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Hurricane Irene Model and Forecast Discussion


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Before you guys get too sucked into the ECWMF... I want to point out the positive changes for a leftward pathway that appeared on the 12z GFS. For the second run in a row the 12z GFS remained pretty flat with the kicker shortwave, and made it even slightly less progressive. thegreatdr also brought up some great points about the leading shortwave (the one located northward of Newfoundland). If this feature trends too strong or too far south, it could flatten the 500mb ridge to the point that it allows for a more eastward progression of Irene. It seems that what happened on the 12z run was that these two shortwaves were counteracting each other in regards to the motion of Irene. The upstream shortwave less progressive, so its not trying to force Irene out too early. In addition while the downstream shortwave is stronger, its actually displaced further north than the previous runs, hence we have a stronger ridge. The 12z GFS is a positive run for an east coast landfall.

13z9xg8.gif

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Haven't chimed in here yet..but just looked at the Euro coming in. Definitely west at 96...center appears to be over southern Delaware.

In Delaware Bay/Cape May at 102...crazy

The models are showing (sporadically) the worst track possible for NYC... while a direct impact is unlikely, I don't think the chances of hurricane force gusts for the city are that low at this point. Surge is certainly looking like an issue, and we saw from Isabel that landfall doesn't have to be that close for major impacts--Annapolis and Baltimore were inundated despite landfall in NC, and the situation in NYC is rather similar (water would be funneled right up into NY harbor with any landfall in NJ, or potentially even the DelMarVa).

The potential exists for significant storm surge into parts of Brooklyn and Queens IMO. I doubt Manhattan will be flooded to Canal Street, but parts of lower Manhattan could also be submerged.... not to mention the subway/PATH...

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If that verifies, the storm surge is going to be insane. NYC is in a perfect location for funneling (as has been mentioned too many times)... but the absolute size of Irene and total momentum on the right side of the storm is going to pile water up like crazy.

yes, It'll be interesting to see if there is some consistancy to this potential solution now and whether the models have a good handle on the strength, positioning and timing of the Canada energy and the potential to allow a more robust ridge to build in the atlantic.

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The models are showing (sporadically) the worst track possible for NYC... while a direct impact is unlikely, I don't think the chances of hurricane force gusts for the city are that low at this point. Surge is certainly looking like an issue, and we saw from Isabel that landfall doesn't have to be that close for major impacts--Annapolis and Baltimore were inundated despite landfall in NC, and the situation in NYC is rather similar (water would be funneled right up into NY harbor with any landfall in NJ, or potentially even the DelMarVa).

The potential exists for significant storm surge into parts of Brooklyn and Queens IMO. I doubt Manhattan will be flooded to Canal Street, but parts of lower Manhattan could also be submerged.... not to mention the subway/PATH...

I agree. There will be at least 3 high tide cycles during an easterly-type fetch with a new moon approaching Monday. The coastal flooding will be pretty intense.

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1821 is close enough-- supposedly a Cat 4 into Cape May and a Cat 3 over NYC

Yeah that looks like the closest one... I keep forgetting about that one since it is pre-1886. A storm like that could make Katrina look like a hot fart. Fortunately, it's just one solution (even though it is the Euro), and there is still plenty of time for the path to change... still, though, the trend is not looking good.

Both of those statements are incorrect, however, the likely Cat 1 1821 cane did bring storm surge to Canal street at low tide!!

Thanks for the clarification on that... either way, it doesn't look wonderful.

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Both of those statements are incorrect, however, the likely Cat 1 1821 cane did bring storm surge to Canal street at low tide!!

yeah, that's why I said "supposedly" lol-- the track is similar-- the strength of that hurricane is what we dont know. The geography of the coastline makes a major hurricane type surge possible with even a minimal storm.

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HM, the last time I remember such a prolonged period of flooding was the December 1992 noreaster-- the water simply never left during low tide and each high tide cycle was successively higher.

Even with the less intense offshore track toward Cape Cod, I still think the coastal flooding will be exaggerated. The acceleration in the track with Irene only amplifies the hurricane-force wind potential for coastal southern New England and Long Island. But more importantly, I think the storm surge/flooding will be pretty intense with the current modeled solutions. Throw in the showers/thunderstorms ahead of this thing (starting tomorrow) and you've got a perfect recipe for flooding (oh and the record monthly August totals).

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12 Z GFDL has 926 mb with 97 MPH winds going into the middle of LI and then due north:

http://moe.met.fsu.edu/cgi-bin/gfdltc2.cgi...;hour=Animation

An important thing to remember about the GFDL and HWRF, the wind is the most important thing to look at regarding intensity, the pressures in those models tend to ramp down too slowly when storms are in a weakening state.

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I agree. There will be at least 3 high tide cycles during an easterly-type fetch with a new moon approaching Monday. The coastal flooding will be pretty intense.

Not to mention the swells that will be pushed out as Irene's winds max out tonight through Friday....and the wind field expands....LF or not...the south shore of LI and/or SNE is in for a once in a, (at least) couple decade storm!

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yeah, that's why I said "supposedly" lol-- the track is similar-- the strength of that hurricane is what we dont know. The geography of the coastline makes a major hurricane type surge possible with even a minimal storm.

Especially a minimal storm that was very recently a major- Katrina was technically a Cat 3 at landfall but the surge was way up over the Cat 5 threshold...

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