The 2008-2009 La Niña has drawn to a close. Image indicates sea surface water temperatures (top) and the departure from the average sea surface temperature (bottom). La Niña is indicative of cooler than normal (blue). The lack of a significant temperature anomaly in the equatorial Pacific indicates to scientists that this year's La Niña has come to an end. Image Source: NOAA

La Niña (Spanish for “the little girl”) is the term used to describe the period when the sea surface temperatures of the equatorial Pacific ocean are cooler than normal. This region of the ocean tends to waiver between periods that are warmer than average (referred to as “El Niño”) and warmer than average – La Niña . In between these extremes are relatively neutral periods where sea surface temperatures are within a degree or two of average. It is this neutral period that the Climate Prediction Center is indicating is now imminent.

The end of the current La Niña indicates that the Pacific Northwest may begin to dry out and the south may return to near-normal rainfall patterns.

La Niña tends to bring nearly opposite effects of El Niño to the United States — wetter than normal conditions across the Pacific Northwest and dryer and warmer than normal conditions across much of the southern tier. The impacts of El Niño and La Niña at these latitudes are most clearly seen in wintertime. In the continental U.S., during El Niño years, temperatures in the winter are warmer than normal in the North Central States, and cooler than normal in the Southeast and the Southwest. During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest.

It is unknown precisely when El Niño will return.

NOAA deployed the final two tsunami detection buoys in the South Pacific this week, completing the buoy network and bolstering the U.S. tsunami warning system. This vast network of 39 stations provides coastal communities in the Pacific, Atlantic, Caribbean and the Gulf of Mexico with faster and more accurate tsunami warnings.

The buoys are ingenous little contraptions, designed to collect an array of quantitative data on the conditions from each site and relay that information back to central data collection and analysis points:

DART stations consist of a bottom pressure sensor anchored to the seafloor and a companion moored surface buoy. An acoustic link transmits data from the bottom pressure sensor to the surface buoy, and then satellite links relay the data to NOAA tsunami warning centers. The DART network serves as the cornerstone to the U.S. tsunami warning system.

This attempt comes via prompting from the catastrophic tsunami that struck Indonesia over three years ago:

Since the Indonesian tsunami of December 2004, NOAA has made significant upgrades to the U.S. tsunami warning system, including:

• Installing 49 new or upgraded tide gages
• Installing or upgrading eight seismic stations
• Expanding the network of DART buoys from six (exclusively in the eastern Pacific) to 39 (from the western Pacific to the Atlantic)
• Growing the number of TsunamiReady communities from 16 to more than 50 today
• Developing 26 inundation forecast models and implementing a new Tsunami Warning System
• Extending the operations of the Pacific and West Coast/Alaska Tsunami Warning Centers to 24 hours a day
• Assisting Australia and Indonesia with installing tsunami warning systems off their coasts.

A warming global ocean — influencing the winds that shear off the tops of developing storms — could mean fewer Atlantic hurricanes striking the United States according to new findings by NOAA climate scientists. Furthermore, the relative warming role of the Pacific, Indian and Atlantic oceans is important for determining Atlantic hurricane activity.

The article, to be published on January 23 in Geophysical Research Letters, uses observations to show that warming of global sea surface temperatures is associated with a secular, or sustained long-term increase, of vertical wind shear in the main development region for Atlantic hurricanes. The increased vertical wind shear coincides with a downward trend in U.S. landfalling hurricanes…

This comes on the heals of research earlier this year that demonstrated a correlation between global temperatures and hurricane frequency that indicated that perhaps hurricane frequency is heightened by cooler temperatures (Hurricanes Frequent in Cooler Times).

Technorati Tags: Hurricanes, Global Warming, NOAA, Tropical Meteorology, Extreme Weather

The sensors are able to monitor lightning strikes from a distance of thousands of miles, allowing scientists to investigate with greater accuracy how lightning produced within a hurricane’s eyewall is tied to the changing strength of that hurricane.

“There are very few observing systems that offer a broad view of a storm over the open ocean where hurricanes tend to build or lose strength,” said study lead author Kirt Squires. “This development is essential to improving the way meteorologists can look at a growing storm to judge just how harsh it will be.”

Researchers are planning on publicizing this new project in American Meteorological Society journal Monthly Weather Review.

“While we can’t officially call it a La Nina yet, we expect that this pattern will continue to develop during the next three months, meeting the NOAA definition for a La Nina event later this year,” said Mike Halpert, acting deputy director of the National Oceanic and Atmospheric Administration’s prediction center.

La Nina refers to the periodic cooling of ocean surface temperatures in the central and east-central equatorial Pacific that occur every three to five years.

With La Nina developing, seasonal forecasters expect wetter than average conditions in the Pacific Northwest and drier than average conditions in the drought stricken Southwestern United States this fall.

“Nearly all operational dynamical models, including the National Centers for Environmental Prediction’s climate forecast system and many of the statistical models also favor a La Nina event,” said Halpert.

The implications?

With La Nina developing, seasonal forecasters expect wetter than average conditions in the Pacific Northwest and drier than average conditions in the drought stricken Southwestern United States this fall.

While this doesn’t directly dispute the popular belief that hurricane frequency increases with warmer ocean waters, it certainly complicates things:

May 24, 2007

Study Finds Hurricanes Frequent in Some Cooler Periods
By ANDREW C. REVKIN

Over the last 5,000 years, the eastern Caribbean has experienced several periods, lasting centuries, in which strong hurricanes occurred frequently even though ocean temperatures were cooler than those measured today, according to a new study.

The authors, from the Woods Hole Oceanographic Institution, say their findings do not necessarily conflict with recent papers asserting a link between the region’s hurricane activity and human-caused warming of the climate and seas.

But, they say, their work does imply that factors other than ocean temperature, at least for thousands of years, appear to have played a pivotal role in shaping storminess in the region.

The study compared a 5,000-year record of strong storms etched in lagoon mud on the Puerto Rican island of Vieques with data on ocean temperatures and climate and storm patterns. The analysis is being published today in the journal Nature.

Read more.

Technorati Tags: Hurricanes, Global Warming, Climate Change

The Atlantic hurricane season will be exceptionally active this year, according to a British forecasting group, raising the possibility that killer storms like Hurricane Katrina could again threaten the United States.

London-based forecaster Tropical Storm Risk on Tuesday said the six-month season, which begins on June 1, was expected to bring 17 tropical storms, of which nine will strengthen into hurricanes with winds of at least 74 miles per hour. Four of those are expected to become more destructive “intense” hurricanes, TSR said.

The long-term average for the Atlantic is for 10 storms to form during the hurricane season and for six of those to reach hurricane strength.

The article goes to cite the inaccuracies in last year’s forecasts:

The United States emerged unscathed from the 2006 season after it spawned a below-average nine storms, of which five became hurricanes. Experts had universally — and erroneously — predicted 2006 would be a busy year for Atlantic storms.

I have a feeling any article mentioning hurricane forecasts will still remind us of the horrors of the 2005 season, as this one has:

None of the hurricanes hit the United States, bringing welcome relief to beleaguered residents of the U.S. Gulf Coast, where Katrina killed 1,500 people, swamped New Orleans and caused about $80 billion in damage the year before.

As of 5:39pm EST 03/21/07, the article cited in the opening of this post yields 13 ‘related articles’ results from a google news search. Let’s see how this count mushrooms over the coming hours and days. I only wish we could somehow see how many (or rather, how few) headlines would have been created had this forecast been for minimal activity this hurricane season. I guess the absence of headlines following last year’s remarkably quiet season was a good indicator.

That said, I am in agreement with the overall opinion of a higher-than-average hurricane season. Sea surface temperatures are one of the best indicators of hurricane season trends and appear favorable for hurricane development this season. It is not the above-average forecasts themselves that I question, rather the play these will get in the mainstream media. After all, the planet has a fever, folks! Read much more about Al Gore’s senate testimony via Noel Sheppard’s Newsbusters posts here and here.

Technorati Tags: Hurricanes, 2007 Hurricane Forecast, Tropical Meteorology, Extreme Weather, Al Gore

With last week’s announced “end” to El Nino, it appears as though the cooling trend pendulum is set to swing right across the midpoint over to La Nina:

Officials at the National Oceanic and Atmospheric Administration announced the official end of a brief and mild El Nino that started last year. That El Nino was credited with partially shutting down last summer’s Atlantic hurricane activity in the midst of what was supposed to be a busy season.

“We’re seeing a shift to the La Nina, it’s clearly in the data,” NOAA Administrator Conrad Lautenbacher said. La Nina, a cooling of the mid-Pacific equatorial region, has not officially begun because it’s a process with several months with specific temperature thresholds, but the trend is obvious based on satellite and ocean measurement data, he said.

This is sure to spark a flurry of media reports about a disasterous hurricane season in the offing. I wonder if this seasons’ reports will reach the fever pitch of doom heard prior to last year’s hurricane season…the season during which not a single hurricane made landfall on the US.