Extended Streamflow Guidance
Issued by NWS

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FGUS65 KSTR 061738
ESGWY
COLORADO BASIN RIVER FORECAST CENTER
NATIONAL WEATHER SERVICE SALT LAKE CITY UTAH


                     SPRING FLOOD POTENTIAL
          FOR THE GREEN AND BEAR RIVER BASINS IN WYOMING

                      May 6, 2015

The 2015 spring runoff flood potential due to snowmelt is
is not high this time for the Upper Green and Bear River
basins due to much below normal snowpack conditions.

There are currently no sites forecast to peak at or above
bankfull or flood flow.

Below and much below average peak flows are expected for southwest
Wyoming based on the current snow conditions. However, it is
important to note that specific forecast procedures and flood
flow levels do not exist for every stream.

April precipitation was again below average in all basins across
southwest Wyoming with values near 90 percent of average in the Upper
Green and 65 percent of average in the Bear River headwaters.
Seasonal precipitation is still below normal near 75 percent of average
for both the Green and Bear River basins.

Temperatures in April were near average. This is the first month
in four consecutive months that the temperatures were not
much above normal. As a result of the warm temperatures
prior to April, the low and middle elevation snow has melted.
Any remaining snowpack is limited to the highest elevations. The
current snow water equivalent is 20 percent of median in the Bear
River basin and 50 percent of median in the Upper Green River basin.

The current volume forecasts for the April through July runoff
period are below average in Green River and Bear River basins
of southwest Wyoming.

Spring temperatures highly affect the pattern of snowmelt
runoff and consequently the magnitude of peak flows. It is
also important to keep in mind that an extended period of much
above normal temperatures or heavy rainfall during the melt
period can cause or exacerbate flooding problems in any year,
regardless of snowpack conditions.

A list of specific spring peak flow forecasts are available at:
http://www.cbrfc.noaa.gov/rmap/peak/peaklist.php

A map of the current spring peak flow forecasts is available at:
http://www.cbrfc.noaa.gov/lmap/lmap.php?interface=peak

CBRFC/A.Nielson,P.Miller

$$








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