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Forecast Forum
MARCH 2009
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.
ENSO
Alert System Status: La Niña Advisory
Outlook:
A
transition to ENSO-neutral conditions is expected during April 2009.
Discussion:
Atmospheric
and oceanic conditions during March 2009 continued to reflect weak La Niña
conditions. The monthly sea surface temperatures (SST) remain below-average
across parts of the east-central and eastern
Pacific Ocean
(Fig. T18).
The Niño-3.4 SST index value was −0.6°C for the month (Table
T2). Negative subsurface oceanic
heat content anomalies (average temperatures in the upper 300m of the ocean)
weakened further across the eastern half of the equatorial
Pacific Ocean
.
At thermocline depth, positive temperature anomalies in the western and
central Pacific expanded eastward, while negative temperature anomalies became
confined to the far eastern Pacific (Fig. T17).
Convection remained suppressed near the Date Line, and enhanced across
Indonesia
, but weakened during
the later part of the month due to Madden-Julian Oscillation (MJO) activity (Fig.
T25).
Enhanced low-level easterly winds and upper-level westerly winds also
decreased across the equatorial
Pacific Ocean
(Figs. T20
and T21).
Collectively, these oceanic and atmospheric anomalies are consistent with a
weakening La Niña.
A
majority of model forecasts for the Niño-3.4 region show that once established,
ENSO-neutral conditions will continue through the remainder of 2009.
Several models indicate La Niña will continue through March-May 2009 (Figs.
F1-F13). Based on current observations, recent trends, and
model forecasts, a transition to ENSO-neutral conditions is expected during
April 2009.
Weekly
updates of oceanic and atmospheric conditions are available on the Climate
Prediction
Center
homepage (El
Niño/La Niña Current Conditions and Expert Discussions).
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www.nws.noaa.gov 
