271 FXUS66 KLOX 091818 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1118 AM PDT Tue Oct 9 2018 .SYNOPSIS...09/804 AM. Cooler conditions will continue through Friday. A bit of a warm up going into the weekend. Night through morning low clouds will return to the coastal areas and will decrease towards the end of the week. High surf is expected Tuesday through Friday. && .SHORT TERM (TDY-THU)...09/908 AM. ***UPDATE*** There is still plenty of cloud cover along the beaches and coastal valleys this morning. Have let the dense fog advisory expire along the central coast but there are still many places with visibility less than a mile. The low clouds should clear by around 11 am with the exception of the Santa Barbara County south coast that will remain cloudy in to the early afternoon. Temperatures are similar to yesterday near the coasts and a few degrees warmer inland. Breezy conditions expected in Antelope valley this afternoon with southwest flow. ***From Previous Discussion*** South of Pt Conception the marine layer is over 4000 feet deep (Both ways of measuring the marine layer depth are down for maintenance at the moment) and low clouds have spread all the way to the coastal slopes. North of Pt Conception the marine layer is much shallower and dense fog has form there with cloud bases 1500 ft lower than those down south. A dense fog advisory is in effect through 900 am for the Central Coast. The inversion is likely not too strong and there should be good clearing this afternoon save for a few beaches. Better onshore flow will cool the Central Coast some but otherwise temps will be similar to Monday. Another trof will whip through the Great Basin early Wednesday. It will further deepen the marine layer. The deepening of the marine layer and the orographic lift should bring some drizzle to the vlys, foothills and coastal slopes. The lower hgts and deep marine layer will knock 3 to 6 degrees of the max temps across the entire forecast area. Clearing will be slower and there is a chance that the skies will only clear to partly cloudy. The trof will elongate along its SW to NE oriented axis on Thursday. There will be another round of extensive low cloud coverage. There will be some patchy drizzle near the coastal slopes and foothills. There are some offshore trends which will help clearing but the deep marine layer could well cook up into an afternoon strata cu deck and keep skies partly cloudy. The slightly better clearing will allow the cst and the vlys to have a degree or two of warming. Temps across the interior will remain the same or even cool a degree as hgts fall with the elongating trof. .LONG TERM (FRI-MON)...09/313 AM. Confidence falls off a cliff on Friday. Both mdls pinch off a weak cut off low from the base of the trof. This low is well removed from the main steering flow which is over the Rockies. This is one of those patterns that the mdls absolutely struggle with. The EC makes quick work of the upper low and sweeps it to the east by Saturday morning. The GFS migrates it to the west where it keeps it spinning through Tuesday. The GFS forecasts screaming offshore flow on Friday while the EC and NAM have weaker offshore flow. The GFS seems overdone and will favor the weaker solns. With this in mind there will be much less marine layer clouds and mostly confined to the LA coast. Max temps will jump everywhere, 3 to 6 degrees not the 5 to 10 degrees the GFS forecasts. The rest of the forecast follows a similar pattern with the EC forecasting warmer temps and less of a marine layer due to higher hgts will the GFS is the opposite due to the lower hgts and cyclonic turning from the upper low. Sunday should be cooler as both GFS and EC show some cooling (although for different reasons) Did not make much change to the fcst. The warming trend for early next week looks on track its just the degree of warming that is in question. && .AVIATION...09/1817Z. At 1709z at KLAX the marine layer depth was 2900 feet. The top of the inversion was at 3800 feet with a temperature of 14 degrees C. N of Point Conception...Good confidence with 18z TAFs. The KVBG sounding showed a marine layer depth of 1800 feet. Little change in the marine layer is expected into Wed. VFR conditions are expected this afternoon before ceilings move back in overnight. IFR ceilings overnight will give way to a brief period of MVFR Wed morning. S of Point Conception... Good confidence in the 18zs TAFs. VFR conditions this afternoon are expected before the clouds move back in tonight with MVFR ceilings. There will be a brief period of VFR ceilings Wednesday morning before the clouds clear late Wednesday morning. KLAX...Moderate confidence in 18z TAF. There is a 30 percent chance of the marine clouds arriving plus or minus two or more hours from the forecasted time. There is a 20 percent chance of east winds of 7 knots or more. KBUR...Moderate confidence in 18z TAF. There is a 30 percent chance of the marine clouds arriving plus or minus two or more hours from the forecasted time. && .MARINE...09/909 AM. Moderate to high confidence that winds will remain below SCA levels across the waters through at least Saturday. Large, moderate-period south to southwest swell will affect much of the waters beginning tonight and persist through Friday, and may persist into the weekend. && .BEACHES...09/915 AM. Hazardous surf conditions including dangerous rip currents will likely redevelop once again this morning or this afternoon, then build through at least Thursday night. The increased surf dangerous rip conditions will be from what is now left of Hurricane Sergio which is weakening and should be downgraded to a Tropical Storm tonight or tomorrow. Estimates of surf heights between 6 to 9 feet with sets to 11 feet during the peak of the event. 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 (THU-MON). 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...Rorke/jld AVIATION...Sweet MARINE...Sweet BEACHES...Sweet SYNOPSIS...Delerme weather.gov/losangeles