Low-Pressure System to Keep Valley Cool

Unseasonably cool weather is being deflected into Southern California because of a low-pressure system from Alaska, and is expected to continue through the week, said Kevin Stenson, meteorologist at WeatherData Inc., which provides forecast information to The Times.

“This creates a trough of low pressure, which follows like a slide, allowing cold air from Alaska to drain down the coast,” he said.

Morning lows will range from the mid-30s to low 40s today in the Valley, giving way to fair skies and afternoon highs in the low to mid-60s, Stenson said.

Morning lows are expected to be 38 degrees in Woodland Hills, 40 in Burbank, 41 in Van Nuys and 42 in Chatsworth today. Afternoon highs are expected to be 64 in Chatsworth, 62 in Burbank and 61 in Woodland Hills and Van Nuys.

A storm system is expected to bring rain Tuesday, with morning lows in the mid-40s to low 50s. Tuesday afternoon’s highs are expected to be in the upper 50s to mid-60s.

Isolated thundershowers are expected Wednesday, with highs in the mid-50s to low 60s. Wednesday morning’s lows are forecast to be in the mid-40s to low 50s.

There is also a chance of rain Thursday morning, giving way to mostly sunny skies and highs in the upper 50s to mid-60s. Morning temperatures are expected to be slightly cooler Thursday, with lows in the low to mid-40s.

Increasing clouds and slightly lower afternoon temperatures are expected Friday, with highs in the mid- to upper 50s. Morning lows Friday are expected to be in the mid-40s to low 50s.