Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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531 FXUS66 KLOX 010433 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 933 PM PDT Tue Apr 30 2024 .SYNOPSIS...30/731 PM. Mostly clear skies and warmer temperatures will continue through this week, with some night through morning coastal low clouds and fog at times. Locally breezy winds will affect the mountains and deserts through Wednesday, then turn NE over interior Ventura and Los Angeles Counties Wednesday night into Thursday. Cooling is expected Friday through the weekend with a slight chance of rain. && .SHORT TERM (TUE-FRI)...30/823 PM. ***UPDATE*** A slightly higher marine layer coverage is expected for coastal and some valley areas tonight into Wednesday morning, compared to previous nights. But that said, cloud cover will be fairly limited north of Ventura County, with portions of Santa Barbara seeing low clouds, including the eastern South Coast and near Santa Maria. Further south, better coverage is expected for the Ventura and L.A. coast and coastal valleys. A Catalina Eddy along with good onshore gradients will help to move the layer inland over these areas. Meanwhile, north winds are just below Advisory levels along the western Santa Barbara South Coast, with gusts up to 40 mph. Expect there will be some isolated gusts up to 45 mph through 10 PM before winds begin to subside there. However, in the western Antelope Valley and foothills and the I-5 Corridor, winds will increase this evening, with gusts of 45 to 50 mph expected by 11 PM. Have issued a Wind Advisory for these areas, in effect through 9 AM Wednesday. Otherwise expect a mostly clear day Wednesday after the morning low clouds scatter out. Temperatures will be similar to, or slightly cooler than, today`s highs. ***From Previous Discussion*** The biggest adjustment to the forecast today was to cut back on the offshore winds for Thursday as models (particularly the NAM) have really reversed course on that. Onshore flow will be lighter but any northeast winds should be confined to the interior and be well below advisory levels. High temperatures will only go up a few degrees at most for Thursday, mainly mid 80s for the valleys and low to mid 70s for coastal zones. Then turning cooler again Friday as a trough approaches from the northwest and gradients shift back to onshore again marine layer coverage expands. .LONG TERM (SAT-TUE)...30/221 PM. Still a lot of uncertainty this weekend with the approaching upper low. The deterministic models are still split with the GFS favoring an inside slider low dropping through interior California while the EC keep the low mainly north of Lake Tahoe. The grand ensemble mean solution is much closer to the farther north EC solution and not surprisingly NBM pops are extremely low. This may ultimately prove to be an accurate assessment of the rain chances at this point there are still enough solutions with at least some light rain or drizzle to have some mention of precip in the forecast by later Saturday into Sunday. For what it`s worth all the higher precip solutions from the earlier GEFS solutions were gone on the 12z run and only 30-40% of the remaining solutions had even light rain, perhaps indicating models are starting to move towards a drier scenario for the weekend. In any case, rain chances are mostly confined to late Saturday and early Sunday so the majority of the daytime periods are expected to be dry. The cooling trend that will have begun Friday will continue through the weekend with highs 4-8 degrees below normal, coolest on Sunday. There will be slightly warming Monday but most models maintain cooler than normal temperatures well into next week. && .AVIATION...30/1851Z. At 1122Z at KLAX, the marine layer was 1800 ft deep with an inversion top at 3500 ft and a maximum temperature of 16 C. Moderate confidence in LA County coast and valley TAFs. Low confidence on KSBA, KOXR, and KCMA, with a 20% chance of no cigs developing, and a 20% chance cigs a category lower than forecasted. High confidence in all other TAFs. Timing of cig arrival/clearing may be off by +/- 2 hours, with a 20% chance of cig developing once category lower than forecast at times. KLAX...Moderate confidence in TAF. Timing of cig arrival/clearing may be off by +/- 2 hours, with a 20% chance of a couple hours of cigs lowering to BKN008. There is a 20% chance of an east wind component reaching 6-8 kts from 08Z-16Z Wed. KBUR...Moderate confidence in TAF. Timing of cig arrival/clearing may be off by +/- 2 hours, with a 20% chance of a couple hours of cigs lowering to BKN008. && .MARINE...30/932 PM. For the outer waters, current Gale Warnings are on track with gusty NW gales expected to continue until late tonight. Swell will continue to be steep and choppy. After gales subside, Small Craft Advisory (SCA) conds are expected for the outer waters, Wednesday through Sunday. However, there is a 30% chance of winds to increase to gale force Wednesday night and a 40-50% chance Thursday afternoon and evening. For the inner waters N of Pt. Sal, SCA level winds are likely through tonight. Then, there is a 60% chance of SCA winds during the afternoon and evening hours Wednesday through Friday. Seas are expected to be above SCA level through Wednesday. For the Santa Barbara Channel, SCA level W-NW winds are expected across the western portion through late night hours tonight and again Wednesday afternoon/evening. Then, there is a 20-30% chance of SCA winds each afternoon/evening Thursday and Friday across the extreme western portion. Winds will likely remain below SCA levels for eastern portions of the channel through Friday night. Saturday afternoon through Sunday, there is a 30-40% chance of widespread W to NW SCA level winds across the entire inner waters. For the southern inner waters, there is a 20% chance of SCA level W to NW winds near Anacapa Island Wednesday evening. Otherwise, good confidence in conds remaining below SCA levels through Friday night. Saturday afternoon through Sunday, there is a 30-40% chance of widespread W to NW SCA level winds across the entire inner waters. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...High Surf Advisory in effect until 2 PM PDT Wednesday for zones 340-346-354. (See LAXCFWLOX). Wind Advisory in effect until 9 AM PDT Wednesday for zones 378-381-383. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zone 650. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...MW/Smith AVIATION...Schoenfeld MARINE...Phillips/Schoenfeld SYNOPSIS...Smith weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox