SLCESGNM Mar, 2008
Download http://www.cbrfc.noaa.gov/product/oup/text/SLCESGNM/SLCESGNM.1204831653.000
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FGUS65 KSTR 061926
ESGNM 
TTAA00 KSLR DDHHMM
NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY UT
MAR 6, 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 this spring.

Current snowpack as of March 1st for the entire San Juan Basin is 150 percent
of average. Above Navajo Reservoir currently has 160 percent of average.
February precipitation was 155 percent of average across the entire Basin,
with seasonal totals since October 2007 at 135 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 in any year.

Specific spring peak flow forecasts (maximum mean daily flow) as of March 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 -             4700      1920      6760     4990     2485   5/15 - 6/12
   Pagosa Springs

Animas -               7600      3440     10200     6100     4675   5/28 - 6/14
   Durango

Animas -               8400      3560      9490     7030     4900   5/31 - 6/15
   Farmington

San Juan -            14000*     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
(21-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 3,000 cfs
until May 11th when the maximum Spring Release will begin to ramp up to
5,000 cfs. The normal 21-day 5000 cfs release will be extended 9 days and
then ramp down at 1000 cfs per day until 500 cfs is reached on June 28th. 

CBRFC/tjc


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