San Juan Water Supply Outlook, June 1, 2016

Note: This publication is scheduled for revision. If you have feedback on content, format, or publication frequency, please contact us.
Prepared by Greg Smith
NOAA, National Weather Service
Colorado Basin River Forecast Center
Salt Lake City, Utah
www.cbrfc.noaa.gov

Contents

San Juan Summary






*Median of forecasts within each basin.


San Juan Basin Conditions




Snow Water Equivalent in Percent of Median.
* Percent usable capacity, not percent average contents.
Click for multi-month Graph.


San Juan 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
San Juan
Pagosa Springs April-July180 184 189 88 194 200
June-July73 77 82 85 87 95
Carracas, Nr April-July280 285 295 78 305 315
June-July115 120 129 82 137 148
Navajo Res, Archuleta, Nr April-July515 525 545 74 585 595
June-July187 196 215 74 255 265
Farmington April-July740 760 785 71 815 845
June-July300 320 345 73 375 405
Bluff, Nr April-July750 765 780 71 815 850
June-July300 315 330 73 365 400
Rio Blanco
Pagosa Springs, Nr, Blanco Dam, Blo April-July40 42 45 83 48 50
June-July16 18 21 91 24 26
Navajo
Chromo, Nr, Oso Div Dam, Blo April-July45 47 50 77 53 56
June-July21 23 26 87 29 32
Piedra
Arboles, Nr April-July158 161 166 79 173 178
June-July52 55 60 81 67 72
Los Pinos
Vallecito Res, Bayfield, Nr April-July159 167 172 89 185 191
June-July74 82 87 88 100 106
Animas
Durango April-July310 320 330 80 365 370
June-July158 166 178 81 215 220
Florida
Lemon Res, Durango, Nr April-July34 36 39 71 42 46
June-July17 19 22 81 25 29
La Plata
Hesperus April-July16.4 16.9 17.4 76 18.4 19.4
June-July7 7.5 8 94 9 10
Mancos
Mancos, Nr April-July26 27 27 87 28 29
June-July9 9.7 10 96 11 12

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).

San Juan 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 Los Pinos
Vallecito Res, Bayfield, Nr 120.6 120 96 119.9 119 100.5 125.4
untitled San Juan
Navajo Res, Archuleta, Nr 1549.4 108 91 1266.5 89 1429.7 1696.0
untitled Florida
Lemon Res, Durango, Nr 35.0 109 88 34.2 107 32.1 39.8
untitled
TOTAL 1705.0 109 92 1420.6 91 1562.3 1861.2

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: Greg Smith