Sevier Water Supply Outlook, May 1, 2019

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by B.Bernard
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah
www.cbrfc.noaa.gov

Contents

Sevier Summary




*Median of forecasts within each basin.


Sevier Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.


Sevier Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Sevier
Hatch * April-July61 67 73 152 76 83
May-July52 58 64 152 67 74
Kingston, Nr * April-July63 72 78 236 85 96
May-July48 57 63 242 70 81
Ef Sevier
Kingston, Nr * April-July39 49 52 149 56 60
May-July36 46 49 163 53 57
Sevier
Piute Reservoir, Marysville, Nr * April-July98 113 123 189 136 154
May-July85 100 110 204 123 141
Clear Ck
Sevier, Nr, Diversions, Abv April-July38 46 52 248 54 57
May-July27 35 41 241 43 46
Salina Ck
Emery, Nr April-July9 10.6 11.2 142 11.8 13.6
May-July8.2 9.8 10.4 149 11 12.8
Manti Ck
Manti, Nr, Dugway Ck, Blo April-July14.9 17.7 19 114 19.7 22
May-July13.6 16.4 17.7 114 18.4 21
Sevier
Gunnison, Nr * April-July104 128 144 145 158 187
May-July90 114 130 160 144 173
Beaver
Beaver, Nr April-July35 39 42 162 45 49
May-July30 34 37 161 40 44
Coal Ck
Cedar City, Nr April-July22 25 27 139 28 30
May-July17.1 20 22 139 23 25

*Regulated Forecast, i.e. Observed flow uncorrected for upstream diversion.
Differences between the full period forecasts and the residual forecasts may not exactly equal the actual observed volumes due to rounding conventions (see Definitions section).

Sevier End of Month Reservoir Contents (kaf)

EOM
Contents		Percent
EOM
Average		Percent
Usable
Capacity		Last Year
EOM		Last Year
%Average		EOM
Average		Usable
Capacity
untitled Otter Ck
Otter Creek Reservoir, Antimony, Nr 40.0 91 76 43.5 99 43.8 52.5
untitled Sevier
Piute Reservoir, Marysville, Nr 39.1 72 54 34.2 63 54.4 71.8
untitled Sevier Bridge Reservoir, Juab, Nr
81.8 47 35 73.2 42 172.5 236.0
untitled
TOTAL 160.8 59 45 150.9 56 270.7 360.3

Precipitation Maps




Definitions

10% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 10% chance of being exceeded. Previously referred to as "Reasonable Maximum Forecast".

50% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 50% chance of being exceeded. Previously referred to as "Most Probable Forecast".

90% exceedance forecast: Given the current hydrometeorological conditions, i.e current snowpack, soil moisture and streamflow, the volume that has a 90% chance of being exceeded. Previously referred to as "Reasonable Minimum Forecast".

Acre-Foot (af): The volume equal to one acre covered one foot deep (43,560 cubic feet). See kaf below.

Average: The arithmetic mean. The sum of the values divided by the number of values. Values from 1981-2010 are used for this publication.

Categories: Much Above Average=Greater than 130%, Above Average=111-130%, Near Average=90-110%, Below Average=70-89%, Much Below Average=Less than 70%.

CBRFC: Colorado Basin River Forecast Center.

Forecast Period: The period from April 1 through July 31, unless otherwise noted.

kaf: Thousand Acre-Feet. See Acre-Foot above.

Inflow: The volume of water that flows into a reservoir or lake.

Median: The middle value of an ordered set of values. Half of the values are higher and half of the values are lower. When the set contains an even number of values the median is the average of the two middle numbers.

NOAA: National Oceanic and Atomospheric Administration.

NWS: National Weather Service.

Rounding Conventions:
RangeRound to
0-1.990.01
2.0-19.90.1
20-1991.0
200-9995.0
1000+3 significant digits


Streamflow: The volume of water that flows past a specific stream site.

Water Year: The 12-month period, October 1 through September 30. The water year is designated by the calendar year in which it ends. Thus, the year ending September 30, 2008, is called the "2008 water year."


Additional Information

Water supply forecasts take into consideration present hydrometeorological conditions and use average basin temperatures and precipitation for the forecast period. As the forecast season progresses, a greater portion of the future hydrologic and climatic uncertainty becomes known and monthly forecasts become more accurate. For more information on the tools we use, consult Water Supply Forecasting Tools.

Volume forecasts represent adjusted flows; that is, observed flows with upstream water use taken into account. Adjusted flows will closely approximate natural or unimpaired flows. However, not all upstream diversions or impoundments are measured or quantifiable. For specific adjustments used with each forecast point, consult the Guide to Water Supply Forecasting.

The Water Supply Outlook is issued monthly January through May by the Colorado Basin River Forecast Center. It represents a coordinated effort between the National Weather Service, Natural Resources Conservation Service, Bureau of Reclamation, U.S. Geological Survey and local water district managers.

Note: Data used in this report are provisional and are subject to revision.

For more information, or to be included on the mailing list, please contact:

Colorado Basin River Forecast Center
2242 W North Temple
Salt Lake City, UT 84116
(801) 524-5130
www.cbrfc.noaa.gov


Hydrologist: B.Bernard