Hurricane Irene Surge Threat

[Srain]

We are facing a rather serious surge issue from Hurricane Irene. In fact Hurricane Irene is larger than Hurricane Ike (2008) and a catastrophic surge threat is looming near the landfall point and positions to the N and E extending to Long Island/SNE. Discuss...

[am19psu]

I'm not usually someone that hypes things, but this is the biggest surge threat to the Northeast ever, I think. We've never seen a slow-ish moving Ike-sized storm moving up the Atlantic Seaboard. I'm briefing 4-8' from Long Island to Narragansett Bay and I'm slightly concerned I'm being conservative.

[hazwoper]

Srain - can you post the map for NJ/LI as well? Or, better yet give me the link?

Thanks

[am19psu]

Srain - can you post the map for NJ/LI as well? Or, better yet give me the link?

Thanks

The surge maps aren't particularly useful yet from NHC for that area because there is still a lot of spread in the GPCE tracks.

[hazwoper]

The surge maps aren't particularly useful yet from NHC for that area because there is still a lot of spread in the GPCE tracks.

Got it. Thats what figured after i posted. The percentages should be way down for now.

Thanks

[salbers]

Are there any probability or other maps for higher amounts of storm surge (beyond 2 feet)? Maybe a storm surge model?

Here is a hypothetical storm surge map for NYC and Long Island:

http://www2.sunysuff...surge_maps.html

[Scott747]

Rough gauge but shouldn't be taken literally.

http://www.wunderground.com/hurricane/MidAtlSurge.asp

[Ed Lizard]

Euro 10 meter maps from AccuWx PPV don't have a scale, whether winds are knots are mph. But 10 meter onshore sustained winds were in excess of 75 something at 60 hours, if that is knots I'd imagine absolutely sick surge on the Jersey Shore. Hour 66 onshore winds into Long Island at 65. Knots or mph, I don't know. But a long fetch as well. 12Z and 18Z Sunday.

[LocoAko]

Euro 10 meter maps from AccuWx PPV don't have a scale, whether winds are knots are mph. But 10 meter onshore sustained winds were in excess of 75 something at 60 hours, if that is knots I'd imagine absolutely sick surge on the Jersey Shore. Hour 66 onshore winds into Long Island at 65. Knots or mph, I don't know. But a long fetch as well. 12Z and 18Z Sunday.

Having not seen them, I'm almost certain they'd be in knots.

[Ed Lizard]

Having not seen them, I'm almost certain they'd be in knots.

I suspect that as well, but I hate it when they don't label color scales.

[salbers]

Here's some good probabilistic surge sites from NHC/MDL. These allow one to zoom in on areas of interest.

http://www.nhc.noaa....cs_at4.shtml?gm

http://www.weather.g...urge/active.php

Storm surge values seem a bit low for the NY area however, unless Irene's track is enough offshore. As mentioned earlier

it's most useful for shorter time frames when the model spread is less.

[sojitodd]

Are there any probability or other maps for higher amounts of storm surge (beyond 2 feet)? Maybe a storm surge model?

Here is a hypothetical storm surge map for NYC and Long Island:

http://www2.sunysuff...surge_maps.html

With the size(of tropical storm force winds), and movement of this storm(fairly slow considering), won't NYC and environs get at least a cat 1 storm surge, if not cat 1 winds?

that map is surprising in how much coastal flooding there will be with just a cat 1, to me at least. I guess I did not realize how much they are vulnerable to just a cat 1 surge there.

[Srain]

Surge information from Newport/Morehead City/5:51 PM EDT:

A 5 TO 9 FEET OF SURGE IS EXPECTED ACROSS THE WARNED AREA. AREAS

THAT WILL BE HARDEST HI WILL BE AREAS ADJACENT TO THE PAMLICO

SOUND INCLUDING THE LOWER REACHES OF THE NEUSE AND PAMLICO

RIVERS...OCEANSIDE AREAS SOUTH OF CAPE HATTERAS...AND SOUNDSIDE

OUTER BANKS DARE AND HYDE COUNTIES. THESE WATER LEVELS WILL PRODUCE

MODERATE TO MAJOR FLOODING OF HOMES...ROADS...AND PROPERTIES.

[hm8]

With the size(of tropical storm force winds), and movement of this storm(fairly slow considering), won't NYC and environs get at least a cat 1 storm surge, if not cat 1 winds?

that map is surprising in how much coastal flooding there will be with just a cat 1, to me at least. I guess I did not realize how much they are vulnerable to just a cat 1 surge there.

Just so you know, storm surge amounts were removed from the Saffir-Simpson scale in 2010 because the correlation between wind speed and storm surge was far from perfect. There are plenty of examples of weaker storms that produced more storm surge than stronger storms due to their size and location of landfall. So you can't really say something has a "cat 1 storm surge"

[salbers]

That is true, though it seems that a lot of the preparedness maps out there use categories as a guide to evacuation zones...

[sojitodd]

Just so you know, storm surge amounts were removed from the Saffir-Simpson scale in 2010 because the correlation between wind speed and storm surge was far from perfect. There are plenty of examples of weaker storms that produced more storm surge than stronger storms due to their size and location of landfall. So you can't really say something has a "cat 1 storm surge"

yeah, I know that wind speed does not necessarily correlate with storm surge(Katrina, Ike) especially with large storms like Ike, or storms that are undergoing an ERC before landfall, or have weakened just before landfall from a much stronger state-and that wind speed does not necessarily correlate well with pressure and all in certain storms(again, Katrina).

*I know people on the Mississippi coast died from Katrina because in their eyes 'it weakened to just a cat three..so if we are here and Camille did not flood here, we will be ok..etc' and of course the surge was not only higher than Camille's, but higher over a much wider area.

I was just going by what that particular map indicated as 'cat 1 storm surge'

Exacty what are they calling for in the NYC area, and how does that correlate with what that map indicates is a cat 1 storm surge? would be a better question?

*thanks salbers, and I checked the NYC forum and it is all pretty much there-should have checked there to begin with.

[salbers]

NHC is calling for a 4-8 foot storm surge. Hard to say exactly, but it might be close to what that map has for Cat 1.

Also see this:

http://dotearth.blog...not-off-charts/

and this:

http://stormy.msrc.sunysb.edu/zoomhome.htm

[A-L-E-X]

I'm not usually someone that hypes things, but this is the biggest surge threat to the Northeast ever, I think. We've never seen a slow-ish moving Ike-sized storm moving up the Atlantic Seaboard. I'm briefing 4-8' from Long Island to Narragansett Bay and I'm slightly concerned I'm being conservative.

Pretty similar to what Goldberg has for here-- 4-8' for NYC and 10' for Long Island with 80 mph gusts in NYC and up to 100 mph on Long Island.

[PSUBlizzicane2007]

Ah... just saw this thread.... reposting this here for consistency/further comment

There really isn't a good way to give hard numbers right now.

If I had to estimate for NYC, somewhere between 10-14 feet with very local areas of up to 17-18 ft possible assuming it is a category 1 when it gets there and doesn't go over too much land mass.

If it goes over more land, you can decrease all of those numbers by 2-4 feet.... if it becomes a moderate-strong tropical storm, decrease by 1-3 feet.

Keep in mind that this is a very rough estimate for maximum potential storm surge.

[wxsmwhrms]

Here's some good probabilistic surge sites from NHC/MDL. These allow one to zoom in on areas of interest.

http://www.nhc.noaa....cs_at4.shtml?gm

http://www.weather.g...urge/active.php

Storm surge values seem a bit low for the NY area however, unless Irene's track is enough offshore. As mentioned earlier

it's most useful for shorter time frames when the model spread is less.

Yes, the probabilities will get higher and more focused as the impact time gets closer and the forecast becomes more certain.

[pazzo83]

The more and more I'm seeing/reading, the more it looks like the surge in NYC proper could be catastrophic.

[LocoAko]

The more and more I'm seeing/reading, the more it looks like the surge in NYC proper could be catastrophic.

(Not being snarky) What exactly have you been seeing/reading? Just curious. I'm under the impression that it has to take a track up into NY Harbor for the surge to affect NYC? Or is it almost guaranteed now that NYC will experience surge? I had sort of assumed earlier that all of those evacuations were a bit much but perhaps they aren't.

[TheTrials]

(Not being snarky) What exactly have you been seeing/reading? Just curious. I'm under the impression that it has to take a track up into NY Harbor for the surge to affect NYC? Or is it almost guaranteed now that NYC will experience surge? I had sort of assumed earlier that all of those evacuations were a bit much but perhaps they aren't.

you mean a track like this? 00Z NAM, pretty close to the Euro too

[jm1220]

The more and more I'm seeing/reading, the more it looks like the surge in NYC proper could be catastrophic.

I can just imagine the huge size of Irene now and the massive mound of water it's carrying, and how it will interact with NY Harbor and the system of rivers/canals, etc branching off. Ike and Katrina both had huge surges for their sizes, and even if it drops down to tropical storm just before impacting us, the storm surge will have a grossly outsized impact.

This could knock many parts of NYC and Long Island/NJ out for days/weeks I fear if it strikes at high tide. Even low tide could be very damaging.

[pazzo83]

(Not being snarky) What exactly have you been seeing/reading? Just curious. I'm under the impression that it has to take a track up into NY Harbor for the surge to affect NYC? Or is it almost guaranteed now that NYC will experience surge? I had sort of assumed earlier that all of those evacuations were a bit much but perhaps they aren't.

Just about the literal shape of the coastline, the funneling of water up the harbor into the East River, and then the reverse surge coming from the sound back into the East River. There is so much real estate on either side of the river in Manhattan and Bkln/Queens. This is not going to be pretty.

[LocoAko]

Just about the literal shape of the coastline, the funneling of water up the harbor into the East River, and then the reverse surge coming from the sound back into the East River. There is so much real estate on either side of the river in Manhattan and Bkln/Queens. This is not going to be pretty.

I'm worried that if I lose power I won't know what is happening in NYC and even Downtown JC. Surge maps placed Hoboken and downtown JC, home of so many financial buildings (and residences) under water with a "Cat 1/2" surge. So far just voluntary evacuations there.

I know NYC is the big story, but it frustrates me how they only ever show the surge potential for the 5 boroughs but the graphics leave the rest of the metro area looking unscathed. Both Nassau County and Hudson County are at extreme risk for surge as well... grrr.

[Dsnowx53]

(Not being snarky) What exactly have you been seeing/reading? Just curious. I'm under the impression that it has to take a track up into NY Harbor for the surge to affect NYC? Or is it almost guaranteed now that NYC will experience surge? I had sort of assumed earlier that all of those evacuations were a bit much but perhaps they aren't.

Is NYC storm surge an all-or-nothing thing? I thought the NY Harbor track was the "worst" case scenario, but I'd still think that if the storm was JUST off-shore of NJ, there'd still be plenty of on shore flow from east to west which would affect downtown Manhattan. But I'm not really a storm surge expert.

[NorthNJwx]

Is NYC storm surge an all-or-nothing thing? I thought the NY Harbor track was the "worst" case scenario, but I'd still think that if the storm was JUST off-shore of NJ, there'd still be plenty of on shore flow from east to west which would affect downtown Manhattan. But I'm not really a storm surge expert.

It's actually not an all-or-nothing thing for the city. Hurricanes with tracks further east can and do produce significant surges into NYC - Donna being a prime example. I'm not really sure why surges can be that large in NYC with tracks over LI; perhaps most of the water being piled up is from the LI Sound? Either way, both scenarios can produce surge, though the NY Harbor track is indeed the worst case scenario.

The same thing happened on the Jersey Shore in 1944: east track, but still a tremendous surge. Belle and Gloria also produced tides right up there with the historic nor'easters in Jersey as well. So any hurricane can do it, but those tracking especially close and with more of a northerly component are more dangerous.

[A-L-E-X]

(Not being snarky) What exactly have you been seeing/reading? Just curious. I'm under the impression that it has to take a track up into NY Harbor for the surge to affect NYC? Or is it almost guaranteed now that NYC will experience surge? I had sort of assumed earlier that all of those evacuations were a bit much but perhaps they aren't.

Well NYC experienced big surges with Donna and Gloria (10 feet or more), even though both were well to the east. The geography of the coastline and the size of the storm determines the surge, more than the track does. Ugh, Jake, we have been talking about this all week

[phil882]

Well NYC experienced big surges with Donna and Gloria (10 feet or more), even though both were well to the east. The geography of the coastline and the size of the storm determines the surge, more than the track does. Ugh, Jake, we have been talking about this all week

I'd tend to agree... the storm could go just to the east of NYC but the way Long Island sound works you need easterly and then southeasterly winds to really drive in the water inland into NYC metro from the sound.... so actually a track further east would allow the southeasterly flow to bring the water inland. A further westward track would increase the storm surge threat for the southern shorelines of Long Island, but decreases the surge potential for the sound since the winds never get forced into the inlet to begin with.