By Reginald Stanley. Posted January 7, 2018, 7:33 PM.

A major Pacific storm, also the first significant storm of the season so far, is expected to affect Southern California this week - potentially bringing heavy rain with it.

A cutoff-low pressure system is expected to tap into subtropical moisture as it moves over the region late Monday. This will bring potentially heavy rain on Tuesday, when rain chances are highest. The National Weather Service has issued Flash Flood Watches for inland communities west of the mountains through Tuesday evening. Burn areas from December's wildfires will be of high concern as these very dry areas receive rain faster than the soil can absorb it. Heavy snow is expected in the mountains, where the National Weather Service has issued Winter Storm Warnings for the same period. High Wind Watches will be in effect for the deserts. Conditions are expected to be at their most hazardous during the AM hours of Tuesday.

Precipitation totals are forecast to amount between one and 1 1/2 inches through Wednesday in the valleys, with locally higher amounts in the mountains and foothills. Maximum wind gusts are forecast to be between 25 and 40 MPH on average, and potentially over 60 MPH in canyons and mountain passes. Snow levels could drop to around 5,000 feet above sea level by Tuesday evening.

The cutoff low will be replaced by warmer temperatures and offshore flow later in the week.