Upper Colorado Water Supply Outlook, April 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-July185 210 235 107 265 300
Willow Ck
Willow Ck Res, Granby, Nr April-July45 53 60 128 70 83
Fraser
Winter Park April-July16.5 18.2 20 103 22 25
Williams Fork
Williams Fork Res, Parshall, Nr April-July80 90 100 104 112 124
Muddy Ck
Wolford Mountain Reservoir April-July46 54 63 117 74 84
Blue
Dillon Res April-July165 185 205 126 225 245
Green Mtn Res April-July265 295 325 118 355 390
Colorado
Kremmling, Nr April-July790 880 975 113 1100 1240
Eagle
Gypsum, Blo April-July310 345 385 115 430 485
Colorado
Dotsero, Nr April-July1280 1430 1580 113 1800 2060
Frying Pan
Ruedi Res, Basalt, Nr April-July130 148 170 122 190 210
Roaring Fork
Glenwood Springs April-July675 745 820 119 900 990
Colorado
Glenwood Springs, Blo April-July2000 2200 2410 114 2700 3110
Cameo, Nr April-July2320 2550 2780 118 3100 3600
Plateau Ck
Cameo, Nr April-July140 161 182 147 205 235
Colorado
Cisco, Nr April-July4750 5250 5750 130 6450 7150
Lake Powell, Glen Cyn Dam, At April-July7000 8260 9200 128 9980 12000


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-July105 115 122 123 135 156
Almont April-July165 183 195 126 220 255
East
Almont April-July195 210 230 126 250 285
Gunnison
Gunnison, Nr April-July400 425 475 128 520 610
Tomichi Ck
Gunnison April-July78 87 100 135 118 140
Lake Fork
Gateview April-July126 146 160 130 182 215
Gunnison
Blue Mesa Res April-July780 850 925 137 1030 1200
Morrow Point Res April-July870 940 1020 138 1120 1290
Crystal Res April-July990 1060 1140 137 1240 1410
Muddy Ck
Paonia Res, Bardine, Nr March-June95 110 118 123 130 143
April-June92 107 115 126 127 140
April-July99 114 122 126 134 147
Nf Gunnison
Somerset, Nr April-July290 325 360 122 390 425
Surface Ck
Cedaredge April-July19 22 24 143 26 29
Uncompahgre
Ridgway Res April-July96 111 123 122 137 155
Colona April-July125 145 160 117 182 210
Delta April-July95 116 137 121 158 185
Gunnison
Grand Junction, Nr April-July1570 1800 2000 135 2120 2500


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-July280 310 350 143 385 420
Mcphee Res April-July350 385 430 146 480 530
San Miguel
Placerville, Nr April-July125 139 155 121 168 190
Dolores
Cisco, Nr April-July645 715 800 142 915 975

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 343.2 109 70 431.8 137 314.3 490.3
untitled Willow Ck
Willow Ck Res, Granby, Nr 9.0 109 99 8.8 107 8.2 9.1
untitled Williams Fork
Williams Fork Res, Parshall, Nr 64.2 105 66 66.9 110 60.8 96.9
untitled Muddy Ck
Wolford Mountain Reservoir 33.6 77 51 54.0 124 43.7 66.0
untitled Blue
Dillon Res 179.0 83 70 236.1 110 215.5 254.0
Green Mtn Res 49.4 75 34 65.8 100 65.9 146.9
untitled Homestake Ck
Homestake Res 18.3 73 43 40.9 163 25.1 43.0
untitled Frying Pan
Ruedi Res, Basalt, Nr 55.9 88 55 64.8 103 63.2 102.0
untitled Plateau Ck
Vega Res, Collbran, Nr 7.8 55 24 12.2 86 14.2 32.9
untitled Taylor
Taylor Park Res 60.4 97 57 70.7 113 62.4 106.2
untitled Gunnison
Blue Mesa Res 249.7 55 30 533.5 117 454.9 829.5
Morrow Point Res 106.7 96 91 103.8 93 111.7 117.0
Crystal Res 16.9 104 96 15.5 96 16.2 17.5
untitled Muddy Ck
Paonia Res, Bardine, Nr 4.0 129 24 5.7 186 3.1 16.7
untitled Uncompahgre
Ridgway Res 50.0 71 60 62.4 89 70.0 83.0
untitled Dolores
Mcphee Res 168.2 59 44 277.4 97 285.4 381.1
untitled
TOTAL 1416.2 78 51 2050.3 113 1814.5 2792.1
Colorado
Lake Powell 9049.0 53 37 12956.1 76 16941.7 24322.0
untitled
TOTAL 9049.0 53 37 12956.1 76 16941.7 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