Upper Colorado Water Supply Outlook, April 1, 2017

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




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

Gunnison Basin Conditions




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

Dolores Basin Conditions




Snow Water Equivalent in Percent of Median.
* 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		70%
Exceedance
Volume		50%
Exceedance
Volume		Percent
Average		30%
Exceedance
Volume		10%
Exceedance
Volume
Colorado
Lake Granby, Granby, Nr April-July180 210 230 105 245 300
Willow Ck
Willow Ck Res, Granby, Nr April-July43 51 60 128 67 83
Fraser
Winter Park April-July17 19 21 108 23 26
Williams Fork
Williams Fork Res, Parshall, Nr April-July85 95 105 109 115 135
Muddy Ck
Wolford Mountain Reservoir April-July25 32 40 74 49 60
Blue
Dillon Res April-July140 165 180 110 190 225
Green Mtn Res April-July240 280 300 109 325 370
Colorado
Kremmling, Nr April-July750 840 940 109 1010 1220
Eagle
Gypsum, Blo April-July235 270 310 93 350 410
Colorado
Dotsero, Nr April-July1140 1250 1450 104 1600 1900
Frying Pan
Ruedi Res, Basalt, Nr April-July95 115 130 94 145 175
Roaring Fork
Glenwood Springs April-July565 645 690 100 745 865
Colorado
Glenwood Springs, Blo April-July1730 1950 2150 102 2350 2850
Cameo, Nr April-July1920 2150 2400 102 2600 3150
Plateau Ck
Cameo, Nr April-July75 100 110 89 125 165
Colorado
Cisco, Nr April-July4000 4550 4950 111 5300 6400
Lake Powell, Glen Cyn Dam, At April-July7500 8500 9300 130 10200 12000


Gunnison 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
Taylor
Taylor Park Res April-July100 111 118 119 130 144
Almont April-July160 177 190 123 210 240
East
Almont April-July200 225 245 135 260 295
Gunnison
Gunnison, Nr April-July400 435 500 135 550 625
Tomichi Ck
Gunnison April-July80 95 110 149 126 148
Lake Fork
Gateview April-July110 130 145 118 165 190
Gunnison
Blue Mesa Res April-July790 845 930 138 1030 1180
Morrow Point Res April-July875 930 1020 138 1110 1260
Crystal Res April-July1000 1060 1140 137 1240 1390
Muddy Ck
Paonia Res, Bardine, Nr March-June80 95 105 109 118 129
April-June70 85 95 104 108 119
April-July76 91 100 103 114 125
Nf Gunnison
Somerset, Nr April-July245 285 315 107 345 390
Surface Ck
Cedaredge April-July12 15 18 107 21 24
Uncompahgre
Ridgway Res April-July88 102 118 117 130 150
Colona April-July118 137 158 115 175 210
Delta April-July94 114 133 118 155 189
Gunnison
Grand Junction, Nr April-July1500 1750 1870 126 2100 2350


Dolores 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
Dolores
Dolores April-July290 320 350 143 385 420
Mcphee Res April-July345 380 420 142 470 510
San Miguel
Placerville, Nr April-July118 137 150 117 164 190
Dolores
Cisco, Nr April-July610 680 760 135 850 915

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 381.2 121 78 378.4 120 314.3 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.5 91 82 9.2 112 8.2 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 73.2 120 76 75.7 124 60.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 52.0 119 79 41.9 96 43.7 66.0
untitled Blue
Dillon Res 214.0 99 84 235.9 109 215.5 254.0
Green Mtn Res 64.0 97 44 61.6 93 65.9 146.9
untitled Homestake Ck
Homestake Res 32.5 129 76 41.1 164 25.1 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 66.2 105 65 67.5 107 63.2 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 14.7 104 45 14.2 100 14.2 32.9
untitled Taylor
Taylor Park Res 68.7 110 65 67.4 108 62.4 106.2
untitled Gunnison
Blue Mesa Res 571.4 126 69 563.0 124 454.9 829.5
Morrow Point Res 108.3 97 93 111.2 100 111.7 117.0
Crystal Res 16.7 103 95 16.8 103 16.2 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.8 89 16 3.2 104 3.1 16.7
untitled Uncompahgre
Ridgway Res 65.6 94 79 64.5 92 70.0 83.0
untitled Dolores
Mcphee Res 347.1 122 91 263.6 92 285.4 381.1
untitled
TOTAL 2085.7 115 75 2015.2 111 1814.5 2792.1
Colorado
Lake Powell 11364.0 67 47 11019.0 65 16941.7 24322.0
untitled
TOTAL 11364.0 67 47 11019.0 65 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