Isaac Having a Hard Time Strengthening as New Orleans Prepares Aug 27, 2012

We continue to track the very latest on Isaac. The storm moved out into the Gulf of Mexico waters overnight after bringing heavy rains and gusty winds to Florida. Isaac is still moving toward the northern Gulf coast. Numerous areas have declared states of emergency across the Gulf coast, telling residents to evacuate or they may be stuck there with no power for days after the storm. New Orleans is even warning residents there will be no shelter of last resort in town.

Isaac as of 11 AM ET

As of the 11 AM ET update from the National Hurricane Center in Miami, FL Isaac still only had winds of 65 mph, and was continuing to move to the NW at 14 mph. National Hurricane Center meteorologists are waiting for an eye feature to form that might indicate a strengthening system. So far it has occasionally appeared, but has not been persistent. Also, the system as been dragging in some mid-level dry air, which is helping prevent strengthening of the system.

You can still see some of the gust wind conditions over Florida this morning, via the wind map.

Forecast Track

The National Hurricane Center hasn’t change the track of the storm too much. A ridge to the to the north of Isaac will allow a northwest direction to continue over the next 36-48 hours, which would bring landfall near New Orleans sometime in the early morning hours on Wednesday. After that the exact path that the storm will make is somewhat unclear, but model consensus right now would have it moving more northward through the end of the week. We are currently looking at a less intense storm in terms of wind speeds as this system moves towards the coast, maybe only peaking at 90 mph as the storm comes ashore. That doesn’t mean there won’t be other worries from the storm, however, that can occur even outside the forecast cone that poses a threat.

Above is a storm surge map for a 1 in 10 change that a certain storm surge height would happen. For example, in the New Orleans area there is a 1 in 10 chance storm surge could exceed 10 feet in the area. There is a strong likelihood that we could see some coastal and inland flooding due to storm surge and the total rainfall expected. More on the rainfall next.

This is the current rainfall forecast for the Gulf coast over the next 5 days. The models are outputting 12″+ in areas that would be mainly in the right front quadrant of the system, which is typically the strongest part of a tropical storm or hurricane.

Here’s the national rainfall forecast. After Isaac hits the Gulf coast, that moisture will then push northward over the coming days, bringing much needed rain to drought-stricken areas. Often the best way to bust a drought is with a tropical system. Even though we really don’t want a tropical system causing extensive damage, those in the Midwest are definitely hoping for the rain from this system!

Another threat with a land-falling system is always tornadoes. You can read more about tornadoes that have previously occurred with northern Gulf of Mexico land-falling systems via ustornadoes.com.

As for model spread for the system, a good amount of the models now have landfall near New Orleans, so confidence is increasing that landfall would be in this area. (Graphic via weatherbellmodels.com)

New Orleans Impacts


Here is what the National Weather Service office in New Orleans is currently expecting for impacts across their region. They are telling people to quickly finish their preparations for the storm and to follow any evacuation orders. Here is some information from one of their statements:

…WINDS… AS TROPICAL STORM ISAAC APPROACHES…SUSTAINED TROPICAL STORM FORCE WINDS ARE EXPECTED TO BEGIN TUESDAY MORNING. SUSTAINED HURRICANE FORCE WINDS ARE EXPECTED TO BEGIN TUESDAY NIGHT AFTER MIDNIGHT. HURRICANE FORCE WINDS ARE EXPECTED TO LAST MANY HOURS. MAXIMUM WINDS ARE FORECAST TO BE IN THE 65 TO 80 MPH RANGE WITH GUSTS TO 100 MPH.

…STORM SURGE AND STORM TIDE… AS TROPICAL STORM ISAAC APPROACHES THE COAST…THERE IS AN INCREASING CHANCE FOR COMBINED STORM SURGE AND ASTRONOMICAL TIDE WATERS UP TO 9 FEET ABOVE MEAN SEA LEVEL WITHIN AREAS CLOSER TO THE COAST AND TIDAL LAKES…RESULTING IN WORST CASE FLOOD INUNDATION OF 6 TO 9 FEET ABOVE GROUND LEVEL IN LOW LYING AREAS AND IN AREAS OUTSIDE OF HURRICANE PROTECTION LEVEES.

…INLAND FLOODING… STORM TOTAL RAINFALL OF 8 TO 12 INCHES WILL BE POSSIBLE WITH TROPICAL STORM ISAAC. ISOLATED LOCATIONS COULD SEE RAINFALL TOTALS APPROACHING 20 INCHES. THERE IS A MODERATE THREAT OF INLAND FLOODING DUE TO THE HIGH RAINFALL TOTALS.

…TORNADOES… ISOLATED TORNADOES WILL BE POSSIBLE AS TROPICAL STORM ISAAC APPROACHES THE COAST AND MOVES INLAND.

With expected landfall seven years to the date that Katrina made landfall, you can tell there must be some rattled nerves in the area. However, in an interview we held with the Weather Service office in New Orleans yesterday, they said the levies are the best they’ve ever been, and that they are ready for the storm.

State of Emergency

Numerous parishes, counties, cities and states across the Gulf coast in the path of this storm have declared a state of emergency, and in some cases have told residents they need to evacuate. St. Charles Parish has told their 53,000 residents they need to leave. New Orleans has declared a state of emergency and has told people to leave or prepare to stay in their homes as there will be no shelters of last resort. And mandatory evacuations have been ordered in the lower-lying areas around Mobile, AL. The states of Alabama, Mississippi, and Louisiana are all preparing for the storm the best they can. The Governor of Mississippi says a 16-foot surge of water could inundate Hancock County, MS (home to Gulfport and Biloxi). It’s the lowest lying county on the Gulf coast of Mississippi, and would feel the brunt of that right front quadrant of the storm. This storm is posing a big threat to areas hit hard by Katrina in 2005 and the Gulf Oil Spill in 2010. Make sure you stay alert of the forecast path if you live anywhere along the Gulf coast, and heed all watches and warnings as well as alerts from local officials.

You can also keep up-to-date with the very latest by watching our live stream on the WeatherNationTV homepage, just click on the red tab that says “Live” next to the video feed. You can also watch our headline segments and the weather forecast for each region on the home page.

And we would also love to see your videos and photos of the storm, of evacuations in your area, and of preparations being made in your area — of course, only if you can do it safely! Your safety is ALWAYS our number one concern here at WeatherNation. If you do so, you can upload them to the WeatherNationTV website by clicking here. You can also post them on our Facebook page, on Twitter, or upload them via our app for iOS devices (like the iPhone). You can help tell the story of how Isaac is affecting your area!

How To Prepare

Remember you still have time to prepare. Check out some of the tips below to help prepare yourself and your property for the storm.

We’ll continue to update you with the very latest — stay with WeatherNation!


Meteorologist D.J. Kayser
Follow me on Twitter at: @weathrlver

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