Upper Colorado Water Supply Outlook, February 1, 2020

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Cody Moser, Ashley Nielson
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-July140 172 200 91 245 305
Willow Ck
Willow Ck Reservoir, Granby, Nr April-July20 29 38 81 53 72
Fraser
Winter Park April-July14 16.5 19.4 100 22 25
Williams Fork
Williams Fork Reservoir, Parshall April-July62 77 88 92 108 127
Muddy Ck
Wolford Mountain Reservoir April-July32 44 56 104 68 80
Blue
Dillon Reservoir April-July115 142 160 98 185 210
Green Mtn Reservoir April-July185 230 265 96 310 360
Colorado
Kremmling, Nr April-July540 670 800 93 990 1200
Eagle
Gypsum, Blo April-July210 255 290 87 355 430
Colorado
Dotsero, Nr April-July870 1090 1270 91 1580 1880
Frying Pan
Ruedi Reservoir, Basalt, Nr April-July90 110 130 94 150 180
Roaring Fork
Glenwood Springs April-July465 540 615 89 720 855
Colorado
Glenwood Springs, Blo April-July1360 1670 1950 92 2300 2800
Cameo, Nr April-July1500 1820 2130 90 2600 3100
Plateau Ck
Cameo, Nr April-July60 75 90 73 118 150
Colorado
Cisco, Nr April-July2800 3250 3650 82 4400 5300
Lake Powell, Glen Cyn Dam, At April-July3950 5000 5700 80 6550 9330


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 Reservoir April-July68 82 85 86 95 115
Almont April-July103 126 133 86 146 176
East
Almont April-July93 119 138 76 149 194
Gunnison
Gunnison, Nr April-July205 260 290 78 325 415
Tomichi Ck
Gunnison April-July38 53 65 88 79 112
Lake Fork
Gateview April-July76 94 111 90 123 162
Gunnison
Blue Mesa Reservoir April-July395 505 560 83 610 820
Morrow Point Reservoir April-July440 560 610 82 665 890
Crystal Reservoir April-July500 630 685 82 745 1000
Muddy Ck
Paonia Reservoir, Bardine, Nr March-June48 59 65 68 76 104
April-July50 59 65 67 76 106
Nf Gunnison
Somerset, Nr April-July157 190 210 71 235 320
Surface Ck
Cedaredge April-July7.6 9.6 11 65 12.5 16.8
Uncompahgre
Ridgway Reservoir April-July58 77 84 83 90 121
Colona April-July70 95 106 77 117 165
Delta April-July43 70 80 71 92 144
Gunnison
Grand Junction, Nr April-July880 1080 1200 81 1290 1800


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-July134 171 205 84 235 305
Mcphee Reservoir April-July152 197 235 80 270 370
San Miguel
Placerville, Nr April-July62 90 98 77 112 146
Dolores
Cisco, Nr April-July245 360 420 74 485 655

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 436.3 124 89 391.1 111 352.2 490.3
untitled Willow Ck
Willow Ck Reservoir, Granby, Nr 8.6 108 94 8.2 104 8.0 9.1
untitled Williams Fork
Williams Fork Reservoir, Parshall 76.3 119 79 67.3 105 63.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 50.8 114 77 34.2 77 44.6 66.0
untitled Blue
Dillon Reservoir 227.8 102 90 180.7 81 223.2 254.0
Green Mtn Reservoir 71.9 89 49 55.1 68 81.1 146.9
untitled Homestake Ck
Homestake Reservoir 41.2 129 96 41.3 129 31.9 43.0
untitled Frying Pan
Ruedi Reservoir, Basalt, Nr 73.2 101 72 58.2 80 72.4 102.0
untitled Plateau Ck
Vega Reservoir, Collbran, Nr 6.4 51 19 6.4 51 12.6 32.9
untitled Taylor
Taylor Park Reservoir 74.1 111 70 59.2 89 66.9 106.2
untitled Gunnison
Blue Mesa Reservoir 554.0 108 67 251.7 49 514.6 829.5
Morrow Point Reservoir 107.2 96 92 106.8 96 111.4 117.0
Crystal Reservoir 14.8 97 85 15.1 99 15.3 17.5
untitled Muddy Ck
Paonia Reservoir, Bardine, Nr 3.8 90 23 3.5 82 4.2 16.7
untitled Uncompahgre
Ridgway Reservoir 65.3 94 79 46.4 67 69.2 83.0
untitled Dolores
Mcphee Reservoir 288.3 106 76 168.6 62 270.9 381.1
untitled
TOTAL 2099.9 108 75 1493.6 77 1942.5 2792.1
Colorado
Lake Powell 12280.7 71 50 9629.2 56 17338.2 24322.0
untitled
TOTAL 12280.7 71 50 9629.2 56 17338.2 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: Cody Moser, Ashley Nielson