A cold and wet storm is coiled in the Gulf of Alaska, and it will hurl snow and rain into Southern California late this week, forecasters said.
The cold low-pressure system will affect the region starting Wednesday afternoon, and last through Friday afternoon, National Weather Service forecasters said.
That will be an abrupt change from the warm and somewhat uneventful weather the region can expect early in the week, they said.
Forecasters expect a 20 percent chance of rainfall Wednesday evening in the Arcadia area, according to the NWS. That will rise to 50 percent Thursday.
The storm was expected to be stronger in San Diego County than in the Los Angeles area, forecasters in the Oxnard forecast office said. Light to moderate showers will start over mountains Wednesday afternoon, spreading to the flatlands along the coast by Wednesday night.
Snow levels will start between 4,000 and 4,500 feet above sea level, and then drop to as low as 3,500 in some places, the forecast said. That may be low enough to affect Interstate 5 over the Grapevine, Route 14 near Acton, Interstate 15 in Cajon Pass and Interstate 8 east of Alpine.
Here is the 7-day forecast for Monrovia, per the NWS:
- Today: Sunny, with a high near 69. Calm wind becoming south southwest around 5 mph in the morning.
- Tonight: Mostly clear, with a low around 45. Calm wind becoming east southeast around 5 mph.
- Wednesday: A 30 percent chance of rain after 10am. Increasing clouds, with a high near 61. South southeast wind 5 to 15 mph.
- Wednesday Night Rain: Low around 45. South wind 5 to 10 mph becoming light southwest in the evening. Winds could gust as high as 15 mph. Chance of precipitation is 90%.
- Thursday: Showers and possibly a thunderstorm, mainly before 4pm, then a slight chance of showers and thunderstorms after 4pm. High near 55. Southwest wind around 5 mph. Chance of precipitation is 90%.
- Thursday Night: A 20 percent chance of showers before 10pm. Mostly cloudy, with a low around 41.
- Friday: Mostly sunny, with a high near 59.
- Friday Night: A slight chance of showers. Mostly cloudy, with a low around 42.
- Saturday: A slight chance of rain. Mostly sunny, with a high near 62.
- Saturday Night: A chance of rain. Mostly cloudy, with a low around 42.
- Sunday: A chance of rain. Mostly cloudy, with a high near 64.
- Sunday Night: A slight chance of showers. Mostly cloudy, with a low around 45.
- Monday: Mostly sunny, with a high near 67.