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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Quoting atmoaggie:

Just have to put on the mathematician hat from time to time...the bane of many a met-hopeful.

Get past cal 2 and nothing else will slow you down.


scared me away to a career of GIS/Geography
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283. xcool
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Quoting DestinJeff:


just don't want that jackass associated with you guys in anyway shape or form.

probably correct that it is effective for the use that you need it for. and good thinking about having something simple to broadcast ... best of luck this season!


Many thanks!

BTW: I just found out how much it costs to rent 4,000 watts of portable, generator-powered lighting for use during hurricanes.

The cost per week is surprisingly affordable. And I already carry 50 gallons of gas on the roof of the van...

So...what this means is that we will be able to roll cameras during night storms.

We've also got a case of red flares, too...just in case. :)

Oz---
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There's a good chance of seeing a few isolated severe thunderstorms over Florida today,

However, the summertime pattern appears to be taking a hick in the next couple of days due to that hybrid low and a weak backdoor cold front expected to nose down the spine of the peninsula(indirectly connected with that same feature).

Quoting MississippiWx:
May 23, 2010:



May 23, 2005:



Appears that 2005 SSTs are now higher in the MDR than 2010. The MDR has slowed its rate of warming over the past 2 weeks, also allowing for the anomalies to drop.

Anomalies from the week of May 5, 2010:



Anomalies from the week of May 19, 2010:



Warming has stalled significantly across the entire Atlantic. I just went through NAO charts and didn't notice any spike to positive. The A/B high seems to be pretty strong. Could that be the culprit? Drak, StormW, or Weather456: Do you guys have any input?


Yeah that is strange. That coupled with ridges developing in the East this month despite the odds(a negative/neutral NAO/AO and a somewhat positive PNA at times).
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280. xcool



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Quoting KEEPEROFTHEGATE:
its a bad habit from my hacker days


Do tell...
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Just stopped in to catch up on the first six pages, looks like it is going to be a long season, maybe we should relax while we can. :)
Will check back in later.
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Quoting IKE:

looks to me like 90L is breaking from the front-like feature to the east. Just need one bomb of convection near the center and this should be named.
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18Z model runs

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Quoting StormW:


Yes...it's because the A/B high has been stronger...been around 1030-1032mb. I expect a recovery though, as we go into more of a negative NAO.


Thanks, Storm! I figured that was the case. Was looking at the GFS a little while ago and the A/B high seems to "disappear" in the coming week. I'm thinking the next week or two the temps will rebound significantly.
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Quoting Patrap:
Oil 70.21 a BBL..
Buy now...

Or just hit the GOM with some empty BBLs and grow yer own gas.

I was actually considering collecting some in glass jars .... I wonder if it would corrode any seal I tried to use .... Keep some for my posterity ... "See kids, this is what British people try to do to our beaches because they dont have pretty ones like we do (did)"
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Thanks,StormW.
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Quoting weathersp:


It's so derivitive..


Yea derivatives, antiderivatives, integral etc
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its a bad habit from my hacker days
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Quoting Patrap:
I see KOTG is back..

Here I found some of these for ya

................................................................................................... .........................................................

Feel free to use um .
i tried to stay away from that stuff myself
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Quoting KEEPEROFTHEGATE:
just came back i see as the blog turns been interesting today

We're in BAD need of a diversionary hurricane.
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Quoting java162:


roseau is on the west coast.almost no rain fell there but in myat least estimation at least six inches fell last night on the central and southern eastern coast

www.dominicanewsonline.com

OK, thanks.
Member Since: October 24, 2005 Posts: 0 Comments: 24653
Quoting Drakoen:


Yea. I'm not a fan of Calculus


It's so derivitive..
P.S. I am going to Millersville University for Meteorology in the fall, I got into both FSU and OU but decided to stay closer to home.
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I see KOTG is back..

Here I found some of these for ya

................................................................................................... .........................................................

Feel free to use um .
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http://www.tepcoproducts.com/avi.cfm
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just came back i see as the blog turns been interesting today
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May 23, 2010:



May 23, 2005:



Appears that 2005 SSTs are now higher in the MDR than 2010. The MDR has slowed its rate of warming over the past 2 weeks, also allowing for the anomalies to drop.

Anomalies from the week of May 5, 2010:



Anomalies from the week of May 19, 2010:



Warming has stalled significantly across the entire Atlantic. I just went through NAO charts and didn't notice any spike to positive. The A/B high seems to be pretty strong. Could that be the culprit? Drak, StormW, or Weather456: Do you guys have any input?
Member Since: Posts: Comments:
Quoting atmoaggie:

Just have to put on the mathematician hat from time to time...the bane of many a met-hopeful.

Get past cal 2 and nothing else will slow you down.


Yea. I'm not a fan of Calculus
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Storm w when do you think is the first chance for a major hurricane this year?Any chance of any majors in july?
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Oil 70.21 a BBL..
Buy now...

Or just hit the GOM with some empty BBLs and grow yer own gas.
Member Since: Posts: Comments:
256. IKE
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Quoting atmoaggie:

Just have to put on the mathematician hat from time to time...the bane of many a met-hopeful.

Get past cal 2 and nothing else will slow you down.

Cal 2 this fall =( along with Latin I and Cal based physics .... oh and marketing (industrial meteorology)
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Quoting twhcracker:


and if you find oil on your property, and some big oil company comes out and digs a well and pumps it and refines it, they only give you every fifth or eighth barrel, I forget which. So how come they get to drill offshore and the american people dont get at least the fifth or eighth barrel. *&^*&%&$

BP has become aware of that oversight and is giving them the oil now... in the GOM.
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Quoting StormW:


Aye...I mean, from what I've seen here, he knows enough about thermodynamics to not have any problems!

Just have to put on the mathematician hat from time to time...the bane of many a met-hopeful.

Get past cal 2 and nothing else will slow you down.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
250. xcool
so Caribbean storm in few days
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249. IKE
BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1645 UTC...

...SPECIAL FEATURE...

A DEEP-LAYERED LOW PRESSURE COVERS THE W ATLC NE OF THE BAHAMAS.
TWO 1007 MB CYCLONIC SURFACE CIRCULATIONS ARE CURRENTLY ANALYZED
NEAR 28N70W AND 25N69W. THE SERN CENTER IS FORECAST TO DISSIPATE
AS THE NWRN CENTER SLOWLY PROGRESSES TOWARDS THE NNW. A SURFACE
TROUGH EXTENDS THROUGH BOTH CIRCULATIONS TO TURKS AND CAICOS
ALONG 28N70W 25N68W 20N72W. THE SYSTEM REMAINS DISORGANIZED WITH
THE MAJORITY OF THE CONVECTION WELL REMOVED TO THE NE. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 22N BETWEEN 56W-62W.
SIMILAR ACTIVITY IS N OF 28N BETWEEN 62W-74W. ISOLATED SHOWERS
ARE FROM 15N-20N BETWEEN 56W-60W. GALE FORCE WINDS CONTINUE TO
THE NE OF THE SYSTEM. AT THIS TIME THERE IS A MEDIUM CHANCE...30
PERCENT...OF THIS SYSTEM BECOMING A SUBTROPICAL CYCLONE DURING
THE NEXT 48 HOURS.
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Quoting DestinJeff:


doesn't a troll on here have a handle that is similar ... ?


The call-out is handy for you guys, but it's really for network news viewers should we get a live interview.

The troll name similarity is coincidence and completely irrelevant to our cause.
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Go to this Link and animate it,watch the EPAC and Caribbean.
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246. IKE
Quoting Drakoen:


Thank You and I will be majoring in Meteorology at Florida State University this fall.


Congrats to you. You'll be about 120 miles east of me.
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Quoting Jeff9641:
Hi Guys, Expect strong to severe thunderstorms across C and N Fl today as there is very cold air aloft. Also, 90L looks like it will relocate itself along or just off the FL east coast as a disturbance that is over N and S Carolina drops down to just off the Florida coast an spawns a more potent low very near ST. Augustine it is this new low that will be much more impressive and this UL spin over S Carolina is impressive.


we have had some powerful little fast moving afternoon t-storms three days in a row now. sorta like dog days when its hot and a storm blows thru to cool it down.
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Quoting pottery:


Although I did check the weather at Canefield Airport, Roseau.
Precipitation yesterday 0"
Precipitation today 0"

What's up?


roseau is on the west coast.almost no rain fell there but in myat least estimation at least six inches fell last night on the central and southern eastern coast

www.dominicanewsonline.com
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Listening to WWL now..thanx for the update.

Spuds da man
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OK i am out now to mow my grass. We all need one thing to happen no matter who is at fault and that is to plug that dam hole from leaking. I LOVE THE FUN AND PLEASURE I get from it.



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Quoting Jeff9641:


To be honest I could care less. I'm just going off the NAM and I see what the NAM is picking up on. This next disturbance as it rotates around will form a new more potent low near the FL east coast. Whether this system moves ashore or not is mute as no matter what we will see strong to severe weather due to the cold air aloft and low lapse rates.


hey jeff who is "we" in this case? Any bad weather for the central GOM?
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Dr. Masters will be on the Spud show on WWL in a few minutes. Dont know quite when, but will give an update for anyone wanting to listen.

Believe he's going to be speaking on the possible effects of a hurricane in the gulf. Spud also mentioned 90L.

Wwl.com stream for you out of towners.
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Quoting Drakoen:


Thank You and I will be majoring in Meteorology at Florida State University this fall.


Congradulations! but Free Shoes U...


Can't help it (Canes fan).
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Quoting Drakoen:


Thank You and I will be majoring in Meteorology at Florida State University this fall.


GOOD choice I spent 5 years of my life there at FSU, youll be very happy and work right under the NWS on campus.
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Quoting wadedanielsmith:
182:

Personally, I don't think L.A. gets anywhere near as much money out of the oil as we should.

The companies come over here and drill the oil, which is our resource, and yet they make a profit that is as big as a state budget, and CEOs that make more money than an entire town's income...That guy gets paid like ten times more money in one year than most people make in their entire life times, and he doesn't deserve it.


and if you find oil on your property, and some big oil company comes out and digs a well and pumps it and refines it, they only give you every fifth or eighth barrel, I forget which. So how come they get to drill offshore and the american people dont get at least the fifth or eighth barrel. *&^*&%&$
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Thanks everyone!
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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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