Little change to 90L; flow of oil southwards towards Loop Current shuts off
An extratropical low pressure system a few hundred miles northeast of the Bahamas (90L), has changed little over the past day. (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 depression or subtropical storm, and could be a threat to the Southeast U.S. coast by Tuesday or Wednesday. The SHIPS model predicts that shear will be in the high 30 - 40 knot range through Tuesday, though. The high shear combined with the large amount of dry air to 90L's west seen on water vapor satellite loops will greatly hamper transition of this system to a subtropical storm. This system is expected to move slowly north and then northwestward towards the Southeast U.S. coast over the next three days, and could bring 20 - 30 mph winds and heavy rain to the coast of North Carolina by Tuesday night. Most of the models indicate that Wednesday will be when 90L gets closest to the coast, with a position just off the North or South Carolina coast. All of the major models currently indicate that 90L will not make landfall, but will move slowly northeastward out to sea late next week as a trough of low pressure moving across the Eastern U.S. picks up the storm. 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 by Wednesday. 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 counter-clockwise flow of air around this low will probably lead to offshore 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.
Heavy rainfall threat for Haiti diminishes
Moisture is expected to increase across most of the Caribbean next week, leading to seasonally heavy rains across much of the region. A concentrated tropical disturbance capable of bringing dangerous flooding rains to Haiti is no longer being indicated, but the normal heavy rains that we can expect this time of year will likely begin affecting the island over the next several weeks.
Flow of oil southward towards the Loop Current shuts off
Light southeast to east winds are expected to blow over the northern Gulf of Mexico today through Monday, 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 shut off the flow of oil southwards towards the Loop Current, as seen in the latest SAR satellite imagery (Figure 2). However, winds will shift to offshore out of the north or northeast Tuesday and Wednesday, due to counter-clockwise flow of air around the approaching 90L storm. This wind direction change should give some relief to the hard-hit Louisiana coast. 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 late next week.
Figure 2. Synthetic Aperture Radar (SAR) image of the oil spill taken at 8:53am EDT May 22, 2010, by the Canadian Radarsat-1 satellite, operated by MDA GeospatialServices of Richmond, Canada. The plume of oil being drawn south towards the Loop Current has been cut off. 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 threat to the Keys uncertain
Satellite imagery from today's pass of NASA's Terra satellite and the European Envisat satellite were inconclusive as to the presence of oil in the Loop Current. It is likely that the oil has dispersed significantly over the 500-mile course it has taken from the site of the Deepwater Horizon blowout. I expect some oil is close to completing the full loop of the Loop Current and is now headed east towards the Keys, as depicted in the "Uncertainty" area in the latest NOAA 72-hour offshore trajectory forecast. If this estimate is correct, the Keys could see oil as early as Wednesday. 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, and they note in today's discussion that there appears to be a developing eastward flow of water directly from the Yucatan Peninsula to the Florida Keys. 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. My guess is that the oil will be too thin and scattered to cause significant problems in the Keys, but there is great uncertainty on this.
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 Monday morning.
Jeff Masters
Reader Comments
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 — Blog Index
I'm not liking this: the SSTs near the Bay of Bengal are as warm as 34C. Should a tropical cyclone form near India and enter the area, the results could be devastating. Also, the northwest quadrant of 90L will likely tap into the Gulf Stream on Wednesday, which would provide an extra boost for the baroclinicly-driven storm.
90L has turned into a fairly large system, with two convection centers, with the southeast center feeding moisture and heat into the main northwest center, and an extra stream of moisture feeding in from the warm Caribbean. Kind of reminds me of Philippe (September 22, 2005), but even larger.
The area near the coast of the Carolinas and New England, and has a miniscule chance of developing near the warm-cold boundary of the Gulf Stream, looks interesting on the visible and has some circulation. Computer models merge this system with 90L.
..Now orange Circles-o-doom,
The Drama is palatable..
yaWNnnn......
Stretch..
18z
My feeling zactly on dat one scott39..and im a Veteran,,enlisted.
Rather it indicates the improvement of conditions around 90L are improving.
Should be a pretty clear cut verdict. It gets a name or it doesn't. Not much wiggle room there, lol.
I thought they had all figured that out long time.....
heheheheh
Its May..
!!!!!!!!WE HAVE A CODE ORANGE I REPEAT WE HAVE A CODE ORANGE EVERYONE BE ON ALERT!!!!!!!!!!!!
WARNING WARNING WARNING WARNING WARNING WARNING
Well those colors, while an improvement from before, are still on the low end of the graph.
I can tell ya from a unique perspective. The PC's yesterday were strained at best...between BP the CG,Thad Allen and the State.
And the Holiday weekend to come,and the media front row in the News cycle this week is gonna show America and the World just how Bad this situation is becoming.
The Pucker factor for BP is about to increase like a Well run wild.
The 00z coordinates have come in. 90L continues to strengthen too, pressure now at 1006 MB and winds have increased to 40 MPH.
A wind shear forecast for 14 days is not very reliable
But I will still tell you what it says.
The subtropical jet remains in place around 30N (high shear)
Low shear dominates below 20N throughout the Basin due to the sub-equatorial ridge.
Low shear is also found where the subtropical and polar jet stream split near 40N but that is not in the tropics.
Shear over the GOM changes with each transient frontal trough.
This is a fairly seasonal pattern
It certainly opens up the deep tropics for development early in the season.
June 8
The negative tilt is lining the shortwave up to close-off and phase(merge) with the trough-split currently beginning to take place over Virginia. The shortwave will likely slingshot a piece of upper energy off to the east, which will look like a frontal extension off of 90L, but it won't really be.
You can already see this piece of energy taking shape within the cloud-shield east of 90L's center. There is a low-level vorticity max associated with it as well, indicating a surface disturbance.
And it verified nicely.
Nicely done. Thanks.
See post 1830. Hopefully that helps.
2km Storm Relative IR Imagery with BD Enhancement Curve
ABNT20 KNHC 240024
TWOAT
SPECIAL TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
825 PM EDT SUN MAY 23 2010
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
A NON-TROPICAL LOW PRESSURE SYSTEM CENTERED ABOUT 500 MILES
SOUTH-SOUTHWEST OF BERMUDA IS PRODUCING A LARGE AREA OF
DISORGANIZED SHOWERS AND THUNDERSTORMS OVER THE SOUTHWESTERN
ATLANTIC OCEAN ALONG WITH GALE-FORCE WINDS. THIS LOW IS EXPECTED
TO MOVE SLOWLY TOWARD THE NORTH-NORTHWEST AND HAS SOME POTENTIAL
TO GRADUALLY ACQUIRE SUBTROPICAL OR TROPICAL CHARACTERISTICS DURING
THE NEXT COUPLE OF DAYS. THERE IS A MEDIUM CHANCE...30
PERCENT...OF THIS SYSTEM BECOMING A SUBTROPICAL OR TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. FOR ADDITIONAL INFORMATION...PLEASE SEE
HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER
AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC. THE NEXT
STATEMENT ON THIS SYSTEM WILL BE ISSUED BY MIDDAY MONDAY.
$$
FORECASTER BLAKE
Looks like they are averaging between the obvious spin that has been the center and an area of independent low-level turning near 27.5N, 70W.
SO IS THAT GOOD NEWS FOR THE POSSIBLE 91L IN THE SW CARIBBEAN NEXT WEEK?
convection alot..yayyyy
Sounds like you are getting desperate for one to come your way...
Looks like a baroclinic low with a nice deformation zone haha.
so it says 35 1006
That is 40mph?
Viewing: 1801 - 1851
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 — Blog Index