Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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011 FXUS66 KLOX 021954 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 1254 PM PDT Thu May 2 2024 .SYNOPSIS...02/937 AM. Dry weather will continue through Saturday as the region remains between high pressure aloft to the west and an exiting trough to the east. Warming will continue to take shape across the northern and interior portions of the area today, while a persistent marine layer will moderate the warming across the South Coast of California. An unseasonably cold storm system will brush the area to the north this weekend and bring cooler temperatures, gusty winds, and a chance for light precipitation later Saturday into Sunday. A warming and drying trend will develop next week. && .SHORT TERM (TDY-SUN)...02/950 AM. ***UPDATE*** Onshore flow to the east has weakened today, but not to the extent models had been showing. As a result, a strong eddy circulation developed over the southern coastal waters and is supporting a 1500-2000` marine layer between Santa Barbara and LA. Meanwhile, across the interior and along the Central Coast, northeast winds have developed with local gusts earlier this morning to around 40 mph. For areas in the marine layer today will feel a lot like yesterday with highs in the 60s to low 70s at the coast and mid 70s to lower 80s for the valleys. Warm temperatures expected along parts of the Central Coast today with the offshore flow there. ***From Previous Discussion*** With the ridge aloft and offshore flow weakening later today, the marine layer cloud field should become a bit more entrenched tonight and into Friday morning. Ridging aloft should tighten the marine inversion some and possibly inhibit clearing on Friday at the beaches. A return of low clouds and fog should occur along the Central Coast, but there is a moderate chance that the low cloud forecast could be a little too expansive along the Central Coast for late tonight and into Friday morning. By Friday night, cyclonic flow will start to develop and a deepening marine layer should be expected as onshore flow strengthens. Marine layer induced low clouds and fog should be fairly aggressive on Friday night and Saturday as low clouds and fog will likely push into the coastal slopes of the mountains. Much cooler temperatures will start to spread into areas north of Point Conception on Saturday as an unseasonably cold upper-level trough digs into northern California. A cold frontal boundary will drop south into the region late Saturday and bring an increase in chances for precipitation on Saturday night. .LONG TERM (MON-THU)...02/455 AM. The frontal boundary will continue to move south and east over the area into Sunday while weakening some. The highest chance for precipitation will be for areas north of Point Conception, along the northern slopes of the mountains, and into the San Gabriel Valley between Saturday night and Sunday. EPS, GEFS, and CMC ensemble members buy into this idea emphasizing these areas being wetter. Southern Santa Barbara County, Ventura County, and western Los Angeles County could end up being in a rain shadow effect as downsloping occurs from the Transverse Ranges. PoPs break away from NBM values between Saturday night and into Sunday, and go higher than the previous forecast for the wetter areas. Likely PoPs may be needed by future shifts if the pattern continues for areas north of Point Conception, along the northern slopes of the mountains, and into the San Gabriel Valley. Almost all solutions of the EPS suggest rain for terminals north of Point Conception, KSDB, KEMT, and KPOC. Temperatures will be quite cool for Sunday across the area. Record cold high temperatures could be tied in some areas as a cold pattern for May sets up. Temperatures go colder than NBM values for Sunday. Gusty winds could end being the main story with this system. EPS members produce a broad period of gusty winds between Sunday and Monday morning. Gusty west to northwest will likely develop on Sunday across most areas, and a wide swath of wind advisories might be needed for Sunday afternoon and evening. Gusty northwest to north are likely to linger through the Interstate 5 Corridor and into southern Santa Barbara County for Sunday night and into Monday morning. A warming and drying trend should develop for the work week next week as forecast ensemble advertised a consistent warming trend in the temperature means. && .AVIATION...02/1953Z. At 1844Z at KLAX, the marine layer was 2600 ft deep with an inversion top at 5000 ft and a temperature of 16 C. High confidence in desert TAFs and KPRB, moderate confidence elsewhere. Timing of flight cat changes could be off by +/- 2 hours. There is a 20% chance of IFR-MVFR cigs at KSBP after 10Z and a 30% chance of VFR conds through the period at KSMX. For sites south of Point Conception, cigs could arrive as IFR upon arrival, then lift to MVFR. KLAX...Moderate confidence in TAF. Timing of flight cat changes could be off by +/- 2 hours. Cigs could arrive as low as BKN008 and will lift through the period. There is a 20% chance of an east wind component of 7-8 kt 09Z-15Z Fri. KBUR...Moderate confidence in the 12Z TAF. Timing of flight cat changes could be off by +/- 2 hours, with a 30% chance of cigs will arrive as early as 07Z tonight. && .MARINE...02/917 AM. In the outer waters, an extended period of gusty winds are expected with periods of Gale Force possible through much of next week. Small Craft Advisory (SCA) level winds are expected to increase to Gales (70-80% chance) this afternoon, then continue thru late tonight. Winds will likely drop to SCA levels late tonight thru Fri afternoon, then Gales are likely for the waters north of Point Conception (60-70% chance) late Fri afternoon thru late Fri night. Winds will drop Sat morning, possibly even below SCA levels, but seas will remain at SCA levels. SCA level winds are expected Sat afternoon thru Mon, with a 40% chance of Gales Sun afternoon/evening. In the inner waters N of Pt. Sal, SCA level winds and seas will develop this morning, then continue thru late tonight. SCA level winds are likely during the afternoon/eve hours Fri, Sun, and Mon (60-70% chance), with a 40-50% chance Sat afternoon/eve. In the SBA Channel, SCA level winds are likely in western portions of the channel during the late afternoon thru late night hours today and Fri (50% chance), and in most of the SBA Channel during the late afternoon thru late night hours Sat thru Mon. There is a 20% chance of gales Sun afternoon/eve. In the southern inner waters, there is a 20% chance of SCA level winds in NW portions (from Anacapa Island to Malibu) during the late afternoon/eve hours today and Fri. SCA level winds are likely during the late afternoon thru late evening hours Sat thru Sun, especially in western portions, then there is a 40% chance Mon. There is a 20% chance of gales Sun afternoon/evening. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zones 645-650. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...MW/Hall AVIATION...Lund MARINE...DB/Lund SYNOPSIS...MW/Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox