Weekly Probabilistic Coral Bleaching Heat Stress Outlook
Warning and higher --(Warning and Alert Levels 1 and 2)
(Weekly Outlooks from Weeks 2 to 15 and often up to Week 20 were used in deriving the Four-Month Bleaching Outlook.)
Due to limitations in model physical processes, numerical calculations, initializations, and
inherent unpredictability of the climate system, the accuracy of forecasts depends
significantly on geographic locations and forecast lead-time. For the same geophysical
location, the forecast accuracy decreases with increasing lead-time.
In general, a model performs better for regions where the processes are controlled by large
scale variations; for example, over the central-eastern tropical Pacific Ocean and also the
central-eastern tropical Indian Ocean and Caribbean. The skill is relatively high even for
longer lead-times in these regions when large-scale climate signals, such as ENSO, prevail.
Ensembles (repeated runs of the model using slightly different initial conditions) used in
probabilistic forecasts help to increase the chance of capturing the reality among a set of
possible future climate patterns generated.
CRW's Coral Bleaching Heat Stress Outlook products are based on NOAA's Climate Forecast
System (CFS). Assessment of the CFS SST forecast skill is available
While acknowledging these limitations, longer lead-time predictions are helpful in preparing
coral reef stakeholders to understand potential future thermal stress; use it to support
effective reef management and conservation decisions; and to communicate with the public and
local decision makers. Coral Reef Watch suggests caution in the use and analysis of outlooks,
especially with lead-times longer than 20 weeks.