El Niño is done; Haiti at risk of heavy rains next week; oil spill update
El Niño rapidly weakened during late April and early May, with sea surface temperatures over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", falling a significant 0.65°C in just one month. Temperatures in the region are now in the "neutral" range, just 0.18°C above average, and well below the 0.5°C threshold to be considered an El Niño, according to the Australian Bureau of Meteorology. The speed of the collapse of El Niño makes it likely that a La Niña event is on its way this summer. This is what happened during the last strong El Niño event, in 1998--El Niño collapsed dramatically in May, and a strong La Niña event developed by hurricane season. Six of the sixteen El Niño models (updated as of April 15) are predicting La Niña conditions for hurricane season, and I expect more models will jump on the La Niña bandwagon when the May data updates later this week. The demise of El Niño, coupled with sea surface temperatures in the tropical Atlantic that are currently at record levels, have prompted two major hurricane forecasting groups (tropicalstormrisk.com and Colorado State University) to predict a significantly above average 2010 Atlantic hurricane season. Over the full 160-year period we have records of Atlantic hurricanes, La Niña years have typically had more hurricanes, and more strong hurricanes, compared to neutral years. However, since 1995, there hasn't been any difference between neutral and La Niña years in terms of hurricane activity. La Niña conditions typically cause cool and wet conditions over the Caribbean in summer, but do not have much of an impact on U.S. temperatures or precipitation.
Figure 1. Oil spill edge over the Gulf of Mexico on Wednesday, May 19, as seen from NASA's M ODIS instrument. Note that a band of cumulus clouds formed along the edge of the oil spill. I theorize this is because the low level wind flow out of the southeast moves faster over the oil, since the oil suppresses wave action. As the winds cross the spill boundary into rougher, clean water, they slow down, forcing the air to pile up and create updrafts that then spawn cumulus clouds. See my post on what oil might do to a hurricane for more information on how oil reduces wave action.
Oil spill update
Clouds over the Gulf of Mexico have again foiled satellite imaging of the extent of the Deepwater Horizon oil spill, though through breaks in the clouds it appears that a significant amount of the oil that was pulled southwards towards the Loop Current is now caught in a counter-clockwise rotating eddy just to the north of the Loop Current. However, some oil has escaped this eddy and is on its way south towards the Florida Keys. According to the latest trajectory forecasts from NOAA, the tongue of oil flowing southwards has at most "light" concentrations. The oil will grow more dilute as it travels the 500 miles to the Florida Keys. My present expectation is that the oil entering the Loop Current this week will cause only minor problems in the Keys next week. However, there is a lot of uncertainty about what the oil may do to the fragile Keys ecosystem. See my post yesterday for answers to many of the common questions I get about the spill.
Oil spill resources
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
HYCOM ocean current forecasts from LSU
Figure 2. Precipitation forecast from today's 8am EDT run of the NAVY NOGAPS model, valid 7 days from now. Precipitation amounts in excess of 70 mm (2.8") in 12 hours are predicted over Haiti, due to a tropical disturbance in the Western Caribbean. Image credit: U.S. Navy.
Potential serious rainfall threat to Haiti next week
Long-range forecasts from the GFS and NOGAPS models over the past few days have consistently been predicting an increase in moisture and decrease in wind shear over the Western Caribbean 5 - 7 days from now, and I expect that a tropical disturbance with heavy rains will develop 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 NOGAPS model shows heavy rains in excess of six inches impacting Haiti Wednesday through Thursday of next week. Rains of this magnitude are capable of causing a serious emergency with high loss of life in earthquake-shattered Haiti, and all interests in that nation should closely monitor the situation over the coming week. It is too early to speculate on the possibility of the disturbance becoming a tropical depression. The wunderblogs of StormW and Weather456, who are now featured bloggers for the coming hurricane season, have more information on this potential development, plus the possible development of a subtropical storm between Florida and Bermuda next week.
Major severe weather outbreak over Oklahoma expected tonight
NOAA's Storm Prediction Center has put much of Oklahoma in its High Risk region for severe weather today, warning that "The setup appears most favorable for large, relatively slow moving intense storms with large hail. A couple strong tornadoes also may occur."
I'll be back with a new post Thursday morning.
Jeff Masters
Reader Comments
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Don't know if ya'll saw this. My wife just showed it to me. whoa
AMEN
Tell me about it...it's pretty damned funny in mine!
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My goodness, poor Oklahoma, gonna be a looong summer...
Didn't know it was raining there already, lol.
Because you are not looking for it!! I have cleaned tar off my feet many a times with mineral spirits after stepping in it!! Just because these tar balls are not from the BP spill does not take away from the story of the spill. Jeff I read your post on here a lot and you are good but it is okay to be wrong every once in awhile!
Bingo...we go to Key West once or twice a year for the last 12 years. Ne'er a tar ball. Just so happens that one of the biggest oil spills on the planet happens and all of a sudden tar balls start showing up? You gotta be a gulla-bull if you believe that crapola.
wait wait so you go there for at the most 1 month out of the year and that is your basis for saying you dont buy that story?
I thought you lived there lol
As for the hybrid low, winds may exceed 50 mph during any stage of its life cycle.
I'm not sure there's a closed low over the Yucatan. Seeing converging winds more than circulation over the Yucatan on satellite from the surface trough over the region. But, one could definitely be developing as the latest CIMSS 850mb Vorticity product does show improving lower level vorticity in the region as shown below with a more defined center.
It's a fairly safe bet that it's closed. Westerly low-level winds are quite evident over Belize on high-res visible satellite.
WOW!!
I had NO IDEA how violent that could be>
So what happens if you get caught outside in that??
post1043 aspectre "Thanks for the heads-up. Certainly closer to other US-affecting offshore blowouts: 8,000to10,000barrels per day averaged over 10days at Santa Barbara; and 11,000to12,000barrels per day averaged over 295days at Ixtoc I, Gulf of Mexico.
The ExxonValdiz wreck spilled ~11million gallons. At 5,000barrels/210,000gallons per day, the DeepwaterHorizon spill will reach that level by June11th.
In 2005, TropicalStorm Arlene reached near-hurricane strength in the Gulf of Mexico on June10th."
Comparisons with the day before TropicalStorm Arlene began spinning on 8June2005
18May2010
7Jun2005
18May2010
7Jun2005
18May2010
Its closed on visible satellite winds too
That isn't the same cell that caused the tornado in northern texas last night at this time, is it? That would be amazing.
Using that satellite imagery, I do agree that there indeed is a closed low over Belize with the surface trough across the NW Caribbean. It appears to be getting better defined over the Yucatan as, as you stated Levi, westerly winds have become quite evident on satellite imagery and now with surface observations that I just checked.
Its Mesoscale Convective System...
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The National Oceanic and Atmospheric won’t be issuing its outlook for hurricane season this Thursday, as had been scheduled.
A press conference, which was to be held on Thursday morning at NOAA’s Hurricane Research Division on Virginia Key in Miami, has been delayed.
Why? Susan Buchanan, NOAA spokeswoman in Washington, D.C., couldn’t say. It was a decision made far up the ladder for reasons unknown.
Some possibilities:
-- NOAA doesn't want to hold the press conference in South Florida, when the region is preoccupied with the threat of the oil spill coming this way.
-- NOAA Administrator Jane Lubchenco got tied up and couldn't make it on Thursday.
-- NOAA is waiting for more data before finalizing its forecast.
I'm sure the agency will tell us the real reason in days upcoming.
Meanwhile, Buchanan said the outlook likely will be released next week, which will be cutting it close, considering the season starts on June 1.
There also is a chance that the outlook will be issued in Washington, she said
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