Forecast Forum
NOVEMBER 2007
Forecast Forum
The
CPC and the contributors to the Forecast Forum caution potential users of
this predictive information that they can expect only modest skill.
Outlook:
La
Niņa is expected to continue into the Northern Hemisphere spring 2008.
Discussion:
La
Niņa reached moderate strength during November 2007, with below-average sea
surface temperatures
(SSTs) extending from 160šE to the South American coast (Fig.
T18). All
of the Niņo region indices, except for Niņo-4, were lower than −1.4°C (Table
T2). The
upper-ocean heat content (average temperatures in the upper 300 m of the ocean)
in the central and east-central equatorial Pacific remained below average, with
temperatures ranging from 2°C to 5°C below average at thermocline depth (Fig.
T17).
Consistent with these oceanic conditions, low-level easterly winds and
upper-level westerly winds strengthened across the central equatorial Pacific (Figs.
T20 and T21), convection remained suppressed throughout
the central equatorial Pacific, and an area of enhanced convection covered the
far western Pacific (Fig. T25). Collectively, these oceanic and atmospheric conditions reflect La Niņa.
The
recent SST forecasts (dynamical and statistical models) for the Niņo 3.4 region indicate a continuation of La Niņa into the Northern Hemisphere spring
2008 (Figs. F1-F13).
Over half of the models indicate a moderate-to-strong La Niņa through February,
followed by a gradual weakening thereafter. Current atmospheric and oceanic
conditions and recent trends are consistent with the model forecasts.
Weekly
updates of oceanic and atmospheric conditions are available on the Climate
Prediction
Center
homepage (El
Niņo/La Niņa Current Conditions and Expert Discussions).
|