370 FXUS66 KLOX 041124 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 324 AM PST Tue Dec 4 2018 .SYNOPSIS...04/323 AM. Rain and mountain snow will move into most of the region by this evening and will continue through Thursday and possibly early Friday. Temperatures will be cool through the end of the week then warm into the weekend. && .SHORT TERM (TDY-THU)...04/322 AM. The main story over the next few days will be a complex storm system moving into the region beginning this morning across NW SLO County then spreading into SBA County late this afternoon then into Ventura and L.A. Counties this evening or tonight. This will be a tricky forecast as there is plenty of moisture sitting off the coast tonight into Wednesday. However a persistent easterly wind will cause rainfall totals to be lower than what we would see normally with a storm of this size. Moderate offshore winds gusting between 20 and 35 mph in some areas will generate a downsloping effect which will not be favorable for significant rainfall. In fact, the higher resolution models are able to resolve the wind and it's affects on the rainfall totals, which are much less than the GFS and ECMWF through Thursday night. The earlier Day shift did cut back on rainfall totals, and will continue to follow their lead. Rainfall totals along the coast should be lighter due to downsloping while mountains and valleys should see higher amounts. This is strange as the highest precip totals will end up occurring across the coastal waters. looking at the latest GEFS plumes from LAX continues to show quite a huge spread of rainfall amounts from a quarter inch to over 1.5" in the San Gabriel Mtns. Therefore will continue to buy into the higher resolution NAM model with this event. The other factor with this system is the best convective parameters will remain off the coast as the upper low pivots around Pt Conception to the west then onshore over northern Baja. With the best convective parameters expected to remain to our south, expect a showery situation versus a steady rain. 500 mb temps will be -22 degrees C overhead, so I would say it's not out the question that an isolated strong cell could develop Thursday afternoon just about anywhere over L.A. or Ventura Counties, but because of the easterly winds, hourly rainfall rates overall should remain at or below a half inch. At this point we are not expecting hourly rainfall rates to reach debris flow thresholds. However, if driving on canyon roads that were affected by the Woolsey and Hill burn areas, such as Kanan Rd and Malibu Cyn, be vigilant in looking for falling rocks and boulders, as it will not take a lot of rain to cause this to occur. Snow levels will start out around 5000-6000' late today into early Wednesday then rise during the event to 6500-7000'. Should see some accumulating snow at resort levels on the order of 3-6". .LONG TERM (FRI-MON)...03/157 PM. By Friday the upper low is expected to be moving into northern Baja with ridging setting up for the weekend. Light offshore flow will continue and temps expected to be warming up close to normal by Sunday. The next system for early next week has trended weaker on both the GFS and ECMWF but still lots of time for this to change. && .AVIATION...04/0557Z. At 03Z, the marine layer depth was around 500 feet deep at KLAX. The top of the inversion was near 1100 feet with a temperature near 15 degrees. VFR conditions are expected through at least 20Z. There is a chance of moderate wind shear and turbulence after 12Z as a frontal boundary approaches the area. There is an increasing chance of MVFR conditions after 20Z at terminals north of Point Conception. KLAX...VFR conditions are expected throughout the period. There is a 50 percent chance for easterly winds greater than 7 knots after 08Z Tuesday. KBUR...VFR conditions are expected throughout the period. No wind impacts are expected at this time. && .MARINE...03/958 PM. Southerly winds will increase through Tuesday night. Small Craft Advisories were added for the northern waters, near Point Conception, and the Santa Barbara Channel from Tuesday morning and continue through at least Wednesday or Wednesday night. Small Craft Advisories are likely to be expanded for the southern inner and outer waters for Tuesday night through Wednesday night. There is a 60-70 percent chance of gales across the northern outer waters, near Point Conception, and near the Channel Islands between Tuesday afternoon/evening through Wednesday. There is a lesser chance (30-50 percent) for the Santa Barbara Channel, the nearshore waters north of Point Conception, the southern outer waters. Short-period hazardous seas may also develop between Tuesday night and Wednesday night. Marine weather conditions will likely improve on Thursday through Friday. && .BEACHES...03/641 PM. Minor coastal flooding and tidal overflows are possible between Wednesday night and Thursday as a frontal system moves into the region. Astronomical high tides above 6 feet are forecast during the morning hours. The tides, in combination with the southerly wind driven swell, could bring minor overflows into parking lots and walkways, along with minor beach erosion. A Beach Hazards Statement might need to be issued as this event gets closer. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory in effect until noon PST today for zones 44-45-53-54-88. (See LAXNPWLOX). PZ...Small Craft Advisory in effect from 9 AM this morning to 3 PM PST Wednesday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 9 AM this morning to 9 PM PST Wednesday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 3 AM to 9 PM PST Wednesday for zone 655. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PST this afternoon for zone 670. (See LAXMWWLOX). Gale Warning in effect from 3 PM this afternoon to 3 PM PST Wednesday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect from 9 AM this morning to 9 PM PST this evening for zone 673. (See LAXMWWLOX). Gale Warning in effect from 9 PM this evening to 3 PM PST Wednesday for zone 673. (See LAXMWWLOX). Small Craft Advisory in effect from 9 PM this evening to 9 PM PST Wednesday for zone 676. (See LAXMWWLOX). && .HAZARD POTENTIAL OUTLOOK (THU-MON). Periods of rain are expected through Thursday. There is a potential for limited burn scar impacts such as rockslides but no major debris flow are expected. Snow is also possible in the mountains. && $$ PUBLIC...Kaplan/MW AVIATION...Hall MARINE...Hall BEACHES...Hall SYNOPSIS...Kaplan weather.gov/losangeles