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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StormW is up past his bedtime!
(me, too...G'Nite)
For the carribean, its just a wait and see. Dont get too excited if you see the GFS,GFDL or CMC or TBH any model forecast a tropical system, cause anything more than 2 days out.. forget it!!
The system off the bahamas and the carolinas has a better chance only cause its not going to be tropical
when it gets going. But will it become subtropical or tropical in 5 days or more? Well 5 days is too far out, we
do know it will be a rain maker and gusty winds 40-50mph to the N of the center. And where will it make landfall
if any? Well its too early to say that also. This may just meander around 30dg N over the next 3-5days. Too far
out to tell if this heads SW towards Florida or E with the westerlys as the subtropical Jet heads further north to 25-30N.
All in All... just wait and see, by Monday-Tuesday we will see whats happening, but for now models change.
Lol. Well naturally. I learned from the best. Thanks Teach. :D
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT MAY 22 2010
TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.
BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC...
...SPECIAL FEATURES...
AS OF 22/0300 UTC...A SURFACE TROUGH IS JUST E OF THE BAHAMAS
ALONG 30N73W 25N73W 20N71W. A 1012 MB LOW IS EMBEDDED ON THE
TROUGH AXIS NEAR 25N73W. SCATTERED SHOWERS ARE OVER THE SOUTHERN
BAHAMAS AND ALONG THE COAST OF HISPANIOLA. THIS LOW IS FORECAST
TO DISSIPATE OVER THE NEXT 24 HOURS...WHILE A NEW LOW FORMS SOME
240 NM FURTHER E. THIS NEW LOW WILL BE A DEEP LAYERED LOW WITH
AN UPPER LEVEL LOW ABOVE IT PROVIDING DIFFLUENCE E OF THE UPPER
CENTER AND CONVECTION. THIS SURFACE LOW WILL DEEPEN OVER THE
NEXT 72 HOURS AND THE PRESSURE GRADIENT WILL TIGHTEN N OF THE
CENTER. GALE FORCE WINDS ARE FORECAST TO BEGIN ON SUNDAY 1800
UTC. THE AREA OF GALE FORCE WINDS WILL MOVE N WITH TIME AS THE
LOW CENTER TRACKS N.
Yeah what he said. :) 240 NM to the east and strengthening! Quite a change from now.
Tropical Cyclone Advisory NUMBER TWENTY
CYCLONIC STORM BANDU (ARB01-2010)
8:30 AM IST May 22 2010
=======================================
At 3:00 AM UTC, Cyclonic Storm Bandu over Gulf of Aden and adjoining area remained practically stationary and lays centered near 12.5N 50.5E, or about 70 kms north of Alula, Somalia.
The Dvorak intensity of the system is T2.5. 3 minute sustained winds near the center is 40 knots with a central pressure of 994 hPa. The state of the sea is high around the system's center. System has tracked westward with a speed of about 4 knots during the past 12 hours.
The system is associated with curved band pattern. Broken intense to very intense convection is seen over Arabian sea between 11.0N to 14.0N and west of 52.0E, Gulf of Aden, and northeast Somalia in asssociation with the system. Cloud top temperature due to convection is -65 to -70C.
The upper level steering winds in association with anticyclonic circulation to the north northeast of the system center are favorable for west northwestward movement of the system over the Gulf of Aden.
The vertical wind shear is moderate and shows increasing tendency. The lower level vorticity, convergence, and upper level divergence suggest the system will maintain the same intensity for some time. Subsequently, Due to increase in vertical wind shear along with the entrainment of drier air from adjoining land areas, cooler sea surface temperature over the Gulf of Aden, and interaction with land surface the system is expected to gradually wealen the system and dissipate over Gulf of Aden during the next 48 hours.
Forecast and Intensity
========================
21 HRS: 12.5N 49.5E - 35 knots (Cyclonic Storm)
45 HRS: 13.0N 48.5E - 25 knots (Depresion)
Tropical Cyclone Outlook
=================================
In association with the low pressure area, former Laila over north coastal Andhra Pradesh and neighborhood. Broken low medium cluds embedded with moderate to intense convection are seen over the Bay of Bengal between 15-20N and east of 87.0E.
Yup. I still want to see ROV video of the kinked riser above the BOP. And I want the guy at Purdue to see it as well.
newwww
key words: "at least" ... the longer they put it off, the worse we can assume the situation to be.
Link
The flipflopping of the models over the last 24 hours leads me to believe that all interests along the East Coast from Florida to Virginia should carefully monitor the progress of this system over the next several days, as it could go anywhere within that area. Of course, it could also stay offshore. Time will tell.
Still, the GFS seems to be depicting a highly unrealistic scenario with regards to the vigorous north Atlantic extratropical low, as it absorbs Alex as it moves away from the coast in about six days.
Time Lat Lon Wind(mph) Pressure Storm type
-------------------------------------------------------------
12 GMT 05/21/10 27.5N 72.3W 25 1013 Invest
18 GMT 05/21/10 25.1N 72.9W 25 1012 Invest
00 GMT 05/22/10 24.9N 73.3W 25 1011 Invest
90L is deepening and coming to Florida
may be STS Alex...
OH MY GUARD but it may be possible
Not a bad idea on number of named storms, but probably high in the numbers of hurricanes and majors (try 15 and 5). Maybe 1 or 2 Category 5's, but that's probably about it.
530 AM EDT SAT MAY 22 2010
.SYNOPSIS...COMPLEX LOW PRESSURE MEAN CENTER NEAR 25N70W 1011
MB. THE LOW WILL MOVE N BETWEEN 68W AND 72W THROUGH TUE WHILE
TRAILING A BROAD TROUGH S TO HISPANIOLA. THE LOW WILL MEANDER
NEAR 30N73W WED.
Those coordinates...25/70...under 50+ knots of shear...
The NHC seems to think that a center reformation is possible. Perhaps that will help it a little bit?
"LONG TERM /WEDNESDAY THROUGH FRIDAY/...
MODEL SOLUTIONS CONTINUE TO WIDELY RANGE IN THE STRENGTH AND TRACK
OF AN APPROACHING HYBRID TROPICAL SYSTEM MID WEEK. PREFER TO LEAN
TOWARD MORE RECENT CONSERVATIVE SOLUTIONS THAT SUGGEST A BLOCKING
PATTERN ALOFT COULD CAUSE THE SURFACE SYSTEM TO LINGER OFFSHORE
WEDNESDAY...BEFORE WEAKENING AND DRIFTING BACK EAST INTO THURSDAY.
HAVE THUS CAPPED SHOWER/THUNDERSTORM PROBABILITIES IN THE CHANCE
CATEGORY...AS BEST UPPER SUPPORT COULD SLIP EAST AWAY FROM THE
REGION ALONG WITH THE STACKED LOW SYSTEM."
LOL...it needs something, from it's appearance this morning.
It looks awful.
And so this is weather related, it's a partly cloudy beautiful morning here. :P
Blog Update
Non-Tropical Invest 90L
When I click your link it goes to a yahoo search for the term http.
To provide further specificity on the flow rate, the US government has created a Flow Rate Technical Team (FRTT) to develop a more precise estimate. The FRTT includes the US Coast Guard, NOAA, MMS, Department of Energy (DOE) and the US Geological Survey. The FRTT is mandated to produce a report by close of business on Saturday, May 22.
90L is struggling, but it was expected. We won't see any real organization until around the 24th (Monday) when the shear lessons.
Awwwww. Toooo cute.
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