Flood Potential Outlook
Issued by NWS Riverton, WY

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Probabilistic Hydrologic Outlook
National Weather Service Riverton WY
1058 AM MST THU MAR 3 2016


  ...Spring 2015 Flood and Water Resources Outlook...

This Spring and early Summer 2015 flood outlook includes the Wind,
Big Horn, Green, Powder, Sweetwater, Shoshone, and Upper Yellowstone
River Basins. A small portion of the Snake and the Lower North Platte
Basins is also used to make this runoff forecast. The outlook is from
today through the end of June.

Many basins east of the continental divide receive up to 55 percent
of their water year total for precipitation during the months of
March through May. Accordingly, mountain snowpack can drastically
change from late winter to late spring for basins east of the
continental divide.

Wyoming generally does not see any significant mountain snowmelt
runoff until early to middle May, with mountain snowmelt runoff
peaking around early June. Therefore, at this time, it is way too
early to make any long range prediction on & 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 likely temperature and
precipitation trends into late spring/early summer.

...Current water precipitation is averaging near 85 percent of normal
across Wyoming...

...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...

 ...Additional information...

Other hydrological information for Wyoming can be found at the NOAA
website: www.weather.gov/riw/local_hydrology

For the current Wyoming spring flood potential graphic, please refer
to: www.weather.gov/images/riw/hydro/floodoutlook.png

For the current Wyoming water supply graphic, please refer to:
www.weather.gov/images/riw/hydro/watersupply.png

For the latest Wyoming average monthly precipitation by basin
graphics, please refer to:
www.weather.gov/images/riw/hydro/wyomingprecip.png

For the latest monthly Wyoming hydrologic summary and graphics,
please refer to: www.weather.gov/media/riw/hydro/hydro_report.pdf

For current and forecast Wyoming streamflows and/or river stages,
please refer to: www.water.weather.gov/aphps2/index.php?wfo=riw
www.waterdata/usgs/gov/wy/nwis/rt

For Wyoming drought information, please refer to:
www.weather.gov/riw/drought
$$
jtfahey



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