ATL: SANDY - Remnants - Discussion

[MHurricanes]

Tweets from Ryan Maue of Weatherbell.com:

See this intensification:

http://weatherbellmodels.com/weather/wr ... t_anim.gif

Ryan Maue ‏@RyanMaue
Mesoscale models all showing extreme wind enhancement Sunday evening on south side of #Sandy pic.twitter.com/1gQKEZeb

Ryan Maue ‏@RyanMaue
Hopefully NOAA/NHC has scheduled recon tomorrow between 18z-23z to sample the SW & S side of #Sandy, could find 100-120 knot

Ryan Maue ‏@RyanMaue
Wave model shows wave+swell large area of 35-feet up to 52 feet east of center. pic.twitter.com/kebrgcpX

[ozonepete]

On another weather blog, current Nam through +18 is further east and weaker with less pronounced phase? Any of you following this run?

This is not an official forecast. See NHC.

The NHC never uses the NAM and nither do most of us. It just doesn't handle tropical systems or hybrids well at all.

[CrazyC83]

You know I was thinking usually with a tropical system there is always a threat of tornado activoty...yet no talk of it...why is that?

Air mass is too cold. Not enough instability.

[ozonepete]

Buoy bat 31036 reports water temp at 74.5. How can Sandy fuel up with that water temp? Shouldn't she be loosing power? And moving north to cooler water temps?

Hurricanes need 79-80F water to ramp up. As long as the SST is above 70F or so they often can maintain strength. But that's only part of it. In addition if they are moving north where the atmosphere is less thick and there is colder air overhead they can derive strength from the difference in temps from the less warm water to the very cold air aloft. Thus you can't go by SSTs here other than that anything over 70F is not going to hurt Sandy and SSTs can even be lower once it has transitioned to a hybrid storm - at that point it could still even strengthen due to baroclinic effects.

[MHurricanes]

Another Tweet from Ryan Maue, modeler at Weatherbell.com:

Mesoscale models all showing extreme wind enhancement Sunday evening on south side of #Sandy pic.twitter.com/1gQKEZeb

http://weatherbellmodels.com/weather/wr ... t_anim.gif

[cheezyWXguy]

its not old news......450 NM is equal to 517.851 miles...which is still tied with lili and sandy....

Im sorry I misread your post, I didn't realize it was in nautical miles. My bad hah.

[ozonepete]

Looks to be strengthening again on the satellite presentation.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[WeatherLovingDoc]

Thanks for the info, OzonePete. I was reaching for hope the blocking would retreat, but apparently it's not to be.

[cycloneye]

BULLETIN
HURRICANE SANDY ADVISORY NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012
1100 PM EDT SAT OCT 27 2012

...SANDY CONTINUING NORTHEASTWARD PARALLEL TO THE COAST OF THE
SOUTHEASTERN UNITED STATES...
...STRONG WINDS AND SIGNIFICANT STORM SURGE ARE EXPECTED IN THE
MID-ATLANTIC STATES AND SOUTHERN NEW ENGLAND...


SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...30.9N 74.3W
ABOUT 360 MI...580 KM ESE OF CHARLESTON SOUTH CAROLINA
ABOUT 305 MI...490 KM SSE OF CAPE HATTERAS NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NE OR 40 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...960 MB...28.35 INCHES


11 PM Track.

http://oi46.tinypic.com/33fgguh.jpg

[Terri]

Not sure I quite understand the rationale behind the (non)evac plans for NYC ...

[MaryEllen71]

Not sure I quite understand the rationale behind the (non)evac plans for NYC ...

The mayor said in his press conference that its not going to be that bad because its not a TS or Hurricane.

[Ken711]

BULLETIN
HURRICANE SANDY ADVISORY NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012
1100 PM EDT SAT OCT 27 2012

...SANDY CONTINUING NORTHEASTWARD PARALLEL TO THE COAST OF THE
SOUTHEASTERN UNITED STATES...
...STRONG WINDS AND SIGNIFICANT STORM SURGE ARE EXPECTED IN THE
MID-ATLANTIC STATES AND SOUTHERN NEW ENGLAND...


SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...30.9N 74.3W
ABOUT 360 MI...580 KM ESE OF CHARLESTON SOUTH CAROLINA
ABOUT 305 MI...490 KM SSE OF CAPE HATTERAS NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NE OR 40 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...960 MB...28.35 INCHES


11 PM Track.

http://oi46.tinypic.com/33fgguh.jpg

Thanks. Landfall estimate slightly North now?

[SouthernBreeze]

Thanks. Landfall estimate slightly North now?

I noticed that too -- showing an ever so slight northerly landfall

NOT A FORECAST - just an observation

[kat61]

Buoy bat 31036 reports water temp at 74.5. How can Sandy fuel up with that water temp? Shouldn't she be loosing power? And moving north to cooler water temps?

Baroclinic effect is taking over. It's not a purely tropical system any more.

Any baroclinic history that is significant to look to for a possible outcome?

[KBBOCA]

Besides the intensification or tightening, the other thing that worries me is that east swing.

If the average non-hurricane geek and not-too-well-informed resident of the NY metro area sees that they'll likely think "AHA, it's going out to sea, WE'RE SAFE!" When that is in fact far from the case.

People need to get the word out that the east turn is expected and that there is a REASON why a very HARD LEFT TURN into the coast can still happen even though it is almost unprecendented!!!

[ozonepete]

Looks to be strengthening again on the satellite presentation.

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

From the 11PM discussion:
SATELLITE IMAGERY SHOWS THAT THE CENTRAL CONVECTION ASSOCIATED WITH SANDY HAS INCREASED DURING THE EVENING. IN ADDITION...DATA FROM AIR FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT INDICATE THAT THE CIRCULATION AT 10000-12000 FT IS STRONGER THAN 24 HOURS AGO...AND THERE ARE INDICATIONS OF AN INNER WIND MAXIMUM NEAR THE CONVECTION. HOWEVER...THIS HAS NOT YET RESULTED IN ANY INTENSIFICATION...AND THE INITIAL INTENSITY REMAINS NEAR 65 KT. THE AIRCRAFT-REPORTED PRESSURE IS ABOUT 960 MB.

[kat61]

Buoy bat 31036 reports water temp at 74.5. How can Sandy fuel up with that water temp? Shouldn't she be loosing power? And moving north to cooler water temps?

Hurricanes need 79-80F water to ramp up. As long as the SST is above 70F or so they often can maintain strength. But that's only part of it. In addition if they are moving north where the atmosphere is less thick and there is colder air overhead they can derive strength from the difference in temps from the less warm water to the very cold air aloft. Thus you can't go by SSTs here other than that anything over 70F is not going to hurt Sandy and SSTs can even be lower once it has transitioned to a hybrid storm - at that point it could still even strengthen due to baroclinic effects.

Tx OZPete- baroclinic is a new one I've not heard before here, but 2nd time in reference to my post.

[jinftl]

Forecast storm surge in the Battery in Lower Manhattan is 5.5' on Monday night, a little over a foot higher than during Irene. By comparison, the Battery saw an 8' storm surge in Dec. 1992 and 8.36' during Hurricane Donna. During the 1992 surge, mass transit was flooded and was shut down for 10 days.

Main focus is on subway flooding with these predicted surge values - and some low lying areas will see some water. I think that is the basis for the non-evacuation at this time. Folks questioned New Orleans not evacuating for Isaac too and that, to be honest, was a much riskier propositon in terms of potential to loss of life from a below sea level city with levees vs. below infracstructure flooding as the primary threat in NYC. The cost of the subway system flooding would be billions, but there should be limited threat to safety with the current forecast surge levels.



From Dr. Jeff Master's blog:

Predicted storm surge for Hurricane Sandy at The Battery on the south shore of Manhattan, New York City, from the experimental Extratropical Storm Surge model, run by NOAA"s Meteorological Development Laboratory. This model used winds from this morning's 12Z (8 am EDT) run of the GFS model, and predicts that the peak storm surge from Sandy will reach 5.5' on Monday night October 29, which is 1.4' higher than Irene's storm surge. This forecast has the peak surge occurring near high tide, bringing the maximum storm tide--the water level reached as a result of the combined action of the tide and the storm surge--to 10.5', a foot higher than Irene. At this level, water will very likely pour into the Lower Manhattan subway system, unless efforts to sandbag the entrances are successful. Notice: this is not an official NHC storm surge forecast, and the storm surge may be higher or lower than this, depending upon the strength, track, and timing of Sandy.

Sandy's storm surge may flood New York City's subway system, costing billions
Sandy is expected to have tropical storm-force winds that extend out more than 400 miles from the center, which will drive a much larger storm surge than its peak winds would ordinarily suggest. The full moon is on Monday, which means astronomical tides will be about 5% higher than typical, increasing the potential for damaging storm surge flooding. Fortunately, Sandy is now predicted to make a fairly rapid approach to the coast, meaning that the storm surge will not affect the coast for multiple high tide cycles. If Sandy hits near New York City, as the GFS model predicts, the storm surge will be capable of overtopping the flood walls in Manhattan, which are only five feet above mean sea level. On August 28, 2011, Tropical Storm Irene brought a storm surge of 4.13' to Battery Park on the south side of Manhattan. The waters poured over the flood walls into Lower Manhattan, but came 8 - 12" shy of being able to flood the New York City subway system. However, the town of Lindenhurst (population 28,000), on the south side of Long Island, was mostly under water due to the storm surge, and fresh water run-off from Irene's torrential rains, riding on top of a 3 to 4-foot storm surge, allowed the swollen East and Hudson Rivers to overflow at the edges of Manhattan.

New York was not as lucky on December 12, 1992, when a 990 mb Nor'easter drove an 8-foot storm surge into Battery Park, flooding the NYC subway and the Port Authority Trans-Hudson Corporation (PATH) train systems in Hoboken New Jersey. FDR Drive in lower Manhattan was flooded with 4 feet of water, which stranded more than 50 cars and required scuba divers to rescue some of the drivers. Mass transit between New Jersey and New York was down for ten days, and the storm did hundreds of millions in damage to the city. The highest water level recorded at the Battery in the past century came in September 1960 during Hurricane Donna, which brought a storm surge of 8.36 feet to the Battery and flooded lower Manhattan to West and Cortland Streets. According to the latest storm surge forecast for NYC from the experimental

[cheezyWXguy]

Not sure I quite understand the rationale behind the (non)evac plans for NYC ...

The mayor said in his press conference that its not going to be that bad because its not a TS or Hurricane.

I know we're not supposed to bash people here, but that has to be the stupidest thing I have ever heard (directed at the mayor, not you MaryEllen). I cant believe he would be so ignorant as to put millions of lives at risk by downplaying the event simply because its not tropical. And the problem is, people are buying it, especially since the NHC refuses to treat it has a hurricane even though it would better convey the seriousness of the situation.

This is a quote from the Annapolis, MD forecast discussion:
"Also...with forecast 850 hpa 80-110
knots winds advertised in the models...how much/when these winds mix
down is difficult to pin down. These winds are just amazing in
terms of their high speed. I cannot recall ever seeing model
forecasts of such an expansive areal wind field with values so
high for so long a time. We are breaking New Ground here."

This is clearly an extremely serious situation, and on top of that, one with still quite a degree of uncertainty as to how much of those winds will mix down to the surface. It may not technically be a "hurricane" at landfall, but max sustained winds of 80mph as seen in the official forecast clearly puts it hurricane strength. If the models are right and Sandy goes in like this, heads are gonna roll...

[ozonepete]

Buoy bat 31036 reports water temp at 74.5. How can Sandy fuel up with that water temp? Shouldn't she be loosing power? And moving north to cooler water temps?

Hurricanes need 79-80F water to ramp up. As long as the SST is above 70F or so they often can maintain strength. But that's only part of it. In addition if they are moving north where the atmosphere is less thick and there is colder air overhead they can derive strength from the difference in temps from the less warm water to the very cold air aloft. Thus you can't go by SSTs here other than that anything over 70F is not going to hurt Sandy and SSTs can even be lower once it has transitioned to a hybrid storm - at that point it could still even strengthen due to baroclinic effects.

Tx OZPete- baroclinic is a new one I've not heard before here, but 2nd time in reference to my post.

A lot of us spent a lot of time in class learning it so it ain't easy. Basically hurricanes are barotropic and do not have any strong temperature contrasts anywhere in their surface circulations. Baroclinic storms (low pressures) derive their stregth from differences in air temperature across fronts.