019 FXUS66 KLOX 111019 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 319 AM PDT Thu Oct 11 2018 .SYNOPSIS...10/804 PM. Below normal temperature will continue through Thursday. Offshore flow on Friday will bring a little warming into the weekend. Night through morning low clouds will return to the coasts until Friday. High surf likely through Friday. && .SHORT TERM (TDY-SAT)...11/256 AM. The marine layer depth has increased to 5200 feet. A weak inversion has formed on top of it and extends to 6200 ft. Clouds cover all most all of the 4 county forecast area with the odd exception of a large swathe of the coast and vly area of LA county. That clear area is probably the result of a little east flow aloft. There is not much moisture between the sfc and 4000 ft however so there is not much risk of drizzle of sprinkles. The very deep marine layer will not allow much in the way of afternoon clearing and skies will be at best partly cloudy. All of the clouds will keep max temps 4 to 8 degrees blo normal. There will be good offshore trends this evening leading to offshore flow early Friday morning. It will probably be enough to keep the marine layer stratus away and this is backed up by the latest NAM low level moisture forecast which only indicates enough moisture for low clouds to develop around the SBA west coast. There will be some northeast winds Friday morning but they will be below advisory levels. The offshore flow will kick off a nice warm up with most cst and vly areas seeing a jump of 10-20 degrees. Max temps will come in close to normal. The upper low that will pinch off from an elongated trof later this evening will hook around and swoop into the SoCal bite Saturday morning. The will be decent SW difluent flow over LA county and to a lesser extent VTA county in the morning. It will bring clouds to VTA/LA counties and portions of SBA county. There will also be a slight chc of rain through the day with the greatest chc up against the coastal slopes of the San Gabriels. There is some instability with this system as well but not enough currently forecast to add TSTMs. Rainfall amounts if any will be on the light side. Max temps will cool dramatically over the coasts and vlys of LA county and to a lesser extent VTA county. Offshore flow wrapping around the upper low across Western SBA county and SLO counties will keep max temps above normal in those areas. .LONG TERM (SUN-WED)...11/316 AM. Sunday will be a transition day from the cloudy (well at least for VTA and LA counties) onshore flow day Saturday to the offshore days coming up early next week. The upper low will push off to the east and NNE upper level will set up over the state. Skies will clear out and max temps will warm across the coasts and vlys but will not change much inland. On Monday the first good sized Santa Ana event will arrive. A trof will move through the great basin and shift the upper flow to the NE. At the same time a strong and cold sfc high will settle between NV and UT. Offshore grads will increase to 5 to 6 MB. This much of a sfc push in conjunction with the upper support will bring advisory level NE canyon winds to the LA and VTA counties. There will be no clouds and max temps will jump and humidities will plunge. Fire Wx concerns will be heightened as well. Both the GFS and EC show little change in the pattern for Tuesday so look for a so over day. It will probably be the warmest day as over night lows will be elevated given the daytime highs a running start. The offshore flow weakens some Wednesday but there are still easterly winds aloft and its possible that there will be advisory level gusts in the morning. There will be an early seabreeze which will cool things across the coasts and to a lesser degree the vly. Inland areas should see little change. Three days of offshore flow will be large concern for the fire weather people. && .AVIATION...11/0936Z. At 0930Z, the marine inversion at KLAX was based at 5200 feet. The top of the inversion was 6100 feet with a temperature of 10 degrees Celsius. Overall, moderate to high confidence in 12Z TAFs. For coastal and valley sites, moderate confidence in TAFs as BKN-OVC conditions between 035 and 050 will continue into early afternoon with a 20% chance of MVFR CIGs 12Z-18Z. High confidence in desert TAFs. KLAX...moderate confidence in 12Z TAF. There is a 30% chance of MVFR CIGs 12Z-18Z. KBUR...moderate confidence in 12Z TAF. There is a 30% chance of MVFR CIGs 12Z-18Z. && .MARINE...11/236 AM. For the Outer Waters, high confidence in current forecast. Winds and seas are expected to remain below Small Craft Advisory (SCA) levels through Monday. For the Inner Waters, high confidence in current forecast. Winds and seas are expected to remain below SCA levels through Monday. Large, moderate-period south to southwest swell from Tropical Cyclone Sergio will affect much of the waters beginning today. The swell is expected to build through early Friday, then diminish Friday night into Saturday. && .BEACHES...11/236 AM. Hazardous surf conditions including dangerous rip currents will continue through much of this week as south to southwest swell from Tropical Cyclone Sergio moves through the waters. Surf and swell will build through Friday midday, with high surf expected starting late this evening. Surf heights are expected to be between 5 to 8 feet with sets to 10 feet during the peak of the event tonight and Friday, with the highest surf along south to southwest facing beaches. Surf should begin to subside Friday night, but there is a chance that dangerous and strong rip currents could linger into Saturday. In addition, there will be the potential for minor to moderate coastal flooding, especially Friday morning when the peak surf coincides with high tides. A High Surf Advisory will be in effect from this evening through late Friday evening. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect through Friday evening for zones 34-35. (See LAXCFWLOX). Beach Hazards Statement in effect from 7 AM PDT this morning through this evening for zones 40-41-87. (See LAXCFWLOX). High Surf Advisory in effect from 8 PM this evening to 11 PM PDT Friday for zones 40-41-87. (See LAXCFWLOX). PZ...NONE. && .HAZARD POTENTIAL OUTLOOK (SAT-WED). Dangerous rip currents are possible Saturday across south and southwest facing beaches as additional swell energy from Sergio moves into the coastal waters. Gusty Santa Ana winds are expected Sunday through Tuesday with critical fire weather conditions possible. && $$ PUBLIC...Rorke AVIATION...RAT MARINE...RAT BEACHES...RAT SYNOPSIS...Delerme weather.gov/losangeles