Upper Colorado Water Supply Outlook, May 1, 2016

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-July160 180 195 89 205 230
May-July145 165 180 88 190 215
Willow Ck
Willow Ck Res, Granby, Nr April-July40 48 52 111 60 65
May-July35 43 47 109 55 60
Fraser
Winter Park April-July18 19.5 21 108 22 25
May-July17 18.5 20 108 21 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July82 89 95 99 102 117
May-July75 82 88 98 95 110
Muddy Ck
Wolford Mountain Reservoir April-July42 50 55 102 62 72
May-July35 43 48 104 55 65
Blue
Dillon Res April-July140 153 170 104 178 200
May-July130 143 160 105 168 190
Green Mtn Res April-July230 255 270 98 290 330
May-July210 235 250 98 270 310
Colorado
Kremmling, Nr April-July730 810 850 99 910 1040
May-July650 730 770 98 830 960
Eagle
Gypsum, Blo April-July250 280 305 91 330 400
May-July230 260 285 90 310 380
Colorado
Dotsero, Nr April-July1120 1250 1340 96 1430 1680
May-July1000 1130 1220 95 1310 1560
Frying Pan
Ruedi Res, Basalt, Nr April-July102 112 125 90 132 172
May-July95 105 118 91 125 165
Roaring Fork
Glenwood Springs April-July495 530 575 83 615 745
May-July450 485 530 83 570 700
Colorado
Glenwood Springs, Blo April-July1670 1820 1940 92 2120 2420
May-July1500 1650 1770 92 1950 2250
Cameo, Nr April-July1790 1990 2140 91 2340 2690
May-July1600 1800 1950 91 2150 2500
Plateau Ck
Cameo, Nr April-July80 92 115 93 135 160
May-July60 72 95 91 115 140
Colorado
Cisco, Nr April-July3230 3530 3800 86 4080 4730
May-July2700 3000 3270 85 3550 4200
Lake Powell, Glen Cyn Dam, At April-July4210 5060 5500 77 6060 7110
May-July3400 4250 4690 77 5250 6300


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-July71 77 82 83 87 99
May-July62 68 73 81 78 90
Almont April-July109 118 124 80 132 154
May-July95 104 110 78 118 140
East
Almont April-July112 118 130 71 141 157
May-July95 101 113 68 124 140
Gunnison
Gunnison, Nr April-July245 255 270 73 285 325
May-July210 220 235 70 250 290
Tomichi Ck
Gunnison April-July42 49 54 73 61 74
May-July33 40 45 73 52 65
Lake Fork
Gateview April-July93 107 114 93 124 143
May-July85 99 106 91 116 135
Gunnison
Blue Mesa Res April-July455 505 525 78 565 660
May-July380 430 450 75 490 585
Morrow Point Res April-July495 550 570 77 610 700
May-July415 470 490 75 530 620
Crystal Res April-July560 605 630 75 675 765
May-July470 515 540 73 585 675
Muddy Ck
Paonia Res, Bardine, Nr March-June69 73 80 83 85 96
April-July66 72 79 81 87 98
May-June41 45 52 75 57 68
May-July43 49 56 75 62 74
Nf Gunnison
Somerset, Nr April-July198 210 230 78 245 280
May-July155 166 187 78 200 235
Surface Ck
Cedaredge April-July11.3 12.8 14.8 88 17.3 19.3
May-July8 9.5 11.5 82 14 16
Uncompahgre
Ridgway Res April-July74 79 93 92 98 111
May-July65 70 84 92 89 102
Colona April-July90 107 125 91 137 160
May-July75 92 110 92 122 145
Delta April-July79 91 104 92 114 134
May-July50 62 75 80 85 105
Gunnison
Grand Junction, Nr April-July995 1110 1200 81 1280 1450
May-July780 890 980 79 1060 1230


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-July172 184 197 80 215 230
May-July135 147 160 80 177 195
Mcphee Res April-July185 200 215 73 240 260
May-July140 156 170 77 195 215
San Miguel
Placerville, Nr April-July98 109 118 92 126 138
May-July85 96 105 93 113 125
Dolores
Cisco, Nr April-July355 385 410 73 450 490
May-July270 300 325 78 365 405

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 380.6 122 78 491.3 158 311.8 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.8 101 85 7.5 97 7.7 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 76.7 126 79 83.7 137 60.9 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 47.0 99 71 49.7 104 47.7 66.0
untitled Blue
Dillon Res 239.3 112 94 247.1 116 213.6 254.0
Green Mtn Res 67.0 105 46 72.1 113 63.9 146.9
untitled Homestake Ck
Homestake Res 41.4 220 96 20.6 110 18.8 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 70.1 112 69 75.9 121 62.6 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 18.2 99 55 19.7 107 18.3 32.9
untitled Taylor
Taylor Park Res 71.0 116 67 82.1 134 61.2 106.2
untitled Gunnison
Blue Mesa Res 570.7 125 69 597.3 131 457.1 829.5
Morrow Point Res 111.1 99 95 109.5 98 111.8 117.0
Crystal Res 16.5 99 94 16.6 99 16.7 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 3.3 51 20 14.0 218 6.4 16.7
untitled Uncompahgre
Ridgway Res 68.0 102 82 71.6 108 66.6 83.0
untitled Dolores
Mcphee Res 299.1 93 78 208.6 65 323.0 381.1
untitled
TOTAL 2087.8 113 75 2167.6 117 1848.0 2792.1
Colorado
Lake Powell 11013.5 64 45 10836.8 63 17122.8 24322.0
untitled
TOTAL 11013.5 64 45 10836.8 63 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