After Katrina.. what Gulf or Atlantic city do..

[Jim Cantore]

What about a Cat 3 for NYC? Granted thats quite unlikely, but still, I wonder how much worse it would be than a 2.

Heres the answer

[Derek Ortt]

Are those values for an averaged sized hurricane, or for the very broad and spread out storms, with a radius of hurricane force winds well over 100NM that would affect the region.

I will be the first to say it, a major hurricane in NYC may cause as many casualties due to the population density and impossible evacuations as a Bengledesh cyclone, or as many as were killed at Sobibor during the second world war. This is based upon the 60,000 dead from the Pam Scenario of a cat 3 direct hit on New Orleans, and the fact that NYC is more surge prone, and has a MUCH greater population, plus, the building codes for the wind are poor; thus, the winds will also cause many deaths

[Jim Cantore]

[Air Force Met]

OK...got a question? From what I can tell...that image is a cat 4 coming in at 60 mph or something like that...that is NOT realistic at all.

What are the parameters for that graphic?

[Jim Cantore]

Dont ask me, I just found it

I'm certain this thing is moving at more then 35mph

[Air Force Met]

OH...you have it set for ALL direction at 60 MPH of movement at a CAT 2, 3 and 4...

That is NOT the answer...that is a totally unrealistic answer.

That is not the way SLOSH is meant to be used. First, pick a direction...and then a speed. So...a Cat 3 will be moving fast but not too fast to make it fall apart...and it will be moving towards the NNE most likely to maximize the proximity to warmer water...so...


That 28 foot surge now turns into a 10' surge for a Cat 3 in Queens.

And the Cat 4 moving at 60 mph is so far out of the question it should not even be included as a possibility.

A Cat 2 moving at 30 produces a 9 foot surge.

So...regardless of where you are...the max you get is about 17 feet and that is on the Jersey side. 14' is the realistic max on New York's side.

[Air Force Met]

Dont ask me, I just found it

I'm certain this thing is moving at more then 35mph

Not as a Cat 2, 3 or 4 it isn't...not in that kind of cold water. Doesn't happen.

But as I said, that is not an accurate display of the SLOSH data. That is an "all directions" projection and as we know...a storm only moves in one direction...and as we also know...Cat 3's and 4's don't move at 60 mph.

It's either someone's ignorance or someone's attempt to scare people.

[Derek Ortt]

The 1938 hurricane, was a cat 3 that moved in excess of 60 mph, so it is possible

The only way this can come to pass, IMO, is for there to be a negatively tilted trough, to bring the storm to the NNW, into northern NJ, placing NYC in the right front quadrant. Basically, an Isabel with a stronger trough, with this trough located a couple of hundred miles to the east

[Jim Cantore]

NJ is extremely surge prone at the coast and very populated,
Gloria Flooded Cape May.

[Air Force Met]

NJ is extremely surge prone at the coast and very populated,
Gloria Flooded Cape May.

Yeah...they get hammered. It's a quick hit too.

[beachbum_al]

Awe thank you since I live on Mobile Bay. Yes, the thought has gone through my mind what would had happen to my hometown if Katrina had hit here. Considering where she did go in and the amount of damage we had here is scary. I imagine if the Mobile and Bay surrounding areas (Spanish Fort, Daphne, Fairhope, Point Clear, Dauphin Island, Fort Morgan) might be wiped off of the face of the map. It would be terrible but I am not moving! I love living near the Coast and my house and the things in it are materialistic. They can be replace if the unfortunate happens.

[Jim Cantore]

NJ is extremely surge prone at the coast and very populated,
Gloria Flooded Cape May.

Yeah...they get hammered. It's a quick hit too.

thats another problem

[Derek Ortt]

In 1821, stunned colonial New Yorkers recorded sea levels rising as fast as 13 feet in a single hour at the Battery. The East River and Hudson Rivers merged over Lower Manhattan all the way to Canal Street. According to Coch, the fact that the 1821 storm struck at low tide "is the only thing that saved the city."

http://www.nypress.com/18/29/news&colum ... arstek.cfm

Even worse than I thought for NYC for a cat 2 landfall. Even at dead low tide, the surge was still of rediculous levels.

A major into NYC and it will not matter if it hits at high or low tide, the tide is coming in, very high and very rapidly

[Jim Cantore]

they say that storm was about 130mph when it hit the Jersey Shore

yea and Lee was a cat 5

[Jim Cantore]

Heres what Gloria did to Cape May

[wxmann_91]

Just for kicks, you have a Cat 5 SLOSH for NYC, Floyd?

[Air Force Met]

The 1938 hurricane, was a cat 3 that moved in excess of 60 mph, so it is possible

The only way this can come to pass, IMO, is for there to be a negatively tilted trough, to bring the storm to the NNW, into northern NJ, placing NYC in the right front quadrant. Basically, an Isabel with a stronger trough, with this trough located a couple of hundred miles to the east

Sorry I did not see your post until this mornign Derek, or I would have responded earlier.

Well..yes and no. I agree that it must be associated with a negatively titled trough...that part is true. However, the '38 hurricane is a bad example...IMO. It is listed as a Cat 3, but let's be honest, it is already undergoing extratropical transition at this point and even had a frontal structure at landfall. No true tropical cyclone will keep its structure intact at 60 mph and the Long Island Express was no exception.

This is perhaps why the storm surge values, while high, don't match what should be put down by a real Cat 3 moving at that speed. For example, the '38 storm put down 9-10' of suge on the southern shore of long island, a modeled output is closer to 15'. Some areas it was real close to what is predicted, others are off by 6' or more.

So...I guess I shold clarify...there will be no true Cat 3 or 4 warm-core tropical cyclone (that does not have a frontal structure)...not undergoing extratropical transition...moving at 60 mph.

It really throws off the surge values (due to the ETT...spreading out of the wind field) and the only place the stay the same is the Flushing Bay area, northern queens and southern bronx....and this seems to be due to back wash after the storm passes. MAtter of fact, the max surge in those area in '38 occured 5 hours AFTER the storm passed their latitude!

So, while you can still get you hat handed to you by wind damage...at least the surge won't be AS bad as is depicted in the slosh model.

But...and here is the REAL danger. The back wash in those back bays comes hours after the winds abate and the storm passes. The '38 storm was hundreds of miles away when the surge hit Flushing bay, Rikers Island. NOw, given the people...will people be around milling about and be caught off guard thinking it is over? Or will emergency management have the sense to say...WAIT...stay away...there is a back surge coming!

[Air Force Met]

Just for kicks, you have a Cat 5 SLOSH for NYC, Floyd?

They don't run a cat 5 for NYC. They only go up to a 4.

[Derek Ortt]

At Monterrey, a reanalysis of the 1938 hurricane was presented, and they concluded that the frontal structure did not form until just after landfall. That said, like Michael in 2000, it was rapidly undergoing ET transition

One note about the 38 storm though. The worst surge occurred in Providence RI, a good 75 miles east of landfall, likely due to the ET transition, which is my basis for saying a hit on northern NJ is far worse for NYC than a direct landfall there. LF at NYC should produce the highest surge near Fire Island and into Connecticut

[Air Force Met]

At Monterrey, a reanalysis of the 1938 hurricane was presented, and they concluded that the frontal structure did not form until just after landfall. That said, like Michael in 2000, it was rapidly undergoing ET transition

One note about the 38 storm though. The worst surge occurred in Providence RI, a good 75 miles east of landfall, likely due to the ET transition, which is my basis for saying a hit on northern NJ is far worse for NYC than a direct landfall there. LF at NYC should produce the highest surge near Fire Island and into Connecticut

When was the reanal done? I've read another paper presented to the AMS about ET storms that speaks to it. They state: "In fact, once a storm is moving at 40mph, ET has either started, or begins within the following twelve hours."

I have a very hard time believing it could not have been undergoing ET already....especially given the forward speed. Also, the pressure field had already spread out significantly with only a couple of mb difference from the center outward to a distance of 20 or more miles and you are only talking about 30-45 minutes (an hour max) after landfall...which is not a lot of time...so there is certainly some ET transition going on before landfall.

If you also look at the barograph from the Western Union lab, you see that the pressure was alreay very low over the area...down near 1000 mb for the day before. That leads me to believe that something else is going else was also going on previously.

Do you have a link or a file? I would love to see what led them to that conclusion. To maintain an eyewall structure at 50 knots woud be phenomenal...and as I said...the surge values just don't match anywhere at the points of landfall...they are all a good 5-6' below what they should be.