This article is not a forecast for Hurricane Marco as it enters the Gulf of Mexico and tracks near the New Orleans LA coast around Lake Pontchartrain and the Mississippi River. We all remember Katrina and the devastation to property and life in 2005. Unfortunately, this tropical system seems to be on a very similar path and may have the same strength that Katrina had. In fact, the HMON and HWRF global computer models on August 21st, 2020 are suggesting that Marco could have a deeper pressure and wind speeds than the 2005 storm. We will continue to update as the National Hurricane Center follows this storm.
Let’s hope this is not another 2005 storm. But, as bad as Katrina was (Category 1), there is another scenario that will again test residents of Orleans Parish, smaller towns and parishes around the city, as well as Lake Pontchartrain and the Mississippi River at greater levels.
For those reading this article and not familiar with the Big Easy, the city is like a bowl with over 80% of land being below sea level. The city is protected by a levee system that keeps the waters of Lake Pontchartrain and the Mississippi at bay during heavy rains and smaller storms like tropical storms and category 1 storms. But, they were not originally designed for storms of Category 3, 4, and 5 unless there are new upgrades in place since 2005 as we discuss below.
During Katrina, several parts of this levee system were inundated by the rising storm surge and ended up flooding many areas in the city at catastrophic levels.
The Worst Case Scenario
Historically, Louisiana leaders, weather people, and engineers have always feared what is considered the worst case scenario for the city. That scenario is one in which a Category 3 or greater storm moving slow (or stalls) makes landfall at Port Eads and continues over Lake Borgne which spills in to Lake Pontchartrain.
Under this scenario, the counter-clockwise winds would push a storm surge towards the bowl of New Orleans via the Mississippi River, Lake Borgne, and Lake Pontchartrain at potentially higher levels than Katrina if Hurricane Marco makes landfall as a Category 2 or higher. Again, under this path and with a Category 2 or 3 storm moving slower and it’s hard to imagine that the levee system will be able to withstand this event. The consequences of this path, category, slow movement, and hitting at high tide is very much unimaginable and I hope that Hurricane Marco does not make landfall under the worst case scenario.
Even if Marco does not take this exact path, and takes the more east path than Katrina did, anything above Category 1 and certainly in the Category 3 or above range will be historical for the big easy and surrounding parishes.
Another concerning path, equally problematic, is if this (and future storms) storm takes a Southeast to Northwest approach with the eye wall staying just south of the city. This will put New Orleans and all of Orleans Parish on the right side of the storm where storm surge and winds are the strongest, and it will push water from Lake Borgne, Lake Pontchartrain, and the Mississippi River in to the bowl of New Orleans.
While New Orleans is at the center of everyone’s mind during storm’s like this because of the large number of people living in the city, the considerable and dangerous impacts from this storm should the current forecast hold true is still very real for all parishes in South Louisiana as it relates to storm surge, flooding from heavy rains, and falling trees.
Updates To This Storm
This section will be updated as the National Hurricane Center release updates to Hurricane Marco as well as commentary about each update that is not meant as a forecast.
August 23: Officially named as of the 11 am advisory as a Category 1 storm, but continues to battle dry air and shear which should keep intensification from happening towards landfall. In looking at the latest radar and satellite imagery, Marco is very small in size and not very impressive. The NHC is going with a Category 1 hurricane until landfall, but I would not be surprised if this system slips below 74 mph winds before landfall unless the upper-level shear component relents in the next 12 hours.
August 23: This storm was upgraded to a 70 mph system about 6 hours ago, but is expected to enter an area of considerable shear and dry air that very well could inhibit deep intensification. The question is, do these two factors stay with the storm in to landfall or relent and allow for rapid intensification. Expect this system to reach Category 1 today, but watch the shear and dry air closely.
August 22: Meteorologist at the National Hurricane Center, along with other researchers, are warning of a potential double hit by Marco and Laura starting Tuesday with Marco and then Laura 48 hours later. This potential double hit will have the effect of a long duration event. Let’s seriously hope that the category level intensity stays low for both storms and that Marco disrupts atmospheric and sea surface temperatures for Laura. We will continue to provide updates as they are released by the government.
August 21, 2020: Marco started life as a Tropical Storm in the south Caribbean Sea and the early forecast for this storm was for it to threaten south Texas coastal regions. Then on August 22nd, the National Hurricane Center changed the forecast to landfall near the middle part of South Louisiana coastal regions.
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For those living in the coastal region of South Louisiana on the Gulf of Mexico, what levee system infrastructure upgrades are in place around the city and other places compared to 2005?
Are there any upgrades to the interstate that allows for easier or more orderly evacuation from the lowest lying areas in this area compared to the 2005 storm?
Outside of upgrades to the levee system and evacuation routes, what is new in the area to help the more vulnerable citizens of Orleans Parish and citizens in outlying parishes if Marco makes landfall under the worst case scenario?
Fast rising storm surge is the number one threat to human life and animal life during landfall.
Severe weather, storm surge, heavy rains and wind, falling trees, widespread electricity outages, and tornadoes and waterspouts do happen outside of where the center of circulation occurs. Do not focus on the center of this storm.
Please have all preparations in place and ready to evacuate the area at the VERY minimum of 2 days before landfall. Know your evacuate route at least 3 days before landfall.
Continue to take the advice of local emergency management officials in your local parish, especially when told to evacuate.