Upper Colorado Water Supply Outlook, May 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-July200 220 235 107 250 275
May-July174 194 210 102 225 250
Willow Ck
Willow Ck Res, Granby, Nr April-July50 58 65 138 75 80
May-July35 43 50 116 60 65
Fraser
Winter Park April-July17.5 19 21 108 23 26
May-July16.3 17.8 19.8 106 22 25
Williams Fork
Williams Fork Res, Parshall, Nr April-July90 97 105 109 110 125
May-July82 89 97 108 102 117
Muddy Ck
Wolford Mountain Reservoir April-July30 34 40 74 45 57
May-July20 24 30 65 35 47
Blue
Dillon Res April-July140 155 175 107 185 210
May-July125 140 160 105 170 195
Green Mtn Res April-July240 270 295 107 315 355
May-July210 240 265 104 285 325
Colorado
Kremmling, Nr April-July790 880 930 108 980 1100
May-July670 760 810 103 860 980
Eagle
Gypsum, Blo April-July240 265 300 90 330 390
May-July210 235 270 86 300 360
Colorado
Dotsero, Nr April-July1200 1320 1410 101 1500 1710
May-July1020 1140 1230 96 1320 1530
Frying Pan
Ruedi Res, Basalt, Nr April-July95 105 125 90 135 170
May-July83 93 113 87 123 158
Roaring Fork
Glenwood Springs April-July550 595 650 94 700 800
May-July490 535 590 92 640 740
Colorado
Glenwood Springs, Blo April-July1780 1950 2070 98 2200 2550
May-July1540 1710 1830 95 1960 2310
Cameo, Nr April-July1950 2100 2250 95 2400 2800
May-July1700 1850 2000 93 2150 2550
Plateau Ck
Cameo, Nr April-July60 70 95 77 110 135
May-July44 54 79 76 94 119
Colorado
Cisco, Nr April-July3850 4150 4500 101 4700 5500
May-July3150 3450 3800 98 4000 4800
Lake Powell, Glen Cyn Dam, At April-July7200 8300 8800 123 9500 11000
May-July5590 6690 7190 118 7890 9390


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-July98 105 111 112 118 133
May-July85 92 98 109 105 120
Almont April-July147 167 177 114 187 215
May-July125 145 155 110 165 195
East
Almont April-July215 225 240 132 250 280
May-July180 190 205 123 215 245
Gunnison
Gunnison, Nr April-July435 455 475 128 495 565
May-July360 380 400 119 420 490
Tomichi Ck
Gunnison April-July87 94 106 143 115 132
May-July60 67 79 127 88 105
Lake Fork
Gateview April-July107 122 130 106 138 163
May-July94 109 117 101 125 150
Gunnison
Blue Mesa Res April-July765 825 850 126 885 1020
May-July620 680 705 118 740 880
Morrow Point Res April-July835 895 920 124 955 1100
May-July680 740 765 118 800 940
Crystal Res April-July940 1000 1030 123 1060 1200
May-July775 835 860 117 895 1030
Muddy Ck
Paonia Res, Bardine, Nr March-June68 74 82 85 87 95
April-July62 68 76 78 81 89
May-June38 44 52 75 57 65
May-July42 48 56 75 61 69
Nf Gunnison
Somerset, Nr April-July225 235 255 86 275 310
May-July160 173 192 80 210 245
Surface Ck
Cedaredge April-July12.6 13.6 16 95 17.6 21
May-July9 10 12.4 88 14 17
Uncompahgre
Ridgway Res April-July81 91 102 101 108 124
May-July69 79 90 99 96 112
Colona April-July113 124 137 100 145 173
May-July95 106 119 99 127 155
Delta April-July82 96 112 99 121 152
May-July60 74 90 96 99 130
Gunnison
Grand Junction, Nr April-July1420 1570 1650 111 1740 1980
May-July1100 1250 1330 107 1420 1660


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-July255 275 295 120 315 340
May-July180 200 220 110 240 265
Mcphee Res April-July285 305 335 114 360 395
May-July189 210 240 109 265 300
San Miguel
Placerville, Nr April-July120 128 138 108 145 160
May-July100 108 118 104 125 140
Dolores
Cisco, Nr April-July530 565 605 107 645 710
May-July380 415 455 110 495 560

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 392.3 126 80 380.6 122 311.8 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.0 104 88 7.8 101 7.7 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 74.8 123 77 76.7 126 60.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 60.5 127 92 47.0 99 47.7 66.0
untitled Blue
Dillon Res 215.5 101 85 239.3 112 213.6 254.0
Green Mtn Res 69.5 109 47 67.0 105 63.9 146.9
untitled Homestake Ck
Homestake Res 23.7 126 55 41.4 220 18.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 68.8 110 67 70.1 112 62.6 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 20.6 112 63 18.2 99 18.3 32.9
untitled Taylor
Taylor Park Res 73.2 120 69 71.0 116 61.2 106.2
untitled Gunnison
Blue Mesa Res 657.6 144 79 570.7 125 457.1 829.5
Morrow Point Res 108.8 97 93 111.1 99 111.8 117.0
Crystal Res 16.6 99 94 16.5 99 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.3 36 14 3.3 51 6.4 16.7
untitled Uncompahgre
Ridgway Res 62.9 94 76 68.0 102 66.6 83.0
untitled Dolores
Mcphee Res 353.2 109 93 297.7 92 323.0 381.1
untitled
TOTAL 2208.4 119 79 2086.4 113 1848.0 2792.1
Colorado
Lake Powell 12149.5 71 50 11013.5 64 17122.8 24322.0
untitled
TOTAL 12149.5 71 50 11013.5 64 17122.8 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