900 FXUS66 KLOX 291442 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 642 AM PST Sat Dec 29 2018 .SYNOPSIS...28/805 PM. Fair skies, below normal temperatures and gusty offshore winds will impact mountains and valley areas through early next. Some overnight low could reach freezing temperatures over some coastal valleys and Antelope Valley through Saturday morning. Warmer temperatures are possible by mid week as offshore flow weakens. && .SHORT TERM (TDY-MON)...28/819 PM. ***UPDATE*** An upper low over Arizona will remain nearly stationary tonight, then slowly shift south over Mexico through Sunday. An upper high over the East Pacific will change little through Saturday, but will weaken Saturday night into Sunday as a trough moves over the Pacific Northwest. The system will eventually turn into an inside slider and bypass Southwest California on Monday. Meanwhile, the surface pattern supports the development of gusty Santa Ana winds overnight, as high pressure builds over the Great Basin. By 12Z Saturday, the high will peak near 1038 mb over northern Nevada, with the LAX to DAGGETT gradient forecast to be around -4 mb at that time. Winds now are in a relative lull, with NNE gusts around 40 mph in the mountains. The models show winds increasing after 10 PM, and more so around midnight as the gradient strengthens. At this time, a moderate Santa Ana event is likely, with mountain gusts between 50 to 55 mph, and 35 to 45 mph gusts for the valleys. A Wind Advisory is in effect for the L.A. Mountains, Santa Clarita and San Fernando Valleys, and the Ventura Valleys. This will likely be extended to the coast of both counties, including the coastal strip from Point Mugu to the Hollywood Hills, with gusts up to 35 mph. Also on tap will be cold temperatures in wind sheltered valleys overnight into early Saturday. Freeze Warnings have been issued for the Central Coast and the Ojai Valley, with a hard Freeze Warning in the Antelope Valley, with lows potentially dropping into the upper teens. Frost Advisories are in effect for the wind sheltered areas of the L.A. and Ventura Valleys, and the SBA South Coast. ***From Previous Discussion*** Really very little change in the forecast through Monday. High pressure anchored over the eastern Pacific will continue to shunt storms well to the north and east but in doing so will maintain a moderate north to northeast flow aloft and at the surface. The high pressure will expand a little farther east and help temperatures warm up a few degrees but still stay slightly below normal through early next week, especially inland. Offshore flow weakens Saturday night and Sunday and any winds should be well below advisory levels. Little change to temperatures expected. Another inside slider Sunday night into Monday will provide another burst of northerly flow to southern SB County and the I5 corridor area, possibly leading to another round of wind advisories there. Temps about the same or slightly warmer. .LONG TERM (TUE-FRI)...29/300 AM. The Monday inside slider ends up over west/central AZ New Years morning. This will bring both northeasterly upper level and thermal support and will setup for moderate to strong Santa Ana wind event across LA/Ventura Counties. Both the GFS and EC operational runs support this, though the EC is a little weaker with the gradients. So confidence is pretty high at this point that there will be another moderate Santa Ana event on New Years Day. Temperatures will still be on the cool side due to the cold advection from the upper low. The upper low is expected to move east Wednesday which will significantly reduce upper support though there will still be enough lingering offshore gradient to generate locally gusty northeast winds. A warming trend will begin Wednesday as a east pack ridge moves into the area from the west. Hgts rise to near 580 DM and highs will warm into the low to mid 70s by Thu/Fri. && .AVIATION...29/1440Z. At 12Z at KLAX, there was no marine layer. High confidence in CAVU conditions through the forecast period. Gusty north to northeast winds will affect much of the area, strongest over the mountains and through mountain passes. LAX...High confidence in CAVU 12Z TAF. There is a 10 percent chance of east winds up to 10 knots through 18Z. KBUR....High confidence in CAVU 12Z TAF. Gusty N to NE winds are possible, especially between 16Z and 21Z. Moderate turbc sfc-140 through 21Z. && .MARINE...29/638 AM. Across the northern two outer waters zones, moderate to high confidence that conds will remain below SCA levels thru tonight, then SCA conds are likely Sun thru Mon night. Across the southern outer zone (PZZ676) SCA level NE winds are expected today. Winds will drop below SCA levels this afternoon. SCA level NW winds are expected Sun afternoon through Mon, and SCA level NE winds are expected Tue. Across the inner Waters N of Point Conception...SCA conditions are not expected through Sunday afternoon, then there is a 40% chance of SCA winds Sunday night. From Monday through Wednesday, mostly light winds are expected. Inner Waters S of Point Conception...Moderate to high confidence in SCA level NE winds thru this afternoon, with the strongest winds over zone PZZ655, and in zone PZZ650 south of Ventura. Choppy short period seas between 3 and 6 feet are expected. Gusty winds and rough seas will likely affect east and northeast facing harbors such as Avalon Harbor. SCA level NE winds are expected again late Mon night and Tue. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Freeze Warning in effect until 8 AM PST this morning for zones 34-35-44. (See LAXNPWLOX). Frost Advisory in effect until 8 AM PST this morning for zones 39-45-547. (See LAXNPWLOX). Wind Advisory in effect until 3 PM PST this afternoon for zones 44>46-54-88-547. (See LAXNPWLOX). Hard Freeze Warning in effect until 8 AM PST this morning for zone 59. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 PM PST this afternoon for zones 650-655-676. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK (MON-FRI). There is the potential for strong and gusty Santa Ana winds New Years Eve and New Years Day, mainly for Los Angeles and Ventura Counties. && $$ PUBLIC...MW/Smith AVIATION...Rorke/DB MARINE...DB SYNOPSIS...Delerme weather.gov/losangeles