After record snowfall, California braces for melting snowpack and flood risks

After three months of heavy rain and record snow, California is now facing the risk of floods due to melting snowpacks, as temperatures rise in the Central Valley and Sierra Nevada regions.

After experiencing heavy rain and snow for three months, California is now confronting another environmental challenge – the melting snowpack due to rising temperatures. State officials have expressed concern over the possibility of floods in the Central Valley, particularly in the Tulare Lake Basin, which has already seen storm flooding this year.

Although temperatures are forecasted to rise in the coming days, experts warn that the most significant threat will likely arrive when temperatures exceed 32 °C (90 °F) for an extended period — which is likely to occur around mid-summer.

The National Weather Service’s River Forecast Center shows that rivers such as the Merced River at Stevinson and the San Joaquin River remain above flood stage, indicating a potential for hazardous conditions. Water levels are expected to stay high in these areas over the next few months. As a result, authorities are closely monitoring the situation and preparing for possible flooding events.

Predicting the exact timing of the massive snowmelt is difficult, as it depends on various factors such as the duration of sunny days and the depth of the snowpack.

Reservoir operations also play a role in flood risks. Water managers releasing water from dams to make room for incoming flows can add pressure to rivers and tributaries downstream, keeping water levels high. The National Weather Service has issued flood advisories along the Kings River in Fresno, Kings, and Tulare counties, as well as in Fresno and Madera counties along the San Joaquin River.

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See also:

Historic Tulare Lake back to life after nearly a century, California – The Watchers – April 5, 2023

Historic Tulare Lake back to life after nearly a century, California

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In Southern California, officials from the Los Angeles Department of Water and Power are preparing the aqueduct and nearby waterways in the eastern Sierra for a lengthy runoff season that could last until September. Although Los Angeles is not expected to face major floods, stream flows collected in the city’s reservoirs are anticipated to last well into the summer due to the large amount of precipitation during the storm season.

With the potential for floods in the coming months, Governor Gavin Newsom issued an executive order to prepare the Tulare Basin for possible flooding and support response and recovery efforts throughout the state. State officials are advising agencies about the expected volume of snowmelt this year and expanding aerial remote sensing operations to collect more data on snowpack and runoff.

References:

¹ California snowmelt flood risk to last for months, experts say – Los Angeles Times – April 5, 2023

Featured image credit: NOAA-20/VIIRS. Acquired on April 5, 2023