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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yes what is it showing me and us
Anyway, things are starting to come out at what went technically wrong to cause this oil spill disaster...
Link
Notice that they initialize something down south of the Yucatan Channel. My feeling on this is, the high is setting up over the Bahamas and will the deciding factor in where this blob goes.
We are used to seeing sub tropical or non tropical lows be labeled as invests at this time of the year. Look discuss this, but dont wishcast this early.
23.836 N 70.863 W
Conditions at 41046 as of
(5:50 pm EDT)
2150 GMT on 05/21/2010:
Wind Direction (WDIR): S ( 190 deg true )
Wind Speed (WSPD): 9.7 kts
Wind Gust (GST): 11.7 kts
Wave Height (WVHT): 5.6 ft
Dominant Wave Period (DPD): 8 sec
Average Period (APD): 6.1 sec
Mean Wave Direction (MWD): ESE ( 113 deg true )
Atmospheric Pressure (PRES): 29.87 in
Pressure Tendency (PTDY): -0.02 in ( Falling )
Air Temperature (ATMP): 78.3 °F
Water Temperature (WTMP): 79.3 °F
Dew Point (DEWP): 74.8 °F
Heat Index (HEAT): 81.1 °F
There's not exactly room for wishcasting development-wise on 90L. There is a pretty high chance of it becoming subtropical storm Alex.
You know it.
And QIUKSCAT is STILL nowhere to be found!!! GOSH!
It is still a possibility yes. We are still waiting for a low to form down there, but if one does, any tropical system that develops out of it will likely stay weak due to wind shear moderating it.
..no,more.,a lil more..
DOH,,..!
BP Oil Spill LIVE FEED ROV CAM
Pretty nice actually. The dry air wrapping around the upper-level feature from the north should keep skies clear and generally nice weather. 90L will be moving off to the east and north.
No app needed.
for all yer Oil related cool updates to show your friends and co-workers.
DATE: May 21, 2010 17:31:12 CST
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East of the Yucatan? Or the Bahamas? With both systems the convection and areas of low pressure were both induced by a disturbance aloft over each system, not a front, which forced air to rise in both areas. Neither of them were self-sustaining tropical systems and thus it means nothing that convection was firing despite the shear.
This did not developed along a front. This was initiated by a shortwave that was accompanied by a front.
May 18
Models are also indicating that a trough-split scenario may give rise to a non-tropical feature east of the Bahamas basically around the same time frame.
May 19
The first solution dictates that a shortwave begins to dig across the Western Atlantic through the next 3-7 days inducing a surface trough of low pressure east of the Bahamas in the process.
May 20
Models have been indicating with good consensus, that the shortwave will begin to initiate an area of low pressure near the Bahamas as it interacts with the southern portion a dying front in two days.
Live video link from the ROV monitoring the damaged riser
nicknamed "JFV" by BP.
Is this low that the the CMC is predicting, that area of convection?:
If it is it keeps it just symmetrically warm core and shallow warm core. It it makes it to the Caribbean it should be a good source of rain.
Jindal questions spill response; Coast Guard official takes blame
After a helicopter tour with Coast Guard officials over miles of Terrebonne Parish coastline, Gov. Bobby Jindal called on BP and the federal government to act with more urgency.
From the looks of Dr. M's image, it appears Dr. Roffer has misplaced some oil...
Just as weather models are suspect beyond a few days out, I suspect that may be off 6 days out. Already there is some of the current bypassing the loop, I expect more (maybe most?) will be by about the 27th.
Not sold that HyCOM is all that good that far out with a dynamic event like the gulf loop isolating an eddy.
80% STD1 or TD1
75% STS Alex
60% TS Alex
10% Hurricane Alex (If that happens it will probably be a Vince like storm)
Nope your percentages dont total 100
How about (from your numbers)
80-85% Chance STD
75-80% Chance STS
60-75% Chance TS
20% Chance Hurricane Alex
STD: 90%
TD: 10%
STS: 75%
TD: 25%
SH: 50%
H: 50%
***SH= Subtropical Hurricane
***H= Hurricane
No I don't think it is associated with any convection yet, look east about 100 miles.
Love this site...am paid member for a few years and will continue to be BUT trying to follow these posts is really difficult. Anyone have a suggestion for maximizing this discussion area? I am totally frustrated. But then again if you have suggestions HOW WILL I KNOW?
Have a good weekend everyone.
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