Great Basin Water Supply Outlook, January 1, 2013

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

Great Basin Summary






*Median of forecasts within each basin.


Bear Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Weber Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Six Creeks Basin Conditions




* Percent usable capacity, not percent average contents.
Click for multi-month Graph.

Utah Lake Basin Conditions




* 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		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Bear
Utah April-July48 90 80 126
Woodruff Narrows Rsvr, Abv April-July46 100 83 155
Montpelier, Nr, Stewart Dam, Blo * April-July94 150 82 256
Smiths Fork
Border, Nr April-July50 80 90 110
Logan
Logan, Nr, State Dam, Abv April-July63 100 90 150
Blacksmith Fork
Hyrum, Nr, Upnl Dam, Abv April-July20 36 84 64
Little Bear
Paradise April-July18 35 74 60

*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		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Weber
Oakley, Nr April-July48 92 78 137
Rockport Res, Wanship, Nr April-July41 98 78 165
Coalville, Nr April-July40 99 77 174
Chalk Ck
Coalville April-July12 32 78 57
Weber
Echo Res, Echo, At April-July52 129 78 210
Lost Ck
Lost Ck Res, Croydon, Nr April-July3.4 10.5 78 15
East Canyon Ck
East Canyon Res, Morgan, Nr April-July12 22 81 39
Weber
Gateway April-July101 250 78 425
Sf Ogden
Huntsville, Nr April-July23 47 84 75
Ogden
Pineview Res, Ogden, Nr April-July50 95 84 165


Six Creeks Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Little Cottonwood Ck
Salt Lake City, Nr April-July23 33 87 46
Big Cottonwood Ck
Salt Lake City, Nr April-July20 31 86 48
Mill Ck
Salt Lake City, Nr April-July3 5 78 7.6
Dell Fk
Little Dell Res April-July2.1 4.3 78 7.1
Parleys Ck
Salt Lake City, Nr April-July5.2 11 77 19
Emigration Ck
Salt Lake City, Nr April-July1.1 3 75 5.6
City Ck
Salt Lake City, Nr April-July3.6 5.7 74 9.6
S Willow Ck
Grantsville, Nr April-July1.4 2.5 81 4.3


Utah Lake Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Spanish Fork
Castilla, Nr April-July27 52 75 97
Provo
Woodland, Nr April-July48 88 88 124
Hailstone, Nr April-July52 92 79 138
Deer Ck Res April-July56 108 82 188
American Fork
American Fork, Nr, Up Pwrplnt, Abv April-July19 28 90 46
West Canyon Ck
Cedar Fort, Nr April-July0.39 1.1 63 2.7
Jordan
Utah Lake, Provo, Nr April-July133 260 79 495

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 55.8 7.4 13 43.0 77
untitled Bear River
Bear Lake, Nr Lifton 1302.0 875.0 67 958.8 74
untitled Little Bear
Hyrum Res Abv 15.3 10.7 70 8.9 58
untitled Willard Reservoir Storage
215.0 131.9 61 186.8 87
untitled Sf Ogden
Causey Res 7.1 3.6 51 4.3 61
untitled Ogden
Pineview Res, Ogden, Nr 110.1 43.3 39 86.2 78
untitled Lost Ck
Lost Ck Res, Croydon, Nr 22.5 15.3 68 19.4 86
untitled Weber
Rockport Res, Wanship, Nr 60.9 25.9 42 38.2 63
Echo Res, Echo, At 73.9 16.6 22 44.9 61
untitled East Canyon Ck
East Canyon Res, Morgan, Nr 49.5 26.0 53 43.2 87
untitled Dell Fk
Little Dell Res 20.5 10.7 52 11.7 57
untitled Mountain Dell Dam
3.0 1.5 49 1.3 45
untitled Jordanelle Dam
311.0 191.3 62 269.9 87
untitled Provo
Deer Ck Res 149.7 110.8 74 142.8 95
untitled Jordan
Utah Lake, Provo, Nr 870.9 685.1 79 879.5 101
untitled
TOTAL 3267.2 2155.3 66 2738.9 84

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