Extended Streamflow Guidance
Issued by NWS

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FGUS65 KSTR 031924
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, 2014

The 2014 spring runoff flood potential due to snowmelt
is high at this time for the Upper Green River and
higher than usual in the Bear River basins in Wyoming due
to much above and above normal snowpack. Snow can
accumulate into April and any significant increase in the
snowpack or delay of the melt will enhance the threat. However,
a change to dry conditions or a slow orderly melt during
the spring can alleviate any flood threat.

Currently, the following sites are forecast to peak at or above
the bank full or flood flow at the given exceedance level
(for example, there is a 50% chance the Green River near LaBarge
will exceed flood flow):

Flood Flow:
Green River near LaBarge              50%
Green River at Green River,Wyoming    25%

Bankfull:
Green River at Warren Bridge          50%
New Fork River near Big Piney         10%
Bear River near UT/WY State Line  10%

It is important to note that specific forecast procedures
do not exist for every stream. Above average peak flows and
bankfull or flood conditions are possible on several streams
and small tributaries in southwest Wyoming due to the
significant snowpack.

March precipitation on average was above average
in the Green and Bear River basins at 115 percent of average.
However, precipitation was much above average in the headwaters
of the Upper Green River. Similarly, seasonal precipitation is
above average for both basins at 120 percent of average. As a
result, the snow water equivalent is much above median and many
Snotel locations are much above the average seasonal peak.

Current snowpack conditions in Green and Bear River basins as a
percent of median are:

Green River above Fontenelle           160%
Ham`s Fork River                       140%
Green River above Flaming Gorge        145%
Bear River Basin                       115%


The current volume forecasts for the April through July runoff
period also follow a similar pattern with much above average
volumes forecast the Green River Basin and above average volumes
for the Bear River Basin.

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/gmap/gmapbeta.php?interface=peak

The spring runoff flood potential will be re-evaluated in early
May an updated product will be issued at that time.

CBRFC/A.Nielson

$$




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