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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I'm going with a 70% chance of Alex next week.

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Member Since: July 3, 2005 Posts: 420 Comments: 127536
Anyone have a link for a loop showing the CAtl Wave?> Not the cen.alt or East Atl Rainbows, neither shows the entire wave.
Thankee.
Member Since: October 24, 2005 Posts: 0 Comments: 24012
Quoting Hurricanes101:


Lets get the extreme generalizations of the CMC out of the way now please

The CMC is clearly not the best model, but at the same time it does not develop anywhere near as many ghost storms as it used to and last season did no worse than any other forecast model.


Exactly...after the extremely poor performance in the 05 and 06 seasons they made a few modifications, as it were
Member Since: August 2, 2006 Posts: 10 Comments: 9922
nice update doc but I don't think that it will be pulled ENE or or north of due east I am thinking more north moving NNE-NE toward Jamaica Cayman Cuba way rather than Haiti
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Quoting Drakoen:
After looking at the 12z models, it appears increasing likely for tropical cyclone development to occur in the southern Caribbean potentially leading to our first named storms. Models are more aggressive suggesting at least a tropical storm forming and moving ENE


Yep but ENE?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
37% development
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Quoting Levi32:


It seems to have the low utilize the 200mb trough digging into the NW Caribbean as an outflow channel, but it is in pretty close proximity on the model. It seems most of the models are having a tendency to do that. The orientation would have to be perfect for it to not shear it apart.




Isn't it also sitting right on top of that hot tub eddy in the NCaribb?
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Link


live
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Quoting Levi32:
12z UKMET is also on board in the Bahamas.

Now we have the UKMET, GFS, CMC, NOGAPS, and ECMWF forecasting development for next week. Let's see what unfolds...
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Acemmett90 oh really lol
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Quoting Drakoen:
After looking at the 12z models, it appears increasing likely for tropical cyclone development to occur in the southern Caribbean potentially leading to our first named storms. Models are more aggressive suggesting at least a tropical storm forming and moving ENE
How about the hybrid system east of the Bahamas?
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12z UKMET is also on board in the Bahamas.

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Drakoen hey ..
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NEXRAD Radar
Enid/Vance AFB, Base Reflectivity 0.50 Degree Elevation Range 124 NMI
Member Since: July 3, 2005 Posts: 420 Comments: 127536
haha Acemmett90
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After looking at the 12z models, it appears increasing likely for tropical cyclone development to occur in the southern Caribbean potentially leading to our first named storms. Models are more aggressive suggesting at least a tropical storm forming and moving ENE
Member Since: October 28, 2006 Posts: 57 Comments: 29886
I'm going to have fun this hurricane season .
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Quoting Acemmett90:
wtf is the gfs merge its scary as hell


That run is from November 2009....lol
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Quoting WPBHurricane05:


Except for the 500 hurricanes it forecasts every year to hit S. Florida.


Lets get the extreme generalizations of the CMC out of the way now please

The CMC is clearly not the best model, but at the same time it does not develop anywhere near as many ghost storms as it used to and last season did no worse than any other forecast model.
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Quoting Acemmett90:
wtf is the gfs merge its scary as hell
November of 2009?
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Quoting Acemmett90:
Models at 144hrs

Gfs

Cmc

NOGAPS

Hmmm, when all three say about the same thing about a single feature, it might be about time to start paying attention to the models.

Nah. I'll wait and see if they are saying the same thing for the next 24 hours. someone let me know if it does...
(in a mood to ignore the models until something begins to coalesce given that it's May...)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
lmao Acemmett90
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Quoting Levi32:


It seems to have the low utilize the 200mb trough digging into the NW Caribbean as an outflow channel, but it is in pretty close proximity on the model. It seems they are all having a tendency to do that. The orientation would have to be perfect for it to not shear it apart.



Something similar to what the GFS was showing yesterday

Member Since: July 24, 2005 Posts: 407 Comments: 19076
cmc on speed...
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Quoting KEEPEROFTHEGATE:
thanks for update doc all eyes will be on sw carb. next week
Yeah and the hybrid one too.
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Quoting leo305:


and CMC tends to be pretty accurate..


Except for the 500 hurricanes it forecasts every year to hit S. Florida.
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Quoting Weather456:
Thanks for the update

I had not seen this 12Z NOGAPS 168 hrs, really agressive south of Hispaniola



That's a devestating graphic...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Hmmm, not going to say "I told ya so".

Seemed like a number of folks were just ready to assume...

Florida Keys Tar Balls Not From Gulf Oil Spill
http://www.benzinga.com/press-releases/10/05/b291050/coast-guard-florida-keys-tar-balls-not-from-gu lf-oil-spill
Member Since: August 16, 2007 Posts: 6 Comments: 12461
thanks for update doc all eyes will be on sw carb. next week
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Quoting Weather456:
Thanks for the update

I had not seen this 12Z NOGAPS 168 hrs, really agressive south of Hispaniola



It seems to have the low utilize the 200mb trough digging into the NW Caribbean as an outflow channel, but it is in pretty close proximity on the model. It seems most of the models are having a tendency to do that. The orientation would have to be perfect for it to not shear it apart.

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Quoting atmoaggie:

One thought that came to mind is that boat wakes from those not sensitive to it could help push heavy oil into/onto places it might not have gotten otherwise. In the marshes, there is very little wave action, so a sizable boat, moving quickly is about the only thing that pushes waves up onto marsh grasses most of the time.

Just a thought...I dunno if this is why.


It's causing confusion, trust me the coast guard knows whats going on and half of the people doing oil spill stuff are wrong or don't understand all aspects of the situation. Were giving press chances to see whats going on, they can make a appointment.
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Quoting MiamiHurricanes09:
Wow, CMC going very intense.



and CMC tends to be pretty accurate..
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17. JRRP
interesting blog Dr. Masters
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so when was the last time we had a hurricane in May?
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Looks like the 12z NOGAPS takes it up to moderate tropical storm strength.
Member Since: June 9, 2007 Posts: 4 Comments: 15776
Quoting Weather456:
Thanks for the update

I had not seen this 12Z NOGAPS 168 hrs, really agressive south of Hispaniola

Wow.
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Quoting lilElla:
Why is the Coast Guard turning away the press and well known scientists from documenting what is going on where the oil has come ashore?

One thought that came to mind is that boat wakes from those not sensitive to it could help push heavy oil into/onto places it might not have gotten otherwise. In the marshes, there is very little wave action, so a sizable boat, moving quickly is about the only thing that pushes waves up onto marsh grasses most of the time.

Just a thought...I dunno if this is why.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Wow, CMC going very intense.

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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.

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