Clouds, rain move into SoCal, starting several days of wet weather

Dark clouds and rain moved across much of the Southland Wednesday as the first wave of a two-storm front arrived in the area, with wet weather expected to persist into the weekend.

Rain began falling in some areas by late Wednesday morning. The National Weather Service even reported a strong thunderstorm that developed over Long Beach and began moving north toward downtown and the San Gabriel Valley. In Orange County, lightning was spotted off the coast, prompting a midday closure of the Seal Beach Pier and beach.

Forecasters said a slight chance of thunderstorms will continue in the area Wednesday and Wednesday evening, while the overall storm system is expected to extend wet conditions into the weekend.

Wednesday’s rain was part of the first wave of the two-pronged system, with coastal and valley areas expected to receive between a quarter- to half-inch of rain by Thursday morning, with up to an inch falling in the mountains. Some localized areas in the San Gabriel Mountains could see 1.5 inches, forecasters said.

Totals were expected to be slightly lower in the Antelope Valley, with about one-tenth to a quarter-inch of rain anticipated.

But forecasters said the rainfall amounts could vary widely due to the changing nature of the storm system.

“There is a moderate-to-high chance that amounts could be between 1.5 and 2 times higher than the amounts forecast through Thursday morning,” according to the NWS.

Gusty winds will also impact many areas, with winds of 45 to 50 mph possible in particularly wind-prone areas.

Conditions are expected to dry out on Thursday before the second wave of the system moves in on Friday. The second wave is expected to be stronger and wetter, with rain anticipated to continue through Saturday.

“As the second piece of the storm system possesses a little more instability and higher precipitable water values, there is a higher chance for rainfall rates to range between 0.25 and 0.50 inch per hour on Friday and Friday night,” according to the NWS. “Minor flooding of low-lying areas and area roadways could develop during this timeframe.”

Forecasters said earlier that some areas could receive as much as 3 inches of rain by the time the storm systems pass.

The showers should begin to taper off between Saturday night and Sunday morning, with a warming trend anticipated for early next week.

Rain in forecast for Inland Empire

The first rains of the fall season are forecast throughout the Inland Empire beginning Wednesday and continuing off and on to Saturday morning, according to the National Weather Service.

“We’re monitoring an incoming low pressure system that is currently developing north off the coast of the Pacific Northwest,” according to an NWS statement. “This low will slowly move south and east over much of this week, eventually bringing cooler and wetter conditions to Southern California.”

The storm system is not anticipated to turn intense until Friday afternoon or evening, with only scattered light rain in the region Wednesday and Thursday, forecasters said.

“Count on at least some measurable rainfall Wednesday night and Thursday,” the NWS stated. “Think sprinkles to one quarter of an inch. The mountains are expected to see accumulations on the upper end of that range.”

Surface prognostication charts published by the agency indicated back- to-back troughs crossing the region over the three-day period, but meteorologists said the bulk of the moisture will stay off the coast and to the south until Friday.

“The highest (probability) for heavier rainfall rates is late Friday for most locations,” the Weather Service said. “So that period holds the greatest potential for any significant runoff or flood threat.”

After the storm system exits to the east Saturday, it will be replaced by a ridge of high pressure, which will influence weather patterns going into next week, with generally warmer, drier conditions for the Thanksgiving holiday period, according to the NWS.

Temperatures in the Riverside metropolitan area Monday and Tuesday will reach 80 degrees during the day and the low 50s overnight, but Wednesday to Saturday will see a slight cooling trend, with daytime highs peaking in the low 70s and lows holding in the 50s.

San Diego area to get rain beginning Wednesday

San Diego County was expected to get multiple days of rain starting Wednesday.

Rainfall estimates for Wednesday through Saturday range from 1 to 1.5 inches in the coast and valleys, a quarter inch to 1 inch in the deserts, and 1.5 to 3 inches in the mountains, according to the National Weather Service.

Along the coast, mostly cloudy conditions are expected through Friday, with high temperatures hitting the mid-70s. Inland valley areas are expected to be partly cloudy through Friday, with highs reaching the low 70s.

San Diego County desert areas are expected to see highs in the upper 70s throughout the week, with daytime temperatures ranging from the high 50s to mid-60s in the mountains.

Forecasters predict that once the storm system moves out, likely next Sunday or Monday, dry weather will return with warmer temperatures.

No hazardous marine conditions are expected through Wednesday, but current projections are for winds to mostly remain under 20 knots.

Updated Nov. 15, 2023, 12:08 p.m.

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