CPC and the contributors to the Forecast Forum caution potential users of
this predictive information that they can expect only modest skill.
Alert System Status: La
expected to last at least into the Northern Hemisphere spring 2011.
November 2010, the ongoing La Niña was reflected by below-average sea surface
temperatures (SSTs) across the equatorial Pacific Ocean (Fig. T18). The
Niño SST index values were between –1.3°C to
–1.6°C for the month (Table T2).
The subsurface oceanic heat content (average temperatures in the upper
300m of the ocean) also remained well below-average in association with a
shallower-than-average thermocline across the central and eastern equatorial
Pacific (Fig. T17). Convection
remained enhanced over Indonesia and suppressed over the western and central
equatorial Pacific (Fig. T25). Enhanced low-level easterly
trade winds and anomalous upper-level westerly winds continued over the
equatorial Pacific (Figs. T20, T21). Collectively,
these oceanic and atmospheric anomalies reflect a moderate-to-strong La Niña.
with nearly all ENSO forecast models (Figs.
F1-F13), La Niña is
expected to peak during November-January and to continue into the Northern
Hemisphere spring 2011. Thereafter,
the fate of La Niña is more uncertain. The
majority of forecast models and all of the multi-model combinations (thicker
lines) indicate a return to ENSO-neutral conditions during the Northern
Hemisphere spring and early summer. However,
a smaller number of models, including the NCEP Climate Forecast System, suggest
that La Niña could persist into the summer.
Historically, there are more multi-year La Niña episodes than El Niño
episodes, but other than support from a few model runs, there is no consensus
for a multi-year La Niña at this time. Consequently,
La Niña is anticipated to continue into the Northern Hemisphere spring, with no
particular outcome favored thereafter.
updates of oceanic and atmospheric conditions are available on the Climate
Niño/La Niña Current Conditions and Expert Discussions).