SLCESGNM Apr, 2008
Download http://www.cbrfc.noaa.gov/product/oup/text/SLCESGNM/SLCESGNM.1207334496.000
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SLCESGNM
TTAA00 KSLR DDHHMM
NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY UT
APRIL 3, 2008
INTERNAL NWS PRODUCT FOR GUIDANCE PURPOSES ONLY
SAN JUAN RIVER BASIN SPRING FLOOD POTENTIAL OUTLOOK
The potential for spring 2008 flooding due to snowmelt in the San Juan Basin
is higher than average. Most rivers and streams over the upper portions of the
San Juan, Navajo, Piedra, Animas and La Plata are forecast to reach or exceed
bankfull. This is due to much above average snowpack in these areas. Depending
on future precipitation and temperatures, all of these rivers will have to be
monitored closely during runoff over the next several months.
Current snowpack as of April 1st for the entire San Juan Basin is 125 percent
of average. Above Navajo Reservoir currently has 130 percent of average.
March precipitation was 35 percent of average across the entire Basin,
with seasonal totals since October 2007 at 120 percent of average. The volume
forecast for the April-July runoff period is much above average.
It is also important to keep in mind that an extended period of high
temperatures resulting in rapid snowmelt, or heavy rainfall during the peak
flow period when stream channel capacities are reduced, may cause or exacerbate
flood problems this year.
Specific spring peak flow forecasts (maximum mean daily flow) as of April 1st.
Forecast peaks for this year are 50% exceedance values. For full probabilistic
distributions of possible peaks, see:
http://www.cbrfc.noaa.gov/product/peakpeak.cgi
2008 Normal
Fcst 2007 Flood Bankfull Average Period
Peak Peak Flow Flow Peak of
River / Site (cfs) (cfs) (cfs) (cfs) (cfs) Peak
------------------ ------- ------- ------- ------- ------ -----------
San Juan - 4300 1920 6760 4990 2485 5/15 - 6/12
Pagosa Springs
Animas - 6750 3440 10200 6100 4675 5/28 - 6/14
Durango
Animas - 7350 3560 9490 7030 4900 5/31 - 6/15
Farmington
San Juan - 13050* 7250 40700 29330 7340 5/21 - 7/4
Bluff
* - Peak flow forecast on the San Juan below Navajo Reservoir include
the maximum spring releases for 2008 by a proposed modified Spring Release
(55-days at 5,000 cfs) would be made as determined by the Flow
Recommendations. The modifications would extend the Spring Release by
beginning sooner to by-pass the larger than average inflow and also
running it longer to meet end-of year target storage. The final
decision on the exact nature of this modified Spring Release has not
been determined, but Reclamation's current proposal is to hold at 4,000 cfs
until late May when the maximum Spring Release will begin to ramp up to
5,000 cfs. The normal 21-day 5000 cfs release will be extended 34 days and
then ramp down 1000 cfs each day in mid July to the target baseflow of
750 cfs.
CBRFC/tjc
NNNN
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