Monthly Webinar 12.07/2010

Monthly Webinar 12.07/2010

-Assessment of current water conditions - Precipitation Forecast - Recommendations for Drought Monitor

Upper Colorado Normal Precipitation Upper Colorado River Basin Normal Monthly Precipitation 6 5 KREMMLING GRAND LAKE 6 SSW BERTHOUD SUMMIT Precipitation (in) 4 3 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

Upper Colorado Headwaters 145% of average

Snotel Percentile Rankings (at least 25 years of data)

Upper Colorado River Basin

Green River Basin above Flaming Gorge

Snowpack % of average to date: 117% Seasonal average: 34%

Duchesne River Basin

Snowpack % of average to date: 149% Seasonal average: 38%

Upper Colorado above Kremmling

Snowpack % of average to date: 142% Seasonal average: 35%

San Juan Basin

Snowpack % of average to date: 55% Seasonal average: 16%

Michael Lewis USGS

7-day average discharge compared to historical discharge for the day of the year (December 4)

Upper Colorado River Basin- Comparison of 7-day Average Discharge For December 4, 2002-2010 Percentage of streamgages in discharge category 100 90 80 70 60 50 40 30 20 10 0 Discharge Category high much above normal above normal normal below normal

Colorado River near CO-UT State Line 34 th Percentile 84% of Normal Green River at Green River, UT 41 st Percentile 92% of Normal San Juan River near Bluff, UT 37 th Percentile 90% of Normal

Cumulative Runoff Colorado River at CO-UT Line December 4, 2010 Total runoff: 3.5 M acre-ft 78% of normal

Cumulative Runoff Green River at Green River, UT December 4, 2010 Total runoff: 3.2 M acre-ft 74% of normal

Cumulative Runoff San Juan River at Bluff, UT December 4, 2010 Total runoff: 0.85 M acre-ft 49% of normal

4000 3500 Flaming Gorge November Reservoir Storage Max Capacity 3000 1971-2000 Ave 2500 2000 1500 1000 500 0 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Thousand AF

Lake Granby November Reservoir Storage 600 500 Max Capacity 400 Thousand AF 300 1971-2000 Ave 200 100 0 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010

Green Mountain November Reservoir Storage 160 140 Max Capacity 120 100 1971-2000 Ave Thousand AF 80 60 40 20 0 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010

300 Lake Dillon November Reservoir Storage 250 Max Capacity 1971-2000 Ave 200 150 100 50 0 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Thousand AF

900 Blue Mesa November Reservoir Storage 800 Max Capacity 700 600 1971-2000 Ave 500 400 300 200 100 0 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Thousand AF

Navajo Lake November Reservoir Storage 1800000 1600000 Max Capacity 1400000 1971-2000 Ave 1200000 Acre Feet 1000000 800000 600000 400000 200000 0 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Lake Powell November Reservoir Storage 30000000 25000000 Max Capacity 20000000 1971-2000 Ave Acre Feet 15000000 10000000 5000000 0 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011

Temperature Departure from Normal 11/1/2010 11/30/2010

Temperature Departure from Normal 12/1/2010 12/6/2010

Upper CO Briefing 07 XII 2010 Upper Colorado Outlook into 2012 Klaus Wolter University of Colorado, CIRES & NOAA-ESRL PSD 1, Climate Analysis Branch klaus.wolter@noaa.gov La Niña: Too Big to Fade! MEI Outlook into 2012 (1 st cut) Expectations for next few weeks What does La Niña mean for the Upper Colorado Basin? Other influences?

Current state of ENSO (bottom) compared to three weeks ago (top): our La Niña weakened for about a month or so (top), almost losing its SST anomalies of more than -1C; 2 nd wind has kicked in, with easterly wind anomalies right along the Equator across much of the basin helping to maintain this event. Niño 3.4

How long will this La Niña last? Two year analog cases, plus climatology and persistence thru next April (green line): 5 of 6 twoyear analog predictions show persistent La Niña into 2012

What can we expect in the next two weeks? Agreement between European (left) and American model (GFS; right) for middle of next week troughs to our west & east, and weak ridging right over us; negative NAO déja vu renders much of Europe and U.S. East coast cold!

What can we expect in the next two weeks? Precipitation chances for 4-6, 6-10, and 8-14 days from last night show a familiar wet pattern from northern California into northwest Colorado, weakening by next week. Best shot at precip statewide will be over the weekend, with southeast Colorado being least favored.

A little refresher on seasonal ENSO impacts: our mountains tend to be WET with La Niña rather than El Niño during WINTER only - spring goes back to being dry with La Niña. This year: a wet October-November was a good set-up for our northern mountains!

What is difference for Year 1 vs. Year 2 Las Niñas? For Upper Basin, the second snow accumulation season (right) tends to be drier than the first one (left) in prolonged La Niña scenario. This is based on seven La Niña cases since 1949 with at least a tendency to continue into following winter.

What is difference for Year 1 vs. Year 2 Las Niñas? Mean flow for Year 1: 16.75 MAf ( = +1.7MAf) Mean flow for Year 2: 13.64 MAf ( = -1.4MAf) Difference is significant with more than 0.7 standard deviations! A drier outcome has been typical (8 of 10 cases) for 2nd year runoff for the Colorado River. Six of the first year runoff totals were clearly above the long-term mean, while seven of the second year runoff totals were clearly below that.

Lees Ferry naturalized runoff in Water Year 2011 - onset behavior of ENSO (left) + early season precip (right) ENSO flavor favors low runoff (left), while early wetness favors high runoff (right) so far. Need to assess what a near-normal forecast has meant in the past.

Lees Ferry naturalized runoff in Water Year 2012 Since 1980, this particular tendency in the north-south temperature difference across the Arabian Sea has been highly related to Year-2 runoff this would favor the opposite (wet) outcome than the typical Year-2 La Niña scenario. Need to assess hindcast skill stay tuned!

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