Extended Streamflow Guidance
Issued by NWS
FGUS65 KSTR 171832
NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY, UTAH
MARCH 17, 2015
FLOOD POTENTIAL OUTLOOK
The flood potential for Arizona rivers and streams is not high at this
time. It is not high because of the below median snowpack and the low
probability of a significant rain event during the rest of this month.
Because the nature of flooding in Arizona is associated with rainfall
events versus snow melt it`s difficult to ascertain 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-February precipitation was 80 percent of average in
the Salt-Verde River Basin, 85 percent of average for the Gila Basin and
100 percent for the Little Colorado Basin. February precipitation was
60 percent of average in the Salt-Verde River Basin, 35 percent in the
Gila River Basin, and 85 percent of average in the Little Colorado Basin.
Basin snowpack conditions on March 1st were near 35 percent of average
in the Salt-Verde River Basin, 35 percent of average in the upper Gila,
and 30 percent of average in the Little Colorado River Basin.
Modeled soil moisture states remain near to above average in the Gila and
Little Colorado Basins. Soil moisture states have improved significantly
in the Salt-Verde Basins from the late February and early March storms.
Based on these existing conditions, the Gila, Salt-Verde and Little
Colorado are likely to have a low response due to snowmelt alone.
El Nino climate conditions suggest above average precipitation. The CPC
suggests a possibility of below average precipitation in Arizona for the
remainder of March. CPC also forecasts the possibility of above average
precipitation for April through May. If this forecast verifies, there
could be a small increase in runoff response due to snowmelt and