Dynamical Seasonal Rainfall Prediction for Hawaii
H. Annamalai, J. Hafner (IPRC)
A. Kumar, H. Wang (NOAA Climate Prediction Center)
Hawaii Rainfall Prediction (DJF)
Seasonal skill (model-observations corr.)
Moisture advection
Temperature advection
A 24-member ensemble hindcast with NOAA’s
Climate Forecast System version 2 (CFSv2) was
diagnosed for its ability to predict seasonal rainfall
during 1981–2012 for the US Affiliated Pacific
Islands. The skill for the South and West Pacific
islands is better than the results shown here for
Hawaii, which has lower interannual rainfall variance.
Top panel: the model’s ability to hindcast winter
rainfall anomalies over Hawaii shows that it is useful
for leads of 0-6 months. Particularly notable is the
model’s quite skillfull rainfall prediction during El
Niño winters (1982–83; 1997–98; and 2010–11; see
red arrows) at a 6-month lead.
Second panel: the model’s skill as represented by the
correlations of model projections with observations is
modest for the spring and summer seasons.
Bottom panels: Analysis of the moist and radiative
processes in the model shows that the dry, cool
climate in Hawaii during the 1997/98 El Niño was
largely due to cold and dry air advection.
A comparison with similar diagnostics of reanalysis
products (not shown) reveals that CFSv2 represents
well the physical processes contributing to the drought
during that year.