623 FXUS66 KLOX 101015 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 315 AM PDT Wed Oct 10 2018 .SYNOPSIS...09/905 PM. Cooler than normal conditions will continue through most of the week then warm a bit into the weekend. Overnight and morning low clouds and fog will be patchy early in the week then becomes wide spread across the region. High surf is likely Tuesday through Friday. && .SHORT TERM (TDY-FRI)...10/301 AM. Weak pva and onshore flow have lifted the marine layer up to 2300 ft. The capping inversion is pretty weak and as a result the low clouds have been slow to form. By dawn the low clouds should cover all of the coasts and vlys and should extend onto the coastal slopes. SW sfc flow across the Central Coast has advected low clouds into the SLO interior vly as well as (somewhat oddly) the Cuyama Vly. A little trof will move into the area after dawn and will produce enough lift to wring out some drizzle esp near the foothills. Onshore flow and cyclonic flow aloft will keep the coasts mostly cloudy all day. The vlys should see better clearing but there is a chc it will be cloudy all day as well. Below normal hgts and above normal cloud cover will conspire to keep max temps 8 to 12 degrees blo normal. The cyclonic flow will increase Thursday as a trof bulges westward from the great basin. Thursday will likely be very similar to today with a very deep marine layer, clouds extending into the mtns, patchy morning drizzle and limited afternoon clearing for the csts and vlys. Max temps will be similar to today as well. Wednesday looks like a day where most areas will struggle to clear and temperatures will likely be problematic. The forecast for temperatures remains unchanged for now, but it is possible that temperatures are about 3-5 degrees too warm if there are more clouds than sun. A few mountain showers cannot be ruled out Wednesday afternoon and evening, especially along the coastal slopes. Mdls now are in pretty good agreement for Friday. All mdls agree that the upper trof will pinch off a cut off low just of the Central Coast early Friday morning. At the same time a SFC high will move into the great basin setting up a weak to moderate offshore event. Right now this offshore event does not look too strong and will likely come in under advisory levels. The offshore push will limit the marine layer clouds to the LA south coast. Max temps will jump about ten degrees across most of the coast and vlys (the SBA south coast and the coast north of SLO-town will not feel much of the effects) Max temps will be near normal for most areas. .LONG TERM (SAT-TUE)...10/315 AM. The EC and the GFS now agree a little better for the xtnd forecast which leads to better confidence that the forecast will work out. Saturday looks like an interesting day esp for most of LA county. The upper low that was off of the Central Coast is now forecast to swing to the SE and set up SW of LA. This is a very favorable position for Rain from San Diego to LA county as the low will scoop up low level moisture and move it on the land with both PVA and some diffluence aloft. So expect for the northern mtns and the Antelope Vly LA county will have mostly cloudy skies and a slight chc of rain. The effects of the upper low will fall off dramatically away from LA county with VTA county only seeing partly cloudy skies and SLO and SBA counties seeing sunshine and slightly above normal temps. LA county on the other hand will have blo normal temps. A little disagreement on Sunday as the GFS is quick to move the upper low to the east while the EC keeps it to the west of San Diego. The EC soln is wet but its is the odd mdl out and have leaned the forecast to the dry and warmer GFS soln. Looks like the first decent offshore event of the season will arrive Monday which is pretty late date. Mdls struggling with the exact amount of offshore flow but it looks like there will be advisory level gusts at least. Skies will be clear and there will be a good warm up to the lee of the mtns. Grad reverse on Tuesday and its likely that a weak marine layer stratus deck will develop. Max temps will cool (esp along the coast) due to the switch from offshore to onshore flow. && .AVIATION...10/1005Z. At 1000Z, the marine inversion at KLAX was based at 2500 feet. The top of the inversion was 3300 feet with a temperature of 15 degrees Celsius. Overall, moderate confidence in 12Z TAF package. All coastal and valley sites will have MVFR CIGs this morning. These CIGs should dissipate by afternoon across the valleys, but will linger at coastal sites into the afternoon. There is a 30% chance that coastal sites will scatter out 20Z-03Z. KLAX...moderate confidence in 12Z TAF. Timing of change from MVFR to VFR CIGs could be +/- 2 hours of current 19Z forecast. There is a 30% chance of SCT conditions 20Z-03Z. KBUR...moderate confidence in 12Z TAF. There is a 30% chance that skies will remain BKN this afternoon with either MVFR or VFR heights. Timing of return of MVFR CIGs tonight could be +/- 2 hours of current 07Z forecast. && .MARINE...10/302 AM. For the Outer Waters, high confidence in current forecast. Winds and seas are expected to remain below Small Craft Advisory (SCA) levels through Sunday. For the Inner Waters, high confidence in current forecast. Winds and seas are expected to remain below SCA levels through Sunday. Large, moderate-period south to southwest swell will affect much of the waters beginning tonight. The swell is expected to build through early Friday, then diminish Friday night into Saturday. && .BEACHES...10/302 AM. Hazardous surf conditions including dangerous rip currents will continue through much of this week. Surf and swell will build through at least Thursday night. The increased surf and dangerous rip conditions will be from Tropical Storm Sergio. Estimates of surf heights between 5 to 8 feet with sets to 10 feet during the peak of the event Thursday night and Friday. The highest surf will be observed at south and southwest facing beaches. Surf should begin to subside late Friday, but there is a chance that dangerous and strong rip currents could linger into Saturday. In addition, there will be the potential for some minor to moderate coastal flooding during peak of the high surf combined with high tides. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect through Friday afternoon for zones 34-35-40-41-87. (See LAXCFWLOX). PZ...NONE. && .HAZARD POTENTIAL OUTLOOK (FRI-TUE). High surf and dangerous rip current are likely across south and southwest facing beaches through Friday as additional swell energy from Sergio moves into the coastal waters. Minor/moderate coastal flooding will also be possible during times of high tide along low lying areas due to the combination of high surf and fairly high tide levels. Locally gusty offshore winds are possible Friday with low humidities and elevated fire danger. && $$ PUBLIC...Hall/jld AVIATION...RAT MARINE...RAT BEACHES...RAT SYNOPSIS...Kj weather.gov/losangeles