EXTREME WEATHER EVENTS IN THE SOUTHERN HEMISPHERE TO LAST UNTIL SPRING:NOAA

The La Niña event established this year is particularly intense and maybe the most severe in a 100 years. Such events are known to give warm sea surface temperatures and greater evaporation giving heavy rains in the Western Pacific in Australia, less rain in the Eastern Pacific on the western coast of S. America (coastal Chile and Peru) but increased rain on the east coast in southern Brazil and northern Argentina.


Australia floods: La Niña to blame


[link to www.ibtimes.com]




Hundreds killed in Brazil floods, mudslides
[link to www.dailymail.co.uk]



EL NIÑO/SOUTHERN OSCILLATION (ENSO)
DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP
6 January 2011


ENSO Alert System Status: La Niña Advisory



Spanish Version


Synopsis: La Niña is expected to continue well into the Northern Hemisphere spring 2011

A moderate-to-strong La Niña continued during December 2010 as reflected by well below-average sea surface temperatures (SSTs) across the equatorial Pacific Ocean (Fig. 1). All of the Niño indices were –1.5oC at the end of December, except for the easternmost Niño-1+2 region (Fig. 2). The subsurface oceanic heat content (average temperatures in the upper 300m of the ocean, Fig. 3) continued to reflect a large reservoir of below-average temperatures at depth in the central and eastern equatorial Pacific (Fig. 4). Convection remained enhanced over Indonesia and suppressed over the western and central equatorial Pacific (Fig. 5). Also, enhanced low-level easterly trade winds and anomalous upper-level westerly winds continued over the equatorial Pacific. Collectively, these oceanic and atmospheric anomalies reflect the ongoing La Niña.

The current ENSO model forecasts have not changed significantly compared to last month (Fig. 6). La Niña is currently near its peak and is expected to persist into the Northern Hemisphere spring 2011 at a lesser intensity. Thereafter, there remains considerable uncertainty as to whether La Niña will last into the Northern Hemisphere summer (as suggested by the NCEP CFS and a few other models), or whether there will be a transition to ENSO-neutral conditions (as suggested by the CPC CON and a majority of the other models).

Likely La Niña impacts during January-March 2011 include suppressed convection over the west-central tropical Pacific Ocean, and enhanced convection over Indonesia. Impacts in the United States include an enhanced chance of above-average precipitation in the Pacific Northwest, Northern Rockies (along with a concomitant increase in snowfall), Great Lakes, and Ohio Valley. Below-average precipitation is favored across the southwestern and southeastern states. An increased chance of below-average temperatures is predicted for much of the West Coast and northern tier of states (excluding New England), and a higher possibility of above-average temperatures is forecast for much of the southern and central U.S. (see 3-month seasonal outlook released on December 16th, 2010). While seasonal temperature and precipitation patterns in the U.S. are strongly influenced by La Niña, these signals can be modified by other factors, such as the Arctic Oscillation (AO)/ North Atlantic Oscillation (NAO).

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts for the evolution of El Niño/La Niña are updated monthly in the Forecast Forum section of CPC's Climate Diagnostics Bulletin. The next ENSO Diagnostics Discussion is scheduled for 10 February 2011. (but where is it?)
[link to www.cpc.ncep.noaa.gov]