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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Someone posted this site on here this morning..I hope it doesnt happen..we're in big trouble if it does....Link
Member Since: September 8, 2005 Posts: 0 Comments: 1382
Quoting stormwatcherCI:
For future reference if I need it how do you delete a post ? TIA


Click the modify button, you may need to do it more than once. You can delete what was origionally there, but you have to have something, just a period will do.
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Quoting twhcracker:


do they tell you if they ban you for life??


you seem more concerned about how long you will be banned than you are getting rid of the post that may cause you to be banned

the longer you keep it up there, the longer you will likely be banned

If I were you I would get rid of it now.
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting Ossqss:


Click the modify button under your comment and delete the text
Thanks and to aquak9 also.
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I updated my blog on 90L, tell me what you think!

http://www.wunderground.com/blog/winter123/show.html

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i didnt know i could delete. will try and do it now. thanks
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578. xcool
twhcracker no
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting stormwatcherCI:
For future reference if I need it how do you delete a post ? TIA


Just go to your post and click on the "modify comment" button. You can then either substitute something else or just leave a single letter or punctuation mark. I don't believe it will let you leave a complete blank space.
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576. xcool
pottery haha no?
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting pottery:

That's not true///
How do you know that?


do they tell you if they ban you for life??
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twh- go back to that post, click on "modify" and type something new. You'll get to come back if you're banned, after a day or two....just some bloggers will lose respect for you, this is Dr. Master's blog and we should conduct ourselves accordingly.
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Quoting twhcracker:
i apologize. i heard it on the Jon Stewart show.


Click the modify button under your comment and delete the text
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Quoting WaterWitch11:



why? i just think you should delete it so you don't get banned.
For future reference if I need it how do you delete a post ? TIA
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Storm, that one made me laugh out loud. Just showed our floor director your post. It was great meeting you on Saturday, but no, that one I caught "on my own"! :P Have a great night!
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Quoting pottery:

That's not true///
How do you know that?
I think that is just a bit of "Fear Factor"
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Quoting xcool:
twhcracker ban for life...

That's not true///
How do you know that?
Member Since: October 24, 2005 Posts: 0 Comments: 23080
Quoting stormwatcherCI:
Thank you and it didn't hurt a bit now did it ?
Lol. Not at all.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting twhcracker:
i apologize. i heard it on the Jon Stewart show.



why? i just think you should delete it so you don't get banned.
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Quoting twhcracker:


omg i have never been banned. what will happen if i am banned?? can I come back?
LOL, if it's the first one should only be for 24 hours and almost everyone has been there at some point. Even the esteemed 456 and myself.
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Quoting stormhank:
Hey Kman how are you today?? been hot n sultry up here in fla panhandle


Hi there

Hard at work in the office but wrapping up now :-(

We have the hot and sultry stuff here as well, along with the odd shower. The end of May is when we start to see things develop in the SW and NW Caribbean IF anything starts early in the season. However, until 90L decides what it is doing and gets out of the way shear values across all but the very extreme Southern Caribbean will likely remain too high for anything tropical to organise.

It will be interesting to see if the GFS does better on the May 29th set up it is seeing than it did recently for the SW Caribbean that did not materialize.
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Quoting Patrap:
Well John Goodman,James Carville and Sandra Bullock my neighbors here Uptown ,along with James Rivers are real paupers I hear.

JF and I kinda live a tad east of them.

And they never ask us to dinner neither.

Goodman shops at Walgreens and Winn Dixie and parked in a Handicapp spot too.


And he is HUGE.


what about Brad Pitt!! And Ann Rice.
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563. xcool
twhcracker ban for life...
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting Patrap:
www.wwltv.com NOLA CBS LIVE NEWS


the damage that is being done that you can't even see
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Quoting MiamiHurricanes09:
Well there is a lot of factors going for a system developing in the Caribbean late this week/beginning next week. Below I will list them "in-depth".

Hot SSTs (Sea surface temperature): Temperatures in the SW Caribbean, where this development should take place, are reaching to about 30C (86F). This waring pattern should continue as per models.

Low shear: Normally during this time of year there is a large wide band over the caribbean of heavy shear, it's a complicated subject so we're not going to get in to that. This band has been lifting northward and thining thus development down there should be probable. Currently anything below 20N has a chance of development.

Good model support: Several good models have been showing development in this region so it's no surprise. I now expect more models developing this system.

Upward MJO pulse (Madden-Julian Oscillation): This moistens up the enviorment, so the chances of this system developing go up. We are curently in one plus a stronger one is expected to come through.

With so many factors in favor of a system developing I would be surprised if we didn't at least get an invest down there, if models are correct.
Thank you and it didn't hurt a bit now did it ?
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Is it, "dont run with Glitter", and "decorate with scissors"...or the other way round ?

I get confused so easily sumtimes.
Member Since: July 3, 2005 Posts: 414 Comments: 125540
i apologize. i heard it on the Jon Stewart show.
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Quoting WaterWitch11:
twhcracker hon, you might get banned for that one.


omg i have never been banned. what will happen if i am banned?? can I come back?
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Quoting kuppenskup:
I heard this morning they found two new tar balls in the keys. At first they thought they came from the oil spill but after further observation it turns out they belong to Tiger Woods. Seems him & his wife were fishing in the keys last wknd and she got mad and cut em off. Then they happened to wash up on shore this morning.

If this one didnt result in a ban, that one wont...
I flagged it, by the way.
Member Since: October 24, 2005 Posts: 0 Comments: 23080
family site, twh- please modify
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Great graphics AllStar!
Member Since: September 10, 2007 Posts: 0 Comments: 10578
www.wwltv.com NOLA CBS LIVE NEWS
Member Since: July 3, 2005 Posts: 414 Comments: 125540
Quoting kmanislander:
The first ban of the pre-season may not be far away.
Definetly.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Hey Kman how are you today?? been hot n sultry up here in fla panhandle
Member Since: September 8, 2005 Posts: 0 Comments: 1382
Quoting JFLORIDA:
That question Dr M took on rain and oil was interesting - I didnt think about sea spray. That would be a real mess.


In Opal Seaspray killed trees for miles inland.
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Quoting stormwatcherCI:
I agree. Make it public. It is just your opinion and not set in stone so no reason not to publicize it.
Well there is a lot of factors going for a system developing in the Caribbean late this week/beginning next week. Below I will list them "in-depth".

Hot SSTs (Sea surface temperature): Temperatures in the SW Caribbean, where this development should take place, are reaching to about 30C (86F). This waring pattern should continue as per models.

Low shear: Normally during this time of year there is a large wide band over the caribbean of heavy shear, it's a complicated subject so we're not going to get in to that. This band has been lifting northward and thining thus development down there should be probable. Currently anything below 20N has a chance of development.

Good model support: Several good models have been showing development in this region so it's no surprise. I now expect more models developing this system.

Upward MJO pulse (Madden-Julian Oscillation): This moistens up the enviorment, so the chances of this system developing go up. We are curently in one plus a stronger one is expected to come through.

With so many factors in favor of a system developing I would be surprised if we didn't at least get an invest down there, if models are correct.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
549. xcool



new 18z


Member Since: September 26, 2009 Posts: 2 Comments: 15603
I'll assume that NOAA will release their outlook this thursday,,,wonder what their numbers will be??
Member Since: September 8, 2005 Posts: 0 Comments: 1382
Quoting AllStar17:


Yes. I'll answer it later.

This is the current position of 90L per the W-Underground main tropical site.


THANKS SOOOO MUCH!!!
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twhcracker hon, you might get banned for that one.
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Quoting cyclonekid:

Hi.
Did you get my email?


Yes. I'll answer it later.

This is the current position of 90L per the W-Underground main tropical site.
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The first ban of the pre-season may not be far away.
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Quoting reedzone:
Looking at the northeast side of 90L, some deep storms trying to blow up, I think if 90L get's going, it's gonna be tonight, we'll see.
well, people have been saying that for awhile.
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542. xcool
yeah 91l come soon in 72hr imo and models too
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting CybrTeddy:
Most likely going to see 91L in this area..



Classic cloud pattern beginning to take shape, I expect something there in either the Caribbean or EPAC within the next 7 days
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Most likely going to see 91L in this area..

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Quoting stormhank:
That area of weather down near central america suppose to develope in carribean??


The GFS brings a 1008 mb low across Central America in the vicinity of the border between Guatemala and Honduras, takes it into the Gulf of Honduras and then NE across the Cayman Islands and into the Atlantic in the 29th to 30th May date range.

Remains to be seen how this verifies.

29th May



30th May



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TY Miami 09, lots to think about and as usual, wait and see. Tks again
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Quoting Hardcoreweather2010:
18Z model runs



Anyone have any thoughts on NOGAPS taking 90L back south and east after the move to the northwest? (NGPI = nogaps, NGXI = 6 hr interpolated) Bad init?
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Quoting Minnemike:

blocking the camera... it's working too.. BP crisis management.

Yep. Switching the camera to different views to create the illusion that they are doing something other than marking time until the relief well is done.
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Quoting reedzone:
Maybe it's me.. but I can see a new well developed center forming right underneath the new convection, see how it's starting to roll around?

Possible center relocation around 31N 68W


The upper level low is closing in on it, which means it's best chance for transition is TONIGHT! We'll see what happens, but I think a center may form there do to deep convection trying to wrap around that location.


Agreed on the new center forming, but I still think it won't transition till at least this time tomorrow.
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About JeffMasters

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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