Hurricane Sandy - LIVE - Meteorological Discussion

[Srain]

Heh

933 on the Euro as it approaches the NE.

Beven at the forecast desk. The 5 AM full package disco should be an interesting read...

[EasternUSWX]

Looks like we have an eye.

[dan88]

60kt with the 5am advisory, recon over the gulf and on it's way for the morning mission.

[Roger Smith]

Reality check says Euro track probably most likely to verify, but intensity could be overdone. This would still mean a potential high impact storm on Monday and Tuesday in the New York City region including much of NJ, Long Island and New England, and possible snow problems at higher elevations to the southwest, so by no means should we say that being spared on the intensity will mean no big deal, this would be a big deal on the Euro track at 965 mbs so there is a 30-mb spectrum at least between the evident catastrophic damage from the depicted system and the considerable damage or at least disruption from a 965 mb storm at landfall.

It's a tough situation when you have one model saying winds SE 100-150 mph, storm surge 20-40 ft, possible 8-16 inches of rain, and another one saying winds NE 20-40 mph, no storm surge, possible half inch of rain mixed with sleet. How do you blend those and get a consensus for your five-day outlook?

I guess the NYC mets will be warning their viewers and clients that a major, potentially destructive storm warning could be declared at any time within 24-48 hours, or could be waved off and an all clear sounded. We should echo this on the forum and simply say it's not possible to choose between the two options yet, what we are looking at is (in layman's terms) whether or not Sandy threads a needle and gets past a block in its path -- if it does, then the conditions may be ideal for it to max out and reach the intensity of a major hurricane. It may even still be a major hurricane (but if not, same difference, larger wind field). But at the same time, it could be weakened by this process and could arrive as a much weaker system, or, it could be blocked out and forced to turn right and head east, looking for some other weakness in the block and perhaps becoming a problem days later somewhere well to the east.

That's my suggestion, to say basically there's maybe a one in three chance of a weather disaster, one in three chance of a weather "event" that is not a disaster, and one in three that nothing much will happen, it will get colder and perhaps rain or sleet a bit.

My feeling is that we will have model consensus by 12z Friday but this gives perhaps 48h for effective evacuations over a busy weekend when many people will perhaps be distracted by politics, football, Halloween, month end concerns, etc etc. If the Euro were exactly right, anyone who could leave Long Island or the coastal parts of NJ, se NY and CT-RI should plan to do so and move valuables away from harm's way. With the reputation of the Euro, if I lived there, I would probably get ready to do that but wait a day or two and see what happened on the models. If this was just one other model, it would be less ominous. But the Euro? I am not aware of the Euro as being a major over-developer like the GGEM sometimes does, but in this case, you have 20-30 mbs of slack before a model error even becomes significant to the result. This would be just about as scary at 953 mbs as it is at 933 mbs.

[HurricaneJosh]

It's a tough situation when you have one model saying winds SE 100-150 mph, storm surge 20-40 ft, possible 8-16 inches of rain, and another one saying winds NE 20-40 mph, no storm surge, possible half inch of rain mixed with sleet. How do you blend those and get a consensus for your five-day outlook?

150-mph winds and 40-ft surge? Since that didn't even happen in the 1938 hurricane, it's not going to happen with a Cat 1 drifting out of the Caribbean at the end of October. I have zero forecasting skills, and I can tell you now, that scenario is not on the table-- nor is anything near that on the table.

Could be a big, messy nontropical thing with winds of 50 kt-- but it's not going to be an apocalypse.

[Scott747]

TROPICAL STORM SANDY ADVISORY NUMBER 8NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012500 AM EDT WED OCT 24 2012

A TROPICAL STORM WATCH HAS BEEN ISSUED FOR THE EAST COAST OF FLORIDA

FROM JUPITER INLET SOUTH AND WEST TO FLAMINGO...INCLUDING FLORIDA

BAY.

A TROPICAL STORM WATCH HAS BEEN ISSUED FOR THE FLORIDA UPPER KEYS

FROM OCEAN REEF SOUTHWARD TO CRAIG KEY.

[Scott747]

Beven at the forecast desk. The 5 AM full package disco should be an interesting read...

Looks like Stewart with the shift change.

[dan88]

Reality check says Euro track probably most likely to verify, but intensity could be overdone. This would still mean a potential high impact storm on Monday and Tuesday in the New York City region including much of NJ, Long Island and New England, and possible snow problems at higher elevations to the southwest, so by no means should we say that being spared on the intensity will mean no big deal, this would be a big deal on the Euro track at 965 mbs so there is a 30-mb spectrum at least between the evident catastrophic damage from the depicted system and the considerable damage or at least disruption from a 965 mb storm at landfall.

It's a tough situation when you have one model saying winds SE 100-150 mph, storm surge 20-40 ft, possible 8-16 inches of rain, and another one saying winds NE 20-40 mph, no storm surge, possible half inch of rain mixed with sleet. How do you blend those and get a consensus for your five-day outlook?

It's worth noting that, despite it's intense central pressure, the Euro is relatively limited on wind speeds, having ~60kt sustain winds over water and along the immediate coast as it nears landfall in the Northern Mid-Atlantic. The surge, while significant, would also not be in that range.

[Scott747]

ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN FAVORABLE FOR

ADDITIONAL STRENGTHENING TO OCCUR UP UNTIL SANDY MAKES LANDFALL ON

JAMAICA IN ABOUT 12 HOURS OR SO. AFTER THAT...LAND INTERACTION WITH

JAMAICA AND EASTERN CUBA...COMBINED WITH INCREASING SOUTHWESTERLY

VERTICAL WIND SHEAR SHOULD INDUCE SOME GRADUAL WEAKENING.

HOWEVER...THE AMOUNT OF WEAKENING THAT TYPICALLY OCCURS UNDER SUCH

NEGATIVE CONDITIONS IS EXPECTED TO BE LIMITED DUE TO STRONG

BAROCLINIC INTERACTION/FORCING ASSOCIATED WITH THE STRONG

UPPER-LEVEL TROUGH. THE NHC INTENSITY FORECAST FOLLOWS THE TREND OF

THE PREVIOUS ADVISORY IN SHOWING A 60-KT INTENSITY AFTER 36 HOURS

AND THE CYCLONE BECOMING POST-TROPICAL BY 120 HOURS. HOWEVER...

THIS REMAINS A LOW CONFIDENCE FORECAST FOR BOTH THE INTENSITY AND

THE STRUCTURE OF THE CYCLONE AFTER 48-72 HOURS DUE TO UNCERTAINTY

IN THE AMOUNT OF BAROCLINIC INTERACTION.

[Roger Smith]

Well if it did manage to deepen to 933 mbs then winds would certainly be in the 100 mph range. Look how close the isobars are on the map, you have to go full mag just to resolve them. But as noted I am talking about what the map says, not what I would forecast. It makes more sense to me that a 960 mb low with 50-70 knot winds would actually happen. Let's hope we don't find out, but I am very sure that a 933 mb low would create massive winds and storm surges, Katrina at landfall was about 940 mbs.

[HurricaneJosh]

The models are really just being silly. It's going to exit the Caribbean with a pressure in the 970s, maybe. Even with some structural evolution and baroclinic enhancement, the pressure ain't gonna drop 30 to 40 mb. It makes no sense. The models are going haywire. If this curves toward the coast, it's going to have 50-kt winds and there will be some erosion and flooding.

[Superstorm93]

Roger,

You're not understanding the baroclynic process that actually gets this down to a sub 940 pressure.

Tropical wind/pressure correlation has no business with that aspect.

Sent from Tapatalk

[jconsor]

I agree that the Euro and CMC low pressure biases with tropical or semi-tropical systems north of 25N have to be considered. I do think baroclinic enhancement could give Sandy or its remnants a significant boost, especially considering how dynamic and negative tilt the trough is as modeled, and how SSTs off the SE/mid-Atlantic coast are 2-4C above normal. At this point, I think a pressure in the 950s-960s is most likely at the latitude of the mid-Atlantic/New England.

The speed of the storm and duration of the winds will ultimately be critical for how severe the coastal impacts are. Anytime you have an upper low closing off and a blocking high preventing the upper low from moving much, that tends to slow down the sfc system considerably.

Also agree that given how large Sandy is likely to become due to interaction with the upper trough/low, it would be tough to achieve sustained winds over 50 kt for land areas. The faster and further west Sandy moves (a la NOGAPS and a few ECMWF ensemble members), the more likely it can produce winds stronger than 50 kt. But I consider those scenarios outliers at this point.

The models are really just being silly. It's going to exit the Caribbean with a pressure in the 970s, maybe. Even with some structural evolution and baroclinic enhancement, the pressure ain't gonna drop 30 to 40 mb. It makes no sense. The models are going haywire. If this curves toward the coast, it's going to have 50-kt winds and there will be some erosion and flooding.

[Superstorm93]

Recon data is acting funny.

Plane should be very close though:

[Srain]

Eye splash suggests 981mb

[Superstorm93]

Cirrus looks pretty impressive this morning.

Waiting on a VDM form recon.

[NaoPos]

Check out sandy's size compared to tony..

[Srain]

000

URNT12 KNHC 241220

VORTEX DATA MESSAGE AL182012

A. 24/11:48:00Z

B. 16 deg 34 min N

076 deg 56 min W

C. 700 mb 2940 m

D. 60 kt

E. 322 deg 17 nm

F. 060 deg 54 kt

G. 322 deg 22 nm

H. 981 mb

I. 9 C / 3042 m

J. 14 C / 3049 m

K. 5 C / NA

L. open wnw

M. C48

N. 12345 / 7

O. 0.02 / 1 nm

P. AF308 0418A SANDY OB 09

MAX OUTBOUND FL WIND 69 KT SE QUAD 11:59:30Z

RAGGED EYEWALL

;

[Superstorm93]

[Srain]

12Z Tracks & Intensity:

[Drz1111]

The models are really just being silly. It's going to exit the Caribbean with a pressure in the 970s, maybe. Even with some structural evolution and baroclinic enhancement, the pressure ain't gonna drop 30 to 40 mb. It makes no sense. The models are going haywire. If this curves toward the coast, it's going to have 50-kt winds and there will be some erosion and flooding.

Northward churned the strengthening storm

Josh said "'Its a boring yawn"

"Hurricane", you call it? Please;

That is but a sprightly breeze

As it moved up through the Stait

Pressure falls did not abate

Josh said, "At this latitude

This storm is crap; why bother, dude?"

Soon it perched off Hatteras

October did not matter as

It deepened, perched atop the Stream

And turned into the next Katrin'

But Josh remains a stubborn man

"Its not near to the Yucatan

Or driving west into Belize

Maybe it will bend some trees"

Now Fire Island's just a dream

And Cape Cod turned to Cape Sardine

With billions ruined, and hundreds dead

"When's my next chase?" Joshua said.

[eurojosh]

Northward churned the strengthening storm

Josh said "'Its a boring yawn"

"Hurricane", you call it? Please;

That is but a sprightly breeze

As it moved up through the Stait

Pressure falls did not abate

Josh said, "At this latitude

This storm is crap; why bother, dude?"

Soon it perched off Hatteras

October did not matter as

It deepened, perched atop the Stream

And turned into the next Katrin'

But Josh remains a stubborn man

"Its not near to the Yucatan

Or driving west into Belize

Maybe it will bend some trees"

Now Fire Island's just a dream

And Cape Cod turned to Cape Sardine

With billions ruined, and hundreds dead

"When's my next chase?" Joshua said.

That.Is.Awesome.

[Superstorm93]

Maybe if I photoshop the Yucatan over the NE every time the ECM is posted, Josh will become much less pessimistic.

[Superstorm93]

Pressure down to 977 on this pass

132600 1657N 07642W 6970 02963 9791 +136 +091 110013 018 024 002 00

132630 1655N 07642W 6971 02959 9790 +135 +091 131008 011 022 001 00

132700 1654N 07643W 6969 02965 9773 +154 +079 115005 007 024 002 00

132730 1652N 07644W 6965 02972 9777 +151 +076 090003 005 024 002 00

[Scuddz]

74.8 the highest SFMR reading in the NE quad

[Ed Lizard]

This archive of recent HDOBS is so full of win it isn't even funny...

http://www.nhc.noaa.gov/archive/recon/2012/AHONT1/?C=M;O=D

[Srain]

URNT12 KNHC 241407

VORTEX DATA MESSAGE AL182012

A. 24/13:27:50Z

B. 16 deg 51 min N

076 deg 44 min W

C. 700 mb 2930 m

D. 65 kt

E. 029 deg 15 nm

F. 123 deg 63 kt

G. 032 deg 19 nm

H. 980 mb

I. 9 C / 3012 m

J. 16 C / 3049 m

K. 7 C / NA

L. OPEN WNW

M. C48

N. 12345 / 7

O. 0.02 / 1 nm

P. AF308 0418A SANDY OB 13

MAX FL WIND 69 KT SE QUAD 11:59:30Z

MAX OUTBOUND FL WIND 66 KT SW QUAD 13:36:30Z

Ragged eyewall

[Casualbrain]

URNT12 KNHC 241407

VORTEX DATA MESSAGE AL182012

A. 24/13:27:50Z

B. 16 deg 51 min N

076 deg 44 min W

C. 700 mb 2930 m

D. 65 kt

E. 029 deg 15 nm

F. 123 deg 63 kt

G. 032 deg 19 nm

H. 980 mb

I. 9 C / 3012 m

J. 16 C / 3049 m

K. 7 C / NA

L. OPEN WNW

M. C48

N. 12345 / 7

O. 0.02 / 1 nm

P. AF308 0418A SANDY OB 13

MAX FL WIND 69 KT SE QUAD 11:59:30Z

MAX OUTBOUND FL WIND 66 KT SW QUAD 13:36:30Z

Ragged eyewall

980 MB would make Sandy an official Cat 1. If my math is correct 65KT would be 74.8mpg too - baseline Cat. 1.

[jconsor]

The dropsonde that reported 980 mb had 22 kt of winds at the sfc and about 20 kt up to 850 mb, so real minimum pressure is likely closer to 978 mb.

URNT12 KNHC 241407

VORTEX DATA MESSAGE AL182012

A. 24/13:27:50Z

B. 16 deg 51 min N

076 deg 44 min W

C. 700 mb 2930 m

D. 65 kt

E. 029 deg 15 nm

F. 123 deg 63 kt

G. 032 deg 19 nm

H. 980 mb

I. 9 C / 3012 m

J. 16 C / 3049 m

K. 7 C / NA

L. OPEN WNW

M. C48

N. 12345 / 7

O. 0.02 / 1 nm

P. AF308 0418A SANDY OB 13

MAX FL WIND 69 KT SE QUAD 11:59:30Z

MAX OUTBOUND FL WIND 66 KT SW QUAD 13:36:30Z

Ragged eyewall

[Kmlwx]

980 MB would make Sandy an official Cat 1. If my math is correct 65KT would be 74.8mpg too - baseline Cat. 1.

You have to remember that the hurricane categories have nothing to do with pressure - all about wind speed. You could technically have a 970 cat 1 too.