Buffeted by cold, heavy rains and faced with diminished storage options, the greater Los Angeles Basin could experience a possible shortfall in natural gas supplies, according to an advisory Monday from Sempra Energy’s Southern California Gas Co. (SoCalGas).

In a morning advisory, SoCalGas called for its customers to “immediately” reduce their gas use to help “lower the risk of possible gas and electricity shortages.”

SoCalGas and its sister Sempra utility, San Diego Gas and Electric Co. (SDG&E), also issued a system-wide curtailment watch for large commercial/industrial (noncore) customers, including the region’s electric generating plants. The two Sempra utilities indicated that they have so far met system demands using both storage withdrawals and flowing gas supplies.

“However, due to forecasted cold weather conditions throughout [the two utility] service territories, there is a potential for a supply shortfall,” the utilities warned, adding that large customers could be receiving notices to curtail their use of gas.

As it did earlier this winter, SoCalGas urged customers to lower thermostats, delay using gas appliances and to wash clothes in cold water.

Last week, California regulators proposed to “significantly limit” volumes of gas that could be stored in the now shuttered Aliso Canyon field, the state’s largest underground storage facility. They noted that the 86-Bcf capacity facility could reopen, albeit at a fraction of past capacity, as about one-third of the storage wells have passed a battery of tests.

Since a four-month storage well leak at the storage facility last winter, months of review have been completed by the state, and SoCalGas submitted a detailed report asking to reopenthe facility last November. Nearby residents dislocated by the prolonged leak have vowed to close the storage facility permanently.

“The state’s energy experts and independent third parties have concluded in three consecutive technical assessments that Aliso Canyon is needed to meet the region’s natural gas and electricity needs,” a SoCalGas spokesperson said. “The ability to resume injections at Aliso Canyon will further enhance the reliability of the region’s gas and electricity systems.”

Late last year, the California Public Utilities Commission ordered the creation of the “SoCalGas Advisory” program to help address the concerns of state agencies about regional energy reliability this winter, given the moratorium on injecting additional supplies at Aliso Canyon.

More than 95% of the use of gas in Southern California goes to home heating, and about 60% of the electricity used in the region come from gas-fired power plants, the gas utility spokesperson said.