Will Katrina weaken at the mouth of the mississippi river?

[logybogy]

I think I remember reading on the boards here about a paper someone wrote that as Hurricanes approach freshwater runoff from river channels that the water and heat content is cooler there and they will weaken.

This was given as an explanation why Ivan, Dennis, and lots of other strong cat 4's and 5's dissipate upon landfall in the gulf.

[smashmode]

True..but it was also said that there is a area off of SE louisana, that is the warmest on the basin..that could explode katrina.

[Scorpion]

Actually quite the opposite. It would strengthen at the mouth of the Mississippi.

[logybogy]

But New Orleans is about 60 miles from the coast of Louisana and the mouth. 60 miles depending upon the forward speed of Katrina could be anywhere from 4 hours to 10 hours before the center hits New Orleans. That is plenty of time to weaken.

We all saw how Dennis weakened right on the coast from a strong 4 to a marginal 2 in just a matter of hours. Add in shear the NHC says could develop and it is more than possible we may only deal with a Cat 2 at landfall.

Everyone is playing up the drama of a Cat 4 or 5, but frankly I think a Cat 2 is just as likely as Cat 4 or 5. Most probable intensity at landfall given the history in the region is Cat 3, IMO.

[logybogy]

How do you figure it would strengthen? The whole theory is that fresh water screws up the heat content the canes need and right at the mouth fresh water would be highest.

[JamesFromMaine2]

I would not count on Katrina weaking! take the actions needed to keep your self safe! Be prepaired for a cat 4 or 5 Hurricane and do not let your self think that alot of other storms have missed you so this one will too! This storm could shift track again but it may not so you need to be prepaired!

[MrsParker]

New Orleans might be 60 miles from the mouth, but there are thousands of people who live in that "toe" that hangs off the state & there are thousands along the coast directly below N.O. There is not much land left due to coastal erosion & oil and gas drilling. I know. I live right in the middle of the "toe" I'm packing now to leave. I really don't expect to come back to much of anything.

[JamesFromMaine2]

How do you figure it would strengthen? The whole theory is that fresh water screws up the heat content the canes need and right at the mouth fresh water would be highest.

The diffrence between water temps would cause it strengthing or something like that! lol

[JamesFromMaine2]

How do you figure it would strengthen? The whole theory is that fresh water screws up the heat content the canes need and right at the mouth fresh water would be highest.

The diffrence between water temps would cause it strengthing or something like that! lol

[Scorpion]

Dennis was NOT a marginal 2 at landfall. A middle 3 was Dennis intensity at landfall. Also, the waters off of LA are the warmest in the basin.

[NEXRAD]

How do you figure it would strengthen? The whole theory is that fresh water screws up the heat content the canes need and right at the mouth fresh water would be highest.

Theories on fresh-water effects on hurricanes is controversial. I've read some research suggestive that large freshwater bodies emptying into the ocean contribute sediments that promote ocean conductivity. This, in turn, prompts alterations in the storm's electrical fields, translating to storm strengthening. The processes involved do not appear well understood just yet, and I certainly am not an expert with such.

Climo. suggests that the Gulf basin just south of the Mississippi delta is a ripe spot for Category 4 and 5 storm formation, however.

- Jay
KSC FL

[shaggy]

Intensity is the great unknown with these storms. The "offical" strength of a hurricane and what you actually see reported can oftan be different for instance Hurricane Dennis was "offically" a Cat 3 but seems like the highest gust on land where only in the low 100's MPH and most places saw well less than that.

Here in NC when Hurricane Isabelle came over the pressure in the storm was around 960mb but the storm was a weak cat 2 at best and the highest wind we had here was 51mph, also when Isabelle was at 945 mb it had peak winds of 140-150 mph while the CURRENT NHC DISCUSSION states

"The central pressure has risen as high as
950 mb...with the latest central pressure at 945 mb. The aircraft
have found flight-level winds as high as 119 kt at 8000 ft in the
outer eyewall...although measurements from the NOAA stepped
frequency microwave radiometer suggest the surface winds in this
area are still less than 100 kt. The initial intensity remains
at 100 kt for this advisory."

There is a reason there have ben very few large Cat 4 and Cat 5 hurricanes at landfall it is hard for the storms to maintain this strength and for some reason this is more prevelent for storms to ramp up then crash in the gulf (Opal, Lili, Ivan and Dennis to name a few) however the worst hurricane ever to make landfall did so in the gulf.

[MetroMike]

There is more sediment at the mouth of the Mississippi which can have what is called a "coagulation" process on Katrina. That can cause the Hurricane to have a greater frequency, thus producing a more conductive effect on Katrina.