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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Sunday
• 
• High: 61 °
• Low: 45 °
• Partly Cloudy

• Monday
• 
• High: 54 °
• Low: 36 °
• Chance of Rain

• Tuesday
• 
• High: 56 °
• Low: 40 °
• Partly Cloudy

• Wednesday
• 
• High: 54 °
• Low: 40 °
• Chance of Rain

• Thursday
• 
• High: 61 °
• Low: 40 °
• Partly Cloudy

Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California 
345 PM PST sun Feb 12 2012 


Synopsis... 
weak high pressure will bring dry and cool conditions to the area today. 
Two more low pressure systems will affect the area through middle 
week...bringing another threat of showers mainly on Monday...and 
again Wednesday. It will be breezy at times along with cool 
temperatures. Drier and warmer conditions are expected for later in the 
week...with another chance of showers by Sunday. 


&& 


Short term (tonight-wed)... 
northwest flow aloft combining with onshore flow near the surface 
has brought another cool day across the Southland. Considerable low 
level moisture in place has generated some partly cloudy conditions. 
Next storm system currently centered over northern California will 
bring a weak cold front across our forecast area later tonight into 
Monday. Light rain will become likely across slo/sba counties late 
tonight...with a threat of showers spreading into Ventura and Los 
Angeles counties by Monday morning. The cold upper level low pressure 
system is expected to dive southeastward into interior California 
on Monday afternoon and evening. As this occurs...there will be increasing 
dynamics and cold air aloft that will continue to maintain a threat 
of showers...mainly across interior sections of the forecast area 
into Monday night. While lifted index parameters are not that 
impressive...there is enough cold air advection aloft (500 mb temperatures 
falling to -27 degrees) and dynamics to warrant a slight chance of 
thunderstorms across the la/Ventura County mountains and Antelope Valley 
for Monday afternoon and evening. In addition to the potential for brief 
heavy downpours...there could also be some reports of small hail with 
this system. 


While most areas are expected to receive less than a quarter inch of rainfall 
with this system due to limited moisture availability...there could be locally 
higher totals if convection develops. Main impacts with this weather system 
will be winds and potential low snow levels. Will be issuing Wind Advisory 
for portions of the forecast area...with the strongest winds expected 
across immediate coastal...mountain...and desert areas...with gusts in the 
40 to 50 miles per hour range. Initially...the winds will be focused in a more westerly 
direction...then shift to the northwest on Monday night...which will favor 
the Santa Ynez range and Interstate 5 corridor. While overall snow totals are 
only expected to range from 2 to 4 inches with this upcoming system...felt it 
was prudent to issue a Winter Weather Advisory for the la/Ventura County 
mountains due to the high likelihood of low snow levels and wind gusts to 
50 miles per hour...that will likely have an impact on Interstate 5 near the 
Grapevine. Initially...snow levels are expected to range from 5000 to 5500 
feet...but will lower to 3000 to 3500 feet later Monday night. The most 
significant snowfall accumulations are expected on north facing slopes. 


Conditions are expected to generally dry out on Tuesday...except a few lingering 
snow showers on north facing slopes. The 12z GFS and European model (ecmwf) solutions coming 
into better agreement on Wednesday forecast...with both models dropping another 
cold low pressure system right over Southern California. Based on this 
trend...bumped up probability of precipitation and lowered snow levels accordingly. Again...this 
system will likely have limited moisture...but could have some very cold air 
aloft and dynamics. With this in mind...could see locally heavy showers and 
can not rule out the possibility of thunderstorms if the cold pool aloft tracks 
right over the forecast area. 


Long term (thu-sun)... 
drying and warming trend is expected Thursday into Saturday. There is 
the potential for some gusty offshore winds Wednesday night through 
Friday. By Sunday...there is the potential for another cold low pressure 
system to drop down across Southern California...bringing yet another 
threat of showers and low snow levels. 


&& 


Aviation...12/2345z... 


Main story for the taf package will be approaching storm system. 
Showers with MVFR ceilings/visibilities will begin across the central coast 
after 08z...and spread into Ventura/la counties during the day on 
Monday. Behind the storm system...gusty west to northwest winds will 
develop on Monday...especially across the coasts as well as the 
mountains and deserts. There will likely be some low level wind shear/turbulence 
issues through the day. 


Klax...moderate confidence in 00z taf. There is a 40% chance that 
the MVFR ceilings could develop earlier than 13z. Timing of shower 
threat is low confidence. 


Kbur...moderate confidence in 00z taf. There is a 405 chance that 
the MVFR ceilings could develop earlier than 14z. Timing of shower 
threat is low confidence. 


&& 


Lox watches/warnings/advisories... 
Gale Warning (see laxmwwlox). 
Small Craft Advisory (see laxmwwlox). 
Wind Advisory (see laxnpwlox). 
Winter Weather Advisory (see laxwswlox). 
High surf advisory (see laxcfwlox). 
High rip current risk (see laxsrflox). 


&& 


$$ 


Public...gomberg 
aviation...rat 
synopsis...Smith 


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