573 FXUS66 KLOX 180053 AAA AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 453 PM PST Sun Nov 17 2019 Updated aviation section .SYNOPSIS...17/114 PM. Temperatures are well above normal today with moderate offshore winds in many areas. Monday will be cooler but still warm and dry then cloudy and cool weather develops on Tuesday. There is a chance of rain and mountain snow on Wednesday and Thursday then dry with near normal temperatures next weekend. && .SHORT TERM (TDY-WED)...17/217 PM. Synoptically, there is a ridge of higher pressure extending from the eastern Pacific into mid-California, a cut-off 569 DM low to our south, and the remnants of post-tropical cyclone Raymond further south providing a good deal of moisture. The ridge will retreat to the west allowing a trough to dig southwards by Tuesday evening. As the trough and cut-off merge and are fed by the extra moisture, the area will get its first storm of the winter season. Expecting rain, and snow at higher elevations, to last into Thursday when the low will exit to our east. For today - many stations in Los Angeles and Ventura Counties remain at or near Red Flag conditions. Still expecting the wind to end by about 3pm, but breezy conditions will remain into this evening and tomorrow, but below advisory strength. The offshore flow and higher thickness has already broken the record high in Camarillo and many areas will be near record by the end of the day as high temperatures climb into the lower to mid 90s across warmest locations. Overnight lows will be quite warm in the breezy areas. Monday will be similar to today with weaker Santa Ana winds. Inland temperatures will only cool a little while the coasts will cool more due to the onset of a sea breeze in the afternoon. By Monday night the upper level trough will begin moving in from the northwest. Lower heights, increasing cyclonic flow and the onshore flow at the surface will all combine to bring a return of marine layer stratus to many of the coasts and portions of the lower valleys on Tuesday morning. By Tuesday the offshore flow will have reversed to onshore and increased. Skies will turn mostly cloudy in the afternoon as mid- and high-level clouds move in from the north along with the trough. The clouds and onshore flow will drop temperatures 10-15 degrees, bringing them back down to normal values. EC and GFS ensembles agree that the trough produce an upper low that will cut off settle over SoCal. GEFS still moves the upper low more to the east while the the EC is more to the west and over the water. The EC solution starts earlier on Wednesday and produces more rain from its over water position. Still favoring this solution. As most of the rain dynamics are on the southern half of the upper low, Ventura and Los Angeles counties will see the more rain than Santa Barbara and San Luis Obispo Counties. There is a chance of light rain late Tuesday night and early Wednesday morning in the south, then showers will spread over the whole area later on Wednesday through Wednesday night. Shower activity will diminish Thursday and end Thursday evening as the upper low pulls out and moves to the east. There is a non-zero convective threat on Wednesday that will be closely monitored. The further west placement of the upper low would place it in a good position to bring in cold air aloft for destabilization, upper level diffluence to enhance updrafts and good PVA to the area. All of this could add up to heavier convective showers or thunderstorms. Still have not added thunder into the forecast due to the continuing positional uncertainty. Any strongly convective showers could produce rainfall intensities that may produce problems over and near to the new burn scar areas, especially the Tick and Saddleridge. Early rainfall amount estimates call for about a tenth in San Luis Obispo County, a tenth to a quarter of an inch for SBA county, a quarter to a half inch for VTA county and generally a half inch to an inch for LA county. The eastern San Gabriels will see the most rain with up to 1.5 inches expected. If the system takes the easterly track then expect half of the rain amounts and a later start. Snow will also be a concern as snow levels will drop to about 6,000 feet and there could be several inches or more of snowfall in the mountains. A winter storm advisory for the Los Angeles and Ventura County mountains is possible. .LONG TERM (THU-SUN)...17/217 PM. The upper-level low will move off to the east on Thursday night and higher pressure will return to the area on Friday, lasting through the weekend. Skies will clear to only partly cloudy and heights will rise, increasing the temperatures over the weekend back to seasonal levels. Offshore winds will make yet another return over the weekend but look to be below advisory strength. && .AVIATION...18/0050Z. At 22Z, there was no marine layer at KLAX. There was a surface based inversion with a top near 650 feet and a temperature around 30 degrees Celsius. High confidence in the current forecast. VFR conditions are expected through the period at terminals. There is a chance of moderate wind shear between 04Z and 14Z at Ventura County coastal terminals. KLAX...VFR conditions are expected through the period. Any east winds that could develop between 08Z and 18Z should remain less than 5 knots. KBUR...VFR conditions are expected through the period. There is a 10 percent chance of moderate winds shear between 10Z and 14Z. && .MARINE...17/1144 AM. For the Outer Waters, moderate to high confidence in current forecast through Monday for winds and seas remaining below Small Craft Advisory (SCA) levels. On Tuesday and Wednesday, good confidence in SCA level winds and seas with a 20% chance of Gale force gusts. On Thursday, moderate confidence in conditions dropping below SCA levels as winds and seas subside. For the Inner Waters north of Point Sal, high confidence in current forecast. Winds and seas will remain below SCA levels through Monday. On Tuesday and Wednesday, high confidence in winds and seas increasing to SCA levels. On Thursday, winds and seas are expected to drop below SCA levels. For the Inner Waters south of Point Conception, moderate confidence in current forecast. There is a 60% chance of SCA level northeast winds into this afternoon from Ventura southward to Malibu. Otherwise, winds and seas are expected to remain below SCA levels through Tuesday. On Wednesday, there is a 60% chance of SCA level westerly winds. && .FIRE WEATHER...17/311 PM. A Red Flag Warning remains in effect for Ventura County and for the mountains, and Santa Clarita and San Fernando Valleys of L.A. County through 6 PM this evening. Santa Ana winds will continue to gradually diminish in strength and areal coverage through the remainder of the afternoon hours, with Red Flag Warnings likely to expire at 6 pm this evening. From tonight through Monday morning, northeast winds are generally expected to gust between 15 and 30 mph. The offshore breezes will continue to reinforce the very warm and dry air mass across the region on Monday. There will be poor overnight humidity recoveries tonight across the mountains and foothills, followed by widespread humidity readings between 7 and 15 percent on Monday. As a result, elevated to brief critical fire weather conditions will continue tonight through Monday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Red Flag Warning in effect until 6 PM PST this evening for zones 240-244>246-253-254-288-547. (See LAXRFWLOX). PZ...NONE. && .HAZARD POTENTIAL OUTLOOK (WED-SUN). A cooler and showery weather pattern is expected Wednesday through Friday. Brief heavy downpours are possible, especially Wednesday to Thursday morning. High surf is likely at all beaches late Tuesday through early Thursday. && $$ PUBLIC...Rorke/jld AVIATION...Hall MARINE...Sweet FIRE...Gomberg SYNOPSIS...Kj weather.gov/losangeles