90L heads for North Carolina, drenches Bermuda; oil spill changing little

By: Dr. Jeff Masters , 2:54 PM GMT on May 24, 2010

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An extratropical low pressure system (90L) between the Bahamas and Bermuda is moving north-northwest towards North Carolina and is close to tropical storm strength. Last night's ASCAT pass saw a large area of 35 mph winds to the north and east of the center, and buoy 41048 to northeast of 90L's center was seeing sustained ENE winds of 36 mph, gusting to 43 mph this morning. Bermuda is seeing some heavy weather from this storm, with winds blowing at 35 mph on the west end of the island, and the Bermuda radar showing an area of moderate to heavy rain moving over the island. Seas are running 5 - 10 feet in the outer waters of Bermuda today, and are expected to increase to 10 - 14 feet tonight before diminishing on Tuesday.


Figure 1. Visible satellite image of 90L this morning.

Strong upper-levels winds out of the west are creating about 25 knots of wind shear over 90L, but the shear has been gradually decreasing over the past day. Visible satellite loops show that 90L does not have a well-defined surface circulation. The main thunderstorm activity is in a large curved band to the north and northeast of the center. This band is several hundred miles removed from the center, which is characteristic of subtropical storms. I expect that 90L will continue to grow more subtropical in nature today through Wednesday as the shear continues to fall. Sea surface temperatures are near 25°C today and will fall to 23 - 24°C on Tuesday. This is warm enough to support a subtropical storm, but probably not a tropical storm. On Wednesday, 90L will be nearing the warm waters of the Gulf Stream, and SSTs will warm again, to the 24 - 25°C range. This is still pretty cool for a tropical storm, and I expect 90L will never become fully tropical. To understand the difference between a tropical and subtropical storm and why we care, see my subtropical storm tutorial.

The SHIPS model predicts that shear will fall to the medium 10 - 20 knot range by Tuesday. A large amount of dry air to 90L's southwest associated with the upper-level trough of low pressure on top of the storm, as seen on water vapor satellite loops , will hamper transition of 90L to a subtropical or tropical storm. The system will move slowly towards the Southeast U.S. coast over the next two days, making its closest approach to the coast on Wednesday, when most of the models indicate the center will be 200 - 400 miles southeast of Cape Hatteras, North Carolina. All of the major models currently predict that 90L will not make landfall, but will move slowly eastward out to sea on Thursday, when a trough of low pressure moving across the Eastern U.S. picks up the storm. There presently isn't much to be concerned with about this storm, as it appears that it will remain offshore and will become, at worst, a 40 - 50 mph subtropical storm. The National Hurricane Center (NHC) is giving 90L a medium (30% chance) of developing into a depression or tropical/subtropical storm. Wunderbloggers Weather456 and StormW have more on 90L.

Western Caribbean disturbance
A small region of disturbed weather has developed in the Western Caribbean, off the east coast of Nicaragua. Moisture is expected to increase across in this area in the coming days, and by Saturday, the GFS and NOGAPS models predict that shear will drop low enough to permit the possible development of a strong tropical disturbance or tropical depression. This storm would then move northeastward over eastern Cuba early next week. The other models keep the shear high in the Caribbean all week, and do not show anything developing. Thus, the Western Caribbean bears watching later this week, but the conditions appear marginal for development.

Moderate risk of severe weather today in northern Plains
The Storm Prediction Center has placed western Nebraska and portions of South and North Dakota under their "Moderate" risk for severe weather today. They warn that "a couple of strong and possibly long-track tornadoes appear possible given the forecast scenario." Keep an eye on the activity today with our Severe Weather Page.

Major oil threat continues for the coast of Louisiana
Light winds are expected to prevail across the northern Gulf of Mexico all week, resulting in continued oiling threats to the Louisiana shoreline from the mouth of the Mississippi River westward 150 miles, according to the latest trajectory forecasts from NOAA. There is no longer a flow of oil moving southwards towards the Loop Current, and the oil that did move southwards last week was mostly entrained into a counter-clockwise rotating eddy attached to the northern boundary of the Loop Current. Synthetic Aperture Radar (SAR) imagery over the weekend showed that most of this oil has dispersed, and very little of this oil is now visible from space (Figure 2.) Imagery from NASA's MODIS instrument and from NOAA aircraft did not show any oil in the Loop Current headed towards the Florida Keys over the weekend, so that is good news. NOAA comments that there may be some "scattered tar balls" in the Loop Current headed towards the Florida Keys. I expect these scattered tar balls have completed the full loop of the Loop Current and are now headed east towards the Keys, and will pass the Dry Tortugas and Key West sometime Wednesday - Saturday. My guess is that the oil and its accompanying plume of toxic dispersants will be too thin and scattered to cause significant problems in the Keys.


Figure 2. Synthetic Aperture Radar (SAR) image of the oil spill taken at 11:41am EDT Saturday May 22, 2010, by the European Envisat-1 satellite. Only scattered patches of oil are evident in the counter-clockwise rotating eddy on the northern boundary of the Loop Current. A small amount of oil appears to be in the Loop Current, and is moving southward. Image credit: Center for Southeastern Tropical Advanced Remote Sensing, University of Miami Rosenstiel School of Marine and Atmospheric Science. SAR images have a resolution of 8 - 50 meters, and can be taken through clouds and precipitation.

Future threats to the Keys
Mostly offshore winds are expected this week over the northern Gulf of Mexico, thanks to the approach of the 90L storm along the Southeast U.S. coast. It is uncertain if these winds will be strong enough to push oil southward into the Loop Current, though at least one ocean trajectory model does show this occurring. As I discussed in my post Wednesday, the Loop Current is very unstable right now, and is ready to cut off into a giant clockwise-rotating eddy, an event that occurs every 6 - 11 months. At least one ocean model (the Global HYCOM model from the HYCOM consortium) is predicting that such an eddy will form this week. In the event a Loop Current Eddy does break off, it would create a rotating ring of water 250 miles in diameter to the south of the oil spill. Oil moving southwards would tend to enter the giant eddy and circulate around it, not threatening any land areas. Roffer's Ocean Fishing Forecast Service has a nice discussion on the possibility of the Loop Current cutting off into a Loop Current Eddy. Keep in mind, though, that during the first month that a Loop Current Eddy forms, it exchanges a considerable amount of water with the Loop Current. Thus we can expect that a portion of any oil moving southwards into a Loop Current Eddy will find its way into the Loop Current and move past the Florida Keys.

Oil spill resources
My post Wednesday with answers to some of the common questions I get about the spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA trajectory forecasts
Deepwater Horizon Unified Command web site
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Surface current forecasts from NOAA's HYCOM model
Synthetic Aperture Radar (SAR) imagery from the University of Miami

I'll be back with a new post Tuesday morning.

Jeff Masters

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new blowup near what looks like a mid level circulation center to me. (71W 31N)
Member Since: Posts: Comments:
Quoting SevereHurricane:


Thanks dude. Not so bad for a 15 year old, ehh?
So you're in my age group. I'm 13 and will be turning 14 later this year. BTW good job on the synopsis.
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Quoting extreme236:
Perhaps this recent activity in May over the past few years might be enough for the NHC to perhaps consider moving the starting date of the Atlantic hurricane season to some time in May.
I believe that will take place in the next five to ten years.jmo. It has been a while since you have posted.
Member Since: September 27, 2007 Posts: 1 Comments: 21852
Quoting MrstormX:

Hey look there's Alex! lol

new record for rapid intensification!
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Quoting Stormchaser2007:



Impressive synopsis.

Good job.


Thanks dude. Not so bad for a 15 year old, ehh?
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Quoting sarahjola:
yeah i remember that. so the high this season is going to push storms into the gulf? that worries me. after katrina, i don't have the money or resources to run anymore. i never ran before katrina and i will not run again. i don't know what was worse, not having a home or not being able to get back to my home town. both truly suck. my home in mandeville seems to dodge bad weather so i guess i'll be taking my chances this year.
Yeah that sucks. But the Bermuda high is more east and south so pretty much the whole gulf coast and Florida should be on guard.
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Quoting extreme236:
Perhaps this recent activity in May over the past few years might be enough for the NHC to perhaps consider moving the starting date of the Atlantic hurricane season to some time in May.

Well, It is called "Hurricane" Season. So I think they will wait until (if) we get a couple of consecutive years with Hurricanes in May.
Member Since: October 24, 2005 Posts: 0 Comments: 24674
827. DEKRE
Quoting atmoaggie:

Meteorologically, this makes no sense. Hammond never even hit 95 yesterday and did today for one hour. And that ob has a known warm bias.

Does your water freeze at 41? Boil at 221?

Something simply isn't right. Your ob or all of the official ones. Calibration or placement. (In the shade but next to a dark colored wall that gets sun?)

PWS stations are so very badly calibrated sometimes...(I know you said it was calibrated)


This is a strong statement. Obviously, I don't know the geographic situation, but just as an example, within my city, temperature differences can be quite drastic, especially in winter when differences of 10 °C are not uncommon, the colder the bigger the difference. If we have -25 at the airport and a low ice-cover on the St. Lawrence river, -15 is normal close to the river.
In summer the gradient is in reverse.
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Hey look there's Alex! lol
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Quoting all4hurricanes:
How can they say there is a low strike chance in the Caribbean when it is at near record temperatures, I'm fairly certain more than one major hurricane will pass through the Caribbean.
They can say anything they want. It does not mean it will happen.
Member Since: September 27, 2007 Posts: 1 Comments: 21852
90L is circled in yellow by the NHC and all the models show kts decreasing from now on I pretty much gave up on 90L whens the next one?
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Perhaps this recent activity in May over the past few years might be enough for the NHC to perhaps consider moving the starting date of the Atlantic hurricane season to some time in May.
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Quoting SevereHurricane:
Visible satellite imagery along with MIMIC Total Precipitable Water animations show broad cyclonic turning in the Eastern Pacific Ocean off the Coasta Rican coastline. Surface observations along with 850mb Vorticity maps from CIMSS indicate that a broad area of low pressure is forming in this area. Upper Air Maps and Water Vapor imagery indicate that this area of disturbed weather is situated under a broad anti-cyclonic circulation and that this area is embedded in an envelop of deep tropical moisture. In addition to favorable atmospheric conditions, this area of interest is sitting over very warm SST's which are in the 30C to 32C range. All the above parameters indicate that this AOI is in favorable conditions for further slow organization. In fact, the GFS, CMC, and GFDL models all develop this disturbance as soon as Thursday and eventually end up in the Northwest Caribbean where further intensification could occur as models want to build upper level sub-equatorial ridging reducing wind shear. Stay Tuned!

Photobucket



Impressive synopsis.

Good job.
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821. MZV
Drizzling in Charlotte now. It was strange to see weather coming from the northeast on the radar today.
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Quoting sarahjola:
yeah i remember that. so the high this season is going to push storms into the gulf? that worries me. after katrina, i don't have the money or resources to run anymore. i never ran before katrina and i will not run again. i don't know what was worse, not having a home or not being able to get back to my home town. both truly suck. my home in mandeville seems to dodge bad weather so i guess i'll be taking my chances this year.


Buy homeowners and flood insurance...cheaper in the long run.
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Quoting pottery:
90L was downgraded to yellow?
well well well.
I really learned a great deal from many people here, all because of 90L.
Interesting stuff...So for that I am very glad. Thanks for all the input.
I notice that 90L has not gone away, but looks like it should....
Now, on to 91L ??

In the meantime, I must say that the waves coming off Africa these past couple days dont look at healthy as 2 weeks ago. Strange.


I agree with you it is toast, but I have learned many things from this one storm. I don't think I will ever forget it even if it always was an invest. This is the first season I plan on being active for every storm so I am excited none the less.
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Quoting pottery:
90L was downgraded to yellow?
well well well.
I really learned a great deal from many people here, all because of 90L.
Interesting stuff...So for that I am very glad. Thanks for all the input.
I notice that 90L has not gone away, but looks like it should....
Now, on to 91L ??

In the meantime, I must say that the waves coming off Africa these past couple days dont look at healthy as 2 weeks ago. Strange.

I second and third that. Some of the best weather dicussions I have ever had over the last week. Weather456 and Levi had me wanting to change my forecast so many times I started to get confused haha. really enjoyed the convo between levi and drak the other day.
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Quoting all4hurricanes:
How can they say there is a low strike chance in the Caribbean when it is at near record temperatures, I'm fairly certain more than one major hurricane will pass through the Caribbean.

I agree with you
Member Since: October 24, 2005 Posts: 0 Comments: 24674
I wonder how the bermuda high will set up this year?? could it be a 2004/2005 setup or a year of a trough off east coast that would deflect most storms??
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Quoting HaboobsRsweet:

This one has me all anixous. I really think this one has a shot. See now you all cant call me a downcaster all the time haha.


I think this AOI has a fair chance of becoming the first true topical cyclone on our side of the globe this season.
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814. beell
Quoting hydrus:
You are right. That looks like a satellite loop from last fall or winter.


Quoting Xyrus:


That does look odd. It's also not often where I see clouds/storms moving east to west over where I live.

On a more tropical note, that wave that looks about ready to move off Africa seems pretty strong.

~X~


I mean! The ULL that 90L was to move under is now over N&S Carolina and retrograding (moving west). It and 90l are kind of riding the periphery of the world's largest cut-off low over the east half of the US and extending out into the ATL. All this going on under a ridge trying to build over the center of the country. And a big trough in the west.

We're doomed!
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Quoting Drakoen:


Good thing. The subtropical jet stream will be in place north of the Caribbean.
Good for who ? You do realize that quite a few of us live in the Caribbean, right ?. j/k
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90L was downgraded to yellow?
well well well.
I really learned a great deal from many people here, all because of 90L.
Interesting stuff...So for that I am very glad. Thanks for all the input.
I notice that 90L has not gone away, but looks like it should....
Now, on to 91L ??

In the meantime, I must say that the waves coming off Africa these past couple days dont look at healthy as 2 weeks ago. Strange.
Member Since: October 24, 2005 Posts: 0 Comments: 24674
Quoting SevereHurricane:
Visible satellite imagery along with MIMIC Total Precipitable Water animations show broad cyclonic turning in the Eastern Pacific Ocean off the Coasta Rican coastline. Surface observations along with 850mb Vorticity maps from CIMSS indicate that a broad area of low pressure is forming in this area. Upper Air Maps and Water Vapor imagery indicate that this area of disturbed weather is situated under a broad anti-cyclonic circulation and that this area is embedded in an envelop of deep tropical moisture. In addition to favorable atmospheric conditions, this area of interest is sitting over very warm SST's which are in the 30C to 32C range. All the above parameters indicate that this AOI is in favorable conditions for further slow organization. In fact, the GFS, CMC, and GFDL models all develop this disturbance as soon as Thursday and eventually end up in the Northwest Caribbean where further intensification could occur as models want to build upper level sub-equatorial ridging reducing wind shear. Stay Tuned!

Photobucket

This one has me all anixous. I really think this one has a shot. See now you all cant call me a downcaster all the time haha.
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Quoting MiamiHurricanes09:
Not really. Steering has to do a lot with the location of the Bermuda high. Let me give an example:

In 2009 the Bermuda high was strong but it was very east, this in result caused many storms to curve out to sea.
yeah i remember that. so the high this season is going to push storms into the gulf? that worries me. after katrina, i don't have the money or resources to run anymore. i never ran before katrina and i will not run again. i don't know what was worse, not having a home or not being able to get back to my home town. both truly suck. my home in mandeville seems to dodge bad weather so i guess i'll be taking my chances this year.
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Quoting winter123:

Don't forget lack of shear since el nino is gone.

True, who made that map?
Member Since: Posts: Comments:
Visible satellite imagery along with MIMIC Total Precipitable Water animations show broad cyclonic turning in the Eastern Pacific Ocean off the Coasta Rican coastline. Surface observations along with 850mb Vorticity maps from CIMSS indicate that a broad area of low pressure is forming in this area. Upper Air Maps and Water Vapor imagery indicate that this area of disturbed weather is situated under a broad anti-cyclonic circulation and that this area is embedded in an envelop of deep tropical moisture. In addition to favorable atmospheric conditions, this area of interest is sitting over very warm SST's which are in the 30C to 32C range. All the above parameters indicate that this AOI is in favorable conditions for further slow organization. In fact, the GFS, CMC, and GFDL models all develop this disturbance as soon as Thursday and eventually end up in the Northwest Caribbean where further intensification could occur as models want to build upper level sub-equatorial ridging reducing wind shear. Stay Tuned!

Photobucket
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807. Xyrus
Quoting beell:
This is the oddest dang upper pattern I have seen in a while.

Link


That does look odd. It's also not often where I see clouds/storms moving east to west over where I live.

On a more tropical note, that wave that looks about ready to move off Africa seems pretty strong.

~X~
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Quoting all4hurricanes:
How can they say there is a low strike chance in the Caribbean when it is at near record temperatures, I'm fairly certain more than one major hurricane will pass through the Caribbean.

Don't forget lack of shear since el nino is gone.
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Quoting beell:
This is the oddest dang upper pattern I have seen in a while.

Link
You are right. That looks like a satellite loop from last fall or winter.
Member Since: September 27, 2007 Posts: 1 Comments: 21852
How can they say there is a low strike chance in the Caribbean when it is at near record temperatures, I'm fairly certain more than one major hurricane will pass through the Caribbean.
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803. xcool








Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting clwstmchasr:
I see the GFS 18z is robust with Caribbean development. It looks much like the 12z CMC and the NOGAPS 18z.

Yea but the GFS has been consistent with keeping it well south of Fl.


Good thing. The subtropical jet stream will be in place north of the Caribbean.
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I assume u all read that link about the 28 named storms Do any of you feel thats possible?? Im personally goin with 16 8 4..any season that could top 2005 would be an namoly..and and just in fun could lead to the retirement of a couple of hurricane forecasters
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799. xcool
yellow yayyyyy here we goooo
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Don' mean nothin' drive on...
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At the same time though I do understand that 90L is not dead and it is far from over. Hopefully Bermuda just gets some good rain they need and that is it.
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795. beell
This is the oddest dang upper pattern I have seen in a while.

Link
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Quoting CybrTeddy:


Sorry mate, but your avatar name.. lol enough said. Can I call you 'Hal'? No offense intended.. also I believe you where right about 90L from the beginning..

Haha you all can call me whatever you like. My call sign has been Smurf so names tend not to bother me haha. The name is from forecast haboobs for 4 years. They are a sight to see. One of the craziest weather events out there.
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Quoting stormhank:
does anyone agree with me on that post about wind shear during a hurricane season? true it can be a active season but when u add in troughs and upper lows etc they can cause shear to disrupt storms correct?


Honestly, there's no use in attempting to predict shear 2-5 months out. Its pretty much a wait and see thing.

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I see the GFS 18z is robust with Caribbean development. It looks much like the 12z CMC and the NOGAPS 18z.
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Quoting HaboobsRsweet:


:) good discussions though. We will see what happens tomorrow.


Sorry mate, but your avatar name.. lol enough said. Can I call you 'Hal'? No offense intended.. also I believe you where right about 90L from the beginning..
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does anyone agree with me on that post about wind shear during a hurricane season? true it can be a active season but when u add in troughs and upper lows etc they can cause shear to disrupt storms correct?
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Quoting reedzone:


I think they let go too early, but we'll see.. I'm still giving it a medium chance do to the merging of the two energys.

Or they agree with the other half of us that have said it had no chance all along.
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Quoting CybrTeddy:
If we get 27 named.. what do we Call Alpha - Zeta?
The names would be:

Alex
Bonnie
Colin
Danielle
Earl
Fiona
Gaston
Hermine
Igor
Julia
Karl
Lisa
Matthew
Nicole
Otto
Paula
Richard
Shary
Tomas
Virginie
Walter
Alpha
Beta
Gamma
Epsilon
Zeta
Eta

Above are the 27 names that would be used.

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Quoting MiamiHurricanes09:
Guess I was wrong.


:) good discussions though. We will see what happens tomorrow.
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Quoting MiamiHurricanes09:
Guess I was wrong.


I think they let go too early, but we'll see.. I'm still giving it a medium chance do to the merging of the two energys.
Member Since: July 1, 2008 Posts: 13 Comments: 7423
Quoting Hurricanes101:


Alpha - Zeta lol


Part II

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Quoting nrtiwlnvragn:
This low in the Carribean can't be the one talked about as a potential storm. Also looks like TAFB is leaning toward frontal for 90L




:)
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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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