that.
Gosh I would feel like a target if I lived in that region after living around Tampa Bay Florida aka hurricane haven as I call it!


The persistent patterns that occur in weather always intrigue me, from local to large scale...
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Quoting LurkyMcLurkerson:


Thanks. I know basically nothing about the area, so I have no idea what sorts of impacts would be expected. But I do live in a place where a levee break would be unthinkably bad, so my heart goes out to anybody in that situation.


Any levee break is bad no matter what and where. Let's hope it affects as few homes as possible. I trimmed a house in that area a couple years ago. Most of the houses are right by the water, which was part of the appeal of those particular subdivisions: Guste Island and Port Louis.
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Quoting washingtonian115:
98L looks nice :).Hopefully a quick recurvature out to sea.That high has been playing tricks on us all year long and sending storms more west than the last two years(2010,2011).
nice avatar
Member Since: August 31, 2009 Posts: 0 Comments: 5628
654. vis0
to quote Yogi, ...Dejavu (&) all over again.

: -( (in it) : -o (watching via videos)
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Alaina...you be careful!
Keep the info coming...
Hope Drew Brees is ok,,,,Just drafted hiim in my fantasy league!
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Quoting 4waters:


ok... i've been trying to understand this all day. that really is an eye, right?


More like a belly-button now
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Quoting aislinnpaps:
Is it just me or is it that Isaac has had landfall that the blog is slow? I'd really like some thoughts on what others think the track might be for the next day or two. And I mean the ones who have looked into it with all the factors incorporated.


It is slowish. A lot of regular posters are probably busy dealing with weather or don't have power right now, though I'm glad to see folks checking in as they can.

I am _nothing like_ terribly knowledgeable on this stuff, but I suspect that people who are would say "the track is really hard to judge, probably a slow drift NW for the next day or two."

There's a ridge sitting right above isaac that stretches from the top of TX all the way to the east coast. It's hard for the storm to move much at the moment, there's some weakness in it to his W but it's not a lot and there's a weak trough going NE but it's not a lot either.

I'd expect that he'll meander NW or WNW but move very slowly, probably for the next day at least, and maybe wander around a bit unless something changes in that ridge soon. At the moment, he is seriously barely moving at all.
Member Since: August 26, 2012 Posts: 0 Comments: 368
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
348 PM CDT WED AUG 29 2012

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* TORNADO WARNING FOR...
HARRISON COUNTY IN SOUTHERN MISSISSIPPI...
THIS INCLUDES THE CITIES OF...LONG BEACH...GULFPORT...

* UNTIL 415 PM CDT

* AT 342 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR
GULFPORT...MOVING NORTH AT 50 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO LYMAN
AND SAUCIER

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THE SAFEST PLACE TO BE DURING A TORNADO IS UNDER A WORKBENCH OR OTHER
PIECE OF STURDY FURNITURE. SEEK SHELTER ON THE LOWEST FLOOR OF THE
BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE
BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM
WINDOWS.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 400 PM CDT WEDNESDAY
AFTERNOON FOR SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI.

&&

LAT...LON 3038 8901 3032 8923 3065 8934 3065 8925
3067 8924 3069 8923 3068 8906 3040 8893
TIME...MOT...LOC 2048Z 161DEG 42KT 3037 8908

$$


DUNN
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It seems like Louisiana can't get a break in recent years. Looking back on it, when I saw the models shifting west I couldn't believe they would be accurate. Well, so much for that.
Gosh I would feel like a target if I lived in that region after living around Tampa Bay Florida aka hurricane haven as I call it!


The persistent patterns that occur in weather always intrigue me, from local to large scale...
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Quoting gbreezegirl:
Thank you so much for the info.

Your welcome :)
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98L looks nice :).Hopefully a quick recurvature out to sea.That high has been playing tricks on us all year long and sending storms more west than the last two years(2010,2011).
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This blog has gotten so slow I think because of the number of users/lurkers on line. I will bid everyone adieu and head for home and the TV. God help all of you in Isaac's way.
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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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