Heavy rain — and snow — are on the way and will saturate the Inland Empire, beginning midweek, as storms roll out of the Pacific Wednesday aboard an atmospheric river, forecasters said.
“This plume of moisture is rather deep, so confidence is high that Wednesday, we’ll get widespread rain spreading across the entire region,” the National Weather Service said in a statement. “There may be some decrease in rain late Wednesday into Thursday morning. Then a second plume of moisture arrives Thursday with a more organized trough to provide a little more energy and precipitation output, lasting through Friday.”
The chances of rainfall throughout the region are better than 80% Thursday to Friday, according to meteorologists. “Orographics will come into play with lifting over mountains, enhancing the rainfall there,” the NWS said in a statement. “This will be especially effective in the mountains of San Bernardino County. Snow levels will be rising as the precipitation arrives. Some snow could fall at 5,500 feet Wednesday morning before the snow levels rise to over 7,000 feet Wednesday night and over 8,000 feet late Thursday.”
The Weather Service cautioned that the strength of these low pressure troughs is greater than what the region has experienced so far this winter.
“This will be definitely our wettest storm period in the past year,” the agency said. “The deep moisture of both of these waves raises concerns for flooding, especially in recent burn scars.”
No advisories had been posted as of Monday morning.
The NWS predicted 2 to 3 inches of rain likely in valleys and other lowlands west of the inland mountain ranges Wednesday to Friday, while desert locations may see anywhere from .5 to 1.5 inches over the same period.
“Snowfall above 8,000 feet could pile up to 18 inches or so, but less than 3 inches below 7,000 feet,” according to the agency.
High temperatures in the Riverside metropolitan area Wednesday will top out in the mid 50s, with overnight lows in the low 40s.
The temperature bands will be almost identical for the Coachella and Temecula valleys.
For the weekend, skies will clear, with mostly sunny conditions region-wide, and the mercury generally will climb back into the upper 60s and low 70s during daylight hours, dipping to around 40 at night, forecasters said.