Upper Colorado Water Supply Outlook, February 1, 2019

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-July145 183 210 95 255 315
Willow Ck
Willow Ck Res, Granby, Nr April-July26 35 45 96 58 76
Fraser
Winter Park April-July13 15.5 18.3 94 21 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July60 72 84 88 100 120
Muddy Ck
Wolford Mountain Reservoir April-July29 42 53 98 64 76
Blue
Dillon Res April-July108 130 155 95 175 205
Green Mtn Res April-July180 215 255 93 290 350
Colorado
Kremmling, Nr April-July530 650 780 91 920 1140
Eagle
Gypsum, Blo April-July210 250 295 88 345 430
Colorado
Dotsero, Nr April-July880 1060 1270 91 1500 1860
Frying Pan
Ruedi Res, Basalt, Nr April-July80 100 120 86 140 165
Roaring Fork
Glenwood Springs April-July430 510 590 86 680 810
Colorado
Glenwood Springs, Blo April-July1340 1650 1900 90 2200 2740
Cameo, Nr April-July1500 1800 2100 89 2450 3050
Plateau Ck
Cameo, Nr April-July70 90 110 89 130 160
Colorado
Cisco, Nr April-July2700 3200 3700 83 4200 5200
Lake Powell, Glen Cyn Dam, At April-July3600 4480 5300 74 6050 8800


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-July58 75 81 82 95 115
Almont April-July90 110 124 80 145 175
East
Almont April-July115 140 162 89 180 220
Gunnison
Gunnison, Nr April-July225 275 310 84 350 435
Tomichi Ck
Gunnison April-July30 45 55 74 70 100
Lake Fork
Gateview April-July70 91 110 89 120 160
Gunnison
Blue Mesa Res April-July390 490 550 81 600 800
Morrow Point Res April-July430 530 590 80 640 840
Crystal Res April-July500 600 660 79 710 910
Muddy Ck
Paonia Res, Bardine, Nr March-June54 65 71 74 82 120
April-July55 66 72 74 83 121
Nf Gunnison
Somerset, Nr April-July190 225 245 83 275 370
Surface Ck
Cedaredge April-July11 13 16 95 17.5 22
Uncompahgre
Ridgway Res April-July57 75 81 80 88 117
Colona April-July70 98 105 77 120 165
Delta April-July41 65 79 70 87 145
Gunnison
Grand Junction, Nr April-July880 1000 1200 81 1300 1790


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-July130 165 200 82 235 310
Mcphee Res April-July138 185 230 78 260 365
San Miguel
Placerville, Nr April-July60 80 95 74 105 140
Dolores
Cisco, Nr April-July230 335 400 71 455 630

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 391.1 111 80 491.4 140 352.2 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 8.2 104 91 7.8 98 8.0 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 67.3 105 69 66.0 103 63.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 34.2 77 52 54.5 122 44.6 66.0
untitled Blue
Dillon Res 180.7 81 71 240.1 108 223.2 254.0
Green Mtn Res 55.1 68 37 70.5 87 81.1 146.9
untitled Homestake Ck
Homestake Res 41.3 129 96 41.0 128 31.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 58.2 80 57 69.4 96 72.4 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 10.9 86 33 10.9 86 12.6 32.9
untitled Taylor
Taylor Park Res 59.2 89 56 74.2 111 66.9 106.2
untitled Gunnison
Blue Mesa Res 251.7 49 30 554.5 108 514.6 829.5
Morrow Point Res 106.8 96 91 109.6 98 111.4 117.0
Crystal Res 15.1 99 86 15.5 101 15.3 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 3.5 82 21 2.9 68 4.2 16.7
untitled Uncompahgre
Ridgway Res 46.4 67 56 60.9 88 69.2 83.0
untitled Dolores
Mcphee Res 168.6 62 44 284.5 105 270.9 381.1
untitled
TOTAL 1498.1 77 54 2153.7 111 1942.5 2792.1
Colorado
Lake Powell 9629.2 56 40 13672.3 79 17338.2 24322.0
untitled
TOTAL 9629.2 56 40 13672.3 79 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, Greg Smith