000 
fxus66 klox 201741 
afdlox 


Area forecast discussion 
National Weather Service Los Angeles/Oxnard California 
941 am PST sun Jan 20 2019 


Synopsis...20/939 am. 


There is a chance of showers along the central coast late this 
afternoon and evening and snow in the Ventura and Los Angeles 
County mountains through Monday evening. Otherwise conditions will 
be dry across the region this week. Winds will be breezy this 
evening then gusty Santa Ana winds will develop Tuesday morning. 
Temperatures will be cool today and Monday then there will be a 
warming trend this week. 


&& 


Short term (tdy-tue)...20/305 am. 


There will be increasing high level clouds today. Weak offshore 
flow will turn onshore during the afternoon. This will result in 
a cooling trend today, especially over slo/sba counties where the 
clouds will be thickest in advance of the weak cold front. 


Tonight an upper low will move across northern California and into the 
Great Basin, a weak cold front associated with this low will 
likely bring rain showers to slo and sba counties this evening and 
into Monday morning. The shower threat will move into the northern 
mountain slopes of Ventura and Los Angeles counties early Monday. 
Shower activity across the North Slope will continue through 
Monday evening. Additionally, this system's cyclonic flow 
will produce a chance of light showers across the foothills of 
the San Gabriel valley tonight and into Monday morning. This 
system is pretty dry, so any shower activity will be light, 
generally under 0.10 inches, except up to 0.20 inches on north 
facing mountain slopes. Snow levels will drop rapidly late tonight 
and Monday, bottoming out between 3500 and 4000 feet on Monday. 
1 to 2 inch snow accumulations are possible on the north facing 
slopes, with a dusting to 1 inch accumulation possible for 
Interstate 5 near the Grapevine. The combination of the snow 
showers with strong winds and cold temperatures could make travel 
difficult on Interstate 5 near the Grapevine late tonight into 
Monday. Anyone planning travel in this area should check the 
latest weather and Road conditions. 


Strong northerly winds will be the most significant aspect of 
this system. Strong and gusty northwest to north winds will 
develop in the wake of todays system tonight. The strong winds 
will last through Monday evening. Good confidence in high end 
advisory level winds due to plenty of cold air advection and good 
upper level winds (850 mb winds between 35 and 50 knots, 700 mb 
winds between 40 and 60 knots). Many wind advisories are in effect 
for the mountains, valleys, Antelope Vly and the sba South Coast 
please see the product laxnpwlox for details on these strong winds. 
The northerly direction of the winds could allow for some strong 
winds across Ojai/Lake Casitas area. There will be isolated 
warning level gusts in the windiest locations. The strong winds 
will filter down into other lower elevation coastal/valley areas 
on Monday, and there is a chance of low end advisory-level north 
winds in the San Fernando Valley, Santa Monica Mountains, and la 
County coast. All of the cold air advection will take a toll on 
the Max temps Monday and the entire area will see below normal 
readings. 


Later Monday night and Tuesday strong and cold high pressure will 
build into the Great Basin and will set up a Santa Ana event. 
There is enough upper support to combine with the strong offshore 
sfc gradients to produce northeast advisory-level winds across 
Ventura and Los Angeles counties. With the northeast flow, 
temperatures will rebound a bit but will be tempered by the weak 
cold air advection. Still most Max temps will fall a couple of 
degrees shy of seasonal normals on Tuesday. 


Long term (wed-sat)...20/315 am. 


Both the ec and the GFS agree that a ridge will remain over the 
eastern Pacific Wed thru Fri with the ridge axis moving over the 
state on Saturday. At the surface, weak to moderate offshore 
gradients will continue as surface high pressure remains 
entrenched over the Great Basin. 


The combination of the upper level ridge and offshore surface 
gradients will keep skies mostly clear and rain-free through the 
period. There will be periods of northeasterly winds, but are 
generally expected to remain below advisory levels. There will be 
a warming trend through the period, especially west of the 
mountains. Thursday and Friday look like the warmest day across 
the coasts and vlys with Max temps forecast to be 5 to 10 degrees 
above normal. Wind-protected areas will see chilly below normal 
overnight lows due to the dry air and clear skies. 


&& 


Aviation...20/1145z. 


At 1140z at klax, there was no marine layer. 


Hi confidence in all tafs xcp for kprb. At kprb there is a 30 
percent chc of no LIFR conds. Also, 30% chance that cigs this 
evening could initiate at IFR at coast/valley taf sites. Moderate 
confidence with peak wind gusts at kpmd, kwjf between 06z-11z 


Klax...high confidence in taf. No east wind issues. 


Kbur...high confidence in taf. 


&& 


Marine...20/311 am. 


Across the outer waters, moderate to high confidence in the 
current forecast. Winds and seas are expected to remain below 
Small Craft Advisory (sca) levels through early afternoon this 
afternoon, then there is a 70% chance of Small Craft Advisory winds and seas late 
this afternoon through through Monday night, and possibly through 
Tuesday. There is also a 40% chance of gale force wind gusts 
across the outer waters tonight thru Monday evening, with the 
highest likelihood Monday evening. Conditions should then be below 
Small Craft Advisory levels Tuesday night through Thursday. 


For all the inner waters, there is a 60%-70% chance of Small Craft Advisory winds 
and seas at times late this afternoon or early evening through 
Monday evening. 50% chance that Small Craft Advisory wind gusts could continue for 
the inner waters from pt Piedras Blancas to Point Sal. Conditions 
should then be below Small Craft Advisory levels late Monday night through 
Thursday, except there will be a 60% chance that Santa Ana winds 
will be strong enough in pzz655 and 650 to justify extending the 
Small Craft Advisory for these zones south of Ventura to Malibu, and also across 
the San Pedro Channel to Avalon where short period wind waves 
could cause some hazardous issues in Avalon Harbor Tuesday. 


&& 


Beaches...20/311 am. 


A moderate westerly swell is expected to persist through today. 
Another larger west to northwest swell is expected to move into 
the coastal waters late tonight into early Monday. These swells 
will produce elevated surf and strong rip currents on west-facing 
beaches through Monday. Large astronomical high tides can also be 
expected each morning, peaking Monday. Due to the higher- than- 
normal tides and elevated surf, there could be minor coastal 
flooding near the times of the morning high tide each day. As a 
result of the elevated surf and potential for minor coastal 
flooding, a beach hazards statement is in effect for all west- 
facing beaches through Monday night. 


&& 


Lox watches/warnings/advisories... 
California...beach hazards statement in effect through Monday evening for 
zones 34-35. (See laxcfwlox). 
Beach hazards statement in effect through Monday afternoon 
for zones 39>41-87. (See laxcfwlox). 
Wind Advisory in effect from 10 PM this evening to 10 PM PST 
Monday for zones 39-52>54. (See laxnpwlox). 
Wind Advisory in effect from 4 am to 10 PM PST Monday for 
zones 44-88. (See laxnpwlox). 
Wind Advisory in effect from 10 PM this evening to 4 PM PST 
Monday for zone 59. (See laxnpwlox). 
Pz...Small Craft Advisory in effect from 3 PM this afternoon to 3 
am PST Tuesday for zones 645-670-673-676. (See laxmwwlox). 
Small Craft Advisory in effect from 3 PM this afternoon to 9 
PM PST Monday for zones 650-655. (See laxmwwlox). 


&& 


Hazard potential outlook (tue-sat). 


Advisory level north to northeast winds possible Tuesday. 


&& 


$$ 


Public...rorke 
aviation...Kaplan 



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