Upper Colorado Water Supply Outlook, January 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-July115 145 180 82 215 285
Willow Ck
Willow Ck Res, Granby, Nr April-July18 30 43 91 55 70
Fraser
Winter Park April-July12 15 18 93 20 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July55 69 83 86 93 116
Muddy Ck
Wolford Mountain Reservoir April-July16 26 36 67 45 62
Blue
Dillon Res April-July95 120 141 87 165 200
Green Mtn Res April-July150 190 230 84 265 330
Colorado
Kremmling, Nr April-July425 555 705 82 810 1060
Eagle
Gypsum, Blo April-July145 188 220 66 265 370
Colorado
Dotsero, Nr April-July630 870 1050 75 1220 1660
Frying Pan
Ruedi Res, Basalt, Nr April-July63 80 94 68 110 150
Roaring Fork
Glenwood Springs April-July325 400 450 65 530 715
Colorado
Glenwood Springs, Blo April-July1000 1320 1550 73 1830 2420
Cameo, Nr April-July1070 1420 1680 71 1950 2660
Plateau Ck
Cameo, Nr April-July20 35 50 40 70 100
Colorado
Cisco, Nr April-July1800 2150 2600 59 3050 4400
Lake Powell, Glen Cyn Dam, At April-July2110 2870 3900 54 4690 6460


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-July50 70 76 77 87 115
Almont April-July80 105 115 74 130 180
East
Almont April-July75 105 112 62 147 200
Gunnison
Gunnison, Nr April-July170 220 240 65 300 420
Tomichi Ck
Gunnison April-July24 34 42 57 47 73
Lake Fork
Gateview April-July50 66 79 64 85 115
Gunnison
Blue Mesa Res April-July320 375 435 64 535 670
Morrow Point Res April-July355 400 470 64 575 705
Crystal Res April-July405 445 520 62 625 755
Muddy Ck
Paonia Res, Bardine, Nr March-June26 34 42 44 50 82
April-July27 34 43 44 51 83
Nf Gunnison
Somerset, Nr April-July93 120 140 47 180 250
Surface Ck
Cedaredge April-July3 5 7 42 9 15
Uncompahgre
Ridgway Res April-July40 54 61 60 70 89
Colona April-July39 57 66 48 79 110
Delta April-July25 37 45 40 60 98
Gunnison
Grand Junction, Nr April-July610 715 820 55 1060 1270


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-July70 99 125 51 147 205
Mcphee Res April-July75 105 130 44 160 230
San Miguel
Placerville, Nr April-July40 55 64 50 75 97
Dolores
Cisco, Nr April-July95 140 175 31 230 350

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 512.9 137 105 453.9 121 375.1 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.3 96 80 7.8 102 7.6 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 66.0 99 68 75.8 114 66.5 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 55.0 122 83 51.1 113 45.1 66.0
untitled Blue
Dillon Res 241.3 106 95 228.4 101 226.9 254.0
Green Mtn Res 73.9 82 50 72.4 81 89.8 146.9
untitled Homestake Ck
Homestake Res -9999.0 -99 -99 42.0 128 32.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 72.1 94 71 69.6 91 76.8 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 10.5 88 32 11.0 92 12.0 32.9
untitled Taylor
Taylor Park Res 76.2 112 72 69.2 102 68.1 106.2
untitled Gunnison
Blue Mesa Res 592.6 108 71 592.5 108 549.9 829.5
Morrow Point Res 111.0 99 95 109.4 98 111.6 117.0
Crystal Res 15.9 103 90 16.5 108 15.4 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.2 52 13 1.6 38 4.2 16.7
untitled Uncompahgre
Ridgway Res 60.3 88 73 62.1 90 68.8 83.0
untitled Dolores
Mcphee Res 285.5 106 75 293.1 109 270.1 381.1
untitled
TOTAL 2182.7 110 79 2156.5 107 1987.9 2749.1
Colorado
Lake Powell 14067.6 79 58 11796.9 66 17744.8 24322.0
untitled
TOTAL 14067.6 79 58 11796.9 66 17744.8 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: Cody Moser, Greg Smith