ATL: SANDY - Remnants - Discussion

[SouthDadeFish]

Nothing too impressive yet:

[Macrocane]

Great to see you again Sandy (HURAKAN not the tropical storm)

According to the HPC the rains could reach dangerous amounts:

DISCUSSION FROM OCT 22/00 UTC: THE NHC IS FORECASTING THE
DEPRESSION TO INITIALLY MEANDER OVER THE CENTRAL CARIBBEAN THEN
STARTS TO LIFT NORTH AS A DIGGING TROUGH ESTABLISHES TO THE
WEST...PROVIDING THE STEERING FLOW THAT WOULD ALLOW THIS SYSTEM TO
SLOWLY LIFT TOWARDS JAMAICA THROUGH 54-60 HRS. DUE TO THE SLOW
INITIAL MOTION...THEY EXPECT RAPID INTENSIFICATION OF THIS SYSTEM
DURING THE NEXT 18-24 HRS...AND COULD REACH HURRICANE INTENSITY
PRIOR TO MAKING LANDFALL OVER JAMAICA.

OUTER BAND CONVECTION IS LIKELY TO AFFECT JAMAICA-HAITIAN
PENINSULA THROUGH 36 HRS...WITH RAINFALL AMOUNTS OF 25-50MM/DAY
AND MAXIMA OF 75-150MM/DAY. BY 36-60 HRS...AS THE STORM NEARS
JAMAICA...THIS WILL INCREASE TO 75-125MM/DAY AND MAXIMA OF
250-300MM/DAY. ACTIVITY GRADUALLY BUILDS NORTH INTO WESTERN CUBA
THROUGH 60-84 HRS...WITH RAINFALL AMOUNTS OF 150-200MM/DAY AND
MAXIMA OF 350-500MM/DAY. FURTHERMORE...AS A LONG FETCH
SOUTH-SOUTHWESTERLY FLOW ESTABLISHES ACROSS THE CENTRAL-EASTERN
CARIBBEAN...MODEL GUIDANCE THEN SHOW PERSISTENT RAINFALL AMOUNTS
ACROSS SOUTHERN PORTIONS OF HISPANIOLA...WITH RAINFALL AMOUNTS OF
25-50MM/DAY AND MAXIMA OF 75-150MM/DAY. LOCALLY HIGHER AMOUNTS ARE
HIGHLY LIKELY ACROSS PENINSULA DE BARAHONA OVER THE DOMINICAN
REPUBLIC. STORM TOTAL AMOUNTS WITH THIS SYSTEM ARE LIKELY TO
EXCEED 500MM. THIS IS PARTICULARLY LIKELY ACROSS JAMAICA AND
EASTERN PORTIONS OF CUBA DUE TO STRONG TOPOGRAPHICAL/MECHANICAL
FORCING.

[cycloneye]

BULLETIN
TROPICAL STORM SANDY INTERMEDIATE ADVISORY NUMBER 2A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012
800 PM EDT MON OCT 22 2012

...SANDY GETTING BETTER ORGANIZED AS IT REMAINS NEARLY STATIONARY
OVER THE SOUTHWESTERN CARIBBEAN SEA...


SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...12.7N 78.7W
ABOUT 385 MI...615 KM SSW OF KINGSTON JAMAICA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...STATIONARY
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES

[Sanibel]

Even with the predicted path if you see this in October and you live in Florida -


That envelope is hauntingly similar to Wilma (adds necessary disclaimer that in no way am I saying this will be another Wilma)

[boca]

Sandy will miss us to the east Im not too concerned as of now.

[Laplacian]

This is the late afternoon discussion by Dr Jeff Masters of Sandy and the place in history.

The Hurricane Hunters found a band of 40 mph winds on the southeast side of Tropical Depression Eighteen this afternoon, prompting NHC to upgrade the system to Tropical Storm Sandy. Sandy is over very warm waters of 29.5°C, is in a moist environment, and has light wind shear of 5 - 10 knots. These conditions are very favorable for intensification, and Sandy's heavy thunderstorms are steadily organizing into curved spiral bands, as seen on satellite loops.

Forecast for Sandy

Wind shear is forecast to be in the low to moderate range, 5 - 20 knots, through Wednesday afternoon. This should allow continued development of Sandy, and rapid development is possible. The latest SHIPS model forecast is calling for a 52% chance that Sandy's winds will increase by 30 mph over a 24-hour period. The 5 pm EDT NHC Wind Probability Forecast gave a 25% chance that Sandy will be a hurricane by 2 pm EDT Wednesday, when the center should be close to Jamaica. Wind shear will rise to a high 25 - 30 knots by Thursday, which should weaken Sandy. By Friday, Sandy should be in the Central or Eastern Bahamas, and wind shear may increase further, making Sandy more of a hybrid subtropical storm. It is unclear at this point whether or not the trough pulling Sandy to the north will be strong enough to pull the storm all the way out to sea to the northeast; a very complicated steering environment will develop late this week, and it is possible that a narrow ridge of high pressure could build in over Sandy, and force the storm to the northwest, with a potential threat to the Northwestern Bahamas and U.S. East Coast by Saturday, as predicted by the ECMWF model. Sandy is not a threat to be a hurricane at that time, due to very high wind shear. Heavy rains are the main threat from Sandy.

Sandy's place in history

Sandy is the eighteenth named storm of the 2012 Atlantic hurricane season, tying this year with 1969 for seventh busiest Atlantic season since record keeping began in 1851. Here are the busiest Atlantic hurricane seasons on record:

2005 (28 named storms)
1933 (20 named storms, according to a new re-analysis)
1887 (19 named storms)
2010 (19 named storms)
2011 (19 named storms)
1995 (19 named storms)
1969 (18 named storms)
2012 (18 named storms)

There are two weak and short-lived storms from 2012 that stayed far out sea, and would likely have gone unnoticed in the pre-satellite era (before 1960): Tropical Storm Joyce and Tropical Storm Oscar. And while this season has been very busy for total number of named storms, we've had a below-average number of major hurricanes (just Hurricane Michael), and the total destructive power of the 2012 hurricane season as measured by the Accumulated Cyclone Energy (ACE) is only about 20% above average. See our newly-launched Accumulated Cyclone Energy (ACE) page for a storm-by-storm breakdown of this years ACE, plus historical ACE stats for each ocean basin.

I am struck by the unwavering allegiance to the European model. For medium-range forecasts with a rather high degree of uncertainty (like this one), I prefer GEFS consensus (21 model runs) versus the solution of a single model.

GEFS consensus does not really threaten the East Coast this weekend...the 18Z GEFS consensus for MSLP for 06Z Saturday, 12Z Sunday, and 12Z Monday (bottom panels) gradually weaken the storm with time while gradually taking it away from the coast. Would I accept this as gospel? No, given the uncertainty. But I would never place all of my medium-range eggs in one basket (one model solution) in a situation like this.

https://www.e-education.psu.edu/worldof ... SLP-19.gif

https://www.e-education.psu.edu/worldof ... SLP-24.gif

https://www.e-education.psu.edu/worldof ... SLP-28.gif

I understand that the European model has lots of skill in the short range, but I'll hedge my bets with an ensemble medium-range forecast any day when the situation is rather uncertain.

[cycloneye]

SSD Dvorak.

22/2345 UTC 13.1N 78.5W T2.5/2.5 SANDY -- Atlantic

[ozonepete]

I understand that the European model has lots of skill in the short range, but I'll hedge my bets with an ensemble medium-range forecast any day in an uncertain situation.

I agree. In past seasons many people on here noticed the euro outperforming the GFS on a number of occasions and thus began to think that it was almost always the better model to follow when there was significant divergence in individual model outcomes. Since the GFS upgrade just before this season the GFS solutions have done much better and have outperformed the euro in some important track and strength forecasts, but it seems that, unfortunately, some still think one model is better than the other. I was taught to always look at the ensembles that have few outliers after looking at individual model runs, and it almost always gives a better forecast. Just look at the NHC and their impressive track record. They never use one model. They always use a blend of the models and rely heavily on model consensus - I still find it's almost always foolish in the long run to bet against them.

[cycloneye]

OSCAT pass from Monday afternoon.

[Laplacian]

P.S. I realize that we're not supposed to post "hotlinks," but this one should be good for five days.

12Z run of GEFS for MSLP and ensemble spread (a measure of uncertainty...I prefer the normalized spread on the graphics I published in the previous post.).

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

If this hotlink is not welcome, please let me know and I'll refrain in the future. Thanks.

[Laplacian]

I understand that the European model has lots of skill in the short range, but I'll hedge my bets with an ensemble medium-range forecast any day in an uncertain situation.

I agree. In past seasons many people on here noticed the euro outperforming the GFS on a number of occasions and thus began to think that it was almost always the better model to follow when there was significant divergence in individual model outcomes. Since the GFS upgrade just before this season the GFS solutions have done much better and have outperformed the euro in some important track and strength forecasts, but it seems that, unfortunately, some still think one model is better than the other. I was taught to always look at the ensembles that have few outliers after looking at individual model runs, and it almost always gives a better forecast. Just look at the NHC and their impressive track record. They never use one model. They always use a blend of the models and rely heavily on model consensus - I still find it's almost always foolish in the long run to bet against them.

Music to my ears.

[cycloneye]

00z Best Track at 40kts.

AL, 18, 2012102300, , BEST, 0, 127N, 786W, 40, 998, TS

http://ftp.nhc.noaa.gov/atcf/tcweb/inve ... 012.invest

[SouthDadeFish]

Still nothing incredibly impressive on this 37 GHz Windsat pass:



Spiral banding is beginning to establish itself though.

[SouthDadeFish]

Latest SSD ADT estimate:

2012OCT23 001500 2.1 1008.2/ +0.0 / 31.0 2.1 2.3 3.7 0.5T/hour OFF OFF -46.66 -63.31 CRVBND N/A 12.91 78.51 FCST

Raw numbers at T 3.7 aren't that surprising after seeing this structure:



Look at all that banding

[Caribwxgirl]

So i'm here watching the news and they are interviewing people on the streets asking about their preparation for the storm it ranges from storm? What stor? To no I don't think the storm will come here its going to turn back! I mean seriously! At least one man said he didn't know about it but now he's told he's going home to prepare and one lady says she's had her hurricane supplies together from June.h

[cycloneye]

Latest SSD ADT estimate:

2012OCT23 001500 2.1 1008.2/ +0.0 / 31.0 2.1 2.3 3.7 0.5T/hour OFF OFF -46.66 -63.31 CRVBND N/A 12.91 78.51 FCST

Raw numbers at T 3.7 aren't that surprising after seeing this structure:

http://imageshack.us/a/img546/4039/trop ... r2floa.gif

Look at all that banding

Even getting plenty of feed from the EPAC.

[floridasun78]

Caribwxgirl hope you do well

[Caribwxgirl]

Caribwxgirl hope you do well

Thanks

[sunnyday]

I have two questions, and thank you to whoever answers them. First, will Sandy's stationary status affect its ultimate path? Second, is there any (reasonable) chance that Sandy might go closer to S Fl (could we wake up in the morning and see the cone closer to that area)?
There seems to be such a near consensus on her path several days out. Usually, there are hundreds of miles of possible error/changes in the path this far out.
I really appreciate your time in explaining these points.

[Caribwxgirl]

I have two questions, and thank you to whoever answers them. First, will Sandy's stationary status affect its ultimate path? Second, is there any (reasonable) chance that Sandy might go closer to S Fl (could we wake up in the morning and see the cone closer to that area)?
There seems to be such a near consensus on her path several days out. Usually, there are hundreds of miles of possible error/changes in the path this far out.
I really appreciate your time in explaining these points.

If I remember correctly the GFS did predict it would become stationary before turning to the North. So I don't think it would affect the track but I could be wrong.