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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Hi Chicklet,
What should be being done that's not being done, and what's needed that isn't being supplied? TIA
And fall/early winter....lol.
And no I don't want people to lose their houses, but nature will do what it wants, and it can be terrifingly exciting.
I do believe you've just created the catch-phrase for the Blog. At least during an active part of a season:
Terrifyingly Exciting
It's never good when government agencies are not working for the public benefit and interest.
We have lost our way.
Our Islands in the Stream are Islands in Distress.
What's done is done. Dead is dead.
The EPA has given BP 24 hrs to come up with a less toxic dispersant. People are trying. Just because they make mistakes, doesn't mean they're evil.
Statements such as, "It's never good when government agencies are not working for the public benefit and interest" is true, but suggests that which is untrue. Or highly debatable at the very least. Citizens of this country who comprise the members of our government - despite occasional policies that might suggest otherwise - are not out to destroy the USA. Even the Bush/Cheney administrations (whom I loathed) weren't out to hurt the country, despite some policies and decisions that achieved exactly that.
And saying, "We have lost our way" is just plain discouraging and is not helpful.
Help with the solution Chicklet.
Everybody.
Help.
There used to be; FEMA was, at one time, a free standing Federal Agency...in 2003 it was put under the auspices of Homeland Security and by all accounts, their performance has been abysmal ever since
Agreed...now is the time to get this mess stopped and at least starting on a viable clean up (what has happened so far by way of clean up has been a hippo ballet).
When all is said and done, though, the majority of the cost for this needs to come from the companies involved; despite appearances, the government agencies involved had to operate under the idea that the oil companies were working in good faith, an idea that has proven to be untrue
... EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
SUNDAY... AS THE COLD CORE UPPER LOW ASSOCIATED WITH THE CENTRAL
PLAINS TROUGH DRIFTS INTO THE REGION. PRECIPITATION CHANCES AFTER
MONDAY WILL THEN BE DRIVEN PRIMARILY BY THE APPROACH OF THE WESTERN
ATLANTIC GYRE AND INCREASING DEEP MOISTURE FROM THE SUB-TROPICAL
ATLANTIC. WILL ACCORDINGLY MAINTAIN SLIGHT-LOW CHANCE POPS MONDAY
ONWARD. HOWEVER... IF THE WESTERN ATLANTIC GYRE EVOLVES INTO MORE OF
A WARM CORE SYSTEM... SHOWERS AND THUNDERSTORMS WOULD GRADUALLY
CONSTRICT TOWARD THE CENTER OF THE LOW AND LEAVE A DRIER SUBSIDENT
REGION ON IT/S NORTHWEST PERIPHERY (OVER A PORTION OF THE CAROLINAS)
LATER IN THE PERIOD (TUE-WED).
Now is not how corporations and government work. Please remember that.
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