Upper Colorado Water Supply Outlook, February 1, 2018

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Cody Moser, 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-July124 150 180 82 210 280
Willow Ck
Willow Ck Res, Granby, Nr April-July21 29 40 85 52 70
Fraser
Winter Park April-July12 15 17.5 90 19.5 23
Williams Fork
Williams Fork Res, Parshall, Nr April-July56 70 80 83 90 114
Muddy Ck
Wolford Mountain Reservoir April-July16 24 33 61 42 54
Blue
Dillon Res April-July94 120 140 86 160 188
Green Mtn Res April-July150 195 230 84 260 315
Colorado
Kremmling, Nr April-July455 580 680 79 790 1050
Eagle
Gypsum, Blo April-July146 250 220 66 190 335
Colorado
Dotsero, Nr April-July680 1200 1030 74 880 1550
Frying Pan
Ruedi Res, Basalt, Nr April-July61 105 93 67 80 140
Roaring Fork
Glenwood Springs April-July320 500 450 65 400 670
Colorado
Glenwood Springs, Blo April-July1030 1700 1510 72 1350 2270
Cameo, Nr April-July1110 1800 1620 69 1400 2450
Plateau Ck
Cameo, Nr April-July18 60 45 36 33 90
Colorado
Cisco, Nr April-July1650 2800 2410 54 2000 3800
Lake Powell, Glen Cyn Dam, At April-July1950 2750 3400 47 4200 6200


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-July45 56 70 71 78 90
Almont April-July65 85 104 67 118 135
East
Almont April-July70 88 109 60 130 160
Gunnison
Gunnison, Nr April-July135 175 225 61 270 320
Tomichi Ck
Gunnison April-July20 28 36 49 50 71
Lake Fork
Gateview April-July45 55 74 60 91 109
Gunnison
Blue Mesa Res April-July230 290 400 59 480 600
Morrow Point Res April-July265 325 435 59 475 635
Crystal Res April-July310 370 480 57 520 680
Muddy Ck
Paonia Res, Bardine, Nr March-June18 24 35 36 48 69
April-July17 23 34 35 47 68
Nf Gunnison
Somerset, Nr April-July85 105 135 46 160 235
Surface Ck
Cedaredge April-July2.5 3 4.5 27 6 9
Uncompahgre
Ridgway Res April-July35 43 56 55 68 87
Colona April-July37 49 62 45 83 110
Delta April-July19 27 35 31 54 80
Gunnison
Grand Junction, Nr April-July500 600 725 49 900 1180


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-July60 83 100 41 140 186
Mcphee Res April-July61 86 110 37 155 200
San Miguel
Placerville, Nr April-July38 52 64 50 77 95
Dolores
Cisco, Nr April-July86 120 155 27 195 270

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 491.4 140 100 424.3 120 352.2 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.8 98 86 8.2 104 8.0 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 66.0 103 68 74.4 117 63.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 54.5 122 83 50.7 114 44.6 66.0
untitled Blue
Dillon Res 240.1 108 95 224.0 100 223.2 254.0
Green Mtn Res 70.5 87 48 67.2 83 81.1 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 42.1 132 31.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 69.4 96 68 67.8 94 72.4 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 11.0 87 33 11.9 94 12.6 32.9
untitled Taylor
Taylor Park Res 74.2 111 70 69.5 104 66.9 106.2
untitled Gunnison
Blue Mesa Res 554.5 108 67 586.6 114 514.6 829.5
Morrow Point Res 109.3 98 93 112.0 101 111.4 117.0
Crystal Res 15.5 101 88 16.2 105 15.3 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.9 68 17 1.6 38 4.2 16.7
untitled Uncompahgre
Ridgway Res 60.9 88 73 63.8 92 69.2 83.0
untitled Dolores
Mcphee Res 284.5 105 75 294.4 109 270.9 381.1
untitled
TOTAL 2112.6 111 77 2114.7 109 1910.6 2749.1

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, Greg Smith