Winter Storm Prompts Flood Watch, Wind Advisory In Imperial Beach

IMPERIAL BEACH, CA — A significant winter storm will bring widespread rain, mountain snow and gusty winds to Southern California on Tuesday, prompting National Weather Service advisories and watches for San Diego County.

A flood watch is in effect for the county's coastal areas, mountains and valleys through Tuesday evening due to excessive rain expected throughout the day with isolated afternoon thunderstorms.

Rainfall rates are anticipated to be a half-inch per hour with higher rainfall rates on coastal mountain slopes, according to the National Weather Service. The forecast calls for rainfall to reach 1 to 1.5 inches west of the mountains and 2 to 3 inches along the mountains below 5,000 feet.

Rainfall totals could reach an inch over some parts of the high deserts as well, which can cause flooding where water is unable to drain properly on roadways.

"Flash flooding on Tuesday is possible due to excessive rainfall through the day with isolated afternoon thunderstorms," forecasters said. "Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations."

Periods of moderate to heavy rain and snow are expected to move in from the northwest Tuesday morning and continue through the early evening before the system rapidly ejects to the east, according to the National Weather Service.

Heavy snow is possible above 6,000 feet, but the snow level will fluctuate and likely be above 7,000 feet until late Tuesday evening, forecasters said.

Periods of damaging winds are also likely across the San Diego region.

A wind advisory is in effect until midnight Tuesday for the county's coastal areas and valleys, where 20 to 30 mph winds with gusts up to 35 to 45 mph are expected, according to the National Weather Service.

"Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result," forecasters said. "Use extra caution when driving, especially if operating a high-profile vehicle. Secure outdoor objects."

Meanwhile, a high wind warning is in effect until 4 a.m. Wednesday for the county's deserts and mountains, where 25 to 35 mph winds with gusts up to 60 to 70 mph are expected.

"Damaging winds will blow down trees and power lines," forecasters warned. "Power outages are possible. Travel will be difficult, especially for high-profile vehicles."

Temperatures are expected to stay below average for the remainder of the week with another chance for light rain late Thursday into Friday.

Here is the Imperial Beach forecast from the National Weather Service:

Overnight
Scattered showers before 4am, then rain after 4am. Low around 55. South wind around 15 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

Tuesday
Rain, with thunderstorms also possible after 10am. Some of the storms could produce gusty winds and heavy rain. High near 61. Windy, with a south wind 20 to 30 mph becoming southwest in the afternoon. Winds could gust as high as 35 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.

Tuesday Night
Rain likely and possibly a thunderstorm before 10pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 48. West wind 15 to 20 mph, with gusts as high as 25 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Wednesday
Mostly sunny, with a high near 57. Northeast wind 5 to 10 mph becoming northwest in the afternoon.

Wednesday Night
Partly cloudy, with a low around 45. North wind around 5 mph becoming east after midnight.

Thursday
Mostly sunny, with a high near 58.

Thursday Night
A slight chance of rain. Mostly cloudy, with a low around 50. Chance of precipitation is 20%.

Friday
Mostly sunny, with a high near 59.

Friday Night
Mostly clear, with a low around 46.

City News Service and Patch editor Kristina Houck contributed to this report.