SLCESPAZ

NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY, UTAH
Apr 2, 2018


The following are updated forecasts for the Lake Mead Local 
(or intervening flow).

Forecasts include monthly values for April - June and seasonal 
volumes for April - July.

-------------------------------------------------------------------
March OBSERVED (EST.) DATA: (From USGS gage data) 
                       - values in KAF -
Mar observed (Colorado Diamond Ck 851.9 + Muddy River 3.1 
  + Virgin River 10.1 - Powell Release 830.9) ~ 34.2 KAF

-------------------------------------------------------------------
FORECASTS (using the Ensemble Prediction System):

* All Forecasts are the 50% exceedance probability value *

Lake Mead Intervening Flow:

April - June Forecasts

	   April      50  KAF (48% of average)
	   May        51  KAF (67% of average)
	   June       25  KAF (71% of average)

April - July Forecast:     167 KAF (60% of average)

Lake Mead Evaporation Coefficients to Adjust Intervening Flow:

April - June CBRFC Evaporation amounts

	  Apr       37.8  KAF
	  May       47.1  KAF
	  Jun       57.9  KAF
       
Equation to use: 

Inflow(BOR) = Inflow(NWS) + Evap(BOR) - Evap(NWS) + Bankstorage(BOR)


-------------------------------------------------------------------
Tributaries:

           Virgin River
           nr Littlefield

	   Apr  6.6 KAF (43% of median or 30% of average)
	   May  2.7 KAF (23% of median or 11% of average)
	   Jun  2.0 KAF (40% of median or 19% of average)
	   
          Little Colorado
           nr Cameron

	   Apr  1.2 KAF ( 16% of median or  6% of average) 
	   May  1.0 KAF (100% of median or 24% of average) 
	   Jun  0.0 KAF (  0% of median or  0% of average) 
 
          Paria Creek
           nr Lees Ferry

	   Apr  0.5 KAF (50% of median or 43% of average)
	   May  0.2 KAF (46% of median or 30% of average)
	   Jun  0.1 KAF (36% of median or 27% of average)

       * All Forecasts are the 50% exceedance probability value * 


NNNN

$$