Additional Information


Water supply forecasts take into consideration present hydrometeorological conditions and use average basin temperatures and precipitation for the forecast period. As the forecast season progresses, a greater portion of the future hydrologic and climatic uncertainty becomes known and monthly forecasts become more accurate.

Volume forecasts represent adjusted flows; that is, observed flows with upstream water use taken into account. Adjusted flows will closely approximate natural or unimpaired flows. However, not all upstream diversions or impoundments are measured or quantifiable. For specific adjustments used with each forecast point, consult the Guide to Water Supply Forecasting.

The Water Supply Outlook is issued monthly January through April by the Colorado Basin River Forecast Center, National Weather Service. It represents a coordinated effort between the National Weather Service, Natural Resources Conservation Service, Bureau of Reclamation, Salt River Project, U.S. Geological Survey and local water district managers.


DEFINITIONS:

Acre-Foot:
The volume equal to one acre covered one foot deep (43,560 cubic feet).

Average:
The arithmetic mean. The sum of the values divided by the number of values.

Categories:
Much above Average    Above Average    Near Average   Below Average    Much below Average      
Greater than 130%     111 -130%        90-110%        70-89%           Less than 70%
Forecast Period:
Variable. Current month through May 31.

Median:
The middle value. One half of the observed values are higher and half of the values are lower than this.

Most Probable Forecast:
Given the current hydrometeorological conditions to date, this is the best estimate of what the runoff volume will be this season.

Reasonable Maximum Forecast:
Given the current hydrometeorological conditions, the seasonal runoff that has a ten percent (10%) chance of being exceeded.

Reasonable Minimum Forecast:
Given the current hydrometeorological conditions, the seasonal runoff that has a ninety percent (90%) chance of being exceeded.

Water Year:
The period from October 1 through September 30.



NOTE: Data used in this report are provisional and are subject to revision.



For more information please contact:

Colorado Basin River Forecast Center
National Weather Service
2242 W. North Temple
Salt Lake City, UT 84116
(801) 524-5130
http://www.cbrfc.gov


Water Supply Outlook for the Lower Colorado - March, 2000
Colorado Basin River Forecast Center (http://www.cbrfc.gov)
Last Modified: Friday, 03-Mar-2000 14:37:35 MST