SLCESGNM Mar, 2005
View Product History
FGUS65 KSTR 042100
TTAA00 KSLR DDHHMM
NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY UT
MAR 4, 2005
INTERNAL NWS PRODUCT FOR GUIDANCE PURPOSES ONLY
SAN JUAN RIVER BASIN SPRING FLOOD POTENTIAL OUTLOOK
The 2005 spring runoff flood potential is above average for streams throughout
the San Juan Basin. The Upper San Juan and Animas basins continue to have much
above average snow pack and precipitation conditions. The observed water year
precipitation rose in February to 144% and the monthly was 197% of average.
Snow water equivalents have declined slightly to 155% in the Upper San Juan
and 142% in the Animas drainage. Observed February monthly and seasonal streamflow
numbers were 188% and 157% respectively. High base flows continue to indicate
saturated soil moisture conditions, a leading contributor to high spring runoff
and flood potential. The spring runoff volume forecasts call for above average
to much above average runoff. The median forecast from the sample population of
15 was 157% of average. The range was 130-305% of average.
The Bluff, Utah peak flow forecast for 2005 could set a post regulation (1962)
snow melt peak record. Peak stage values remain unchanged. The current post
regulation historic peak was 15600 cfs set in 1979. Flood stage remains at 23
feet or 40,700 cfs. Prior to Navajo operations peaks were considerably higher.
It is important to note that the next 2 months of the snow accumulation season
and the prevailing May weather pattern critical affect the spring flood threat.
The threat of flooding will largely be determined by hydrometeorologic events
that occur during the next several months.
Computed peak flows for three selected points are as follows:
River/Site Peak/Date Fcst Peak Normal Peak Historic Peak
CFS CFS Period CFS
___________ _________ _________ ___________ ____________
Animas - 3590, 6/8 7450 5/20 - 6/12 10700
San Juan - 1860, 5/11 3550 5/13 - 6/8 4640
San Juan - 4420, 4/6 16200* 5/5 - 6/20 15600
* - Peak flow forecast on the San Juan below Navajo Reservoir include
above average releases for spring 2005 of 5000 cfsd beginning March 23th.
The BOR is currently trying to avoid a spilling situation and will vary
the length of this release but with the current max probable volume
forecast it is set to last until June 14th.