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INTERMOUNTAIN WEST CLIMATE SUMMARY, JANUARY 2008 Colorado Water Availability Snowpack is the primary determinant of water supply esti- mates from December-April 1. Snowpack is lowest in the Yampa, White, and North Platte basin in the north at 93% of average. Snowpack is highest in the southern portion of the state, ranging from 120%-> 160% in the Rio Grande, San Juan, San Miguel, Animas, and San Rafael basins. Snowpack is 296% of average in the Rio Grande Basin and snowpack increased from near record lows to near record highs in December, according to the NRCS (Figure 7a). La Nina conditions are present in the Equatorial Pacific, ho\vever La Nina's impacts to \vinter precipitation in Colorado are not consistent. Reservoir storage is near average, ranging from a low of 83% of average in the South Platte basin to a high of 110% of average in the San Juan, Dolores, Animas, and Miguel basins, according to the NRCS. The USBR expects unregulated inflow to Blue Mesa during December-February to be 99% of average. Initial spring 2008 runoff forecasts released by the NWS River Forecast Centers project near or belo\v average runoff (85-90%) for the North and South Platte Basin and above average runoff (100- 130%) for all other basins. For spring and summer streamflow forecasts, see page 17. January 1 SWSI values are near or above average, ranging from a low of -0.1 in the Yampa, White, and North Platte basin to a high of 2.8 in the Rio Grande basin (Figure 7b). With the major- ity of the snow accumulation season still ahead, water supply conditions may change throughout the winter months. Notes Figure 7a shows accumulated SWE amounts (inches) based on provision SNOTEL data as of January 4, 2008 for WY2005 (blue line), WY2006 (brown line), WY2007 (green line), WY2008 (black line) plotted against the historical average (red line). The Surface Water Supply Index (SWSI- Figure 7b) developed by the Colorado Office of the State Engineer and the NRCS is used as an indicator of mountain-based water supply conditions in the major river basins of the state. The Colorado SWSI is based on snowpack, reservoir stor""1age, and precipitation for the winter period (November-April). This differs from summer calculations that use streamflows as well. SWSI values in Figure 7b were computed for each of the seven major basins in Colorado on the first of each month, and reflect conditions through the end of the previous month. Upper Rio Grande Basin Time Series Snowpack Summary &1sed 011 Provisioll.1! SNOTEL d.1t.1 .15 of J.111 04, 2008 30 Current ~s Pet of At9: 135% Current FS Pet ofL~st Year 149% Current as Pet of Peak: 63% I Averagel as Pet of ~eak: 46% 25 -Pet-of.Avg-Needed'1o,Reaeh,Reak;...70% Average Peak Date) Apr 10 o N Res Natural R ,ourcl'S Co f'lse rvat n Sel'!i ce 20 15 10 o Oct 01 Nov 01 Dee 01 Jan 01 Feb 01 Mar 01 Apr 01 May 01 Jun 01 Jul01 Aug 01 Sep 01 I-Average -\iVY2005 -\iVY2006 -\iVY2007 -VVY200al Figure 7a. Accumulated SWE for WY2008 (black line) increased nearly 8 inches during December in the Rio Grande Basin (NRCS). Extreme Drought _ Severe Drought D Moderate Drought _Near Normal Abundant Supply Figure 7b. Colorado Surface Water Supply Index as of January 1, 2008 (Colorado NRCS). On the Web Now available from the NRCS are new SWE as a percent of normal state maps available at: http://www.wcc.nrcs.usda.gov/ gis/snow.html. For monthly reports on water supply conditions & forecasts for major CO river basins, visit: http://www.co.nrcs.usda.gov/ snow/snow/snow_all.html and click on "Basin Outlook Reports." Information on regional weather forecasts and information, visit NWS Denver/Boulder Weather Forecast Office at http:// ww. crh. noaa. gov /bou/. The Colorado Water Availability Task Force is scheduled to meet January 18, 2008. Information, including agenda & min- utes of upcoming & previous meetings are available at: http://www.cwcb.state.co.us/Conservation/Drought/taskForceAgen- daMinPres.htm. NRCS SWE line graphs by basin like in Figure 7a available at: http://www.co.nrcs.usda.gov/snow/snow/watershed/current/ daily/maps_g~hs/swe time.html. RECENT CONDITIONS 110