El Niño is done; Haiti at risk of heavy rains next week; oil spill update

By: Dr. Jeff Masters , 8:09 PM GMT on May 19, 2010

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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

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It is appearing more likely that a subtropical storm, with the real possibility of transitioning to a fully tropical entity, will form off the Southeast coast. The consensus among the majority computer models is to have the system hook around back towards the U.S. The 850mb temperatures on both the ECMWF and the GFS along with the cyclone phase diagrams reveal a warm core system embedded within a 500mb trough of the east coast. This system could impact anywhere from North Carolina all the way down to Florida. I place development chances at moderate to high in this region over the next 7 days.

Another concern is low pressure development in the southern Caribbean. The CMC and NOGAPS show development of a strong tropical storm while the GFS and ECMWF only hint at that possibility. The GFS and CMC move it northward while the NOGAPS moves it in a more northeast fashion. I place development chances at moderate.
Member Since: October 28, 2006 Posts: 57 Comments: 30562
CNN this morning - interview with the sec of the Interior - he says they are disbanding the minerals management agency.
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Quoting CycloneUK:
10 days ago:





Today:



Its amazing how quickly the El Nino has collapsed, I wouldn't be surprised if by mid this year there's a moderate La Nina.
Member Since: July 8, 2005 Posts: 259 Comments: 24179
Quoting StormW:


Developing La Nina.


Slightly cooling Atlantic SST's due to a stronger than normal high (for the moment).

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757. IKE
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Quoting StormW:
Good morning all!

Off to preform analysis, and get my kid out to school.
Good morning. Look forward to your analysis.
Member Since: October 9, 2008 Posts: 0 Comments: 8392
755. Skyepony (Mod)
Quoting Stormchaser2007:


For better analysis:


That's text book there.. No wonder the models have differed so. What a volitile moment to be trying to forecast the loop current. Wonder which side most the oil swept down that way ended up on.. Maybe we'll get a good sat pass today.
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AOI

AOI

AOI

AOI
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10 days ago:





Today:

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Quoting doabarrelroll:


I see much concern around the gulf, is the Atlantic warmer than normal?


Just updated a few minutes ago...

The whole basin is above normal:

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With nothing stopping this cold pool, a moderate Nina seems plausible by September.

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Quoting Jeff9641:


Weather forecasters in Orlando were discussing this last night as they said they haven't seen the Gulf this warm in many years. Tampa and Orlando mets are really concerned about this years hurricane season because of the record SST. They also said the Caribbean temps are warm enough to support a Cat. 3 or 4 Hurricane right now.


Some of the Tampa mets are already doing informal "tropical updates" almost nightly because the gulf is so warm.
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Quoting Skyepony:
That SST that StormChaser posted shows really well that the loop current is about to shed an eddy. That circle of extra warmth..


For better analysis:
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Quoting Jeff9641:


Weather forecasters in Orlando were discussing this last night as they said they haven't seen the Gulf this warm in many years. Tampa and Orlando mets are really concerned about this years hurricane season because of the record SST. They also said the Caribbean temps are warm enough to support a Cat. 3 or 4 Hurricane right now.

So the history of Audrey(1957)can be repeated
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So we have NOGAPS, GFS, UKMET, ECMWF, and the CMC all saying a Tropical cyclone might develop in a few days.. this is when now I start giving the models merrit that there might be something soon. I place my bets for a TS in the Caribbean at around 35%, I was thinking 20% yesterday. For a Sub-Tropical cyclone I put the odds at 10%, anything that forms will most likely be completely cold core IMO.
Member Since: July 8, 2005 Posts: 259 Comments: 24179
743. IKE
Still see a low spinning over and near the Yucatan peninsula.
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742. Skyepony (Mod)
That SST that StormChaser posted shows really well that the loop current is about to shed an eddy. That circle of extra warmth..
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The Deepwater Horizon oil spill trajectory ensemble forecast from different numerical models

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Heavy rain for Hati and a STS

6z NOGAPS
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What happens if Haiti floods from a weak disturbance?

Many will die...it's as simple as that...the situation there is dire...hundreds of thousands still living in refugee camps...violence is epidemic...especially against women, as well as children, people with disabilities and the elderly...
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737. IKE
Quoting Jeff9641:


Hey IKE, As this ULL drops in Next Tues and Wed, there could severe wx in your area due to the cold air aloft.


I see the increased rain chances for here early next week. Probably will be higher then what they have listed now.
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The SSTs are at record warmth for the year in the atlantic region ... around the ITZ.
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Quoting Weather456:


This year really makes 2005 look small in terms of SSTs.


It really does and from here on out the only way is up.

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The Deepwater Horizon oil spill trajectory hindcast/forecast based on West Florida Shelf ROMS

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Quoting Jeff9641:


LOL!! Give it until 10am!


Wait until the kids are out of school for summer.
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Quoting Stormchaser2007:
98% of the gulf is at or above 26C



This time 5 years ago...


the watar is getting warmer VERY fast
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Quoting Stormchaser2007:
98% of the gulf is at or above 26C



This time 5 years ago...



This year really makes 2005 look small in terms of SSTs.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Thanks Weather456. Glad to see you back. Looking forward to your input this season.
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98% of the gulf is at or above 26C



This time 5 years ago...

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Quoting breald:
Isn't it today that NOAA is to release their hurricane predictions?


It was rescheduled to next Thursday.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Cold-core with some chance at being named sts.
Quoting Weather456:


What happens if Haiti floods from a weak disturbance? There is no bogus low. It is a real possibility that a disturbance will be heading for Hispaniola next week as indicated by not 1 model, but several. It is by far more dangerous than the subtropical low because of its potential to affect an already struggling country.


Obviously the potential for flooding down in the tropics this time of the year always exist. Almost gave in to the trigger happy gfs. The system of the southeast is cold-core in general with some chance at being named sts.

Not to different from andrea back in 07.

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Quoting breald:
Isn't it today that NOAA is to release their hurricane predictions?


They postponed it to the 27th.
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Quoting Tropicsweatherpr:


Adrian, you think we will have Alex from the area north of Bahamas subtropical or fully tropical?

I think it will be fully tropical 60-mph storm
i'm not Adrian,but I have to give you my opinion
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Isn't it today that NOAA is to release their hurricane predictions?
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718. IKE
Quoting weathermanwannabe:
708. IKE 8:45 AM EDT on May 20, 2010

I can can only hope, but, that's one of the reasons I like the Blog early in the morning...the trolls like to sleep late I think.......... :)


LOL...smart man...you're exactly correct.

Quoting Jeff9641:


LOL!! Give it until 10am!


I doubt admin will allow a lot starting soon. The "time outs" will start.
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I looks like BP and the CG dont want the American people to get a look at some of the oil damage. From Energy Boom:

CBS has footage of their reporters being turned away from a public beach in Louisiana where they were filming oil washing up on shore.

"This is BP's rules, it's not ours," someone aboard the boat said. Coast Guard officials told CBS that they're looking into it. "

Now..since the Coast Guard is a branch of the military, you gotta wonder how closely the government and BP are working together to keep the public from seeing this. I dont even understand how they think that's possible.



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Texas will have a mesoscale event today...
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708. IKE 8:45 AM EDT on May 20, 2010

I can can only hope, but, that's one of the reasons I like the Blog early in the morning...the trolls like to sleep late I think.......... :)
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Quoting hurricane23:
Only feature of concern is with a possible subtropical feature of the southeast coast. 00z ECM in particular was fairly agressive on its last run.


What happens if Haiti floods from a weak disturbance? There is no bogus low. It is a real possibility that a disturbance will be heading for Hispaniola next week as indicated by not 1 model, but several. It is by far more dangerous than the subtropical low because of its potential to affect an already struggling country.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
NVRM
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting hurricane23:
Another bogus low from the GFS...
Only feature of concern is with a possible subtropical feature of the southeast coast. 00z ECM in particular was fairly agressive on its last run.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.