Snow Surveys and Water Supply Forecasting

The Centralized Forecasting System

The snow survey program has a Centralized Forecasting System (CFS), which is automated for handling information related to water supply forecasting such as streamflow, precipitation, snow depth and snow water equivalent, and reservoir data. These data are available for the current water year (October 1 through September 30) and for historical water years. Numerous routines and interactive programs for manipulating water supply data are included in utility programs within CFS. These are mainly intended to aid in applying snow survey program information for conservation in the field.

CFS was developed and is operated by the NRCS National Water and Climate Center (NWCC) in Portland, Oregon. CFS is accessible via approximately 40 telephones lines, through commercial systems, and the Federal Telecommunications System. A manual is available that outlines many CFS products, access methods, and primary contacts. CFS is the primary focal point for snow survey data analyses, streamflow forecasting, data exchange, and product dissemination. It serves as the delivery system to make snow survey and related planning information available to local conservation districts and NRCS offices where it is incorporated into their conservation application programs. It is complementary to NRCS's Field Office Computing System (FOCS), which is designed to automate conservation planning activities. CFS also provides access to hydrologic data and interpretative products for a wide variety of governmental agencies and the general public. The systems can be accessed by most computers, and it is menu driven for ease of use.

Hydrologists use the computer programs in CFS to generate streamflow predictions throughout the West and to analyze and interpret hydrologic and meteorological data into meaningful products useful at the local level. The data in CFS are also important for natural resources management planning. These data reside in an automated database consisting of monthly data for 1,700 snow courses, 600 stream gauges, 300 reservoirs, and 1,200 precipitation stations as well as daily data from 550 SNOTEL sites and 2,000 climatological stations. Data are exchanged routinely with the National Weather Service and numerous agencies as well as private entities.

The 10 Western States and Alaska publish a monthly Water Supply Outlook Report which is generated by CFS. Special reports can be created and stored that include data for specific SNOTEL sites and during specific time intervals. Several utility programs are available that are designed for snow survey personnel use in quality control for measured data and forecast. Various hydrologic models in CFS provide users with an array of forecast products.

Other CFS programs relate snow survey streamflow forecasts to irrigation planning at the farm level. These programs incorporate crop consumptive use data and irrigation planning routines from NRCS State Irrigation Guides. Several other routines concern topics such as center-pivot sprinkler evaluation, irrigation project screening, and regression analysis for relation of streamflow forecasting to local farm and irrigation district supply ditches (fig. 15).

Figure 15. An irrigation water supply ditch carries snowmelt water to the fields.