Flood Potential Outlook
Issued by NWS Cheyenne, WY

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FGUS75 KCYS 031848
ESFCYS
Probabilistic Hydrologic Outlook
National Weather Service Cheyenne Wy
1148 AM MST THU MAR 3 2016

 ...2016 Spring Flood and Water Resources Outlook...

This outlook covers the Cheyenne hydrologic service area (HSA) which
emcompassses 7 counties across southeastern Wyoming and 7 counties
across western Nebraska. This outlook covers the North Platte River
mainstem and its tributaries (the Laramie and Medicine Bow Rivers) in
southeastern Wyoming and the Nebraska panhandle. Likewise, it also
includes the tributaries to the Missouri River (Niobrara and White
Rivers) of extreme northwestern Nebraska. Finally, it also includes
the Little Snake River.

Southeast Wyoming and western Nebraska generally do not experience
any significant mountain snowmelt runoff until May and June. Therefore,
at this time, it is too early to make any long range prediction on
and the magnitude of flooding due to mountain snowmelt runoff.

This outlook is based on various diverse hydrological factors such as
snow water equivalents (SWEs) in the mountain snowpack, basin
morphology (i.e. how basins respond to snowmelt), amount of bark
beetle kill, low elevation snow depths, and temperature and
precipitation trends during the late spring and early summer.

...No significant drought conditions persist across the North Platte
Basin...

...Above average water year precipitation totals across the Cheyenne
HSA...

...Mountain snowpack across Wyoming is 85 to 90 percent of average...

...Wyoming carryover reservoir storages are 115 to 125 percent of
average for February...

...Below normal snowmelt streamflow volumes are expected across major
basins in Wyoming and western Nebraska...

...There is a low potential for flooding due to snowmelt this runoff
season across the Cheyenne HSA...

In the table below, the 90 through 10 percent columns indicate the
chance the river could rise above the listed stage levels in the
next 90 days.

Table 1--Probabilities for minor...moderate and major flooding
               Valid Period:  03/05/2016  - 06/03/2016

                                       :    Current and Historical
                                       :     Chances of Exceeding
                                       :       Flood Categories
                                       :      as a Percentage (%)
                      Categorical      :
                   Flood Stages (FT)   :   Minor    Moderate   Major
Location           Minor   Mod   Major :  CS   HS   CS   HS   CS   HS
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Encampment River
Encampment           6.5    7.5    8.5 :   5    6   <5    5   <5   <5
:North Platte River
Saratoga             8.5    9.5   10.5 :  13   27   <5    9   <5   <5
Sinclair             9.0   10.0   11.0 :   9   20   <5   11   <5   <5
:Medicine Bow River
Hanna                6.0    7.0    8.0 :  <5    5   <5   <5   <5   <5
:North Platte River
Glenrock            10.0   11.0   12.0 :  <5   <5   <5   <5   <5   <5
Orin                 8.0    9.0   10.0 :  <5   11   <5   <5   <5   <5
:Laramie River
Woods Landing        6.0    6.5    7.0 :  <5   <5   <5   <5   <5   <5
Laramie              8.0    9.0   10.0 :   8   33   <5    8   <5   <5
Bosler               7.5    8.5    9.5 :  <5   <5   <5   <5   <5   <5
Fort Laramie         7.0    8.0    9.0 :  <5    6   <5   <5   <5   <5
:North Platte River
Henry                5.5    6.5    7.5 :   5   15   <5   12   <5    9
Mitchell             7.5    8.5    9.5 :   7   16    5   14   <5   12
Minatare             7.5    8.5    9.5 :   5   13   <5   11   <5    6
Bridgeport           9.5   10.0   10.5 :  <5    6   <5   <5   <5   <5

Legend
CS = Conditional Simulation (Current Outlook)
HS = Historical Simulation
FT = Feet

This long-range probabilistic outlook contains forecast values that
are calculated using multiple season scenarios from 30 or more years
of climatolgical data including current conditions of the river, snow
cover, soil moisture, and the 30 to 90 day long-range outlooks of
temperature and precipitaion. By providing the complete range of
probabilities, the level of risk associated with long-range planning
decisions can be determined. These probabilistic forecasts are part
of the National Weather Service`s advanced hydrologic prediction
services (AHPS).

Visit our web site at www.weather.gov/cys for more weather and river
information including graphs of probablilistic river outlooks.

$$

Graphical forecasts are available at:
http://water.weather.gov/ahps2/index.php?wfo=cys
Visit weather.gov/cys and select the rivers & lakes tab for graphical
forecasts and additional information.

$$



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