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<br />Colorado Drou2ht Watch <br /> <br />April 2, 2002 <br /> <br />About SNOTEL <br /> <br />The ~aluraJ Resources Conwrvation Scn"ice (NRCS) installs. operates. and maintains an extensive. automated <br />system to collect snowpack and related climatic data in the Western United States called, SNOwpack TELemetry <br />(SNOTEL). The system evolved from NRCS's congressional mandale in the mid. 1930's "to measure snowpack in <br />the mountains of the West and forecast the w<ller supply." The programs began with manual measurements of <br />snow Courses; since 1980, SNOTEL has reliably and efficiently collected the data nceded to produce water supply <br />forecasts and to support the resource management activities ofNReS and others. <br /> <br />The sites are genem]]y located in remOle high-mountain watersheds where access is often dillicult or restricted. <br />Access for maintenance by NRCS includes various modes from hiking and skiing 10 helicopters. <br /> <br />Sites are designed to oremtc unattended and without maintenance for a year. They are balleI)' powered with solar <br />cell recharge. The condition of each sile is monitored daily when it reports on 8 operational functions. Serious <br />problems or deteriorating pcrfomlance trigger a response frolll the NRCS electronic technicians located in six data <br />collection otTIces. <br /> <br />Common Drought and Moisture Indexes <br /> <br />. Surface Water Suppl~' Index (SWSI) is a weighted index of snow pack. stream now. precipitation and res- <br />ervoir stomge. <br /> <br />. Standardized I)recipitation Index (SPI) is considerl'tlto be the simplest and most robust index fordt'Sl:rib- <br />ing drought patterns. It is based on current and historical precipitation data for a particular location. <br /> <br />. Illlhner Drought Index is a complex soil moisture calculation used by fedeml agricultural agencies in deter- <br />mining drought assistance to local famlers and ranchers. <br /> <br />. Crop :\Ioisture Index. developed Irom the Palmer Drought Index. evaluates shon-tenn moisture conditions <br />across major crop producing regions or the U.S. <br /> <br />. I{cscn'oir Ic\"Cls indicates the amollnt of water in storage at various water supply reservoirs. <br /> <br />About the U,S, Drought Monitor <br /> <br />The Drought Monitor map idemifies gcneml drought areas. labeling droughts by intensity. \vith D1 being the least <br />intense and D4 being the most imense. DO drought watch areas. are either dl)'ing out and possibly heading for <br />drought. or are recovering from drought but not yet back to nonnal. and are suffering long-tenn impacts such as low <br />reservoir Icwls. <br /> <br />Drought IIltensity categories are bascd on six key indicators and numerous supplemental)' indicators. Because the <br />mnges of the various indicators ollen don't coincide. Ihe final drought category tcnds to be based on what the major- <br />ity oflhe indicators show. The analysts producing the map a/so \....eigh the indices according to how well they per- <br />fonn in ....arious pans of the cOUlltl)' and al different times of the year. Also. additional indicators are ollell needed in <br />the West. where winter snowfall has a strong bearing on water supplies. <br /> <br />A partnership consisting of the U.S. Depanment of Agriculture, the National Weather Service's Climate Prediction <br />Center. and the National Drought Mitigation Center at the Univel'5ity of Nebraska Lincoln produces the Drought <br />l\10nilor. However. ad\ice from many other sources is incorpomted III the product. including virtually every go\'em- <br />ment agency dealing with drought. <br /> <br />7 <br />