SLCESPAZ

NATIONAL WEATHER SERVICE
COLORADO BASIN RIVER FORECAST CENTER
SALT LAKE CITY, UTAH
Feb 01, 2018


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

Forecasts include monthly values for February - April and seasonal 
volumes for Feb - July and Apr - July.

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JANUARY OBSERVED (EST.) DATA: (From USGS gage data)
                       - values in KAF -
Jan observed (est.) (Colorado Diamond Ck 928.3 + Muddy River 2.7 
  + Virgin River 7.9 - Powell Release 859.0) ~ 79.9 KAF  

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FORECASTS (using the Ensemble Prediction System):

* All Forecasts are the 50% exceedance probability value *

Lake Mead Intervening Flow:

February - April Forecasts

	   February   45  KAF (45% of average)
	   March      78  KAF (72% of average)
	   April      48  KAF (46% of average)

April - July Forecast:     151 KAF (55% of average)

February - July Forecast:  274 KAF (56% of average)

Lake Mead Evaporation Coefficients to Adjust Intervening Flow:

Feb - Apr CBRFC Evaporation amounts

	  Feb       31.4  KAF
	  Mar       36.3  KAF
	  Apr       37.5  KAF
       
Equation to use: 

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


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Tributaries:

           Virgin River
           nr Littlefield

	   Feb  5.1 KAF (37% of median or 31% of average)
	   Mar 10.5 KAF (71% of median or 45% of average)
	   Apr  8.5 KAF (56% of median or 38% of average)
	   
          Little Colorado
           nr Cameron

	   Feb  0.4 KAF (20% of median or  2% of average) 
	   Mar  1.8 KAF ( 9% of median or  6% of average) 
	   Apr  2.0 KAF (26% of median or 10% of average) 
 
          Paria Creek
           nr Lees Ferry

	   Feb  0.8 KAF (54% of median or 41% of average)
	   Mar  1.4 KAF (86% of median or 63% of average)
	   Apr  0.9 KAF (90% of median or 77% of average)

       * All Forecasts are the 50% exceedance probability value * 


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