598 FXUS66 KLOX 121234 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 434 AM PST Tue Nov 12 2019 .SYNOPSIS...12/228 AM. It will be sunny today except for morning low clouds along the coasts and locally into the valleys. It will be cloudy and cooler during the mid week period. Skies will be clear with warmer temperatures for Friday and the weekend. && .SHORT TERM (TDY-THU)...12/329 AM. The marine layer is about 1200 ft deep over LA county and about half that amount across the Central Coast. Gradients are near neutral and this along with the lack of an eddy has greatly slowed the inland progress of the low clouds. The marine layer is shallow enough across the Central Coast to create plenty of dense fog. A dense fog advisory is in effect for the Central Coast through 900 am. The forecast offshore wind event really is not panning out due to the weaker than forecast gradients. There will be local 15 to 25 mph winds this morning but thats about it. The inversion is pretty steep above the marine layer and this will hinder clearing this morning. Some Central Coast beaches may remain cloudy all day. 585 DM hgts courtesy of a east Pac ridge nosing in from the west along with a weaker than normal sea breeze will allow for max temps to bump up a few degrees esp inland. The marine layer, however, may cool some of the beaches. A slightly unusual pattern sets up for Wed and Thu as trof moving in from the NW tips the ridge over to the east allowing SW flow to establish itself over the state. The SW flow will tap into a grip of mid and high level subtropical moisture and skies will likely be mostly cloudy through the period. There may be some night through morning low clouds as well but the abundance of high level moisture will likely inhibit their formation. There will be 3 to 6 degree of cooling each day and Thursday will be the coolest day for the coast and vlys of the next 7 with max temps 2 to 5 degrees blo normal. .LONG TERM (FRI-MON)...12/328 AM. A weak trough will ripple through southwest California on Friday. This will cut off the mid and high level clouds and skies will clear...except for a coastal marine layer stratus deck that will likely form with weak lift from the trof and the onshore trends. The increased sunshine will balance out the lower hgts across the coasts and vlys and temps will not change much except a little offshore push from KBFL may bring a few degrees of warming to the Central Coast. The cooler air advected in by the trof will bring another 3 to 6 degrees of cooling to the interior which will have its coolest day of the week. Another ridge builds in Friday night and offshore flow will develop. There should be enough of an offshore push to eliminate the marine layer but not enough to bring much in the way of canyon winds. Most areas will see about 6 degrees of warming due to higher hgts and the offshore push. Better offshore flow on Sunday and also a little upper support for a Santa Ana. EC as has been the case all fall is stronger and if it verifies there will likely be some advisory level gusts in the morning in the usual places across LA/VTA counties. Along with the winds will come warming and drying with the usual fire weather concerns. There will be another 3 to 6 degrees of warming and almost all of the coasts and vlys will see highs in the 80s. Both the EC and the GFS weaken both the ridge and the offshore flow on Monday. Still enough offshore flow to keep the low clouds away. But there will be several degrees of cooling across the entire area. EC and many of its ensemble members and to a lesser degree the GFS and a few of its ensemble members show some rain developing on Thursday the 21st. Not a guarantee but something to watch. && .AVIATION...12/1233Z. At 1047Z at KLAX, the marine layer was around 900 feet deep. The top of the inversion was at 2800 feet with a temperature of 23 C. Low confidence in all coastal TAFs through 18Z due to uncertainty in timing in flight category changes. Good confidence 18Z-04Z then low confidence in timing of cig arrival and flight categories tonight. There is a 30% chance of no clearing this afternoon, especially along the Central Coast. There is a 20% chance of low clouds tonight for KBUR and KVNY. KLAX...Low to moderate confidence in TAF. Cigs may fluctuate between IFR and MVFR through 16Z. There is a 30% chance of 6SM HZ SCT010 conds at 17Z. Low confidence in timing of low clouds tonight. Good confidence that any east wind component will be 5 kt or less. KBUR...Good confidence in TAF. There is a 20% chance of low clouds tonight after 06Z. && .MARINE...12/219 AM. For all of the coastal waters, high confidence that winds and seas will remain below Small Craft Advisory (SCA) level through Thursday. Moderate confidence that SCA level winds may impact the offshore waters along the Central Coast and southward towards San Nicolas Island on Friday and Saturday. Patchy dense fog with visibility of one nautical mile may impact all of the coastal waters this morning. A large and long period NW swell is likely to impact the coastal waters Friday into the weekend, but low confidence on timing and strength. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Dense Fog Advisory in effect until 9 AM PST this morning for zones 34-35. (See LAXNPWLOX). PZ...NONE. && .HAZARD POTENTIAL OUTLOOK (THU-MON). There is the potential for moderate Santa Ana winds next Sunday with elevated to critical fire weather conditions possible. && $$ PUBLIC...Rorke AVIATION...Stewart MARINE...Stewart SYNOPSIS...30 weather.gov/losangeles