LAS VEGAS (KLAS) — As Hurricane Hilary barrels toward the West Coast, the Las Vegas valley expects rainfall, thunderstorms, and possible flooding over the weekend and next week. Many are asking how the hurricane could affect Lake Mead water levels as the highest rain totals and flash flooding are possible in mountainous regions of southern Nevada.

When wet winter storms struck the Las Vegas valley in January, National Weather Service officials tempered expectations.

“Rain in the Las Vegas valley does help with Lake Mead’s water levels,” said National Weather Service officials from the Las Vegas office. “However, it is more like a drop in the bucket compared to the contribution from the snowpack in the Upper Colorado River Basin.” The record snowpack this year eased drought restrictions for Nevada and other Southwest states.

In January, Lake Mead saw a 2-foot rise in water levels moving from 1,044.96 feet on Jan. 1 to 1,046.96 feet on Jan. 31. In that same timeframe, southern Nevada received above-average rainfall. According to the National Oceanic and Atmospheric Administration (NOAA), Mt. Charleston saw 3.8 inches of precipitation.

Forecasters say Hilary is expected to bring 1 to 3 inches of rain, with 3 to 5 inches possible where the heaviest rain is expected in mountainous regions. A flood watch has been issued for southern Nevada starting Saturday morning and stretching until Monday afternoon. It’s yet to be determined if the storm’s rainfall totals will be comparable to January’s. However, Bureau of Reclamation Public Affairs Specialist Doug Hendrix said that while the early-2023 storms did affect Lake Mead’s water levels, the accumulation was not enough to dent historic lows at the lake.

“While the amount of precipitation received in the lower basin and from tributary inflows helps, rainfall from recent winter storms, alone, isn’t enough to offset the decades-long reservoir declines,” Hendrix said.

As of Thursday evening, Hilary was rated as a category 4 hurricane with 140 miles per hour sustained winds. Forecasters predict landfall could weaken the storm to a category 1. Washes and low-lying areas of the Las Vegas valley could see flooding with continuous rain and saturated soils, meteorologists say.