Extended Streamflow Guidance
Issued by NWS
FGUS65 KSTR 152017
NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY, UTAH
FEBRUARY 15, 2017
FLOOD POTENTIAL OUTLOOK
The flood potential for Arizona Rivers and streams is above average
at this time.
Because the nature of flooding in Arizona is associated with rainfall
events versus snow melt it`s difficult to determine with much certainty
the flood threat over a season. Existing streamflow, soil, and snowpack
conditions are analyzed for their potential contribution to streamflow
levels during future rainfall events.
Seasonal October-January precipitation was 150 percent of average in
the Salt-Verde River Basin, 125 percent of average for the Gila Basin and
155 percent for the Little Colorado Basin. January precipitation was
200 percent of average in the Salt-Verde River Basin, 195 percent in the
Gila River Basin, and 200 percent of average in the Little Colorado Basin.
January 1st snowpack conditions were 140 percent of median in the
Salt-Verde River Basin, 90 percent of median in the upper Gila,
and 145 percent of median in the Little Colorado River Basin.
Modeled soil moisture states were much below average at the beginning
of the water year. However, Conditions have inproved dramatically since
December. February through May runoff volumes are primarily influenced by
the frequency and magnitude of winter rain events.
Due to the improved soil moisture conditions, above average snow water
equivalents, the flood potential for Arizona is above average. Howewver,
the main driving factor for the flooding threat is the possibility of a
warm, wet event during the latter portion of February into mid March.