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Posted at 5:00 PM ET, 08/31/2008

Gustav Set to Engulf Louisiana

By Jason Samenow
gustav-ssec.jpgSatellite image of Gustav. Courtesy University of Wisconsin-Madison SSEC.

Hurricane warnings are in place, evacuations have been ordered, and we are left to watch as Hurricane Gustav bears down on the coast of central and southeast Louisiana. Already, some of Gustav's outer rain bands are coming ashore. If there's any good news, Gustav weakened as it traversed western Cuba and has not re-intensified over the Gulf of Mexico. As of 5 p.m., it had maximum winds of 115 mph making it a Category 3 storm. Will Gustav strengthen or weaken before hitting land? The National Hurricane Center says:


Keep reading for more Gustav and a short update on Hanna. For Washington, D.C. weather, see our full forecast.

Jeff Masters at indicates Gustav may still strengthen some:

Overall, the upper level wind environment is favorable for intensification, but not as favorable as during yesterday's rapid intensification. Gustav is currently over the Loop Current, containing the highest heat content waters of the Atlantic.

But he also suggests the window for strengthening may soon close:

By this evening, Gustav will be passing over a cold eddy. The heat content of the Gulf will decrease as Gustav approaches the coast.

Another factor which may weaken Gustav as it nears land is entrainment of dry air. Considering the various factors for strengthening and weakening together, the National Weather Service's official intensity forecast brings Gustav ashore as a low-end Category 4 Category 3 hurricane with winds to 130-135 mph 125 mph (updated at 5 p.m.).

While storm intensity will play a major role in the severity of Gustav's impacts, the extent of its impacts will greatly depend on exactly where it strikes land. On Friday, I mentioned the worst case scenario would be landfall just to the west of New Orleans where "just to the west" means within about 50 miles. A landfall further west than that would place New Orleans outside the quadrant of the storm with the strongest winds and highest storm surge.

Fortunately, most track models currently bring Gustav ashore slightly west of the worst case track, but it's so close that New Orleans will still likely experience a serious storm surge and even a devastating storm surge with just a modest shift to the east. The SciGuy at the Houston Chronicle takes an in-depth look at this unwelcome possibility and concludes:

In such a scenario water would flood into the city from the lake, which could drown the city again, and possibly to an even worse degree [than Katrina].

On a positive note, the storm's weakening over the Cuba, has reduced the likelihood of a catastrophic surge in New Orleans. Jeff Masters explains:

The extent of Gustav's current weakening was unexpected, and this could substantially reduce the storm surge. Given the current intensity forecasts, I believe there is a 60% chance that a lower storm surge of 12-15 feet, characteristic of a Category 3 hurricane, will affect the city. If the Army Corps of Engineers' assertion that the levee system can withstand a Category 3 hurricane is correct, the levees will hold.

If the potential for a 12-15 foot storm surge wasn't bad enough, New Orleans and much of Louisiana will likely receive copious amount of rain. NOAA's Hydrometeorological Prediction Center predicts 10-15" of rainfall for most of the state.

Gustav is forecast to officially make landfall at 7 a.m. Monday morning -- which is about the same time Katrina made landfall on a Monday three years ago. Want a sense of what New Orleans is about to face?:

Here's the National Weather Service forecast for New Orleans:

This Afternoon: Scattered showers and thunderstorms. Mostly cloudy, with a high near 89. East wind around 15 mph. Chance of precipitation is 50%.

Tonight: Tropical storm conditions expected, with hurricane conditions possible. Scattered showers and thunderstorms, then showers likely and possibly a thunderstorm after 1am. Some of the storms could produce gusty winds and heavy rain. Mostly cloudy, with a low around 78. Northeast wind 20 to 25 mph increasing to between 30 and 40 mph. Chance of precipitation is 70%.

Labor Day: Hurricane conditions expected. Showers and possibly a thunderstorm. Some of the storms could produce gusty winds and heavy rain. High near 82. East wind 50 to 60 mph increasing to between 50 and 70 mph. Winds could gust as high as 85 mph. Chance of precipitation is 100%.

Monday Night: Hurricane conditions expected. Showers and possibly a thunderstorm. Some of the storms could produce gusty winds and heavy rain. Low around 80. South wind 40 to 60 mph decreasing to between 25 and 30 mph. Winds could gust as high as 75 mph. Chance of precipitation is 100%.

Tuesday: Tropical storm conditions possible. Showers and possibly a thunderstorm. Some of the storms could produce gusty winds and heavy rain. High near 83. Chance of precipitation is 90%.

Even after Gustav departs, it will take a long while for New Orleans to dry out, as showers and thunderstorms remain in the forecast through the weekend.

For more coverage of Gustav, I recommend the following blogs:

There is another storm out there which continues to bear watching: Tropical Storm Hanna. It hasn't strengthened over the last several days, and its intensity forecast remains "problematic" according to the National Hurricane Center, especially in the short term. The long-term forecast does indicate some intensification and track forecasts bring Hanna towards the southeast U.S. coast late next week, although there is some variability. We'll keep you posted on this storm.

By Jason Samenow  | August 31, 2008; 5:00 PM ET
Categories:  Tropical Weather  
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Next: Gustav Closing in on Louisiana Strike


Let's do an informal poll to get some discussion going. What intensity do you predict Gustav will be at landfall and how high will the storm surge be in New Orleans?

I'll bite first: Category 2 (105 mph), 12 foot surge.

Posted by: Jason, Capital Weather Gang | August 31, 2008 2:03 PM | Report abuse

Category 4 (135 mph), 13.5 foot surge.

Posted by: Havoc | August 31, 2008 2:07 PM | Report abuse

Your article neglected to mention that is also a valuable resource for coverage on Gustav and Hanna. You can track the storm, watch animated satelite images and link to more than 1,500 weather stations and cameras located across the entire Gulf Coast.

Posted by: Mara Radis | August 31, 2008 2:08 PM | Report abuse

High Cat 1 - Dry air wrap around is going to make this fizzle. A good thing for all parties.

Posted by: Greg | August 31, 2008 2:41 PM | Report abuse

by the looks of the satellite loop, Gustav seems to be headed directly for the New Orleans area. hopefully it does veer off to the west just slightly as predicted and also lets hope that Gustav doesn't pull a Charlie and strengthen as he comes ashore.

Posted by: jf | August 31, 2008 2:45 PM | Report abuse

Hanna 2 pm models shifted left bringing landfall to SC/NC with some models and other models aiming at FL. Who knows??

Im more impressed with 97L at the moment

Posted by: Anonymous | August 31, 2008 3:48 PM | Report abuse

Watch approach of Gustav over Gulf through observations at offshore buoys:

For example rapid pressure falls wind increasing at buoy 42003:

Posted by: Steve Tracton | August 31, 2008 4:02 PM | Report abuse

5 PM advisory on Hanna has her making landfall south of Savannah, GA as a Category 1 hurricane.

My guess for Gustav is 110 MPH, 12 foot storm surge.

Posted by: weatherdudeVA | August 31, 2008 5:29 PM | Report abuse

Re Hanna: Someone please correct me if I'm wrong... when we were down in Hilton Head this summer I believe I heard that the GA coastline has never been hit by a hurricane.(?)

Posted by: Christina in Centreville | August 31, 2008 5:48 PM | Report abuse

I'd say 115 MPH, 12.5 foot surge. Interesting how the eye disappeared. Models now tightly clustered as to where Gustav will make landfall.

Posted by: Model Monkey | August 31, 2008 6:07 PM | Report abuse

Posted by: weatherdudeVA | August 31, 2008 6:13 PM | Report abuse

Major Hurricanes Spare Georgia For More Than A Century
Major hurricanes occurred fairly frequently in Georgia during the 1800's, when 5 big storms hit the
• Aug. 27, 1881 - a deadly hurricane hit the Georgia coast killing an estimated 700 people
and leaving an unknown number homeless
• Aug. 27-28, 1893 - a major hurricane hit the Georgia and SC coasts drowning 1,000 to
2,500 people and leaving more than 30,000 homeless
• Aug. 31, 1898 - the last Category 3 hurricane to hit Georgia struck Savannah, killing an
estimated 179 people
Although no major hurricanes made direct hits on Georgia during the 1900's, four minor
hurricanes did make direct hits.
• 1911 - a Category 2 hurricane hit Savannah, killing 17
• 1940 - a Category 2 hurricane hit Savannah, killing 50
• 1947 - a Category 2 hurricane hit Savannah, killing 1
• 1979 - a Category 2 (Hurricane David) hit Savannah, no deaths or major damage

Posted by: Rob in Midland | August 31, 2008 6:14 PM | Report abuse

I've followed the 12Z and the 18Z GFS and I predict Hanna to make landfall on the Grand Strand, SC. The 18Z is rarely identical to the 12Z GFS and in this case, it is, which means the GFS has latched on to something the other models are not picking up on yet. Usually when the GFS puts a stake in the ground, the other models come around (Fay is a case in point). If Hanna makes landfall on the Grand Strand, Washington DC is in trouble, because she won't waste time moving northward.

Gustav--I watched the latest GOES IR Floater loop twice and I suspect the eye may reform about 50 miles south of where it is now in the deepest convection. If that occurs, I predict Gustav will make landfall as a Cat 4.

Posted by: Steve Wasko | August 31, 2008 6:48 PM | Report abuse

I'm going to go with a Cat 2, maybe 95-100 at landfall. I'd be very suprised if we get any verified sustained winds over hurricane force. It's a good thing it peaked so early. Looks like it's much less of a grave situation than what could have happened.

Posted by: Brian, Capital Weather Gange | August 31, 2008 7:15 PM | Report abuse

Listen to radio station WWL from New Orleans. Round the clock coverage. They were about the only station to stay on the air in 2005.

Posted by: JT | August 31, 2008 8:18 PM | Report abuse

I'll go with Category 2 winds on landfall, and a Category 3 storm surge.

Posted by: Murre | August 31, 2008 8:22 PM | Report abuse

A forecast for a reduced storm surge is great news! However, from what has been reported, Gustav seems to be very unpredictable. Why is that ?

Posted by: jralger | August 31, 2008 8:43 PM | Report abuse

Hmmmm - looks like the eye is making a come back in the last few frames (9:00pm).

Posted by: Greg | August 31, 2008 9:03 PM | Report abuse

Check out the latest GOES loop. I see an eye and a CDO forming again around the eye, not just in the SW quadrant. Gustav is definitely intensifying and appears to be doing so rapidly. Right now the eye appears to be located at 27.0N,-87.8W.

Posted by: Steve Wasko | August 31, 2008 9:23 PM | Report abuse

looks like gustav is pullin a charlie and intensifiying rapidly

Posted by: sam | August 31, 2008 9:33 PM | Report abuse

No doubt that the storm is up to something that the NHC did not predict in their 5pm update. While earlier today I was almost certain that this storm was looking to fizzle - tonight it is winding up into a tight ball of power and I would not be shocked to now see it as a Cat 4! The damage is going to be tremendous and we might as well say goodbye to New Orleans as we have known and loved it in our lifetime. It just does not make sense to build and maintain a city in a bowl.

Posted by: Greg | August 31, 2008 9:43 PM | Report abuse

The eye is just barely visible now on the long range radar loop out of New Orleans.

Posted by: Steve Wasko | August 31, 2008 9:51 PM | Report abuse

Gustav appears to be regaining some strength and its symmetry.

Steve and Greg- I'm not seeing a well defined eye in satellite loops, although radar is a different story. With the storm's recent better organization however, I would not be surprised to see one in a little while.

Posted by: Model Monkey | August 31, 2008 10:04 PM | Report abuse

Hey folks, I'm looking at IR satellite images and stuff, but none of them come with some sort of key for people who don't already know how to read them. I don't know what all of those colors mean and the scale just has numbers that mean nothing to me. Can anybody give me a brief tutorial on how to look at IR satellite or post a link to a website that can?

Posted by: Laura in NWDC | August 31, 2008 10:11 PM | Report abuse

Laura: Follow this link-
which brings you to an IR loop for Gustav. Once the images load, click the checkbox next to "IR Temp". On the bottom, you will see "DEG C" and numbers corresponding to colors. These indicate the temperature of cloud tops. The colder the cloud tops, generally, the higher the cloud, and the stronger the convection in the storm.

An interesting link:

Hope this helps.

Posted by: Model Monkey | August 31, 2008 10:27 PM | Report abuse

Laura: Here you go, hope this helps:

Posted by: weatherdudeVA | August 31, 2008 10:28 PM | Report abuse

Just minutes away from the 11:00pm update. Guess - 125 mph winds.

Posted by: Greg | August 31, 2008 10:46 PM | Report abuse

Update - NW at 16 mph. Winds 115 mph Pressure 954 - going up a bit. Still a Cat 3.

Posted by: Greg | August 31, 2008 10:52 PM | Report abuse

Eastern US WX boards going crazy tonight. With any luck, they'll be the top Google hit for Gustav instead of us for the next day or two. :)

Posted by: David | August 31, 2008 11:13 PM | Report abuse

Thanks for the satellite help! Now I (kinda) understand what I'm looking at.

Posted by: Laura in NWDC | August 31, 2008 11:37 PM | Report abuse

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