952  
FGUS76 KSTO 031629  
ESFSTO  
CAC003-005-007-009-011-017-021-035-057-061-063-067-077-089-091-095-  
099-101-103-109-113-115-040030-  
 
HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE SACRAMENTO CA  
829 AM PST WED MAR 3 2021  
   
..LOW SPRING SNOWMELT FLOOD THREAT ACROSS CALIFORNIA
 
 
THE POTENTIAL FOR FLOODING DUE TO SPRING SNOWMELT IN THE  
CALIFORNIA-NEVADA RIVER FORECAST CENTER'S (CNRFC) DOMAIN IS BELOW  
NORMAL DUE TO BELOW NORMAL SNOWPACK AND DROUGHT CONDITIONS  
PREDOMINATING ACROSS CALIFORNIA AND NEVADA.  
 
FLOODING IN CALIFORNIA REMAINS A SLIGHT POSSIBILITY DUE TO THE  
SEASONAL THREAT OF HEAVY RAINFALL ALONE, OR COMBINED WITH SNOWMELT  
ANY TIME DURING THE SPRING.  
 
CURRENT BASIN CONDITIONS  
 
SNOWPACK  
EVERYWHERE FROM THE KLAMATH BASIN AT THE NORTHERN PART OF THE  
REGION TO THE TULARE BASIN IN THE SOUTHERN SIERRA NEVADA IS  
EXPERIENCING BELOW AVERAGE SNOWPACK. FOR THE SIERRA NEVADA,  
REGIONAL SNOWPACK LEVELS RANGE FROM AROUND 45%, 60%, AND 70%  
OF AVERAGE FOR THE WATER YEAR TO DATE FOR THE SOUTHERN,  
NORTHERN, AND CENTRAL SIERRA, RESPECTIVELY.  
 
SEASONAL PRECIPITATION  
PRECIPITATION TOTALS ACROSS THE REGION FOR THE WATER YEAR TO DATE  
RANGE FROM ABOUT 35-65% OF AVERAGE. MANY REGIONS IN CALIFORNIA  
HAVE OBSERVED FIVE CONSECUTIVE MONTHS OF BELOW AVERAGE  
PRECIPITATION. LAST YEAR AT THIS TIME PRECIPITATION TOTALS FOR  
CALIFORNIA WERE AROUND 50% OF AVERAGE.  
 
SEASONAL (APRIL-JULY) RUNOFF FORECASTS  
THE SEASONAL RUNOFF FORECASTS CLOSELY FOLLOW THE SNOWPACK  
CONDITIONS. AT THIS TIME, BELOW NORMAL RUNOFF VOLUMES CAN  
GENERALLY BE EXPECTED DURING THE APRIL-JULY PERIOD FOR CNRFC'S  
SNOWMELT-DOMINATED AND NON-SNOWMELT-DOMINATED BASINS.  
 
FLOOD EXCEEDANCE PROBABILITIES  
FLOODING POTENTIAL DURING THE SPRING SNOWMELT SEASONS IS BELOW  
NORMAL DUE TO THE BELOW NORMAL SNOWPACK. THE POTENTIAL FOR LARGE  
SPRINGTIME RAINFALL EVENTS RESULTING IN RIVER FLOODING IS STILL  
PRESENT AND SHOULD BE MONITORED THROUGHOUT THE SPRING. CONSULT  
THE AHPS LONG RANGE FLOOD RISK MAP FOR THE LATEST POINT  
EXCEEDANCE PROBABILITIES:  
HTTP://WATER.WEATHER.GOV/AHPS/LONG_RANGE.PHP  
 
SUMMARY  
RISK OF CALIFORNIA FLOODING DURING THE SNOWMELT SEASON IS BELOW  
NORMAL THIS YEAR FOR THE SOUTHERN CASCADES THROUGH THE SIERRA  
NEVADA. NEVERTHELESS THE POSSIBILITY FOR FLOODING REMAINS  
DUE TO THE POSSIBILITY OF HEAVY RAINFALL OR THE  
COMBINATION OF RAIN AND SNOWMELT AT ANY TIME DURING THE SPRING.  
 
REFER TO THE LONG RANGE OUTLOOK PRODUCT FOR FLOOD EXCEEDANCE  
PROBABILITIES AT PARTICULAR LOCATIONS FOR THE MARCH THROUGH  
MAY PERIOD. FOR SHORT TERM HYDROLOGIC FORECASTS AND GENERAL  
WATER RESOURCE INFORMATION, PLEASES SEE THE CNRFC HOMEPAGE AT:  
HTTP://WWW.CNRFC.NOAA.GOV  
 
THIS WILL BE THE ONLY PRODUCT ISSUED THIS YEAR FOR SNOWMELT FLOODING.  
 

 
 
CNRFC/DO WFO STO/CM  
 
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