Today is forecast to be Much Cooler than yesterday.
Forecast for Los Angeles County San Gabriel Valley
Updated: 3:30 am PST on December 22, 2009
Wind Advisory in effect from 10 am this morning to 9 PM PST this evening...
Today
Mostly cloudy with a chance of light showers in the morning...becoming mostly sunny in the afternoon. Locally windy. Highs in the mid to upper 50s. West winds 10 to 20 mph...becoming northwest 20 to 30 mph with local gusts to 50 mph in the afternoon... strongest in the foothills. Chance of measurable rain 30 percent.
Mostly clear. Patchy frost late. Lows in the 30s. Northwest to north winds 20 to 30 mph with local gusts to 50 mph in the evening...becoming northeast 10 to 15 mph late. Strongest winds in the foothills.
... Wind Advisory now in effect until 9 PM PST this evening...
The Wind Advisory is now in effect until 9 PM PST this evening.
* Timing: winds will strengthen through the morning and peak in the afternoon.
* Winds: west to northwest winds 20 to 30 mph with gusts to 45 mph will be likely. Winds will be strongest in and near to the foothills.
* Impacts: the gusty winds will make travel difficult for high profile vehicles.
Precautionary/preparedness actions...
A Wind Advisory means that winds of 35 mph or greater are expected. Winds this strong can make driving difficult... especially for high profile vehicles. Use extra caution.
Special Weather Statement
Statement as of 4:57 PM PST on December 21, 2009
... Strong winds likely for the Southland Tuesday...
... Sub-freezing temperatures possible across portions of the Southland Tuesday night...
A cold and vigorous upper level low pressure system is expected to dig southward across interior California and Nevada overnight into Tuesday. Due to the expected inland track... this system will likely have limited moisture. A weak cold front is bringing scattered light showers to San Luis Obispo and northern Santa Barbara counties late this afternoon... with a slight chance of showers later this evening into early Tuesday morning for areas south of Point Conception. Any rainfall amounts with this system are expected to be fairly light... generally under a tenth of an inch... with the exception of local amounts up to one quarter inch across San Luis Obispo County.
Snow levels are expected to lower rapidly on Tuesday... generally falling to between 3500 and 4500 feet... with the exception of the north slopes which could see snow down to around 3000 feet. By Tuesday night... very cold air is expected to spread into the area... with snow levels potentially falling as low as 2000 feet. At this point... any threat of snow showers is expected to be confined to the north slopes near the Kern County line... but the expected cold temperatures could bring a threat of black ice to interior portions of the forecast area. A few inches of new snow will be possible across the north facing slopes... with accumulating snow possible along Interstate 5 near the Grapevine.
In addition to the threat of cold temperatures and low snow levels... this system will bring powerful winds across Southern California. In the wake of the front... strong and widespread northwest winds are expected across the region late Tuesday morning into the afternoon... with winds becoming more northerly by Tuesday evening. This system has strong upper level wind support... and could produce damaging wind gusts between 60 and 70 mph across the mountains... Antelope Valley... Santa Barbara South Coast... Santa Clarita valley... and San Fernando Valley. A high wind watch has already been posted for these areas. Many other portions of the Southland will likely require wind advisories... with wind gusts between 35 and 50 mph being common.
The influx of much colder air into the region Tuesday night will also bring the risk of sub-freezing temperatures to wind sheltered portions of southern and central California. Portions of the Antelope Valley... Cuyama Valley... and interior valleys of San Luis Obispo County are expected to have minimum temperatures fall into the lower to mid 20s... but these areas have already experienced two hard freezes this season. Other wind protected locations will likely have minimum temperatures fall into the upper 20s to lower 30s... with frost advisories possibly being issued.
Residents of Southern California are urged to stay tuned to the latest National Weather Service forecasts for this developing weather situation.