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Sandy intensifying, headed towards Jamaica

By: Dr. Jeff Masters , 2:49 PM GMT on October 23, 2012

Tropical Storm Sandy is on the move northwards towards Jamaica, and is slowly intensifying. The Hurricane Hunters are in the storm, and measured surface winds near 50 mph in the storm's northeast quadrant at 9 am EDT. The latest center fix, taken at 10:20 am EDT, found that Sandy's pressure had fallen 2 mb since early this morning, to 995 mb. Intermittent rain squalls from Sandy have been affecting Jamaica since Monday night, and Kingston, Jamaica has picked up 0.82" of rain from Sandy as of 9 am EDT. and Sandy is over very warm waters of 29.5°C, is in an unusually moist environment with relative humidities above 80%, and is experiencing light wind shear of 5 - 10 knots. These conditions are very favorable for intensification, and Sandy's heavy thunderstorms have increased in areal extent, intensity, and organization this morning, as seen on satellite loops.


Figure 1. Morning satellite image of Tropical Storm Sandy.

Sandy a potential threat to New England
Wind shear is forecast to be in the low to moderate range, 5 - 20 knots, through Thursday morning. This should allow continued development of Sandy, and rapid development is possible. The 8 am EDT SHIPS model forecast predicted a 62% chance that Sandy's winds would increase by 30 mph over a 24-hour period. However, the Hurricane Hunters found this morning that the center at 5,000 feet was displaced 7 miles from the surface center, and there was no indication that Sandy was building an eyewall, so I expect that the earliest Sandy could become a hurricane is Wednesday morning. The 5 am EDT NHC Wind Probability Forecast gave a 49% chance that Sandy would 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 and the storm will have to cross the rugged terrain of Cuba, which should weaken Sandy's winds by 20 - 30 mph. By Friday, Sandy should be over warm waters in the Central Bahamas, but only modest re-intensification by 10 - 20 mph should occur, due to high wind shear. At that point, a very complicated meteorological situation unfolds, as Sandy interacts with a trough of low pressure approaching the U.S. East Coast. The trough may steer Sandy northeastwards, out to sea, as predicted by the GFS, HWRF, and GFDL models. However, an alternative solution, shown by the ECMWF and NOGAPS models, is for the trough to inject a large amount of energy into Sandy, converting it to a powerful subtropical storm that hits New England early next week with a central pressure of 948 mb and winds near hurricane-force. The ECMWF and NOGAPS models are off by a full day in their predictions of when the storm would arrive, with the 06Z NOGAPS model predicting Sandy's heavy rains will arrive on North Carolina's Outer Banks on Sunday, then spread into the mid-Atlantic and New England on Sunday. The 00Z ECMWF model forecast predicts that Sandy will arrive in New England on Monday night. Stay tuned.


Figure 2. The Tuesday morning 06Z (2 am EDT) run of the GFS model was done 20 times at lower resolution with slightly varying initial conditions of temperature, pressure, and moisture to generate an ensemble of forecast tracks for Sandy (pink lines). These forecasts show substantial uncertainty in Sandy's path after Friday, with the majority of the forecasts taking Sandy to the northeast, out to sea, but a substantial number predicting a landfall in the Northeast or mid-Atlantic states of the U.S. The white line shows the official GFS forecast, run at higher resolution.


Figure 3. Morning satellite image of Tropical Depression Nineteen.

Tropical Depression Nineteen in the middle Atlantic
There has been little change to Tropical Depression Nineteen since it formed Monday in the middle Atlantic. TD 19 has a modest area of heavy thunderstorms, as seen on visible satellite images, and dry air from an upper-level low pressure system on its west side is slowing development. TD 19 is moving north-northeast at 15 mph, and has moved over waters that are 27°C, a full degree cooler what the storm had to work with on Monday. Wind shear is a moderate 10 - 20 knots, but is forecast to increase to the high range, 20 - 40 knots, on Wednesday. Ocean temperatures will drop below 26°C on Wednesday, so TD 19 has until Wednesday morning to get its act together and develop into Tropical Storm Tony. TD 19 will not threaten any land areas, and will likely be dead by Friday.


Video 1. Impressive weather video of the week: Baseball-sized hail splashing into a swimming pool during a hailstorm in South Africa on Saturday, October 20, 2012. The action gets interesting at about 1 minute into the video.

Tonight (October 23), PBS Frontline airs "Climate of Doubt", which examines the politics of climate change, and how a once generally accepted fact--that humans have contributed to, if not caused, global warming--has been dismissed by many politicians. It's on at 10 pm here in Michigan, but times may vary, depending upon the station.

Jeff Masters

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Quoting Hurricane1956:
Morning!! Largo,don't understand why there is not Tropical Storm watch for the interior of South Florida??,as per the 5:00 AM discussion the NHC said the models keep trending west.


There IS a TS watch, actually.
Member Since: October 20, 2012 Posts: 7 Comments: 4079


Looks like Sandy is pulling NNW and "could possibly" pass just to west of Jamaica. Have to wait for the first fix from Recon
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988MB!!
Member Since: May 23, 2012 Posts: 0 Comments: 5178
Quoting TomTaylor:
00z ECMWF showing what I've been saying for days now. Has Sandy peak on Thursday night or early Friday (in terms of max winds), weakening by Saturday. I've been saying for a while now that the best conditions for Sandy to tropically intensify are in the Caribbean, after which point the ULL will shear the storm, causing it to lose tropical characteristics. People (in particularly Levi) have been insisting the storm will continue to strengthen through Friday and Saturday as the GFS has been showing, thanks to strong divergence. This divergence, however, is coupled with very strong shear. The shear and divergence will provide the storm with plenty of baroclinic energy, which will allow the surface low itself to deepen. However, since this is baroclinic energy, the storm will begin to lose it's identity as a purely tropical storm around this same time (Friday). Also, as the low deepens by baroclinic processes, the wind speeds will actually decrease, since the wind field expands under extratropical or subtropical transitions. If we see Sandy achieve her highest max wind after Friday, I guarantee it will be well removed from the center, which is an indication of the storm not being purely tropical.


Nobody ever listens.
Sure they do. As I said before, the NHC has been following your reasoning pretty much from the get-go. A lot of the discussions have been debating sub-tropical versus extra-tropical transition over the Bahamas.

However, I think Levi and others are thinking the impact of the shear on Sandy won't fully materialize before Saturday, which means there is a small window for it to strengthen again as a purely tropical entity. It's certainly possible.

I will say that based on my experience, the former scenario [yours] seems more likely than the latter; an example that comes to mind [with some limited applications] is Hurricane Michelle of 2001.
Member Since: October 25, 2005 Posts: 20 Comments: 24928
Quoting SFLWeatherman:
WOW!!



She is stacked, and although she is contending with dry air out of the GoM she has a huge battery of ammo behind her to the east....I think she can chew through the dry air and as it is entrained it wont have much of an effect as it reaches the east quads and becomes moistened.....
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65 mph winds and 988 millibar pressure in the Central Dense Overcast so far. Still not to the center.
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Today marks the 7th anniversary of Hurricane Wilma but you can tell that today is no ordinary day in S FL
Member Since: May 23, 2012 Posts: 0 Comments: 5178
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WOW!!
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1480. WxLogic
Quoting GTcooliebai:
Thanks for continuing the run for me. Sandy looks great this more, nice CDO.



Eye should appear as soon as long as it stays long enough over water.
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The SUN is up!!
Member Since: May 23, 2012 Posts: 0 Comments: 5178
Miami NWS Disco

IT IS STILL TO EARLY TO GIVE A RAINFALL TOTAL FOR SOUTH FLORIDA
DUE TO THE UNCERTAINTY OF THE SIZE THAT SANDY WILL BE BY THE TIME
IT GETS INTO THE BAHAMA ISLANDS. HOWEVER...THE BEST COVERAGE OF
RAINFALL FROM SANDY WILL BE OVER THE EAST COAST METRO AREAS
STARTING LATE TONIGHT THROUGH FRIDAY WITH A FEW RAIN BANDS
POSSIBLE SETTING UP OVER THE EAST COAST METRO AREAS AND THE
ADJACENT COASTAL WATERS.
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Quoting ncstorm:
Euro Wind Fields--



Thanks for continuing the run for me. Sandy looks great this more, nice CDO.

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tail of sandy could cause the most life loss
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Quoting SFLWeatherman:
That SUN is coming!!!



gonna be interesting to see the cloud tops as we get the morning sun shining across while the floater takes the photo :)
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Quoting breald:
What are the odds that the jet stream pulls this storm towards New England for a major nor'easter type storm? The local weather people are being cautious but not trying to hype it.

its like they are afaird to say it in case we get lucky andit goes out to sea but when u have so many models now calling for it . i say one this morning already saying it will go out to sea not chance it will make a hit here
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1473. ncstorm
Euro Wind Fields--



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Morning blog update on Sandy and Tony. Check it out.

Gotta go now though.
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Kingston, Jamaica, I know a storm is approaching but 114 mph? LOL


6:00 AM 75.2 °F 75.2 °F 100% 29.53 in 6.2 mi North 113.9 mph - N/A Rain Light Rain
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European Model Wind Field:

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Quoting breald:
What are the odds that the jet stream pulls this storm towards New England for a major nor'easter type storm? The local weather people are being cautious but not trying to hype it.

Well, considering our most reliable model shows it, and half of the ensembles of our second most reliable model show it, I'd say the chances are in the neighborhood of 55%.
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1467. breald
What are the odds that the jet stream pulls this storm towards New England for a major nor'easter type storm? The local weather people are being cautious but not trying to hype it.
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Good morning everyone, Sandy looks good this morning. The HH could find Sandy to be a hurricane this morning, if not she will be one later today.
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1465. WxLogic
Good Morning... Looks like the HH is almost there.
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That SUN is coming!!!
Member Since: May 23, 2012 Posts: 0 Comments: 5178
I do wish the best for the New England states, but I have to say I do miss Sturbridge......If it does hit I guarantee I get deployed, and I will end up right back where I was at for Irene :)

Once this house is paid off in Mobile I plan on staying in the N.E. states during the summer months so I can get the hell out of this hot sauna I call home (Mobile, Alabama) :)
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1462. barbamz
Good morning abroad! Recon mission No 4 is slowly approaching Sandy.
google earth: http://www.tropicalatlantic.com/recon/ge/Atlantic. kmz
It has just reached the south coast of Jamaica.
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1461. beell
Should be interesting to watch Sandy encounter her first test of adverse conditions today as dry air trying to wrap in and southwesterly shear go to work. So far, so good.

Approach of the upper trough, less than ideal conditions, and a date with land interaction may make it hard to lose her lop-sided-ness today.

Member Since: September 11, 2007 Posts: 158 Comments: 18949
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Quoting Tazmanian:





EVERE ONE IS STILL SLEEPING OR GETING READY FOR WORK OR SCHOOL




GET A LIFE MAN WE CANT BE ON THE BLOGS ON THE TIME





You're hurting my ears Taz.
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1457. ncstorm
uggh..where is my COFFEE!

Good Morning..I see the GFS is still on the solution in making the NE turn later and coming very close to NC now..


Full Moon is just two days away and thats not good with an approaching TC and high tide together..
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1456. aimetti
well if it actually does hit us here in southern new england I guess its good that most of the leaves have fallen already.
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tony means 5 after the halfway pt my character picked 4 what about your character?
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lucky she is running out of room
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Quoting Maineweatherguy20023:
Blog is DEAD EVEN THOUGH WE HAVE A STORM TO TRACK!!!



lol its 7:00 am your time, 6:00 here in mobile, 5:00 mst, and 4:00 pacific time....everyone is either a) still asleep, b) waking up stumbling to the coffee pot, or c) getting a shower to get their butts to work :)


lol
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Quoting Thing342:
Hey, does anyone know where I can find the T-numbers for Sandy & Tony?


Link

Link

Link
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Tony looks rather interesting this morning:

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Blog is DEAD EVEN THOUGH WE HAVE A STORM TO TRACK!!!
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1447. Grothar


Member Since: July 17, 2009 Posts: 74 Comments: 29879
1446. Grothar
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1445. air360
All the Euro has to do is take one little jog to the left and it is bye bye Outer Banks - Yikes
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Yes!
Quoting hunkerdown:

I assume you mean NEXT Wednesday...today's forecast is cloudy with rain showers and a high in the mid 80s.
Member Since: May 23, 2012 Posts: 0 Comments: 5178
Good morning. Looks like the models didn't clarify much for us overnight. Sandy looks good right now, lots of deep convection meaning very heavy rain on the way for Jamaica, eastern Cuba, and Haiti:

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1442. Grothar
Member Since: July 17, 2009 Posts: 74 Comments: 29879
Quoting SFLWeatherman:
Is this S FL?? WPB!!
Wednesday

Clear. High of 75F. Winds from the NNW at 5 to 15 mph.

I assume you mean NEXT Wednesday...today's forecast is cloudy with rain showers and a high in the mid 80s.
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Quoting Thing342:
Hey, does anyone know where I can find the T-numbers for Sandy & Tony?
Link If you click on the storm name you will also find the floaters
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1439. Grothar
Member Since: July 17, 2009 Posts: 74 Comments: 29879

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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