Extended Streamflow Guidance
Issued by NWS

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FGUS65 KSTR 031928
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

                       April 3, 2015

The 2015 spring runoff flood potential due to snowmelt is
is not high this time for the Upper Green and Bear River
basins. However, it should be emphasized that snow typically
accumulates into April, therefore conditions may change before
the runoff begins.

Currently, the following sites are forecast to peak at or above
the bankfull (for example, there is a 10% chance the Green River
near LaBarge will exceed bankfull):

Bankfull:
Green River near LaBarge               10%

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.

March precipitation was again below average in all basins across
southwest Wyoming with values around 50% of average.
Seasonal precipitation is now below normal near 75% of average
for the Upper Green River and Bear River basins in Wyoming.

In addition to below average precipitation, the month of March
had much above normal temperatures with many locations having
record warm temperatures. As a result, the majority of
low elevation snow has melted out and melt has occurred at even
the highest elevations. The current snow water equivalent
is 45 percent of median in the Bear River basin and near
80% of median in the Green River basin above
Fontenelle.

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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