RivCo In For A Rainy, Wintry Christmas: What To Know About The 'Pineapple Express'

RIVERSIDE COUNTY, CA — It seems that it will be a wet and wintry Christmas Eve and Christmas Day for Riverside County, according to weather officials.

An atmospheric river — dubbed a Pineapple Express during the wintertime — will dump moderate to heavy rain across the Inland Empire, according to the National Weather Service.

Forecasters explained that the system will materialize in the Golden State after travels from Hawaii, drawing moisture from the Pacific, which will meld with a trough of low pressure coming out of the Gulf of Alaska.

Upwards of an inch of rain is expected in the Riverside metropolitan area, the lower desert communities and up to 2 inches in the mountain areas.

Wednesday is predicted to see the heaviest amount of rain across the region, forecasters said.

"Models suggest Wednesday as the period of the heaviest
rain as the atmospheric river moves through the area from north to south, with additional lighter showers expected on Christmas Day," NWS officials wrote Thursday.

As of Thursday, no winter weather advisories, flood advisories or other alerts had been issued, but forecasters urged commuters to use caution.

"Please plan accordingly if you will be traveling for the Christmas holiday as travel impacts are likely," the NWS said.

Temperatures were expected to dip as the storm system approaches, though forecasters said the cooling would not be significant.

In the Riverside area, temperatures were forecast to remain unseasonably warm through the rest of the week, with daytime highs from Thursday through Sunday ranging from the upper 70s to low 80s and overnight lows in the low 50s. Beginning Tuesday, temperatures are expected to moderate, with highs topping out in the upper 60s and lows near 50.

In the Coachella Valley, highs are expected to reach the low to mid-80s through the remainder of the week and weekend, with overnight lows in the upper 50s. That pattern is expected to hold into early next week, before temperatures drop about 10 degrees by Christmas, meteorologists said.

For the Temecula Valley, highs through the end of the week are forecast to peak in the mid-70s, with overnight lows dipping into the mid-40s. Cooler conditions are expected to arrive Tuesday, with daytime highs settling just below 70 and overnight lows in the low 40s through Christmas.

The National Weather Service said another storm system appears to be developing in the Pacific Northwest and could track into Southern California shortly after Christmas, though its timing and strength remain uncertain.