054 FXUS66 KLOX 101855 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1155 AM PDT Wed Oct 10 2018 .SYNOPSIS...10/747 AM. Cooler than normal conditions will continue through Thursday. Offshore flow on Friday will bring a little warming into the weekend. Patchy overnight and morning low clouds and fog is expected along the coasts until Friday. High surf is likely today through Friday. && .SHORT TERM (TDY-FRI)...10/1006 AM. LAX profiler and pilot top reports indicate the marine layer depth across the LA Basin is now over 3000' and climbing as the trough and upper low continue to drop south along the west coast. Gradients also trending onshore so a cooling forecast certainly looks reasonable. The inversion is quite weak still though and there were a lot of holes in the cloud coverage so it's difficult to predict exactly what sort of clearing we'll see today, but either way temps will be several degrees below normal. Expecting similar conditions tomorrow with some drizzle possible though the difference being gradients will trending offshore as surface pressures increase over the interior and fall over the coastal waters with the approaching low. This may result in slightly better clearing but little change expected in our cool temps. ***From previous discussion*** 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...10/1854Z. At 1720Z, at KLAX, the marine layer depth was 3700 feet. The top of the inversion was 4800 feet with a temperature of 10 degrees Celsius. Rather low confidence in the marine cloud forecast at 18z this morning. A weak inversion is resulting in little temporal or height consistency regarding the ceilings across the coastal and valley locations this morning. There are no other issues for the aviation forecast. Skies may vary from sct-bkn in many areas until early this evening when the skies go back to bkn-ovc. The ceilings will range from MVFR to VFR. KLAX...Low confidence in 18Z TAF. There is a 30 percent chance of the marine clouds going broken plus or minus two or more hours from the forecasted time. KBUR...Low confidence in 18Z TAF. There is a 30 percent chance of the marine clouds going broken plus or minus two or more hours from the forecasted time. && .MARINE...10/902 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...10/903 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. A High Surf Advisory will be issued this afternoon. && .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...MW/Hall AVIATION...Sweet MARINE...Sweet BEACHES...Sweet SYNOPSIS...jld weather.gov/losangeles