FGUS65 KSTR 072002 ESGNM TTAA00 KSLR DDHHMM NATIONAL WEATHER SERVICE COLORADO BASIN RIVER FORECAST CENTER SALT LAKE CITY UT MAY 7, 2009 INTERNAL NWS PRODUCT FOR GUIDANCE PURPOSES ONLY SAN JUAN RIVER BASIN SPRING FLOOD POTENTIAL OUTLOOK The potential for spring 2009 flooding due to snowmelt in the San Juan Basin is low at this time. Most rivers and streams over the upper portions of the San Juan, Navajo, Piedra, Animas and La Plata are forecast to remain below bankfull. Current snowpack as of May 1st for the entire San Juan Basin is 75 percent of average. April precipitation was 95 percent of average across the entire Basin, while seasonal totals since October 2008 were 95 percent of average. The volume forecast for the April-July runoff period is near to below average. It is also important to keep in mind that an extended period of high temperatures resulting in rapid snowmelt, or heavy rainfall during the peak flow period when stream channel capacities are reduced, may cause or exacerbate flood problems in any year. Specific spring peak flow forecasts (maximum mean daily flow) as of May 1st. Forecast peaks for this year are 50% exceedance values. For full probabilistic distributions of possible peaks, see: http://www.cbrfc.noaa.gov/product/peak/peak.cgi 2009 Normal Fcst 2008 Flood Bankfull Average Period Peak Peak Flow Flow Peak of River / Site (cfs) (cfs) (cfs) (cfs) (cfs) Peak ------------------ ------- ------- ------- ------- ------ ----------- San Juan - 2350 2870 6840 5170 2485 5/15 - 6/12 Pagosa Springs Animas - 3900 5850 9555 5970 4675 5/28 - 6/14 Durango Animas - 4000 6080 8810 6580 4900 5/31 - 6/15 Farmington San Juan - 8000* 8850 40485 29325 7340 5/21 - 7/4 Bluff * - Peak flow forecast on the San Juan below Navajo Reservoir include the most probable Spring Release of 14 days at 5,000 cfs. The Spring Release will start with a week long ramp up period from 500 cfs to 5000 cfs in late May and end with a week long ramp down period from 5000 cfs to 500 cfs starting in the middle of June. CBRFC NNNN $$