Lower Colorado Water Supply Outlook, February 1, 2020

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	70% Exceedance Volume	50% Exceedance Volume	Percent Median	30% Exceedance Volume	10% Exceedance Volume
Salt
Roosevelt, Nr	January-May	205	255	315	102	450	645
	February-May	154	205	265	93	400	595
Tonto Ck
Roosevelt, Nr, Gun Ck, Abv	January-May	13.7	22	35	83	66	148
	February-May	5.2	13.1	27	77	58	140
Verde
Tangle Ck, Blo, Horseshoe Dam, Abv	January-May	83	116	151	96	225	455
	February-May	52	85	120	88	194	425

	Forecast Period	90% Exceedance Volume	70% Exceedance Volume	50% Exceedance Volume	Percent Median	30% Exceedance Volume	10% Exceedance Volume
Gila
Gila, Nr	January-May	30	36	48	86	71	92
	February-May	16	22	34	68	57	78
Virden, Nr, Blue Ck, Blo	January-May	38	45	60	79	88	117
	February-May	20	27	42	67	70	99
Solomon, Nr, Head Of Safford Vly	January-May	83	96	131	96	210	275
	February-May	45	58	93	76	173	235
San Carlos Reservoir, Coolidge Dam, At	January-May	58	70	97	102	176	250
	February-May	24	36	63	78	142	215
San Francisco
Glenwood, Nr	January-May	10.5	14.5	19.5	93	30	37
	February-May	7	11	16	88	26	33
Clifton	January-May	37	44	59	97	97	127
	February-May	18	25	40	78	78	108

	Forecast Period	90% Exceedance Volume	70% Exceedance Volume	50% Exceedance Volume	Percent Median	30% Exceedance Volume	10% Exceedance Volume
Little Colorado
Lyman Lk, Abv, St. Johns, Nr	January-June	2.2	3.5	4.4	62	5.9	8.1
	February-June	2	3.3	4.2	64	5.7	7.9
Zuni
Black Rock Res, Abv	January-May	0.02	0.1	0.27	57	0.57	3.2
	February-May	0.02	0.1	0.27	71	0.57	3.2
Chevelon Ck
Winslow, Nr, Wildcat Cyn, Blo	January-May	5	8	12.5	90	19	39
	February-May	2	5	9.5	68	16	36

	EOM Contents	Percent EOM Average	Percent Usable Capacity	Last Year EOM	Last Year %Average	EOM Average	Usable Capacity
Salt
Roosevelt	1212.3	134	73	670.5	74	901.4	1653.0
Horse Mesa	234.7	106	96	225.3	101	222.0	245.1
Mormon Flat	55.9	103	97	54.9	101	54.5	57.9
Stewart Mountain	66.6	107	95	64.4	104	62.2	69.8
Horseshoe	39.6	105	36	22.4	60	37.6	109.2
Bartlett	139.5	119	78	78.3	67	116.8	178.2
untitled
TOTAL	1748.6	125	76	1115.9	80	1394.6	2313.2


Bill Williams
Alamo	137.1	96	13	78.5	55	143.3	1045.0
Agua Fria
Lake Pleasant	757.5	118	87	656.4	102	641.6	869.9
Gila
San Carlos	81.5	22	9	36.6	10	366.8	875.0
Colorado
Lake Powell	12280.7	71	50	9629.2	56	17338.2	24322.0
Lake Mead	11256.2	55	43	10483.8	51	20452.4	26120.0
untitled
TOTAL	24375.9	63	47	20884.6	54	38798.9	52186.9

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, 2020

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