Sandy remains a hurricane, slowly leaving the Bahamas

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

Share this Blog
47
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 906 - 856

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28Blog Index

906. 900MB
Anyone have a storm surge forecast for NYC/LI for Sandy?
Member Since: Posts: Comments:
Quoting Grothar:


Hey, Largo. You have a good memory. I posted that 3 days ago. It was 940 and I wrote that I had never seen anything like that. I had written that it could go into New Jersey around Ocean County or Monmouth county and I wrote it again last night with a map of New Jersey. I hope I am wrong and they are wrong. This is one of the models I had posted.

Hiya Gro..yeah this is going to make weather history if this does unfold
Member Since: Posts: Comments:
Quoting MAweatherboy1:

Wrentham, near the NE tip of RI.


Oh okay, my family is located in the Fall River area. What are local mets saying about the impact of this storm?
Member Since: Posts: Comments:
Quoting Grothar:


Hey, Largo. You have a good memory. I posted that 3 days ago. It was 940 and I wrote that I had never seen anything like that. I had written that it could go into New Jersey around Ocean County or Monmouth county and I wrote it again last night with a map of New Jersey. I hope I am wrong and they are wrong. This is one of the models I had posted.



I believe your words were to the effect of "I have never seen anything this large." That got my attention.
Member Since: August 26, 2008 Posts: 0 Comments: 122
Whens the last time a fully tropical or subtropical storm dumped snow?
Member Since: Posts: Comments:
900. 900MB
TWC just reported 76mph wind at buoy 100 miles west of Sandy. Man, how about that pressure!
Member Since: Posts: Comments:
It's pretty interesting watching all the recon data come in. A NOAA dropsonde just got 72mph at the surface and 104mph not far above the surface.
Member Since: Posts: Comments:
Quoting Neapolitan:
I'm no expert on European meteorology, so must admit that I don't know whether 955 mb is usual on that side of the pond. But here in the States, such low pressures in non-tropical storms don't occur "frequently". Here's a list of a few memorable nor'easters and their lowest measured pressures:

2011 Halloween nor'easter: 971 mb
December 2010 North American blizzard: 961 mb
1991 Perfect Storm: 972 mb
Groundhog Day gale of 1976: 957 mb
Great Blizzard of 1888: 982 mb

FWIW, the lowest barometric pressure officially recognized in the Lower 48 outside a hurricane or tornado was 955 mb at Canton, NY, in 1913 and Nantucket in 1932. So if Sandy makes landfall as a non-tropical entity (which it should) with a pressure lower than 955 mb (which some models are calling for) it will definitely fit the description of "incredible"--at least the way some define the word. ;-)

(Of course, even if the storm is at 960, its massive size and wide distribution of winds is going to make it one of the most memorable Northeast U.S. storms ever. I think that's the important part to remember.)


Nice post, makes my bones hurt just reading it.
Member Since: August 26, 2008 Posts: 0 Comments: 122
Quoting LargoFl:
didnt GRO have a model at 928 or something when she comes ashore?..geez


Hey, Largo. You have a good memory. I posted that 3 days ago. It was 940 and I wrote that I had never seen anything like that. I had written that it could go into New Jersey around Ocean County or Monmouth county and I wrote it again last night with a map of New Jersey. I hope I am wrong and they are wrong. This is one of the models I had posted.

Member Since: July 17, 2009 Posts: 71 Comments: 26473
Member Since: Posts: Comments:
12z models are in. No big changes but agreement continues to improve and the NHC remains on the southern edge:

Member Since: Posts: Comments:
Quoting air360:


I was wondering this too - being on the central NC coast it looks almost as if we will literally "rotate around the edge" of Sandy from now until it goes way inland next week...which would be an insane amount of rain


yeah..insane would be very approriate in that case..no one is talking about that so I hope the Doc sees this and hopefully answer that question..
Member Since: Posts: Comments:
Quoting AustinTXWeather:
Hi - any insight on how conditions are likely to be in DC by late afternoon Sunday?
..here from the nws...........THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...TODAY AND TONIGHT

A SMALL CRAFT ADVISORY IS IN EFFECT TODAY FOR THE MARYLAND PORTION
OF THE CHESAPEAKE BAY...AND THE LOWER TIDAL POTOMAC RIVER. THE
ADVISORY WILL INCLUDE ALL WATERS TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE NATIONAL HURRICANE CENTER FORECASTS TROPICAL STORM SANDY TO TRACK
TO THE NORTH-NORTHEAST TO A POSITION WELL OFF THE NORTH CAROLINA
COAST SUNDAY NIGHT...BEFORE SHIFTING TO THE NORTHWEST AND MOVING
TOWARD THE NEW JERSEY AND DELAWARE COASTS MONDAY INTO TUESDAY. THE
TRACK OF SANDY COULD BRING SIGNIFICANT IMPACTS TO THE REGION
SUNDAY NIGHT THROUGH WEDNESDAY.

IMPACTS INCLUDE...

FLOODING FROM HEAVY RAIN: A FLOOD WATCH HAS BEEN ISSUED FOR THE
DC-BALTIMORE CORRIDOR WEST TO FREDERICK COUNTY MARYLAND AND INTO
LOWER SOUTHERN MARYLAND FROM SUNDAY NIGHT THROUGH TUESDAY. THE
AMOUNT OF RAINFALL WILL DEPEND ON THE TRACK OF THE STORM. RISES ON
RIVERS COULD CONTINUE FLOODING POTENTIALLY WEDNESDAY INTO FRIDAY.

DAMAGING WINDS: IN ASSOCIATION WITH THE HEAVY RAINFALL...STRONG
WINDS ARE EXPECTED SUNDAY NIGHT THROUGH TUESDAY. THESE WINDS WILL
LIKELY RESULT IN DOWNED TREES AND POWER LINES. AT THIS TIME...THE
MOST LIKELY TIME FOR TROPICAL STORM FORCE WINDS APPEARS TO BE LATE
MONDAY INTO TUESDAY.

COASTAL FLOODING: PROLONGED EASTERLY FLOW AND A FULL MOON ARE
EXPECTED TO PRODUCE MINOR COASTAL FLOODING THIS WEEKEND.

SMALL CRAFT ADVISORIES ARE IN EFFECT OVER THE TIDAL POTOMAC RIVER
AND MARYLAND CHESAPEAKE BAY SATURDAY AND SATURDAY NIGHT. A GALE
WARNING IS IN EFFECT FOR SUNDAY FOR PORTIONS OF THE WATERS. GALE
OR STORM WARNINGS MAY BE NECESSARY SUNDAY NIGHT THROUGH TUESDAY.

CONTINUE TO MONITOR NATIONAL HURRICANE CENTER PRODUCTS FOR
UPDATES ON THE TRACK OF SANDY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED TODAY. ACTIVATION MAY BE NEEDED IF
SANDY APPROACHES THE AREA SUNDAY THROUGH TUESDAY.

$$
Member Since: Posts: Comments:
Quoting atris:


I agree that it has hurricane force winds associated but to my eye she lost most tropical features yesterday . I think its a public safety issue still calling it a cane ...as people will relax if they think is not ...but this is an extremely dangerous storm ..and when that front gets into the mix its very bad news


Nah, it's sub-tropical, leaning tropical. The convection it's generating is too deep for a non-tropical system, so some tropical characteristics of a non-tropical system.
Member Since: July 8, 2005 Posts: 259 Comments: 24169
Cape May water temp: 68 degrees. 9 above average this morning.

http://tidesandcurrents.noaa.gov/geo.shtml?locati on=8536110
Member Since: August 26, 2008 Posts: 0 Comments: 122
Quoting atris:
Winter wind storms frequently have low pressure like this.. included is a link that shows pressure of some winter storms

Link
I'm no expert on European meteorology, so must admit that I don't know whether 955 mb is usual on that side of the pond. But here in the States, such low pressures in non-tropical storms don't occur "frequently". Here's a list of a few memorable nor'easters and their lowest measured pressures:

2011 Halloween nor'easter: 971 mb
December 2010 North American blizzard: 961 mb
1991 Perfect Storm: 972 mb
Groundhog Day gale of 1976: 957 mb
Great Blizzard of 1888: 982 mb

FWIW, the lowest barometric pressure officially recognized in the Lower 48 outside a hurricane or tornado was 955 mb at Canton, NY, in 1913 and Nantucket in 1932. So if Sandy makes landfall as a non-tropical entity (which it should) with a pressure lower than 955 mb (which some models are calling for) it will definitely fit the description of "incredible"--at least the way some define the word. ;-)

(Of course, even if the storm is at 960, its massive size and wide distribution of winds is going to make it one of the most memorable Northeast U.S. storms ever. I think that's the important part to remember.)
Member Since: Posts: Comments:
Quoting breald:



MAWeatherboy1 where are you in MA?

Wrentham, near the NE tip of RI.
Member Since: Posts: Comments:
Quoting atris:


I agree that it has hurricane force winds associated but to my eye she lost most tropical features yesterday . I think its a public safety issue still calling it a cane ...as people will relax if they think is not ...but this is an extremely dangerous storm ..and when that front gets into the mix its very bad news


It's more than just public safety. It has lost some tropical characteristics, but the temperatures that recon has been finding show that it still has a fairly deep warm core.
Member Since: Posts: Comments:
Quoting K8eCane:


You could see the sun but might not be able to stand up for the wind. I have experienced that in other noreasters


I have also experienced similar situations. Sun shinning and 60+ mph winds on the back side of a very lop sided (One sided) Tropical Storm.
Member Since: Posts: Comments:
This is going to be one heck of a storm. I hope everyone stays safe and listens to their local authorities.
Member Since: Posts: Comments:
Quoting TomballTXPride:
That is a whole lot of dry air she'll eventually gulp into her circulation. This is keep her intensity in check one would hope.



Even 12Z SHIPS ain't all that impressive anymore for mid-level moisture availability.

700-500 MB RH 50 51 50 53 53 48

That dry air has always been in effect.
Member Since: Posts: Comments:
Quoting yonzabam:


The 14" prediction was for New Jersey.


LOL i knew that had to be wrong
Member Since: Posts: Comments:
Hi - any insight on how conditions are likely to be in DC by late afternoon Sunday?
Member Since: Posts: Comments:
878. atris
Quoting CybrTeddy:


It is a tropical entity per the NHC. It's a strange hybrid, but it's still a hurricane.


I agree that it has hurricane force winds associated but to my eye she lost most tropical features yesterday . I think its a public safety issue still calling it a cane ...as people will relax if they think is not ...but this is an extremely dangerous storm ..and when that front gets into the mix its very bad news
Member Since: Posts: Comments:
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


The 14" prediction was for New Jersey.
Member Since: Posts: Comments:
Quoting ncstorm:


all that will change when she supposed to bomb off the Carolina coast according to the Euro so that should fill in..


I was wondering this too - being on the central NC coast it looks almost as if we will literally "rotate around the edge" of Sandy from now until it goes way inland next week...which would be an insane amount of rain
Member Since: Posts: Comments:
Quoting Sfloridacat5:
Amazing the amount of dry continental air being pulled into the system. If this was a pure tropical system it would be in serious trouble of survival.

You could be very close to the center of circulation (just to the E/ESE) and be in clear weather.


You could see the sun but might not be able to stand up for the wind. I have experienced that in other noreasters
Member Since: Posts: Comments:
Quoting wxchaser97:

Yes, but barely over the center, and it slowly wants to expand.


Isn't it unusual to be able to see the lower circulation like that? It's fascinating, like a hurricane dissected.
Member Since: Posts: Comments:
It is 8:45 am Saturday morning and there is still a consistent NW breeze with frequent moderate gusts. Temp has dropped about 10 degrees from normal.

Regards,
-Gary
Hollywood Florida
Member Since: Posts: Comments:
listening to the marine radio traffic...it's nasty out there...20-25ish foot seas...and the harbor pilots are still bringin' 'em in...
Member Since: Posts: Comments:
Quoting dader:


It won't flood north of Merrick.


Exactly!
Member Since: Posts: Comments:
It's not a fully tropical entity, as you can tell on the water vapor loops, but the recon is finding temperatures that don't support a non-tropical system.

It's sub-tropical, but leaning on tropical, so the NHC will keep it as a Hurricane.
Member Since: July 8, 2005 Posts: 259 Comments: 24169
Quoting LargoFl:
here is the 8am cone, lets see how the 5pm tonight cone looks


Look at that turn! Big adjustment from last night.
Member Since: August 26, 2008 Posts: 0 Comments: 122
here is the 8am cone, lets see how the 5pm tonight cone looks
Member Since: Posts: Comments:
Amazing the amount of dry continental air being pulled into the system. If this was a pure tropical system it would be in serious trouble of survival.

You could be very close to the center of circulation (just to the E/ESE) and be in clear weather.
Member Since: Posts: Comments:
HOLY COW!!!

Member Since: Posts: Comments:
Quoting wxchaser97:

So the GFDL remains on the southern edge, and I think it is too far south.


How far south, in your opinion? I think that turn could be large, even if it goes north a bit. No other forces to prevent it.
Member Since: August 26, 2008 Posts: 0 Comments: 122
Quoting Maryland1:


Largo: If that much rain falls in our areas, TS Agnes' water damage will be a distant mememory to what's going to occur. The storm that I have been comparing it to is the Ash Wednesday storm of 1962. I now concur, with you, that this will be worse.
yes im afraid so, if..she came in then moved away quickly, maybe the flooding wouldnt be so terrific..but..the predict she wont, she will hang around for a few days, one model has her sinking south later after landfall..that would really be bad...but for now we prepare and wait this out..
Member Since: Posts: Comments:
Quoting atris:


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


It is a tropical entity per the NHC. It's a strange hybrid, but it's still a hurricane.
Member Since: July 8, 2005 Posts: 259 Comments: 24169
Quoting LargoFl:


Largo: If that much rain falls in our areas, TS Agnes' water damage will be a distant mememory to what's going to occur. The storm that I have been comparing it to is the Ash Wednesday storm of 1962. I now concur, with you, that this will be worse.
Member Since: August 26, 2008 Posts: 0 Comments: 122
Quoting MAweatherboy1:
The HWRF remains on the very northern edge of guidance in its new run, the center is literally over my house on this frame:



GFDL is coming in now, it's been on the southern edge so we'll see if that continues.



MAWeatherboy1 where are you in MA?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting atris:


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


How is she not a completely tropical entity and a Hurricane per the NHC? That sounds odd.
Member Since: Posts: Comments:

Viewing: 906 - 856

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.