Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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647 FXUS66 KLOX 040411 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 911 PM PDT Wed Jul 3 2024 .SYNOPSIS...03/127 PM. A significant heatwave will affect the region this week and will continue through much of next week, with dangerously hot temperatures across much of the area. High temperatures will reach 95 to 105 degrees in many areas away from the coast, with highs upwards of 105 to 115 over interior valleys and foothills, including the Antelope Valley. Very warm to hot conditions could extend closer to the coast by late this week. Patchy night to morning dense fog will affect the coasts through at least Thursday morning. && .SHORT TERM (WED-SAT)...03/203 PM. Temperatures are heating up today with many interior areas already over 100 degrees and several over 105. No significant changes to the pattern and forecast except just some fine tuning of the high temperatures. Synoptically, high pressure continues to slowly move towards the West Coast. The strong subsidence aloft and warming air mass is squashing the marine layer well under 1000 feet, meaning there will be lots of dense fog across coastal areas during the night and morning hours, at least through Thursday. After Thursday there are increasing signals that the coastal marine inversion will be too shallow to support a stratus layer, especially south of Pt Conception. Temperatures will rise another 3-6 degrees tomorrow and a few more degrees still on Friday, bringing warmer coastal valleys close to 110 and inland coastal areas in the 80s to low 90s. Deserts and other far interior areas will be approaching or even locally exceeding 115. This is the start of what likely will be an unprecedented stretch of high temperatures over 110 degrees there. The record for consecutive days at or above 110 is three for Palmdale and Lancaster and five for Paso Robles. The desert streak will almost certainly be crushed with the current forecast showing highs well over 110 for the next seven days. Paso Robles will be a little more difficult as there is a chance of some cooling sea breezes to get in there later in the weekend. Some daily individual records are likely as well, though a heat wave during this period in 2018 pushed records over 110 in the valleys and over 100 for Downtown LA for coastal and valley areas. Santa Barbara has a special situation there later this week with some northerly flow developing over the Santa Ynez Ranging pushing very hot air down towards the coast with highs in the high 80s and 90s possible. It will be quite warm on the Central Coast as well with highs in the 80s and 90s through Saturday. .LONG TERM (SUN-WED)...03/214 PM. Unfortunately, for many areas the extreme heat will continue well into next week. Most of the ensemble solutions maintain a strong high over the area at least through the middle of next week. However, models are also indicating an increase in onshore flow starting Sunday. While this should bring a few degrees of cooling to coast and coastal valleys, with strong high pressure aloft it`s unlikely this cooling will reach the interior. However, increasing winds with the onshore push will reach the deserts, increasing fire danger there with the continued extreme heat and hot and dry air mass. The Excessive heat warning for the interior areas (mountains, deserts, interior SLO/SB County) has been extended to Wednesday and may need additional day beyond that. Coastal and valley areas will be "cooler" but still 6-12 degrees above normal. && .AVIATION...04/0022Z. At 00Z at KLAX, the marine layer was 800 feet deep. The top of the inversion was at 3600 feet with a temperature of 31 Celsius. High confidence in CAVU TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF. Moderate confidence in remainder of TAFs. For coastal locations, expecting IFR-VLIFR cigs/vsbys due to fog and low clouds returning tonight. Cig/vsby restrictions dissipating from late to early afternoon Thursday. Timing of flight category changes may vary by +/- 2-3 hours of current forecasts, and there is up to a 30% chance for minimum flight categories to be off by at least one category. KLAX...Moderate confidence in TAF. VLIFR conditions due to fog, with a 30% chance cigs/vsbys will be 1-2 hours off in arrival and clearing times. No significant easterly wind component is expected. KBUR...High confidence in TAF. && .MARINE...03/910 PM. For the Outer Waters, Small Craft Advisory (SCA) conditions are not expected through Thursday morning. Areas of SCA winds are forecast to develop over PZZ673 and PZZ676 Thursday afternoon, with SCA winds continuing into Saturday morning for PZZ676, and continuing into Saturday night for PZZ673. There is a 60% chance for SCA winds to occur across PZZ670 from Friday afternoon through Sunday morning. There is also a 10-15% chance of local Gale Force wind gusts for Friday afternoon and evening during the periods of SCA winds across the Outer Waters. For the Inner Waters north of Point Sal, SCA conditions are generally unlikely through early next week, though there is a 30% chance for SCA winds for Friday afternoon and evening. For the Inner Waters south of Point Conception, SCA winds are anticipated from Thursday afternoon through Thursday night across a portion of the western Santa Barbara Channel. The area of anticipated SCA-level NW-N winds is from Santa Cruz Island to the Santa Barbara County coast from Point Conception to Gaviota to Refugio State Beach. Within this area, there is also 10-15% chance of local Gale Force wind gusts just offshore from the immediate coast Thursday afternoon through Thursday night. There is also a 70% chance for SCA-level winds to reoccur in the Western portions of the Santa Barbara Channel for Friday afternoon through Friday night. Dense fog is expected over the coastal waters for the remainder of this week during the overnight to morning hours, with a gradual decrease in the coverage of fog as the week progresses. Please reference the Marine Weather Statement for additional information. && .BEACHES...03/133 PM. A southerly swell front will overspread the Southern California coastal waters Thursday into Friday, followed by 15-17-second southerly swell persisting from late this week into the weekend. While surf is not expected to be particularly high, surf heights upwards of around 5 feet are anticipated at beaches exposed to southerly swell -- especially the LA and Ventura County beaches. Moreover, significant wave energy with the long-period swell will combine with the elevated surf to create dangerous conditions at area beaches, with powerful and dangerous rip currents expected. This is especially the case for the beaches of LA and Ventura Counties. A Beach Hazards Statement is in effect from Thursday mid-day through the weekend to address these concerns. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning now in effect until 6 PM PDT Wednesday for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX). Excessive Heat Warning remains in effect until 6 PM PDT Monday for zones 88-342-348-351-352-356>358-369>375-380. (See LAXNPWLOX). Heat Advisory remains in effect from 11 AM Thursday to 6 PM PDT Sunday for zones 341-347-355-368. (See LAXNPWLOX). Excessive Heat Warning remains in effect from 11 AM Thursday to 6 PM PDT Saturday for zones 349-350. (See LAXNPWLOX). Beach Hazards Statement in effect from Thursday morning through Sunday evening for zones 354-362-366. (See LAXCFWLOX). Heat Advisory remains in effect until 6 PM PDT Sunday for zone 548. (See LAXNPWLOX). Fire Weather Watch in effect from Friday morning through late Friday night for zones 342>345. (See LAXRFWLOX). Red Flag Warning in effect from 6 PM Thursday to 6 AM PDT Saturday for zones 349-351>353-376>378-381. (See LAXRFWLOX). PZ...Small Craft Advisory in effect from 2 PM Thursday to 2 AM PDT Friday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 2 PM Thursday to 5 AM PDT Sunday for zone 673. (See LAXMWWLOX). Small Craft Advisory in effect from 2 PM Thursday to 8 AM PDT Saturday for zone 676. (See LAXMWWLOX). && $$ PUBLIC...MW AVIATION...Lewis/Phillips/Cohen MARINE...Smith/Lewis/Cohen BEACHES...Cohen SYNOPSIS...Cohen/Smith/MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox