532 FXUS66 KLOX 282032 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 132 PM PDT Tue May 28 2019 .SYNOPSIS...28/700 AM. Afternoon temperatures will be notably warmer this week with only a slight chance of afternoon and evening thunderstorms in the mountains. Overnight and morning coastal low clouds will persist through the week. && .SHORT TERM (TDY-FRI)...28/121 PM. An upper level trof currently extends southward through California. It will fill over the next few days, and then an area of closed circulation aloft will slowly work from central California through the CWA and then south of our area during the extended period. A weak impulse associated with the trof will move over the area this afternoon. Afternoon heating will help the clouds build over mountain areas this afternoon. Already seeing some cumulus over the San Gabriel mountains and north of the Ventura County mountains. Watching the LIs drop by the hour, so some rain is looking likely, with a slight chance of thunder. Expecting 3 to 5 degrees of warming today in the coast and valley locations with higher amounts at higher elevations. Max temps will stay below normal today, but this should be the last cool day for the next few days. The HRRR and our local WRF are indicating elevated winds along the western Santa Barbara south coast this evening from roughly 7 pm to 11 pm with sustained winds of 30 mph. Will keep to monitor the area for a possible low-end wind advisory. Increasing onshore flow will help develop marine layer stratus and bring it to the coasts and the lower valleys tonight and into Wednesday norming. The trof fills in a bit Wednesday and the dry and slightly cyclonic flow will persist of the area. Skies should clear by late morning. NAM and the ensembles agree there will be a chance of showers and slight chance of TSTMs over the higher mountains again. The atmosphere will continue to warm under the high sun, and afternoon high temperatures will rise another couple of degrees. Less warming along the immediate coast where the return of stratus will drop the starting point. The marine layer will repeat Wednesday night and it will likely arrive a little sooner since the onshore flow is stronger. A weak upper low moves out of Oregon on Thursday and slides southward down the state. By afternoon the stratus will have pulled off the coast, but the mountain areas will begin to cloud up as the upper low provides both lift and instability. Still looks like Thursday will be the best day for TSTM development, especially over the Ventura County mountains. Thursday will be the warmest day of the week. The upper low moves moves closer on Friday and it will be not too different than Thursday. Heights drop a few DM, so afternoon temperatures will cool back to Wednesday levels. Onshore flow should keep the marine layer stratus as a morning feature. Again a chance of afternoon showers and possibly thunder in mountainous areas. .LONG TERM (SAT-TUE)...28/128 PM. Very little day-to-day change in the extended forecast as the upper level low migrates over us and then to our south. Moderate onshore flow will keep the night through morning low clouds going through the period. Expecting little change in high temperatures until next Tuesday when heights have climbed to 584 DM. While there will be some afternoon cumulus over the mountains each day, there will likely be insufficient moisture and instability to create a risk of thunderstorms. && .AVIATION...28/1823Z. At 17Z at KLAX there was no inversion, just a weak isothermal layer based at 1500 feet. Low clouds were widespread across SLO County and all of SBA County except for the south coast. Conds were mostly IFR to LIFR, except VLIFR in the foothills and mtns. Elsewhere, skies were clear, although a patch of stratus near the VTU County coast could bring IFR cigs to coastal sections of VTU County for a few hours this morning. Expect most widespread low clouds in coastal and valley areas tonight, with generally IFR conds, except likely low MVFR conds across coastal sections of L.A. County. KLAX...Moderate confidence in TAF. There is a 20-30% chance that cigs will arrive as early as 05-06Z tonight or as late as 12Z. There is a 20 percent chance of east winds to 7 kt or more. KBUR...Moderate confidence in TAF. There is a 30% chance that conds will remain VFR thru the period. && .MARINE...28/917 AM. For the outer waters, high confidence in forecast. NW winds will remain at Small Craft Advisory (SCA) levels much of the time thru Wed night. There is a 30% chance of SCA level winds Thu thru Fri. For the inner waters north of Pt. Sal, moderate confidence in forecast. Winds are expected to reach SCA levels this afternoon and evening, then SCA conds are not expected thru Sat. However, there is a 20% chance of SCA level winds during the afternoon and evening hours Wed, and a 30-40% chance during the afternoon and evening hours Thu. For the inner waters south of Pt. Conception, moderate to high confidence in forecast. Winds are expected to reach SCA levels this afternoon and evening across western portions of the SBA Channel. Otherwise, SCA conds are not expected thru Sat. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 670-673-676. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK (FRI-TUE). Showers and thunderstorms are possible each afternoon and evening in the mountains through at least Friday. There is a small chance for heavy rainfall and isolated flash flooding accordingly. && $$ PUBLIC...jld AVIATION...Sweet/DB MARINE...Sweet/DB SYNOPSIS...Kj weather.gov/losangeles