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
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2008 was a terrible year for everyone
2007 had 2 CAT 5s hit the Caribbean
AOI
AOI
AOI
AOI
Humor in Comments
http://rapidfire.sci.gsfc.nasa.gov/realtime/2010143/
? Standard shows direction ~330-360, 1 minute shows ~150-180.
Ok first off, no one has said it would break 2005 marks
Second, 2004 had 15 named storms which we could easily surpass, now in terms of impacts, there is no way to predict that right now.
Dude its May, nobody knows how it is going to be. Remember first storm of 2005 formed in late June, first storm of 2004 formed late July. So we never know, it takes one storm.
Based on what?
Positive??? strong word when it comes to the tropics....
O0h. I don't know. I'm confused what "Highest" 1-min direction means... Maybe the most anomalous 1 minute wind direction?
NATIONAL WEATHER SERVICE WILMINGTON NC
1105 AM EDT SUN MAY 23 2010
AMZ250-252-254-256-240800-
SURF CITY TO CAPE FEAR NC OUT 20 NM-
CAPE FEAR NC TO LITTLE RIVER INLET SC OUT 20 NM-
LITTLE RIVER INLET TO MURRELLS INLET SC OUT 20 NM-
MURRELLS INLET TO SOUTH SANTEE RIVER SC OUT 20 NM-
1105 AM EDT SUN MAY 23 2010
THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ADJACENT COASTAL WATERS.
.DAY ONE...TODAY AND TONIGHT.
HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.
LOW PRESSURE EMERGING FROM THE BAHAMAS WILL MOVE NORTH-NORTHWEST
EARLY NEXT WEEK...AND COULD APPROACH THE CAROLINA COAST BY MID
WEEK. SMALL CRAFT ADVISORY CONDITIONS MAY DEVELOP BY MONDAY NIGHT
OR EARLY TUESDAY. SWELL HEIGHTS WILL INCREASE...AND MAY PRODUCE
DANGEROUS STANDING AND STEEP WAVES ACROSS AREA INLETS...MOST
NOTABLY DURING TIMES OF SWIFT OUTGOING TIDES. STAY TUNED AS THE
TRACK AND INTENSITY OF THIS SYSTEM BECOMES MORE CLEAR IN THE DAYS
AHEAD.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
$$
MBB
2004 wasn't a record breaking season. It was quite active though. I think that the 2010 Hurricane Season will be somewhere in between 2004 and 2005, primarily due to the record breaking SSTs in the Tropical Atlantic. I don't think it will be as active as 2005 was. 2005 was special, and certainly a year for the record books. ;)
Had Katrina been the last storm to form in 2005, it still would have been a horrible, record-breaking season
Instead we got 17 more storms, but it isn't about the numbers, its about the impacts
TC Formation Probability SKYROCKETED
Holy Sh**
Pretty impressive. I give a 60-40 shot this will be our first named storm.
One question though- why does it show development near the Eastern Seaboard?
Lat: 38.76 Lon: -87.6 Elev: 430
Last Update on May 23, 11:53 am CDT
Fair
87 °F
(31 °C)
Humidity: 67 %
Wind Speed: S 7 MPH
Barometer: 30.05" (1017.0 mb)
Dewpoint: 75 °F (24 °C)
Heat Index: 96 °F (36 °C)
Visibility: 10.00 mi.
EDIT: Double post of #1165.
One more time.... Holy Sh**!!
You said it! :o)
Yeah, I didn't see until I had already posted it, I edited my post to refrence yours.
MARK
25.8N/69.9W
And yet, silly NHC is unaware of this. Saying "No Tropical Cyclone Activity Expected in the Next 48 hours." WRONG-O! :P
Link
Exactly...it will be sub tropical at best and just go out to sea haha. Bermuda is the only place that will feel its effects.
000
ABNT20 KNHC 302338
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
700 PM EST MON NOV 30 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS.
TODAY MARKS THE END OF THE 2009 ATLANTIC HURRICANE SEASON. ISSUANCE
OF THIS PRODUCT WILL RESUME ON 1 JUNE 2010. SHOULD ANY SIGNIFICANT
DISTURBANCES DEVELOP DURING THE OFF-SEASON...SPECIAL TROPICAL
WEATHER OUTLOOKS WOULD BE ISSUED AS NEEDED UNDER THE SAME WMO
HEADER ABNT20 KNHC...AND AWIPS HEADER MIATWOAT.
$$
FORECASTER BERG
A SURFACE TROUGH EXTENDS FROM 27N69W THROUGH A WEAKENING 1008 MB
LOW NEAR 25N70W TO THE TURKS AND CAICOS NEAR 22N72W. SATELLITE
SUGGESTS THAT A SECOND LOW IS DEVELOPING TO THE NORTH OF THE
CURRENT LOW AND WILL BE ADDED AT 23/1800 UTC. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE N AND E OF THE LOW WITHIN 120/150 NM
OF LINE FROM 22N58W TO 29N69W AND ISOLATED/SCATTERED SHOWERS
WITH ISOLATED THUNDERSTORMS WITHIN 60/75 NM OF LINE FROM 21N67W
TO 23N65W. GALE FORCE WINDS ARE FOUND FROM 27N-29N BETWEEN
64W-70W. THIS SYSTEM IS EXPECTED TO MOVE N AND BE N OF THE
REGION BY LATE TUE NIGHT THEN WILL DRIFT E THROUGH THU.
Yeah I just found that. A small area of the lowest probability besides none... to this.
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