Lower Colorado Water Supply Outlook, February 1, 2015

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.

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

	Forecast Period	90% Exceedance Volume	50% Exceedance Volume	Percent Median	10% Exceedance Volume
Salt
Roosevelt, Nr	January-May	110	225	73	380
	February-May	85	200	70	355
Tonto Ck
Roosevelt, Nr, Gun Ck, Abv	January-May	20	38	90	113
	February-May	12.1	30	86	105
Verde
Blo Tangle Ck, Abv Horsehoe Dam	January-May	80	141	90	315
	February-May	59	120	88	295

	Forecast Period	90% Exceedance Volume	50% Exceedance Volume	Percent Median	10% Exceedance Volume
Gila
Gila, Nr	January-May	50	62	111	119
	February-May	36	48	96	105
Virden, Nr, Blue Ck, Blo	January-May	54	77	101	148
	February-May	39	62	98	133
Solomon, Nr, Head Of Safford Vly	January-May	115	158	115	300
	February-May	97	140	114	280
San Carlos Res, Coolidge Dam, At	January-May	86	126	133	275
	February-May	70	110	136	260
San Francisco
Glenwood, Nr	January-May	16.1	22	105	43
	February-May	11.8	18.1	99	39
Clifton	January-May	51	68	111	128
	February-May	33	50	98	110

	Forecast Period	90% Exceedance Volume	50% Exceedance Volume	Percent Median	10% Exceedance Volume
Little Colorado
Lyman Lk, Abv, St. Johns, Nr	January-June	1.5	3.3	46	7.2
	February-June	1.3	3.2	48	7.1
Zuni
Black Rock Res, Abv	January-May	0.19	0.35	74	1.3
	February-May	0.11	0.27	71	1.3
Chevelon Ck
Winslow, Nr, Wildcat Cyn, Blo	January-May	4.6	9	65	18.5
	February-May	1.9	6.3	45	15.8

	EOM Contents	Percent EOM Average	Percent Usable Capacity	Last Year EOM	Last Year %Average	EOM Average	Usable Capacity
Salt
Roosevelt	694.4	77	42	788.4	87	901.4	1653.0
Horse Mesa	225.4	101	92	230.7	104	222.0	245.1
Mormon Flat	56.5	104	98	55.5	102	54.5	57.9
Stewart Mountain	64.8	104	93	66.3	106	62.2	69.8
Horseshoe	14.9	40	14	30.1	80	37.6	109.2
Bartlett	99.4	85	56	113.9	98	116.8	178.2
untitled
TOTAL	1155.4	83	50	1284.9	92	1394.6	2313.2


Bill Williams
Alamo	54.2	38	5	61.3	43	143.3	1045.0
Agua Fria
Lake Pleasant	764.9	119	88	619.6	97	641.6	869.9
Gila
San Carlos	84.5	23	10	126.5	34	366.8	875.0
Colorado
Lake Powell	11145.9	64	46	9827.7	57	17338.2	24322.0
Lake Mead	10729.0	52	41	12531.0	61	20452.4	26120.0
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TOTAL	22778.5	58	43	23166.2	59	38942.2	53231.9

Range		Round to
0-1.99		0.01
2.0-19.9		0.1
20-199		1.0
200-999		5.0
1000+		3 significant digits

Lower Colorado Water Supply Outlook, February 1, 2015

Lower Colorado Summary

Salt Basin Conditions

Gila Basin Conditions

Little Colorado Basin Conditions

Salt Specific Site Forecasts (kaf)

Gila Specific Site Forecasts (kaf)

Little Colorado Specific Site Forecasts (kaf)

Lower Colorado End of Month Reservoir Contents (kaf)

Precipitation Maps

Definitions

Additional Information