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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7 AM Tomorrow: 12z NAM

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Highlights:

1. Warm Atlantic
2. Cool Nino 3.4 region
3. Cool Gulf of Guinea
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The oil issue and the possibility of the current trail getting "trapped" in a detached loop eddy might be another possibility....Either way (whether on the way towards the Keys, or, looping around in an eddy) is a huge problem;...Last thing we need is a "dead zone" in the middle of the Gulf undeneath the lingering eddy if oil is entrained in it.
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Quoting Weather456:


I edited the post.


Oh yeah, just saw that, thanks.
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Quoting reedzone:


Oh I know, I meant track wise when it got to the East Coast, it dived south and a trough caught it, pulled it out to sea when it turned Extratropical. Look at that big popcorn storm! haha


I edited the post.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting JamesSA:

That is unfortunately a very big assumption at this point.

The months part isn't; that is how long it takes those eddies to move across the Gulf. Prolly will be there through September to help out any TC that passes over it (yay).

Oil is biodegradable, breaking down the entire time it is in the ocean. Sure, it is an assumption that there will be nothing left to effect the TX coast, but some reasoning behind it.

EDIT: Oh you mean about them actually stopping the flow...yeah, big assumption. (Gotta happen sometime, right?)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
May 25 2009 - Last year's 91L which became TD 1. Except this year we have a blocking high instead of an advancing trough



Current set up then

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:
Genesis of Andrea is a bit different from what is forecast with Alex-wannabe



Oh I know, I meant track wise when it got to the East Coast, it dived south and a trough caught it, pulled it out to sea when it turned Extratropical. Look at that big popcorn storm! haha
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Genesis of Andrea is a bit similar to what is forecast with Alex-wannabe

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:


Correct. And more models foresee something along the lines of 60 mph or greater.

I do not think the SW Carib disturbance will surpass 50 mph.


Thanks!

I hope all the rain starved people along the east coast get some much needed rain but nothing worse.

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It's starting to look more possible for the Subtropical storm to form rather then the Caribbean storm. The GFS and EURO had dropped the potential for the Caribbean storm to form, but has greatly increased the potential for a Subtropical storm to form, then transition to a pure Tropical Cyclone. In fact, the EURO strengthens it to a moderately strong Tropical Storm AFTER passing Florida, heading out to sea. I can see it looping due where the High Pressure would be, it can't go north, so it dives south, then catches a trough, pulls away from the USA and heads out like Andrea in 2007 did.
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Changes to NHC Products for 2010

TWOs now to the nearest 10%

The genesis forecasts for the risk of tropical cyclone development will be provided to nearest 10 percent, in both the text and graphical Tropical Weather Outlooks. In previous years, only risk categories (low/medium/high) were given.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting atmoaggie:

Assuming they do actually stop the oil fairly soon, any oil that gets "trapped" by the loop current eddy would not make it to Texas for months...likely nothing left to foul TX beaches...

That is unfortunately a very big assumption at this point.
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NOAA's Central Pacific Hurricane Outlook released yesterday or today.

Predicting below normal activity in the Central Pacific, likely due to La Nina.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting SomeRandomTexan:


The STS off te SE coast and the Carrib low. Looks as if the STS may have more model support.


Correct. And more models foresee something along the lines of 60 mph or greater.

I do not think the SW Carib disturbance will surpass 50 mph.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:
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.


Feeling a bit more confident in a hybrid low in the SW Atlantic this morning. Whether it gets named or not is anyone's guess, but the Euro appears to be showing it deepening due to convective processes.

SST's in the area are in the mid-upper 70s.
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6z GFS Progged it right over the Gulf Stream, warm corred but shallow...
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PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS

Excerpts:

CFS PREDICTS COLD CONDITIONS TO DEVELOP, REACHING THE NOMINAL -0.5 C CRITERION FOR LA NINA CONDITIONS JUST AFTER MJJ 2010. CFS PREDICTS NINO 3.4 SST ANOMALIES TO HOLD AT ABOUT -0.6 C THROUGH ASO 2010, AND THEN COOL TO BELOW -1.0 C JUST AFTER SON 2010.

THE TEMPERATURE OUTLOOK FOR JJA 2010 INDICATES THAT THE CHANCES OF BELOW NORMAL TEMPERATURES ARE ELEVATED OVER THEIR CLIMATOLOGICAL PROBABILITY FOR MUCH OF THE GREAT PLAINS AND GREAT LAKES REGIONS. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR CENTRAL AND SOUTHERN SECTIONS OF THE INTERIOR WEST, INTERIOR ALASKA, THE GULF COAST, AND SECTIONS OF THE SOUTHEAST.

THE PRECIPITATION OUTLOOK FOR JJA 2010 INDICATES INCREASED CHANCES FOR ABOVE-MEDIAN PRECIPITATION FROM OKLAHOMA THROUGH THE DAKOTAS, THE GULF COAST, AND FLORIDA (BASED ON THE CAS). THE PREDICTION OF ENHANCED LIKELIHOOD OF ABOVE MEDIAN PRECIPITATION IN THE CENTRAL PLAINS HAS SOME SUPPORT FROM CON, CFS, IRI, ECP, AND CAS. THE DRY SIGNAL IN THE NORTHWEST IS BASED ON CON, WHICH IS DOMINATED BY TREND THERE.
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Quoting JamesSA:



So it appears that a bunch of that oil now being pulled into the Loop Current may become trapped in that eddy as it breaks off and drift West to Texas beaches instead of Florida. It is looking like everyone will get to share BP's love.

Here is a discussion on the Loop Current by Dr. Masters that I found with Google... The Gulf of Mexico Loop Current: A Primer

Assuming they do actually stop the oil fairly soon, any oil that gets "trapped" by the loop current eddy would not make it to Texas for months...likely nothing left to foul TX beaches...
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting GrtLksQuest:
Where are CycloneOz and Tornadodude?

More important - How are they?


I'm doing well. Better than ever...and busier than a bee here at home.

tornadodude and his friend, last I heard, had decided to end their chase mission which is roundly viewed as a total success...and head for home.

They should get home today.

Well done, young men! Your work out in the field this past week has been stellar! :)
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Quoting Weather456:


Morning...which storms are you referring to. Storms over Texas or storms in the Atlantic?


The STS off te SE coast and the Carrib low. Looks as if the STS may have more model support.
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Quoting doabarrelroll:


Cant see the image, close low where?


here

NE of Bahamas

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting SomeRandomTexan:
Good morning gang!

Maybe we will get some better model support today for the "upcomming" storms.


Morning...which storms are you referring to. Storms over Texas or storms in the Atlantic?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting aquak9:


been watching every video I can. At the beginning, the oil was coming out, and flowing almost straight up, in big pooofs. Now, the most recent video, shows the oil going further out horizontally, before curving upwards.

My thinking is either the pressure behind the flow has increased, or the oil itself has changed to a thicker, heavier type.

Got past the colostrum, do we? could be, I suppose. (but what do I know?)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
A nicely vertically stack low pressure system

500 mb heights (color) vs MSLP.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
If we could get a STS here along the SE coast, believe it or not, it would be very welcome. Ironically since April 1st it has been one of the driest periods on record after one of the wettest winters on record. Here in Charleston we have only received about an inch of rain since April 1st.
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The deviation among the ECMWFEPS is small reflecting high confidence of the low position just of the southeast coast:

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A large wedge tornado has parked itself right above the 'E' volcano...

or it could be ash... either or ...


http://www.sat24.com/Eyjafjallajokull-volcano.aspx
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Good morning gang!

Maybe we will get some better model support today for the "upcomming" storms.
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2005/2010 may 20 anomaly chart comparison.

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Quoting Stormchaser2007:


For better analysis:



So it appears that a bunch of that oil now being pulled into the Loop Current may become trapped in that eddy as it breaks off and drift West to Texas beaches instead of Florida. It is looking like everyone will get to share BP's love.

Here is a discussion on the Loop Current by Dr. Masters that I found with Google... The Gulf of Mexico Loop Current: A Primer
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Quoting Weather456:


Interesting


?
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6z NAM

Closed low in 24 hours.

Member Since: June 9, 2007 Posts: 4 Comments: 15875
Thanks Drak good synopsis
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Quoting Drakoen:


I would consider using the NAM since this is more of a subtropical storm


Interesting
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:


I would consider using the NAM since this is more of a subtropical storm


Yes, the NAM was the best model for coastal storms last winter. So I guess you could consider this a variation of a coastal storm, but that may be a bit of a stretch. Either way, it should be interesting to see how it handles it in the coming runs.
Member Since: June 9, 2007 Posts: 4 Comments: 15875
Member Since: July 24, 2005 Posts: 407 Comments: 19076
767. Skyepony (Mod)
Occasionally Laila has blown up a blob to the west like it might try & make it to the Arabian Sea..Had to give it the slim outside chance of doing so..Definitely been leaning left of the models. Land is hurting her..
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Quoting StormW:


Developing La Nina.

Yes. Based on the NAO forecast and CFS monthly MSLP mean, I'm expecting a full recovery.


Indeed, looks that way.

Member Since: June 9, 2007 Posts: 4 Comments: 15875
Quoting Stormchaser2007:
Even the NAM has some variation of the possible sub tropical low.



I would consider using the NAM since this is more of a subtropical storm
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Even the NAM has some variation of the possible sub tropical low.

Member Since: June 9, 2007 Posts: 4 Comments: 15875
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.
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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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