Great Basin Water Supply Outlook, February 1, 2016

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

Contents

Great Basin Summary






*Median of forecasts within each basin.


Bear Basin Conditions




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

Weber Basin Conditions




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

Six Creeks Basin Conditions




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

Utah Lake Basin Conditions




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


Bear 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
Bear
Utah April-July73 88 103 92 116 137
Woodruff Narrows Rsvr, Abv April-July59 80 99 82 122 178
Montpelier, Nr, Stewart Dam, Blo * April-July51 70 90 49 109 160
Smiths Fork
Border, Nr April-July54 66 73 82 85 105
Logan
Logan, Nr, State Dam, Abv April-July65 80 92 83 101 128
Blacksmith Fork
Hyrum, Nr, Upnl Dam, Abv April-July24 29 36 84 44 60
Little Bear
Paradise April-July19.1 26 32 68 45 57

*Regulated Forecast, i.e. Observed flow uncorrected for upstream diversion.

Weber 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
Weber
Oakley, Nr April-July69 84 100 85 116 138
Rockport Res, Wanship, Nr April-July63 81 102 77 119 153
Coalville, Nr April-July61 79 101 75 118 156
Chalk Ck
Coalville April-July15.8 22 30 73 40 53
Weber
Echo Res, Echo, At April-July73 104 127 74 159 210
Lost Ck
Lost Ck Res, Croydon, Nr April-July5.4 8.4 10 75 12.7 17
East Canyon Ck
East Canyon Res, Morgan, Nr April-July12.4 16.3 21 78 26 31
Weber
Gateway April-July142 191 255 78 305 400
Sf Ogden
Huntsville, Nr April-July38 45 52 93 61 86
Ogden
Pineview Res, Ogden, Nr April-July59 86 103 91 143 182


Six Creeks 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
Little Cottonwood Ck
Salt Lake City, Nr April-July26 30 33 87 37 42
Big Cottonwood Ck
Salt Lake City, Nr April-July21 25 30 83 33 42
Mill Ck
Salt Lake City, Nr April-July2.1 3.1 4.2 66 4.6 5.7
Dell Fk
Little Dell Res April-July2.6 3.4 4.2 76 5.5 6.1
Parleys Ck
Salt Lake City, Nr April-July6 7.5 10.8 76 14.2 16.4
Emigration Ck
Salt Lake City, Nr April-July1.3 2.3 3.1 78 4.8 6.6
City Ck
Salt Lake City, Nr April-July3.5 4.6 5.5 71 6.8 8.4
S Willow Ck
Grantsville, Nr April-July1.7 2 2.2 71 2.7 3.3


Utah Lake 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
Spanish Fork
Castilla, Nr April-July27 37 45 65 56 92
Provo
Woodland, Nr April-July58 73 85 85 97 118
Hailstone, Nr April-July64 82 94 85 107 131
Deer Ck Res April-July69 90 107 84 121 155
American Fork
American Fork, Nr, Up Pwrplnt, Abv April-July14.5 17.3 21 68 27 33
West Canyon Ck
Cedar Fort, Nr April-July0.73 1.3 1.5 87 2 2.9
Jordan
Utah Lake, Provo, Nr April-July150 199 240 74 290 375

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).

Great Basin 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 Bear
Woodruff Narrows Res, Woodruff, Nr 41.1 142 74 40.3 139 28.9 55.8
untitled Bear River
Bear Lake, Nr Lifton 591.2 84 45 667.1 95 703.9 1302.0
untitled Little Bear
Hyrum Reservoir 9.7 93 63 10.1 97 10.3 15.3
untitled Weber
Rockport Res, Wanship, Nr 36.3 105 66 44.8 130 34.5 55.2
Echo Res, Echo, At 29.5 64 40 28.5 62 46.3 73.9
untitled Lost Ck
Lost Ck Res, Croydon, Nr 11.1 102 49 13.5 125 10.8 22.5
untitled East Canyon Ck
East Canyon Res, Morgan, Nr 23.2 69 47 26.3 78 33.8 49.5
untitled Sf Ogden
Causey Res 4.3 132 60 5.5 170 3.2 7.1
untitled Ogden
Pineview Res, Ogden, Nr 54.3 106 49 60.2 117 51.4 110.1
untitled Jordanelle Dam
175.4 72 55 202.6 83 243.6 320.3
untitled Provo
Deer Ck Res 119.5 109 80 129.5 118 110.1 149.7
untitled Dell Fk
Little Dell Res 10.4 -99 51 13.1 -99 -9999.0 20.5
untitled Jordan
Utah Lake, Provo, Nr 442.9 59 51 547.9 73 753.0 870.9
untitled
TOTAL 1538.6 76 51 1776.2 88 2029.8 3052.8

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: W.P.Miller