WSP02823

• File Number: 8210.137
• Description: Colorado River Basin-Colorado River Basin Organizations/Entities-Colorado River Forecast Committee
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1999
• Author: NOAA
• Title: Water Supply Outlook - Colorado Basin River Forecast Center - Upper Colorado Report
• Water Supply Pro - Doc Type: Report/Study

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 pro-
gresses. a greater portion of the future hydrologic and climatic uncertainty becomes known and
monthly forecasts become more accurate.

Volume forecasts represcnt 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 quantiflable. For specific adjust-
ments used with each forecast point. consult the Guide to Water Supply Forecasting.

The Water Supply Outlook Is Issued monthly January through May by the Colorado Basin River
Forecast Center. National Weather Service. It represents a coordinated effort between the Na-
tional Weather Service. Natural Resources Conservation Service. Bureau of Reclamation. 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
Greater than 130%

Above Average
111-130%

Near Average
90-110%

Below Average
70-89%

Much Below Average-
Less than 70%

Forecast Period:

The period from April I through .,July 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 hydrometeorologlcal conditions to date. this Is the best estimate of what the
runoff volume will be this season.
Reasonable Maximum Forecast:

Given the current hydrometeoroJogical conditions. the seasonal runoff that has a ten percent
(J 0%) 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 I through September 30.

NOTE: Data used in this report are proVisional and are subiect to revision.

For more information, or to be included on the mailing list. please contact:
Colorado Basin River Forecast Center. National Weather Service

2242 W. North Temple. Salt Lake City. UT 84116.[phone]. http://www.cbrfc.gov

.

Colorado Basin River Forecast Center - National Weather Service - Jao-99

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