Extended Streamflow Guidance
Issued by NWS
FGUS65 KSTR 151736
TTAA00 KSLR DDHHMM
NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY UT
February 15, 2017
SAN JUAN RIVER BASIN SPRING FLOOD POTENTIAL OUTLOOK
The flood potential due to snowmelt is considered higher than normal in the
San Juan Basin as of early February. This is primarily due to a signficant
snowpack that ranges from near 140 to 170 percent of median for mid February.
Additionally a few SNOTEL sites in the Animas Basin and upper San Juan
River headwaters have already met or exceeded the annual spring peak snowpack
that typically occurs in early April.
Current hydrologic model guidance does not indicate any forecat points reaching
flood levels due to snow melt runoff this spring. However, procedures do not
exists for all areas. Above average spring runoff peaks are likely with
bankfull conditions possible. This is particularly true for headwaters of the
Animas River Basin and upper parts of the San Juan River Basin above reservoirs.
With a couple of months remaining in the snow accumulation season several
scenarios are still possible including snowpack conditions returning to near
median or normal if a period of dry weather were to occur. Therefore while
the flood potential threat is currently elevated it is too early to make
a final conclusion.
Heavy rain during the peak runoff period or a prolonged period of much above average
temperatures that enhance snowmelt may result in flood related problems in
any year. With above average snow melt runoff anticipated this year rainfall during peak
snow melt runoff will have a larger impact than in a more normal
year and would increase the flood threat.
Further assessment will be made regarding any snow melt flood threat as
the season progresses.
G. Smith/ CBRFC