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NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY UT
Feb 3, 2011

           INTERNAL NWS PRODUCT FOR GUIDANCE PURPOSES ONLY

 SAN JUAN RIVER BASIN SPRING FLOOD POTENTIAL OUTLOOK

The 2011 spring runoff flood potential is not high at this time for streams
throughout the San Juan River Basin. January precipitation was 20% of
average while the observed water year precipitation to date is 105% of
average. Snow water equivalent as of February 1 was 95% in the Upper San
Juan and 110% in the Animas. The current volume forecasts for the April-July
runoff period is near to below average.

It is important to note that it is very early in the snow accumulation season 
and that the spring flood threat due to runoff will largely be determined by 
hydrometeorologic events that occur during the next several months.
February 1st snow water equivalent is 59% of the average seasonal peak and
our models assume near normal precipitation into the future. Although
spring temperatures affect the pattern of snowmelt runoff and consequently
the magnitude of peak flows, peak flows also roughly correspond to volumetric
flows. Therefore, at this time, given normal temperatures and the lack of an
intense, heavy rainfall event during peak runoff, peak flows are expected to
be near normal. By the same token, an extended period of much above
normal temperatures or heavy rainfall during the melt can cause or exacerbate
flooding problems.

CBRFC


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