First Atlantic Invest, 90L is here; oil now 350 miles west of Key West
An extratropical low pressure system has developed a few hundred miles northeast of the Bahamas today, and has been designated as the first "Invest" of the year (90L) by the National Hurricane Center. (For those of you who were wondering, a discussion of what an "Invest" is can be found in the Tropical Cyclone FAQ). This low has the potential to develop into the season's first named storm--Alex--and could be a threat to the Southeast U.S. coast by Tuesday. Wind shear is currently 40 knots over the low, and the high shear ripped apart a low level circulation that was attempting to form this morning. Water vapor loops show a large amount of dry, continental air exists to the west of the storm, and this dry air will hamper transition of 90L to a subtropical storm. This system is expected to move slowly northwestward towards the Southeast U.S. coast, and could bring 20 - 30 mph winds and heavy rain to the coast of North Carolina by Tuesday. While the storm will initially form in a region of high wind shear and be entirely extratropical, it will move into a region of lower wind shear in a gap between the polar jet stream to the north and the subtropical jet stream to its south early next week. At that time, the low will be positioned near the warm waters of the Gulf Stream, and will have the opportunity to develop a shallow warm core and transition to a subtropical storm. The models are divided on whether the storm will eventually make landfall on the Southeast U.S. coast 5 - 7 days from now, and it is too early to offer odds on this occurring. The counter-clockwise flow of air around this low will probably lead to northeasterly winds over the oil spill region Tuesday through Wednesday, keeping oil away from the coasts of Alabama and the Florida Panhandle, but pushing oil southwards towards the Loop Current. Wunderbloggers Weather456 and StormW have more detailed discussions of the potential development of 90L.
Figure 1. Visible satellite image of 90L this afternoon.
Potential heavy rainfall threat to Haiti next week
Long-range forecasts from the NOGAPS model, and to a lesser extent, the ECMWF and GFS models, continue to predict an increase in moisture and decrease in wind shear over the Western Caribbean 4 - 6 days from now, leading to development of a tropical disturbance with heavy rains in the Western Caribbean early next week. A strong subtropical jet stream over the southern Gulf of Mexico will steer the disturbance to the north and east, and the potential exists for heavy rains of 2 - 4 inches to affect eastern Cuba, Jamaica, Haiti, and the Dominican Republic in the Wednesday - Thursday time frame next week. The models are less enthusiastic about the prospects for tropical development than they were in yesterday's runs, and it currently appears that high levels of wind shear will make formation of a tropical depression improbable.
Oil spill continues to impact Louisiana shores
Light southeast to east winds are expected to blow over the northern Gulf of Mexico today through Sunday, resulting in potential oiling of Louisiana shorelines from the mouth of the Mississippi River westward 150 miles, according to the latest trajectory forecasts from NOAA. These winds may be creating strong enough surface currents that the flow of oil southwards towards the Loop Current may be significantly reduced or shut off over the next few days, as suggested by the latest SAR satellite imagery (Figure 2). However, winds will shift to offshore out of the north or northeast by Tuesday, due to counter-clockwise flow of air around the approaching 90L storm. If 90L becomes strong and lingers off the Southeast U.S. coast for several days, a significant amount of oil could get pumped into the Loop Current next week.
Figure 2. Synthetic Aperture Radar (SAR) image of the oil spill taken at 11:53pm EDT May 20, 2010, by the European Space Agency's ENVISAT satellite. The plume of oil being drawn south towards the Loop Current appears truncated, and very little oil may be flowing south. 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.
Oil now 350 miles due west of Key West
Satellite imagery from today's 12:15pm EDT pass of NASA's Terra satellite (Figure 3) shows that a narrow ribbon of oil is caught in the Loop Current. The oil has moved south and then southwest, and the leading edge of the oil is now about 350 miles due west of Key West, Florida. The oil is substantial enough to modify the cumulus clouds in the Gulf of Mexico, though NOAA characterizes this portion of the oil spill as "numerous light sheens with some emulsified patties and streams." The oil is now headed away from the Keys towards a major kink in the Loop Current. By Saturday, the oil should double back towards the Keys in a eastward flowing branch of the Loop Current, and will likely pass just south of Key West by Tuesday. However, this is not a sure thing. 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. This event could occur today or tomorrow, in which case the ribbon of southwestward-moving oil would turn due west and then north, eventually winding up back near the site of the Deepwater Horizon blowout. 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. Even if a Loop Current Eddy forms today, I still expect we will see some oil make the turn eastward and flow past the Florida Keys by Wednesday.
Figure 3. Visible satellite image from NASA's MODIS instrument for 12:15pm EDT May 21, 2010. I've enhanced the region along the eastern boundary of the Loop Current showing the south and southwestward moving ribbon of oil. Note that the oil is substantial enough to be affecting the low level cumulus clouds along portions of the ribbon of oil. The oil has reached the latitude of 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 Saturday afternoon.
Jeff Masters
Reader Comments
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Pat? Aggie? You in?
Candle Light Vigil for Victims of Explosion
Added by Dinah Rogers, The Times-Picayune on May 21, 2010 at 12:50 PM
KERRY MALONEY / THE TIMES-PICAYUNE A candlelight vigil was held Thursday night on the steps across from Jackson Square to to morn the loss of life in the Gulf since the Deepwater Horizon oil rig exploded in the Gulf of Mexico. About one hundred people showed up to raise awareness of the problem still facing the Gulf.
INV/XX/90L
MARK
24.89N/71.11W
no...hence
(from your own numbers)
Models are showing a system in the SW Caribbean with T.S strength so if Alex does develop this would be Bonnie, as per models.
The learning curve is way too steep for these nutbags running BP in the Louisiana Cleanup/response.
They just about to get replaced with Trawlers,Crabbers..with white shrimp boots and wind torn faces of wisdom and hurt.
Oily ones.
....and mo Lawyers than Brooklyn and Dallas have combined.
I noted it may meander earlier since it was embedded in weak steering flow
Also did you see the post, the center you had 25N/71.1W was correct and inline with GOES cloud drift winds.
Hurricane! good to see you on!
90L is naked, and the convection is being sheered away, and a lot of dry air is moving in.. Doesn't look good to me
I don't give percentages because they are too precise and exact and this is not an exact science.
There is a moderate chance of it becoming STS or TS Alex.
Hmmm, wouldn't that have to be the Lafourche parish pres?
LOL! Thank you.
Here are my early thoughts regarding 90L looks semi-impressive now. I will be following the global models because without a well defined LLC we got nothing. We can be confident that we will have a storm near the Carolinas(sorry Press) in a few days as far as Florida... right now I just dont think so, I believe it will be picked up and scooted off.
I like your approach, you are indeed a true weatherman, great to have on board for the 2010 Season.
The Times-Picayune's Outdoors Editor Bob Marshall explains today's news on the BP oil spill in the Gulf of Mexico in this video.
Semi impressive sums it up
Not really...
Cant we all just get along...WHILE WE BOTH BEAT FSU...
A) Numerical model forecasters: those that depend on models as guidance
B) Climatological forecasters: those that depend on climatology as guidance
C) Analogical forecasters: those that depend on analogies with past events
D) The fourth group utilizes all three...
I normally find myself in group C but I utilize all three.
Which one are you mostly found yourself in?
It would, but the way Nunguesser's been going, I wouldnt put it past him.
(And good on him for it.)
You skipped Wishcasters... lot of them here also :)
lurkers are always welcomed to throw in their 2 cents :)
B i am honestly always preaching climatology
LMFAO! That one made my night :)
Sadly yes. But FSU sucks right can we agree there...
Hmmm, I lean towards A, but while looking for reasons to doubt the models' result...I suppose.
Wasn't sure how to answer, though, I'd accept anyone else's notion easily...
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