Sandy remains a hurricane, slowly leaving the Bahamas

By: Angela Fritz , 9:28 PM GMT on October 26, 2012

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Reuters reports that the death toll from Sandy in the Caribbean is now up to 41 people as Hurricane Sandy continues its track toward the U.S. East Coast this afternoon, slowly leaving the Bahamas. States of Emergency have been declared in North Carolina, Virginia, Maryland, and New York. The hurricane is just barely still a Category 1 with surface winds of 75 mph and a minimum central pressure of 971 mb. Ocean buoys off the coasts of Florida and the Carolinas are recording sustained winds of around 45 mph this afternoon, with gusts steadily increasing and now up to 60 mph. Sandy's rainfall, which is limited to the north and northeast parts of the storm, is reaching eastern Florida, though most of it is staying offshore.

Satellite loops show an asymmetric Sandy, with almost all of the thunderstorm activity on its north side. The hurricane still has a very clear center of surface circulation which you can see on visible and infrared loops. Though the hurricane is leaving the influence of an upper level low pressure area over western Cuba, water vapor imagery shows a large area of dry air being pulled into the storm from the south, which is leading to the lack of thunderstorm activity and contributing to the weakening that Sandy is experiencing right now. The hurricane's tropical storm-force winds now extend 240 miles from the center, and could grow to 400 miles from the center by the time it reaches the East Coast.


Figure 1. Visible/infrared satellite image of Sandy as it leaves the Bahamas this afternoon. The mid-latitude trough, which Sandy will interact with over the next few days, is seen approaching from the northwest. The cold front associated with this trough is draped from upstate New York south to Louisiana, and appears as a line of clouds draped across the Midwest and South in this image.

Forecast For Hurricane Sandy

As a tropical cyclone approaches land, the worst storm surge is almost always where the winds are blowing from ocean to shore, where the wind pushes the water toward and onto the shore. In the case of Sandy's potential track, this region is on the north side of the center. In this morning's GFS scenario, Sandy's center passes over eastern Long Island, Connecticut, and Rhode Island. This would result in the highest surge north of New York City: Rhode Island, Massachusetts, New Hampshire, and possibly Maine. The ECMWF forecast from this morning is a bit further to the south. It's suggesting Sandy's center will meet land in New Jersey. This scenario opens up New York City, Long Island, Connecticut, Rhode Island, and southern coastal Mass. to the largest surge. In general, the places that will avoid the largest storm surge are those that are south of where the center of the storm makes landfall. The National Hurricane Center's forecast is similar to the ECMWF, but most importantly, its forecast is also to not focus on the exact point of landfall because of the size of the storm, and that widespread impact is expected.

The Mid-Atlantic and Northeast coasts should be prepared for a storm surge no matter their exact location. A large portion of the coast will feel the impact of up to 60 mph winds and heavy rain. According to the most recent H*Wind analysis from the Hurricane Research Division is that storm surge has a destructive potential of 4.8 out of 6.0, which is a slight increase from previous analyses. Wind damage potential is holding steady around 2.3 out of 6.0. NOAA's HPC is forecasting rainfall totals of 5 to 10 inches in the Mid-Atlantic and Northeast, and possibly more in coastal locations close to the core of the storm. Widespread power outages from Maine south to Virginia are likely, due to the combination of long-lived gale-force winds, leaves on trees, and rain that will moisten the soil and possibly increase the chances of falling trees. Snow in the Appalachians is also possible as the intense moisture meets the cold air being pulled south by the mid-latitude trough.


Figure 2. Departure of sea surface temperature from average for the Atlantic shows a large area of unusually warm waters up to 9°F above average off the U.S. mid-Atlantic coast.

Sandy to feed off near-record warm waters off the mid-Atlantic coast
During September 2012, ocean temperatures off the mid-Atlantic coast in the 5x10° latitude-longitude box between 35 - 40°N, 65 - 75° W were 2.3°F (1.3°C) above average, according to the UK Met Office. This is the 2nd greatest departure from average for ocean temperatures in this region since reliable ocean temperature measurements began over a century ago (all-time record: 2.0°C above average in September 1947.) These unusually warm waters have persisted into October, and will enable Sandy to pull more energy from the ocean than a typical October hurricane. The warm waters will also help increase Sandy's rains, since more water vapor will evaporate into the air from a warm ocean. I expect Sandy will dump the heaviest October rains on record over a large swath of the mid-Atlantic and New England.

Hurricane rains and climate change
Hurricanes are expected to dump 20% more rain in their cores by the year 2100, according to modeling studies (Knutson et al., 2010). This occurs since a warmer atmosphere holds more water vapor, which can then condense into heavier rains. Furthermore, the condensation process releases heat energy (latent heat), which invigorates the storm, making its updrafts stronger and creating even more rain. We may already be seeing an increase in rainfall from hurricanes due to a warmer atmosphere. A 2010 study by Kunkel et al. "Recent increases in U.S. heavy precipitation associated with tropical cyclones", found that although there is no evidence for a long-term increase in North American mainland land-falling tropical cyclones (which include both hurricanes and tropical storms), the number of heavy precipitation events, defined as 1-in-5-year events, more than doubled between 1994 - 2008, compared to the long-term average from 1895 - 2008. As I discussed in a 2011 post "Tropical Storm Lee's flood in Binghamton: was global warming the final straw?", an increase in heavy precipitation events in the 21st Century due to climate change is going to be a big problem for a flood control system designed for the 20th Century's climate.


Figure 3. Time series of the 15-yr running average (plotted at the end point of the 15-yr blocks) of the tropical cyclone Heavy Precipitation Index (red) and the associated 15-yr total of U.S. landfalling hurricanes from Atlantic HURDAT hurricane data base, from 1895 - 2008 (blue). Note the steep rise in heavy precipitation events from tropical cyclones over the past 20 years, which has not been accompanied by a corresponding increase in landfalling hurricanes. Image credit: Kunkel et al., 2010, Geophysical Research Letters.

Angela Fritz and Jeff Masters

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Quoting AussieStorm:
GFDL 06Z 84hrs 933mb


So the GFDL remains on the southern edge, and I think it is too far south.
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wet, windy and rockin' at Charleston Harbor
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just look at the size of her
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Quoting interstatelover7165:
Is convection over her coc again?!

Yes, but barely over the center, and it slowly wants to expand.
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Quoting AussieStorm:
GFDL 06Z 84hrs 933mb

geez thats amazing aussie
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GFDL 06Z 84hrs 933mb

Member Since: September 30, 2007 Posts: 9 Comments: 15935
8 am surf conditions at Indialantic Florida.
Winds have shifted to NW at about 20mph, cleaning up the surf. Hard to tell how big it is when no one is out...yet.

http://youtu.be/j9u7A8Sirgs


http://youtu.be/dEiJszWvKlo
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Is convection over her coc again?!
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846. atris
Quoting Neapolitan:
The 12z ATCF has Sandy at 956mb (28.23") and 65 knots:

AL, 18, 2012102712, , BEST, 0, 288N, 768W, 65, 956, HU, 64, NEQ, 0, 0, 90, 0,

Incredible...


Yes if it was still a completely tropical entity but its No longer the case ...

Winter wind storms frequently have low pressure like this.. included is a link that shows pressure of some winter storms

Link
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Quoting Maryland1:
Remember when everyone looked at the Euro model on this storm three days ago and thought that the pressure was overdone? It seems real plausible this morning.
yes it does now
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Quoting WeatherNerdPR:

I am going to die just looking at this. :|
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......................Nam at 60 hours..time is running out to prepare folks
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Quoting K8eCane:


I doubt we will get THAT much rain in southeastern NC. Yes this is wetter than some noreasters but i doubt it will be that tropically wet
just remember, you could..be getting her rains for 3 days or more,your going to get her rains now thru the time she heads up to canada maybe because she is supposed to be hanging around her landfall area for a few days
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I remember someone telling me that if they HH miss the exact center with a dropsound and it splashes with a pressure but has more then 10 knt winds you have to subtract 1 mb pressure for each 10 knt winds you have is this true???? because the last dropsound has 961 but has 60 knt winds so that would mean 955 mb
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Hatteras webcam. Quite the action!
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Quoting WeatherNerdPR:

"Frankenstorm"

Bleh.
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835. atris
The question is when and where the Front mets Sandy..

UNISYS Radar loop






HPC current Map



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Remember when everyone looked at the Euro model on this storm three days ago and thought that the pressure was overdone? It seems real plausible this morning.
Member Since: August 26, 2008 Posts: 0 Comments: 122
Quoting ncstorm:
I have a question..if I am currently experiencing Sandy outerbands when its almost 500 miles away from me down by Florida, wouldnt I still be experiencing the outerbands when it makes landfall in the NE? For those of us in the middle, we might be experiencing bad weather for the duration of Sandy's lifespan as a hurricane and this storm is still expanding..
check my 808 post on my winds now and im maybe 400 miles away..how far away from you is .hmmm say DC?
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Quoting LargoFl:
this time maybe 14 inches


I doubt we will get THAT much rain in southeastern NC. Yes this is wetter than some noreasters but i doubt it will be that tropically wet
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Quoting Neapolitan:
The 12z ATCF has Sandy at 956mb and 65 knots:

AL, 18, 2012102712, , BEST, 0, 288N, 768W, 65, 956, HU, 64, NEQ, 0, 0, 90, 0,

Incredible...

"Frankenstorm"
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Remember, last night they were only finding 20-40mph flight level winds. Now.

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 27th day of the month at 12:08Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)
Storm Number & Year: 18L in 2012
Storm Name: Sandy (flight in the North Atlantic basin)
Mission Number: 15
Observation Number: 05
A. Time of Center Fix: 27th day of the month at 11:50:30Z
B. Center Fix Coordinates: 2846'N 7648'W (28.7667N 76.8W)
B. Center Fix Location: 258 miles (415 km) to the N (7) from Nassau, Bahamas.
C. Minimum Height at Standard Level: 1,055m (3,461ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 67kts (~ 77.1mph)
E. Location of the Estimated Maximum Surface Wind: 70 nautical miles (81 statute miles) to the SW (223) of center fix
F. Maximum Flight Level Wind Inbound: From 315 at 91kts (From the NW at ~ 104.7mph)
G. Location of Maximum Flight Level Wind Inbound: 93 nautical miles (107 statute miles) to the SW (225) of center fix
H. Minimum Sea Level Pressure: 957mb (28.26 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14C (57F) at a pressure alt. of 1,523m (4,997ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23C (73F) at a pressure alt. of 1,523m (4,997ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 17C (63F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 91kts (~ 104.7mph) in the southwest quadrant at 11:19:30Z
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Quoting trHUrrIXC5MMX:
Yep back to hurricane...big decrease in mb... now 960
didnt GRO have a model at 928 or something when she comes ashore?..geez
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Quoting K8eCane:


I watched a noreaster rip shingles and roofs off, down trees, signs and power lines and we might have had 2 drops of rain one year
this time maybe 14 inches
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The 12z ATCF has Sandy at 956mb (28.23") and 65 knots:

AL, 18, 2012102712, , BEST, 0, 288N, 768W, 65, 956, HU, 64, NEQ, 0, 0, 90, 0, 1008, 460, 75, 0, 0, L, 0, , 0, 0, SANDY, D,

Incredible...
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Quoting Thundercloud01221991:


how many miles across was he

920 miles across, according to Wikipedia.
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Quoting WeatherNerdPR:

Igor 2010.


how many miles across was he
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Quoting Thundercloud01221991:
what is the largest tropical system in the atlantic???

Igor 2010.
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Quoting WeatherNerdPR:

Dat 35kt wind radius. Sandy's size is getting ridiculous.

That thing is huge and it is only going to get larger. Widespread tree and power line damage over a large area in the eastern US.
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what is the largest tropical system in the atlantic???
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Quoting DrewE:


Her southern edge, at this point in time, has basically no convection.

Also, good morning everyone! Is it the day after tonmorrow yet? I still think she's going to bomb right into the Delmarva, but we shall see...


I watched a noreaster rip shingles and roofs off, down trees, signs and power lines and we might have had 2 drops of rain one year
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Quoting DrewE:


Her southern edge, at this point in time, has basically no convection.

Also, good morning everyone! Is it the day after tonmorrow yet? I still think she's going to bomb right into the Delmarva, but we shall see...


all that will change when she supposed to bomb off the Carolina coast according to the Euro so that should fill in..
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Dat 35kt wind radius. Sandy's size is getting ridiculous.
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Yep back to hurricane...big decrease in mb... now 960
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Quoting MAweatherboy1:
AF dropsonde dropped in the center has reported 957mb. She's not only holding her own right now, she's strengthening. We expected the pressure to come down but it's coming down faster than we thought and the winds are coming up, which was also unexpected.


Actually, that was expected by the models, and is expected to continue. If anything, looking at the models, they initialized this system 10-15mb too high, and they still bring it sub 950mb.
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814. DrewE
Quoting ncstorm:
I have a question..if I am currently experiencing Sandy outerbands when its almost 500 miles away from me down by Florida, wouldnt I still be experiencing the outerbands when it makes landfall in the NE? For those of us in the middle, we might be experiencing bad weather for the duration of Sandy's lifespan as a hurricane and this storm is still expanding..


Her southern edge, at this point in time, has basically no convection.

Also, good morning everyone! Is it the day after tommorrow yet? I still think she's going to bomb right into the Delmarva, but we shall see...
Member Since: October 24, 2012 Posts: 0 Comments: 45
Quoting WeatherNerdPR:

A sub-950mb storm for New England doesn't sound that crazy anymore.


the 925 mb pressure on some of the models a couple of days ago doesnt sound crazy anymore either
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Good morning everyone, I see Sandy weakened to a tropical storm but has strengthened to a hurricane. More convection covers the center and recon has the latest pressure at 957mb and 77mph winds.

I wrote a blog on Sandy earlier in the morning.
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Quoting SherwoodSpirit:


I'm actually glad she's a hurricane again, because I think more people will pay attention than they would if she was a 73 mph tropical storm.


True...But Lets not do anyone any FAVORS insurance wise if we are splitting hairs, OK NHC???
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Quoting MAweatherboy1:
AF dropsonde dropped in the center has reported 957mb. She's not only holding her own right now, she's strengthening. We expected the pressure to come down but it's coming down faster than we thought and the winds are coming up, which was also unexpected.

A sub-950mb storm for New England doesn't sound that crazy anymore.
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I have a question..if I am currently experiencing Sandy outerbands when its almost 500 miles away from me down by Florida, wouldnt I still be experiencing the outerbands when it makes landfall in the NE? For those of us in the middle, we might be experiencing bad weather for the duration of Sandy's lifespan as a hurricane and this storm is still expanding..
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 27th day of the month at 12:08Z
Center Fix Coordinates: 28°46'N 76°48'W (28.7667N 76.8W)
B. Center Fix Location: 258 miles (415 km) to the N (7°) from Nassau, Bahamas.

Minimum Sea Level Pressure: 957mb (28.26 inHg)
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Quoting MAweatherboy1:
AF dropsonde dropped in the center has reported 957mb. She's not only holding her own right now, she's strengthening. We expected the pressure to come down but it's coming down faster than we thought and the winds are coming up, which was also unexpected.
whew..this Lady is on a mission and nothing is going to stop her huh....
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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