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NE Tropical Thread


free_man

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It is a good conversation. I doubt most people get "local" storm info from national media outlets. For example during Irene you didn't hear a word about rain in Vermont or surge in Connecticut until the day after lol. In general having a good newsroom and good mets can really communicate a lot of information in a cogent, concise, and accurate manner. The importance of researching different types of weather and the local climate/topography/history is vital to get accurate information out.

None of it's easy.

Absolutely, the best info is certainly given by the local news, unfortunately it seems like a lot of people get info from the big cable news outlets. I actually thought the weather channel did a nice job. Cantore was classic, just saw the video from this morning, being out in that weather for 24 hrs must have been tiring at the end.

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Here's my problem with getting too specific.

1 - Different surge/rain/wind has different impacts in different parts of the country. A cat 3 in S FL, while severe, can be dealt with. Cat 3 winds in New England is a catastrophe. 25" of rain in Louisiana is quite significant and dangerous from one storm... but that in W Mass and CT would be historic and unprecedented.

2 - Categories get too specific when storms are so large. For example let's take Irene. The surge in portions of CT was very impressive... the surge out toward Boston the Cape, Buzzards Bay etc was minimal at best. Do we give different categories for each region?

3 - General public and explaining. Getting too specific can get confusing. People have a hard enough time with watches and warnings... nevermind a tiered scale of a bunch of cateogries!

Great discussion

The goal is to distill complex information into a simple number the public can understand on a relative scale. That works for some things, not for others.

I'm thinking how useless the "Threat level Yellow/Orange" etc scale was and ultimately ignored by the public.

Arguably, some threats like tornadoes can be distilled down to a number like Forbes' Torcon 1-10.

But threats like a hurricane might be too varied over too large a geographic area to distill down to a single number.

Another point: hurricane impacts are always in flux.

How do you convey a surge threat that is mild when the storm is positioned in one way, but then becomes severe when the storm tracks to a different relative position 18 hours later? (Katrina and the north-facing parishes of NO are a great example of this dynamic threat)

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Here's my problem with getting too specific.

1 - Different surge/rain/wind has different impacts in different parts of the country. A cat 3 in S FL, while severe, can be dealt with. Cat 3 winds in New England is a catastrophe. 25" of rain in Louisiana is quite significant and dangerous from one storm... but that in W Mass and CT would be historic and unprecedented.

2 - Categories get too specific when storms are so large. For example let's take Irene. The surge in portions of CT was very impressive... the surge out toward Boston the Cape, Buzzards Bay etc was minimal at best. Do we give different categories for each region?

3 - General public and explaining. Getting too specific can get confusing. People have a hard enough time with watches and warnings... nevermind a tiered scale of a bunch of cateogries!

All the more reason for a modification of the current system. You can't just blanket rank a system based solely on it's wind speeds. Each storm presents it's own set of problems that can be dealt with in different ways in different parts of the country. I do think storms need to be dealt with on a case by case basis as they come closer to impacting specific regions of the country.

I think we've become too fixated on the number in this country and I think we've been jaded to a degree and don't heed warnings enough. If there was a way to put the NESIS rankings to these systems beforehand, maybe it would paint a better/different picture.

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Great discussion

The goal is to distill complex information into a simple number the public can understand on a relative scale. That works for some things, not for others.

I'm thinking how useless the "Threat level Yellow/Orange" etc scale was and ultimately ignored by the public.

Arguably, some threats like tornadoes can be distilled down to a number like Forbes' Torcon 1-10.

But threats like a hurricane might be too varied over too large a geographic area to distill down to a single number.

Another point: hurricane impacts are always in flux.

How do you convey a surge threat that is mild when the storm is positioned in one way, but then becomes severe when the storm tracks to a different relative position 18 hours later? (Katrina and the north-facing parishes of NO are a great example of this dynamic threat)

And more than that... as Litchfield Libations knows... in a place like Fairfield the tide varies significantly between low and high. It's more extreme in the western part of the Sound but regardless an Irene at low tide would have done little if any damage. Irene at high tide washed away entire homes.

So how do you provide a 1-5 number for a storm that's affecting North Carolina to Maine lol.

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All the more reason for a modification of the current system. You can't just blanket rank a system based solely on it's wind speeds. Each storm presents it's own set of problems that can be dealt with in different ways in different parts of the country. I do think storms need to be dealt with on a case by case basis as they come closer to impacting specific regions of the country.

I think we've become too fixated on the number in this country and I think we've been jaded to a degree and don't heed warnings enough. If there was a way to put the NESIS rankings to these systems beforehand, maybe it would paint a better/different picture.

I definitely see the argument... but I think it probably makes more sense to drop/de-emphasize the entire scale than develop 2 additional ones.

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Here's my problem with getting too specific.

1 - Different surge/rain/wind has different impacts in different parts of the country. A cat 3 in S FL, while severe, can be dealt with. Cat 3 winds in New England is a catastrophe. 25" of rain in Louisiana is quite significant and dangerous from one storm... but that in W Mass and CT would be historic and unprecedented.

This is already a problem for those tropical cyclone impact graphics you've seen from LIX with Isaac. When the NHC sends us their finalized, collaborated wind, surge, etc. grids we can then begin to generate those impact graphics. They have to include a separate Northeast modifier to reduce the thresholds for given levels of impact. As you said, a Cat 3 in Florida has a much different meaning than a Cat 3 coming ashore on Long Island.

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Agree with Ryan. The public will likely get confused or even worse ....complacent I the cat 5 rain, surge etc does not happen. I mean how much more can you emphasize 20" of rain, 12' storm surge, and a mandatory evacuation to boot. If people still stay, I don't think a tiered system would help.

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Looks like we may have to to deal with Cane Leslie in SNE around day 10..Euro way west with it

Looks like there is a trough around day 5 or so-if it can miss than connection then maybe it can make it west....I'd bet on a recurve based on climo though...if we don't get this one, we're likely done for this year other than some home brew setup.

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Srain posted this

Isaac continues to bring flooding rainfall and storm surge to the LA and MS coast.

Overnight strong SSW winds have surged the waters within Lake Pontchartrain northward away from New Orleans and into the northern shore of the lake. Severe storm surge flooding of 5-7 feet is currently in progress from the western side of the lake to the eastern side of the lake including the cities of Slidell, Mandeville, and LaPlace. Early this morning a levee was breached near a pump station in the City of Slidell and while the pump station continues to operate, it cannot keep out with the influx of water and portions of the city are now flooding with 3-5 feet of water…all locations in the city at an elevation below 9 ft will be subject to flooding. Overtopping also occurred late yesterday afternoon in St John the Baptist Parish and around LaPlace where at least 1000 residents are still being rescues from their rooftops.

Initial water level readings on the west side of Lake Pontchartrain include that record high storm surge levels may have been produced and flooding west of New Orleans and on the north shore of the lake is equal if not greater than hurricane Katrina and hurricane Gustav. These high water levels are a function of the storm track, as Isaac passed to the south and then west of Lake Pontchartrain allowing a continuous feed of sea water on SE winds into the lake. Hurricane Katrina passed just east of the lake initially pushing sea water in from the east, then sloshing that surge southward on the west side of the eye against the New Orleans levees. Waters levels in portions of Plaquemines Parish are only 3-5 feet lower than Hurricane Katrina 13-14 vs 17-19.

I cannot emphasize enough how poorly the Saffir Simpson scale it at relating storm impacts and the fact that this was only a Category 1 hurricane appears to have resulted in residents not heeding the evacuation orders. The focus during landfalling tropical cyclones must be on the impacts and NOT the category of the storm….the category only suggest wind damage impacts and has no relation on the storm surge or rainfall flood threat. Every hurricane is different, a slow moving large weak hurricane like Isaac can produce significant impacts as shown due to the far reaching effects and the continuous adverse conditions. Below are listed the storm surge values expected for the various portions of the affected coast as issued in an e-mail on Monday at 140pm. As you can see the values for Plaquemines Parish are highlighted in red (7-11ft), with the levees only 8ft tall it was highly likely that they would be overtopped.

SE LA (from the mouth of the MS River west to near Houma): 6-9 ft

SE LA (from the mouth of the MS River to the LA/MS state line): 7-11 ft

SE LA (Lake Pontchartrain): 5-8 ft

MS coast: 8-12 ft

AL coast: 6-10 ft

FL panhandle: 3-6 ft

Storm surge values along the coast will subside today as onshore winds weaken however areas where levees have been overtopped will take days to drain.

Isaac will continue to move inland and weaken however large feeder bands on the east side of the system will continue to produce flooding rainfall over MS and E LA. As the center moves NNW tonight into southern AR, the potential for core rainfall will increase. The threat will be shifting to fresh water flooding as Isaac moves north into AR , MO, and IL over the next 48 hours. While much of this region is suffering in severe drought, the very heavy rainfall of a tropical system in a short period of time can lead to flooding. Additional rainfall amounts of 6-15 inches will be possible along the track of Isaac.

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When the impacts of the storm are mentioned time and time again...I lose sympathy for these residents who stayed. Sorry.

Unfortunately, the NWS can try to change scales..adjust wording all they want...but it will never change the human psyche. People will learn through experience, media saturation of disaster footage, and general self education.

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Heard from my in laws again, and a tornado touched down 5 miles to her south in Pascagula MS; feeder bans just continue to pummel them on the MS/AL border! Can anyone give me some precip estimates for that area, don't always trust NWS site.

BTW, just watching radar trends down there, the NWS must be sick of posting TOR warnings as a new box seems to go up every 15 minutes!

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