Decision support experiments and evaluations using seasonal to ...

BOX 2.3: The CPC Seasonal Drought Outlook
Decision-Support Experiments and Evaluations using Seasonal to
Interannual Forecasts and Observational Data: A Focus on Water Resources
The CPC Drought Outlook (DO) is a categorical prediction of drought evolution for the three months forward from
the forecast date. The product, which is updated once per month, comprises a map that is accompanied by a text
discussion of the rationale for the categories depicted on the map.
The starting conditions for the DO are given by the current Drought Monitor (DM) (a United States map that is
updated weekly showing the status of drought nationwide located: ),
and the DO shows likely changes in and adjacent to the current DM drought areas. The DO is a subjective consensus
forecast that is assembled each month by a single author (rotating between CPC and the National Drought Mitigation
Center [NDMC]) with feedback from a panel of geographically distributed agency and academic experts. The basis
for estimating future drought evolution includes a myriad of operational climate forecast products: from short- and
medium-range weather forecasts to seasonal predictions from the CPC climate outlooks and the NCEP CFS outputs;
consideration of climate tendencies for current El Nino–Southern Oscillation state; regional hydroclimatology; and
medium-range to seasonal soil moisture and runoff forecasts from a variety of sources.
The DO makes use of the most advanced objective climate and hydrologic prediction products currently available,
including not only operational, but experimental products, although the merging of the different inputs is based on
expert judgment rather than an objective system. The DO is verified by comparing the DM drought assessments at
the start and end of the DO forecast period; verification skill scores have been tracked for the last seven years. The
DO is the primary drought-related agency forecast produced in the United States, and is widely used by the drought
management and response community from local to regional scales.
The DO was developed in the context of new
drought assessment partnerships between the
CPC, U.S. Department of Agriculture and the
NDMC following the passage of the National
Drought Policy Act of 1998. The DM was released
as an official product in August, 1999, with the
expectation that a weekly or seasonal drought
forecast capacity would be added in the future. A
drought on the Eastern Seaboard in the fall of 1999
required briefings for the press and the Clinton
Administration; internal discussions between DM
participants at the CPC led to the formation of the
first version of the DO (maps and text) for these
briefings. These were released informally to local,
state and federal agency personnel throughout
the winter of 1999 to 2000, and received positive
feedback.
The CPC decided to make the products official, provided public statements and developed product specifications,
and made the product operational in March 2000. The initial development process was informal and lasted about six
months. In November 2000, the first Drought Monitor Forum was held, at which producers and users (agency, state,
private, academic) came together to evaluate the DM in its first year and plan for its second, providing, in addition,
a venue for discussion of the DO. This forum still meets bi-annually, focusing on both DM- and DO-relevant issues.
Developmental efforts for the DO are internal at CPC or within NCEP, and the primary avenues for feedback are
the website and at presentations by DO authors at workshops and conferences. The DO authors also interact with
research efforts funded by the National Oceanic and Atmospheric Administration (NOAA) Climate Program Office
and other agency funding sources, and with NOAA research group efforts (such as at NCEP), as part of the ongoing
development effort. URL: .
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