Upper Colorado Water Supply Outlook, January 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-July140 180 210 95 260 320
Willow Ck
Willow Ck Res, Granby, Nr April-July21 33 44 94 60 77
Fraser
Winter Park April-July12 15 17.9 92 21 24
Williams Fork
Williams Fork Res, Parshall, Nr April-July54 68 80 83 98 117
Muddy Ck
Wolford Mountain Reservoir April-July22 35 46 85 60 76
Blue
Dillon Res April-July98 120 141 87 168 200
Green Mtn Res April-July155 195 230 84 280 335
Colorado
Kremmling, Nr April-July470 620 760 88 940 1140
Eagle
Gypsum, Blo April-July195 240 280 84 350 435
Colorado
Dotsero, Nr April-July780 1000 1210 86 1520 1860
Frying Pan
Ruedi Res, Basalt, Nr April-July74 92 110 79 135 165
Roaring Fork
Glenwood Springs April-July395 480 550 80 660 795
Colorado
Glenwood Springs, Blo April-July1200 1550 1820 86 2250 2730
Cameo, Nr April-July1340 1700 2000 85 2500 3100
Plateau Ck
Cameo, Nr April-July50 70 85 69 115 155
Colorado
Cisco, Nr April-July2400 2900 3300 74 4000 5000
Lake Powell, Glen Cyn Dam, At April-July2600 3450 4550 64 5580 7600


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 62 75 76 88 115
Almont April-July80 100 113 73 130 183
East
Almont April-July90 120 137 75 172 235
Gunnison
Gunnison, Nr April-July190 240 265 72 335 465
Tomichi Ck
Gunnison April-July23 38 48 65 58 88
Lake Fork
Gateview April-July60 82 98 80 110 138
Gunnison
Blue Mesa Res April-July360 430 500 74 610 755
Morrow Point Res April-July405 460 545 74 650 800
Crystal Res April-July470 520 610 73 720 865
Muddy Ck
Paonia Res, Bardine, Nr March-June40 52 65 68 73 100
April-July40 52 65 67 73 100
Nf Gunnison
Somerset, Nr April-July160 190 215 73 260 330
Surface Ck
Cedaredge April-July9 11 14 83 16 21
Uncompahgre
Ridgway Res April-July50 68 74 73 88 110
Colona April-July55 79 88 64 110 145
Delta April-July35 50 64 57 86 125
Gunnison
Grand Junction, Nr April-July750 900 1030 70 1300 1570


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-July106 135 170 69 220 270
Mcphee Res April-July110 145 190 64 260 325
San Miguel
Placerville, Nr April-July50 71 83 65 98 130
Dolores
Cisco, Nr April-July175 250 330 58 410 575

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 423.9 113 86 511.6 136 375.1 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 7.9 104 87 7.4 97 7.6 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 69.7 105 72 66.0 99 66.5 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 34.8 77 53 55.0 122 45.1 66.0
untitled Blue
Dillon Res 182.6 80 72 241.3 106 226.9 254.0
Green Mtn Res 58.0 65 39 73.6 82 89.8 146.9
untitled Homestake Ck
Homestake Res 41.2 125 96 41.1 125 32.9 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 60.0 78 59 72.1 94 76.8 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 10.4 87 32 10.4 87 12.0 32.9
untitled Taylor
Taylor Park Res 59.0 87 56 76.2 112 68.1 106.2
untitled Gunnison
Blue Mesa Res 248.8 45 30 592.6 108 549.9 829.5
Morrow Point Res 107.6 96 92 111.0 99 111.6 117.0
Crystal Res 14.8 96 84 15.9 103 15.4 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 2.8 66 17 2.2 52 4.2 16.7
untitled Uncompahgre
Ridgway Res 45.9 67 55 60.3 88 68.8 83.0
untitled Dolores
Mcphee Res 168.0 62 44 285.5 106 270.1 381.1
untitled
TOTAL 1535.3 76 55 2222.1 110 2020.8 2792.1
Colorado
Lake Powell 10098.9 57 42 14067.6 79 17744.8 24322.0
untitled
TOTAL 10098.9 57 42 14067.6 79 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