Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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231 FXUS66 KLOX 022126 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 226 PM PDT Tue Jul 2 2024 .SYNOPSIS...02/126 PM. A significant heatwave will impact the region this week through early next week, with dangerously hot temperatures across much of the area. High temperatures by mid to late week are expected to 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 be possible near the coast tonight as well as Wednesday and Thursday mornings. && .SHORT TERM (TDY-FRI)...02/213 PM. High pressure across the eastern Pacific continues to slowly creep toward the West Coast. While onshore flow and night and morning marine layer stratus is still keeping coast and valley areas on the milder side, inland areas have started to heat up. Interior areas are showing temperatures trends up 5-10 degrees today and expecting that trends to continue through the week. Coastal valleys will start noticing the warmup Wednesday as the high starts to compress the marine layer and confine it to the coastal areas at most. And by Thursday and Friday the warming trend will include the coastal areas as well as onshore flow weakens in response to increasing subsidence from the near 600dam high that by then will be centered over northern California, but encompassing the entire western third of the US. Highs across our far interior areas like the Antelope Valley,interior SLO County, and the lower mountain elevations will see highs between 108-116, 15-20 degrees above normal. Warmer coastal valleys expected to reach as high as 107-109. Expecting many high temperature records this weekend, though possibly more on Friday as Saturday`s records are quite a bit warmer due to a heat wave in 2018 that saw Woodland Hills reach 116 and Downtown LA reach 108. The biggest adjustments to the forecast today include the addition of Excessive heat warnings for the south coast of Santa Barbara County and a Fire weather watch for portions of the interior (addressed in the fire weather section). Models continue to advertise an impressive amount of heat along with low grade Sundowners Thu-Sat across southern Santa Barbara County, though mostly Friday and Saturday. The NAM is showing temperatures as high as 40c (104F) at 950mb in the Santa Ynez Range Friday night. For the time being gradients thankfully are not excessive, but enough to bring some wind over and down the coastal slopes of the SY Range. Given these conditions chances are increasing that much of southern SB County will see temperatures in the 90s Fri and Sat, and possibly some lower 100s in the foothills. For this reason an Excessive heat warning has been issued for that area. Other coastal areas will be warming up as well later this week with the possibility of lower 90s away from the immediate coast. No other major changes to the forecast in the short term. Marine layer stratus will decrease in depth and areal coverage through the period. The lowering depth will result in increasing visibility restrictions due to dense fog. .LONG TERM (SAT-TUE)...02/223 PM. Latest ensemble based guidance suggesting this heat wave may continue, at least in some areas well into next week. The ensemble mean 500mb height is still around 597dam as late as next Thursday, though the high does start to shift a little to the east. In addition, models have been indicating increasing onshore flow next week, which would also increase the risk for larger fires. There is certainly a chance that at least for inland areas the current suite of heat warnings will need to be extended beyond Monday. Coastal areas should start to cool off with the onshore flow increase and the possibility of a weak eddy circulation developing over the coastal waters that would also bring a return of marine layer stratus, at least to coastal areas south of Pt Conception. && .AVIATION...02/2034Z. At 20Z at KLAX, the marine layer was 1100 feet deep. The top of the inversion was at 3500 feet with a temperature of 25 Celsius. High confidence in CAVU TAFs for KPRB, KPMD, and KWJF. Moderate confidence in remainder of TAFs, with IFR-LIFR cigs and MVFR-IFR vsbys expected to return tonight and continue into Wednesday morning in low clouds and fog near the coast. Cig/vsby restrictions will dissipate around mid-day Wednesday, with onset and dissipation timing of cig/vsby restrictions varying by +/- 3 hours of current forecasts. KLAX...Moderate confidence in TAF. No significant easterly wind component is expected. KBUR...Moderate confidence in TAF. && .MARINE...02/134 PM. For the Outer Waters, Small Craft Advisory (SCA) conditions are not expected through Thursday. For Friday and Saturday, there is a 40% chance of SCA winds. For the Inner Waters north of Point Sal, SCA conditions are generally unlikely through the upcoming weekend, though there is a 20% chance for SCA winds for Friday into Saturday. For the Inner Waters south of Point Conception, SCA conditions are not expected through the upcoming weekend. Dense fog is expected over the coastal waters for the remainder of this week, with a gradual decrease in the coverage of fog as the week progresses. Please reference the Marine Weather Statement for additional information. && .BEACHES...02/134 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 has been issued from Thursday mid-day through the weekend to address these concerns. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning remains in effect until 6 PM PDT Monday for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX). Excessive Heat Warning remains in effect from 11 AM Wednesday to 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 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 from 11 AM Wednesday to 6 PM PDT Sunday for zone 548. (See LAXNPWLOX). Fire Weather Watch in effect from Thursday evening through late Friday night for zones 349>353-376>378-381. (See LAXRFWLOX). PZ...NONE. && $$ PUBLIC...MW AVIATION...Cohen MARINE...Cohen BEACHES...Cohen SYNOPSIS...Cohen/Smith/MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox