Upper Colorado Water Supply Outlook, April 1, 2013

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

Contents

Upper Colorado Summary




*Median of forecasts within each basin.


Upper Colorado Mainstem Basin Conditions




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

Gunnison Basin Conditions




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

Dolores Basin Conditions




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


Upper Colorado Mainstem Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Colorado
Lake Granby, Granby, Nr April-July87 130 59 180
Willow Ck
Willow Ck Res, Granby, Nr April-July19 33 70 50
Fraser
Winter Park April-July8.5 12.5 64 16.5
Williams Fork
Williams Fork Res, Parshall, Nr April-July45 63 66 80
Muddy Ck
Wolford Mountain Reservoir April-July20 32 59 50
Blue
Dillon Res April-July70 100 61 140
Green Mtn Res April-July125 172 63 240
Colorado
Kremmling, Nr April-July375 510 59 710
Eagle
Gypsum, Blo April-July120 180 54 280
Colorado
Dotsero, Nr April-July595 800 57 1170
Frying Pan
Ruedi Res, Basalt, Nr April-July50 73 53 110
Roaring Fork
Glenwood Springs April-July275 370 54 520
Colorado
Glenwood Springs, Blo April-July900 1220 58 1770
Cameo, Nr April-July1000 1310 56 1930
Plateau Ck
Cameo, Nr April-July38 60 48 100
Colorado
Cisco, Nr April-July1600 2170 49 3350
Lake Powell, Glen Cyn Dam, At April-July1500 2700 38 4650


Gunnison Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Taylor
Taylor Park Res April-July45 55 56 71
Almont April-July60 80 52 115
East
Almont April-July70 90 49 140
Gunnison
Gunnison, Nr April-July135 170 46 255
Tomichi Ck
Gunnison April-July18 25 34 41
Lake Fork
Gateview April-July45 70 57 100
Gunnison
Blue Mesa Res April-July260 315 47 480
Morrow Point Res April-July280 335 45 500
Crystal Res April-July315 370 44 535
Muddy Ck
Paonia Res, Bardine, Nr April-June27 38 42 60
April-July29 40 41 62
Nf Gunnison
Somerset, Nr April-July110 150 51 220
Surface Ck
Cedaredge April-July5 8 48 13
Uncompahgre
Ridgway Res April-July40 55 54 83
Colona April-July44 60 44 100
Delta April-July25 38 34 76
Gunnison
Grand Junction, Nr April-July510 640 43 950


Dolores Specific Site Forecasts (kaf)

Click site name for graph.
Forecast
Period		90%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		10%
Exceedance
Volume
Dolores
Dolores April-July75 120 49 175
Mcphee Res April-July85 125 42 190
San Miguel
Placerville, Nr April-July50 70 55 90
Dolores
Cisco, Nr April-July130 215 38 350

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).

Upper Colorado 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 Colorado
Lake Granby, Granby, Nr 195.8 62 40 412.4 131 314.3 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.7 106 95 8.0 98 8.2 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 41.9 69 43 82.4 135 60.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 24.0 55 36 61.6 141 43.7 66.0
untitled Blue
Dillon Res 163.3 76 64 243.2 113 215.5 254.0
Green Mtn Res 60.4 92 41 79.7 121 65.9 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 0.5 2 25.1 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 61.4 97 60 71.4 113 63.2 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 8.8 62 27 18.8 132 14.2 32.9
untitled Taylor
Taylor Park Res 56.9 91 54 67.2 108 62.4 106.2
untitled Gunnison
Blue Mesa Res 336.0 74 41 539.2 119 454.9 829.5
Morrow Point Res 104.8 94 90 114.0 102 111.7 117.0
Crystal Res 14.5 90 83 16.6 102 16.2 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 1.4 46 8 1.1 36 3.1 16.7
untitled Uncompahgre
Ridgway Res 56.5 81 68 70.9 101 70.0 83.0
untitled Dolores
Mcphee Res 188.4 66 49 303.1 106 285.4 381.1
untitled
TOTAL 1322.8 74 48 2090.1 115 1789.4 2749.1
Colorado
Lake Powell 11651.1 69 48 15458.4 91 16941.7 24322.0
untitled
TOTAL 11651.1 69 48 15458.4 91 16941.7 24322.0

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: Brenda Alcorn, Greg Smith