Storm systems propelled by an atmospheric river will bear down on the Inland Empire toward the end of this week, generating periodically heavy rainfall, stiff winds and thunderstorms, according to the National Weather Service.
“A strong cold front is expected to arrive in SoCal Thursday, with precipitation spreading across the area, becoming heavy in the afternoon,” the NWS said in a statement. “It is associated with an atmospheric river band and strong upper level jet stream.”
A southward bend in the jet that’s common during winter months will drive back-to-back troughs of low pressure from the Gulf of Alaska through the region, with the first sweeping through Thursday and the second on Friday, meteorologists said.
“While it’s too early for a flood watch, there is an excessive rainfall outlook for southwest California on Thursday,” the NWS said. “General rainfall totals are forecast 1 to 2 inches, but also hourly rates of at least .5 inches along the frontal band … Thursday night and Friday.”
Prognostication charts published by the Weather Service indicated unstable conditions, including isolated thunderstorms, will persist from Thursday morning to Friday night. Winds will increase ahead of the fronts, forecasters said.
There will be a lull over the weekend before another, lighter storm front reaches the region Sunday night into Monday.
The San Bernardino Mountains and the area around Idyllwild-Pine Cove will receive some snow at the higher elevations during this week’s storms, according to the NWS.
Daytime temperatures in the Riverside metropolitan area Monday to Wednesday will hover in the mid 70s, dropping to the lows 50s overnight, while Thursday to Saturday, highs will peak in the low 60s, with lows in the mid 40s.
In the Coachella Valley, highs will top out near 80 Monday to Wednesday, with lows in the mid 50s. Thursday to Saturday, the daytime mercury will be in the mid 60s, falling to the mid 40s at night.
In the Temecula Valley, temps will be identical to the Riverside area Monday to Wednesday, but Thursday to Saturday, the highs won’t exceed 60, with lows in the mid 40s, according to the Weather Service.