La Nina developing, could mean more hurricanes

July 8, 2010 By RANDOLPH E. SCHMID , AP Science Writer

(AP) -- The climate phenomenon known as La Nina appears to be developing, threatening more bad news in the efforts to clean up the oil spill in the Gulf of Mexico.

When a La Nina occurs there tend to be more hurricanes than normal in the Atlantic and Caribbean regions, which include the .

The federal Climate Prediction Center said Thursday that La Nina conditions are likely to develop in July and August.

La Nina is marked by an unusual cooling of the sea surface in the tropical Pacific Ocean. Water temperatures in that area can affect air pressure and winds, resulting in changes in the weather in many parts of the world.

In a La Nina, is increased over the Pacific and reduced over the Atlantic. Wind shear is the difference in strength of winds at low levels compared to higher level winds.

A strong wind shear reduces hurricanes by breaking up their ability to rise into the air, while less shear means they can climb and strengthen.

Thus, the Climate Prediction Center notes, "there tend to be more Atlantic hurricanes during La Nina because of this expanded area of low vertical wind shear."

In addition, during a La Nina "more hurricanes form in the deep tropics from African easterly waves. These systems have a much greater likelihood of becoming major hurricanes, and of eventually threatening the U.S. and Caribbean islands," according to the center, a part of the National Oceanic and Atmospheric Administration.

The climate center's current forecast for this season is for 14 to 23 named storms of which 8 to 14 are expected to be hurricanes and 3 to 7 major hurricanes.

The center noted that during June, sea surface temperature continued to decrease across the equatorial Pacific Ocean, with cool areas expanding across the central and eastern Pacific. In addition, increased rainfall persisted over Indonesia, while the area of reduced rain expanded westward over the western and central equatorial Pacific.

Combined with changes in the winds over the Pacific "these oceanic and atmospheric anomalies reflect developing La Nina conditions" which are likely to continue through early 2011, CPC said.

The last occurred from the fall of 2007 to the spring of 2008. The opposite mode, El Nino, with warm Pacific conditions, has been in place since the spring of 2009.

Explore further: Study: La Niña might create severe weather

More information:


Related Stories

Study: La Niña might create severe weather

April 17, 2006

U.S. scientists say La Niña-controlled weather patterns have the potential to produce more severe storms, as those recently seen in the Midwest and South.

U.N. meteorologist predicts cooler summer

April 4, 2008

A U.N. meteorologist says the cooling effect of the La Nina current in the Pacific will likely mean slightly lower temperatures across the world this year.

Forecasters say El Nino may be developing

June 8, 2009

(AP) -- A new El Nino could be approaching. Sea-surface temperatures have been warming in the tropical Pacific Ocean, suggesting the potential for the development of the El Nino climate phenomenon this summer, according ...

New type of El Nino could mean more hurricanes make landfall

July 2, 2009

El Niño years typically result in fewer hurricanes forming in the Atlantic Ocean. But a new study suggests that the form of El Niño may be changing potentially causing not only a greater number of hurricanes than in average ...

Recommended for you

Horn of Africa drying ever faster as climate warms

October 9, 2015

The Horn of Africa has become increasingly arid in sync with the global and regional warming of the last century and at a rate unprecedented in the last 2,000 years, according to new research led by a University of Arizona ...

Could 'The Day After Tomorrow' happen?

October 9, 2015

A researcher from the University of Southampton has produced a scientific study of the climate scenario featured in the disaster movie 'The Day After Tomorrow'.

History shows more big wildfires likely as climate warms

October 5, 2015

The history of wildfires over the past 2,000 years in a northern Colorado mountain range indicates that large fires will continue to increase as a result of a warming climate, according to new study led by a University of ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jul 08, 2010
I submit that these types of changes in weather and extreme weather are part of the category called natural variability.
not rated yet Jul 13, 2010
Paddyl, Duh!! Happens every 3 yrs or so.

But so far it's been weak and there is still wind shear. Now add African dust and by the time hurricanes develop, they won't likely hit the gulf, but the east coast.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.