FXUS66 KLOX 231724 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1024 AM PDT Wed Oct 23 2024 .SYNOPSIS...23/434 AM. An offshore flow pattern will keep a dry and warmer than normal weather pattern in place through today, then some cooling will develop through the weekend. Night through morning low clouds and fog will return to some coastal areas through Friday as onshore flow reestablishes. An area of low pressure aloft will likely bring much cooler temperatures and strong winds to portions of the area during the early to the middle part of next week. Light precipitation cannot be ruled out at this time for the northern areas. && .SHORT TERM (TDY-FRI)...23/821 AM. ***UPDATE*** The forecast is well on-track, and no changes have been made to the ongoing forecast. ***From Previous Discussion*** The latest water vapor imagery shows an upper-level ridge of high pressure over much the West this morning. The ridge, centered off the Baja California coast, will keep a warm and dry air mass will in place through at least Friday. Closer to the surface, an offshore flow will keep any low clouds and fog at bay and confined to just patches off the coast this morning. Otherwise, high cloudiness moving over the top of the ridge will start to increase over the coming days and stream out ahead of an upper-level trough near 35N and 146W. Marginally gusty Santa Lucia winds continue to occur across the San Luis Obispo County mountains and into the Santa Lucia mountain range. Santa Lucia winds are a bit stronger than last night and there is some concern that winds could push into advisory criteria closer to daybreak. Mt. Lowe has recorded wind gusts as high as 34 mph and Whale Rock Reservoir as high as 42 mph. The Santa Lucia winds will tighten the offshore pressure gradient along the Central Coast today and likely bring some warming today. Temperatures have been nudged higher closer to the EPS temperature means and warmed over tabular forecast guidance for today. A remnant offshore flow pattern will remain in place for tonight and into Thursday morning, but winds will be much weaker along the Santa Lucia range tonight and into Thursday morning. A southerly sea breeze surge should begin to establish today across the South Coast of California and bring cooling through Friday. If NAM-WRF solutions play out, an eddy circulation will develop over the southern California bight through tonight and into Thursday morning. A return of low clouds and fog should make their presence known the Southland coastal area tonight and into Thursday morning. The low clouds and fog should start to inch up the coast on Friday morning, possibly push into the Central Coast. .LONG TERM (SAT-TUE)...23/437 AM. Much better cooling should develop over the weekend as the upper- level trough well off the coast flattens the ridge and bring a return of southwest flow aloft. A weakening and dying frontal boundary will drop down the coast early next week and bring a significant cool down for Monday and Tuesday. EPS maximum temperatures means suggest a 20-30 degree drop in temperatures across the mountains, desert, and interior portions of the area as a much cooler air mass is transported southward with the frontal boundary. Light precipitation cannot be ruled with the dying boundary, but its effects may only occur along the northern slopes of the mountains. EPS solutions suggest the highest number of solutions with QPF for KSDB, with lesser solutions and GEFS and CMC ensemble members. The main impact will very likely be the winds with this system. A tightening northerly pressure gradient will bring gusty northerly winds to portion of the area between Monday and Wednesday, such as through the Interstate 5 Corridor, across southern Santa Barbara County, along the Central Coast, and into the Southland coastal areas. EPS wind gusts means continue to suggest widespread advisory levels winds at KSDB, KSBA, and KOXR during the period with a low-to-moderate chance of damaging wind gusts occurring at KSDB. A mix of solutions suggest a moderate to high chance of winds affecting terminals across the Southland and along the Central Coast. Confidence continues to grow for a windy pattern developing for early next week. && .AVIATION...23/1723Z. At 1644Z, the surface based inversion was near 1500 feet deep at KLAX with a temperature around 24 degrees Celsius. High Confidence in TAFs for KPRB, KPMD, and KWJF. Moderate confidence in KSMX, KSBP, KBUR, and KVNY TAFs. There is a 10-20% chance for VLIFR-IFR conds between 10Z and 16Z, with best chances in the LA valley. Low confidence in KSBA, KOXR, KCMA, KSMO, KLAX, and KLGB TAFs. For all sites, minimum flight cat may be off by one cat once cigs arrive. Arrival of cigs may be off by +/- 5 hours. KLAX...Low confidence in 18Z TAF. There is a 10% chance for VV001-002 cigs and/or vsbys of 1/2SM or less between 07Z and 17Z. There is also a 20% chance of cigs greater than OVC005 during this period. Arrival of cigs may be off +/- 4 hours. There is a 10% chance of an east wind component of greater than 7 kt from 07Z to 16Z. KBUR...Moderate confidence in 18Z TAF. There is a low chance (20%) for LIFR to IFR conds at some point between 10Z and 16Z. Low confidence in flight cat if cigs/low vsbys arrive. && .MARINE...23/923 AM. For the Outer Waters (10 NM off the Central Coast south to San Nicolas Island), moderate to high confidence in Small Craft Advisory (SCA) level winds continuing (60-80% chance) thru at least late tonight, with highest confidence in the northern two zones from the Channel Islands to Pt Piedras Blancas. There is a 40-60% chance that SCA level winds will continue into Friday evening from the Channel Islands to Pt Piedras Blancas. Then, SCA conds are not expected through Sat afternoon. SCA level winds are likely (70-80% chance) Sat night thru early next week. For the inner waters along the Central Coast, SCA level winds are likely (50-60%) thru this evening. SCA conds are not expected late tonight through Sun morning. Then, they are likely (70-80% chance) in the afternoon and evening hours Sun afternoon into early next week. For the Santa Barbara Channel, SCA conds not expected thru the Sat morning. There is a 40-50% chance of SCA level winds Sat afternoon into Sat night. SCA conds are likely (70-80% chance) Sun afternoon, lasting into early next week. For the inner waters off the Orange and Los Angeles County coasts, SCA conds are not expected thru the weekend. Local wind gusts to 20 kt are possible San Pedro channel this and evening, and during the afternoon and evening hours Sat and Sun. Then, moderate confidence in SCA level winds late Sun thru early next week. Patchy dense fog is possible during the night thru morning hours tonight through Fri. From late Sun thru early next week, moderate confidence in the development of GALES in the Outer Waters, inner waters along the Central Coast, and the Santa Barbara Channel with an upper level low sweeping into the area. Lower confidence in GALES in the southern inner waters. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Hall/Cohen AVIATION...Lewis MARINE...Lewis SYNOPSIS...Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox