WMOD00527

• Title: Quantitative Precipitation Forecasting for Improving Reservoir Operations
• Date: 4/1/1995
• Weather Modification - Doc Type: Report

precipitation estimates are and will be primarily based upon NEXRAD (NEXt generation
RADar) and ALERT (Automated Local Evaluation in Real Time) data. Better QPFs will
result from faster computer workstations which run higher-resolution mesoscale models, and
the application of GOES-I (Geostationary Operational Environmental Satellite) data coupled
with conceptual models. The future benefit of better mesoscale models in precipitation
forecasting was stated earlier in section 2.8.3; information on the higher resolution and
sounding capabilities of GOES-I is provided in Menzel (1994).

Because the QPFs and headwater runoff forecasts used by Reclamation's water operations
managers are received from the NWS, -many of the managers seem to believe that any
improvement in the real-time precipitation estimates and short-term forecasts is the sole
responsibility of the NWS. However, with the modernization and associated restructuring
of the NWS (see section 2.8.2), the Nation is entering a "new era" of weather monitoring and
prediction. The NWS is attempting to work on many things simultaneously, but like all
Federal agencies, they too have limited resources. Who will ensure that Reclamation's
hydrological needs and problems are being addressed? This concern should be Reclamation's
own responsibility.

Much of the new remote sensing technology equipment is just being installed. For example,
in the northern California area, the NEXRAD radar system at Sacramento will be
commissioned in November 1994; two additional NEXRAD systems, at Beale Air Force Base
and Eureka, are scheduled for commissioning during the fall of 1995. The first new
generation of GOES satellites (GOES-I) was launched in April 1994. More ALERT systems,
whi.ch are essentially the same as Reclamation's Early Warning Systems, are being installed.
Tremendous quantities of data will be available; consequently, new computer workstations
are being installed at the NWS's WFOs and RFCs to process the data, as well as to use NWS
analysis and display products, and to access NMC prognostic gridded field data for input to
local scale models.

ThE~ tasks of incorporating all of the new technology data into operational nowcast and
fOrE~cast procedures, and then to verify the forecasts, are numerous and generally time-
consuming. For example, the NEXRAD precipitation algorithms still need much work.
Presently, only one algorithm for convective rain is being used. Algorithms have to be
developed for stratiform rain, orographic rain/snow, and snowfall resulting from mesobeta-
scale (20 to 200 km) and mesoalpha-scale (200 to 2000 km) weather systems.

NOAA's FSL (Forecast Systems Laboratory), located in Boulder, Colorado, focuses on research
that will lead to the development and transfer of new technologies and scientific
advancements to the NWS and other operational organizations (MacDonald et a1., 1994). One
system under development and testing is LAPS (Local Analysis and Prediction System). The
primary objective of LAPS is to provide real-time, 3-D, mesobeta-scale analyses, and short-
range forecasts (0- to 12-h) for NWS WFOs, RFCs, or other operational facilities. LAPS is
designed to fuse data from existing and future data platforms (e.g., NEXRAD Doppler radar,
wind profiler, ALERT systems, GOES-I, and aircraft observations), provide analyses of
common weather elements, and generate real-time, high-resolution forecasts of precipitation
and other weather parameters.

These short-range forecasts are currently not operationally available, but the potential for
significantly improved QPFs and flood forecasts for individual watersheds, reservoirs/dams,
and river systems is exciting. Analyzing the NEXRAD, automatic remote precipitation gauge,

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