366 FXUS66 KLOX 171113 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 313 AM PST Fri Nov 17 2017 .SYNOPSIS... A weakening cold front will continue to bring isolated light showers to portions of southwest California through today. Cooler and drier conditions are expected behind the front, with the first freeze of the season possible for cooler interior areas this weekend. The push of cold air will support Weak Santa Ana winds Saturday. Warmer conditions are likely early next week. && .SHORT TERM...(TDY-SUN) Synoptically, a narrow but weak stationary front will begin to sag further south over Southern California and weaken further. Hit and miss isolated showers are expected through today. As the trough begins to move east, a ridge of high pressure will begin to strengthen over southern California from the south. Another upper disturbance will sweep through northern California by Monday as the ridge continues to amplify and strengthens over Southern California. Expecting a warming trend next week with any chance of showers remaining to the north of the forecast area Monday and Tuesday. Latest Satellite and radar returns were indicating a narrow band of mostly mid to high level sub-tropical moisture moving across SLO/SBA Counties this morning. This slow moving stationary front will continue to weaken as is it sags south into Ventura/LA Counties this morning. Rainfall totals have been minuscule due to the high based moisture reaching a few areas with hit and miss light showers. Expect isolated to locally scattered showers to continue across SLO/SBA Counties this morning, with only isolated showers for areas to the south including Ventura and L.A. through this afternoon. Rainfall should be limited to the LA/VTU Mountains near the Grapevine and across the Eastern San Gabriel Mtns by late this afternoon.However a few sprinkles can't be ruled out anywhere S of Point Conception this afternoon. Overall rainfall totals will remain very light. Mainly less then a tenth of an inch for most areas. Main impact will be oil surfacing across roads and highways making driving conditions hazardous due to the slick roads. Otherwise skies will remain partly to mostly cloudy through much of today through tonight. A modest cooling trend will occur today as the cooler air mass pushes in behind the exiting frontal boundary. Most inland areas will be 3-5 degrees cooler today. There will be some gusty winds developing across the Antelope Valley today but should remain below wind advisory levels. A relatively strong surface high will develop across the Great Basin behind the exiting front late tonight into early Saturday morning. This will cause the surface pressure gradient to tighten up and bring some gusty Santa Ana winds to the usual wind prone areas across Los Angeles and Ventura Counties Saturday morning. The LAX-DAG pressure gradient looks like it will go from +2 MB this morning to around -6 MB 24 hours later. MOS guidance is not bullish on Santa Ana winds, but with a -8 mb gradient 24 hour trend, I would expect advisory level gusts across the Santa Clarita, Ventura County Valleys and possibly the NW portion of the San Fernando Valley. Also the LA County Mtns including the Santa Monica Mtns for Saturday morning. One parameter not looking great is the 850 mb wind profile for upper level support of the Santa Ana winds. Will let the following shift look a little closer with newer model runs. There will be light offshore flow as well for the Central Coast off the San Lucia Mtns both Sat and Sunday. As far as temps on Saturday, expect widespread warming across the coast and valleys, with 4-6 degrees of cooling for the Antelope Valley, which is typical for offshore winds. High temps are expected to reach the upper 70s along the coast and valleys of LA/VTU Counties, while the Antelope Valley only reaches the mid 60s. For interior valleys of SLO/SBA Counties and the Antelope Valley the dry offshore push will usher in cold air that will drop overnight lows to below freezing in many areas. Sunday will likely be the coldest morning but even Saturday should see plenty of sub-freezing temperatures, especially in the Antelope Valley. A freeze watch has been issued valid for late tonight into Saturday morning for interior SLO and the Cuyama and Antelope Valleys. It's quite likely another one will be needed Sunday. Offshore flow weakens Sunday but still some breezes around. Daytime temps will warm inland but change little at the coast. .LONG TERM...(MON-THU) Both the GFS and ECMWF solutions are now keeping the next upper level disturbance to the north of SLO county Monday. Showers should remain north into Monterey County and as the upper ridge remains fairly amplified over the southern part of the state. Have updated the forecast to pull out POPs for SLO County Mon/Tue. The upper ridge will remain in place most of the weak. This will allow for for mostly clear skies with a modest warming trend beginning Tue, then more significant warming expected Tue through Thanksgiving. Should be a warm Thanksgiving Day across the region with highs reaching the upper 80s across warmest valleys and lower 80s along the coast of LA/VTU. Cooler across other areas, but still warmer than normal for most areas. The ridge and weak offshore flow will be a mainstay at least through Thanksgiving Day with highs possibly reaching 90 for the warmer valleys and interior coast. At that point the ECMWF again tries to break the ridge down and allow an upper low to come through on Friday. Not giving this one high odds at this point and rather prefer the drier/warmer GFS. && .AVIATION...17/06z. At 0430z at KLAX... there was a weak surface based inversion. The top of the inversion was around 600 feet with a temperature of about 22 degrees Celsius. Overall... Moderate confidence in the current TAFs. IFR/MVFR conditions with light rain will slowly spread from north to south overnight with CIGs at or below 6000 feet. Conditions will begin to improve after 14z north of Point Conception and after 18z to the south. Otherwise and elsewhere VFR conditions will prevail. KLAX... Moderate confidence in the current TAF. There is a seventy percent chance of IFR/MVFR conditions 15z-01z then again after 07z. There is a ten percent chance of east winds to ten knots 11z-15z otherwise east winds greater than seven knots are not expected. Otherwise VFR conditions will prevail. KBUR... Moderate confidence in the current TAF. There is a seventy percent chance of IFR/MVFR conditions 15z-01z. Otherwise VFR conditions will prevail. && .MARINE...17/230 AM. Northwest winds behind a weak cold front will bring Small Craft Advisory (SCA) level conditions to the northern and central outer waters today. There is a forty percent chance of the SCA level winds also affecting the southern outer waters and in the nearshore waters north of Point Sal during the same period. SCA winds may also affect the outer waters on Sunday and Monday. There will be local gusts to 25 kt across the Santa Barbara Channel this afternoon and evening. There is a forty percent chance of SCA winds across the inner waters from Ventura to Malibu and out to Anacapa Island on Saturday due to gusty offshore winds. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Freeze Watch in effect from late tonight through Saturday morning for zones 37-38-59. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 9 PM PST this evening for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect from 8 AM this morning to 9 PM PST this evening for zone 673. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK...(SUN-THU) Some interior valley locations may develop frost or freeze conditions this weekend. && $$ PUBLIC...Kaplan AVIATION...Kj MARINE...Kj SYNOPSIS...Munroe weather.gov/losangeles