WATER CONDITIONS: Water supply forecast for March 1st.
The forecasts are posted at: WSI: http://cdec.water.ca.gov/cgi-progs/iodir/wsi Forecast Summary: The projected median April-July (AJ) runoff in the major Sierra river basins ranges from 131 percent on the Inflow to Lake Shasta to 269 percent on the Kern River.
The WSI forecast is based on precipitation and flows observed through February 2017 and can be summarized as follows: Sacramento River Unimpaired Runoff Water Year Forecast (50 percent exceedance)
For the Cosumnes River, the combined flows for January and February this year were a record 754 TAF which is nearly twice the average water year total for that watershed.
Unimpaired flows for the 2016-2017 water year: Region October-February Runoff (%) February Runoff (%) Sacramento Valley Index (4 rivers) 282 431 San Joaquin Valley Index (6 rivers) 426 589 Tulare Lake Basin (4 rivers) 307 482 Precipitation: The 47.0 inches of precipitation measured during January-February in the Northern Sierra 8-Station Index ranks as the highest total during that two month span in the entire record of the 8-Station Index.
The October-February total of 60.6 inches also ranks as the wettest in the San Joaquin Region during this period.
Precipitation for the 2016-2017 water year accumulated at the following rates of average: Hydrologic Region October-February precipitation (%) Sacramento River 215 San Joaquin River 211 Tulare Lake 215 Statewide 190 Precipitation Index Percent of Seasonal Average to Date through March 8, 2017 Northern Sierra 8-Station Index 213 (77.8 inches) San Joaquin 5-Station Index 212 (61.8 inches) Tulare Basin 6-Station Index 202 (41.8 inches) Snowpack: Snowpack is monitored using two complementary methods: automatic snow sensor (or “pillow”) readings and manual snow course measurements.
The snow sensors give us a daily snapshot of snow conditions while the manual snow course measurements provide a monthly verification of snow conditions in locations where snow has been measured in the same manner as far back as 100 years.
The snowpack in the San Joaquin, Tulare Lake, and both North and South Lahontan regions are above 200% of their March 1 historical average and above 175% of their expected April 1 total.
The majority of the expected precipitation will fall today and tomorrow with totals ranging from 0.25 inch up to 1.25 inches over the two day period.