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<br />How Foi'8c8sls
<br />Are Made
<br />
<br />For More IntoRnatlon
<br />
<br />0009H
<br />
<br />Foreword
<br />
<br />Most of the annual streamflow In the Western United States originates as snowfall. This snowfall accumu-
<br />lates high in the mountains during winter and early spring. As the snowpack accumulates, hydrologists
<br />estimate the runoff that will occur when it melts. Predictions are based on careful measurements of snow
<br />water equivalent al selected index points. Precipitation, temperature, soil moisture and antecedent streamflow
<br />data are viewed In conjunction with snowpack data to prepare runoff forecasts. This report presents a
<br />comprehensive picture of water supply outlook conditions for areas dependent upon surface runoff. It
<br />includes selected streamflow forecasts, summarized snowpack and precipitation data, reservoir storage
<br />data and narratives describing current conditions.
<br />
<br />Streamflow forecasts are cooperatively generated by Soil Conservation Service and National Weather
<br />Service hydrologists. Forecasts become more accurate as more data affecting runoff becomes known.
<br />For this reason, forecasts are issued that reflect three future precIpitation conditions - Below Normal,
<br />Average, and Above Normal. These forecasts are termed reasonable minimum, most probable, and reasonable
<br />maximum. Actual streamflow can be expected to fall between the lower and upper forecast values eight
<br />out of ten years.
<br />
<br />Snowpack data are obtained by using 8 combination of manual and automated measurement methods.
<br />Manual readings of snow depth and water equivalent are taken at locations called snow courses on a
<br />monthly or semi-monthly schedule during the winter. In addition, snow water equivalent, precipitation,
<br />temperature, and other parameters are monitored on a dally basis and transmitted via radio telemetry
<br />to central data collection facilities. Both monthly and daily data are used to project snowmelt runoff.
<br />
<br />Copies of Monthly Water Supply Outlook Reports and other reports may be obtained from the states
<br />listed below. Because of the limited space, snow survey measurements are not publiShed in monthly
<br />reports. An annual snow survey data summary Is publiShed by the Soil Conservation Service for each
<br />of the western states. Historical snow survey data may be obtained at those same offices.
<br />
<br />STATE
<br />Alaska
<br />
<br />ADDRESS
<br />201 East 9th Ave., Suite 300, Anchorage, AK 99501-3687
<br />201 East Indienola, Suite 200, Phoenix, I<l. 85012
<br />2490 Wesl 26lh Ave., Denver, CO B0211
<br />517 Gold Ave. SOW" Room 3301, Albuquerque, NM 87102
<br />304 North Slh Slreet, Room 345, Boise, ID 83702
<br />10 East Babcock, Room 443, Federal Building, Bozeman, MT 59715
<br />1201 Terminal Way, Room 219, Reno, NV 89502
<br />1220 Southwest 3rd Ave., Room 1640, Portland, OR 97208
<br />4402 Federal Building, 125 South Stale Street, Sail Lake City, UT 84147
<br />360 U.S. Court House, Spokane, WA 99201
<br />Federal Building, 100 East "B" Street, Casper, WY 82601
<br />
<br />Arizona
<br />
<br />Colorado
<br />New Mexico
<br />Idaho
<br />
<br />Montana
<br />
<br />Nevada
<br />Oregon
<br />Utah
<br />Washington
<br />Wyoming
<br />
<br />In addition to state reports, a Water Supply Outlook for the Western United States is published by the
<br />Soil Conservation Service and National Weather Service monthly, January through May. Reports may be
<br />obtained from the Soil Conservation Service, West National Technical Center, 511 Northwest Broadway,
<br />Room 547, Portland, OR 97209_
<br />
<br />Published by other agencies:
<br />
<br />Water Supply Outlook Reports prepared by other agencies include: California - Snow Survey Branch,
<br />California Department of Water Resources, P.O. Box 388, Sacramento, CA 95802; British Columbia - The
<br />Ministry of Environment, Water Investigations Branch, Parliament Buildings, Victoria, British Columbia,
<br />vav 1X5; Yukon Territory - Department ot Indian and Northern Affairs, Northern Operations Branch, 200
<br />Range Road, Whitehorse, Yukon Territory, Y1A 3V1; Alberta, Environment Technical Services Division, 9820
<br />106th St., Edmonton, Alberta T5K 2J6.
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