Thunderstorms are possible over parts of the Inland Empire Monday evening, and rainy weather will likely continue sporadically through the week amid a cooling trend and unstable conditions, according to the National Weather Service.
Forecasters said that a cut-off trough of low pressure off of the Baja California coast in Mexico, as well as another system rotating in from British Columbia, will generate showers and possibly thunderstorms, though the rainfall amounts are not expected to be significant.
“Cooling and periods of isolated thunderstorms (are likely) into Tuesday afternoon,” according to the NWS. “This … cooling trend will continue through Friday and bring additional chances for precipitation for Thursday and Friday.”
Rain chances are 20-30% in most locations throughout Riverside County, though the chances are greater at higher elevations, meteorologists said.
No flash flood watches or warnings have been issued.
A dip in the jet stream accounts for the instability, forecasters said.
The low off of the Baja coast will move particularly slowly, limping across Southern California and barely edging into Arizona by Saturday morning, according to NWS surface analysis charts.
Temperatures in the Riverside metropolitan area will gradually slide through the week, with the high Monday about 90 degrees, while on Friday it will be just below 70. Lows will generally hover in the upper 50s, according to the Weather Service.
In the Coachella Valley, the cool down will result in highs going from the low 90s early in the week to the upper 70s by the end of it, with lows in the mid-60s. In the Temecula Valley, the highs will begin the week in the mid-80s and by Friday fall to the mid-60s, with lows in the mid to upper 50s, the NWS said.