Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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822 FXUS66 KLOX 151753 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1053 AM PDT Thu Aug 15 2024 .SYNOPSIS...14/800 PM. Daytime highs will be near normal for most areas through the weekend, followed by a warm up early next week. Patchy overnight into morning low clouds and fog will impact coastal areas at times. Gusty winds are likely across Southwest Santa Barbara County and the Antelope Valley during the evening into overnight hours through Thursday night. && .SHORT TERM (TDY-SAT)...15/951 AM. ***UPDATE*** Last night advisory level Sundowner winds occurred across the Santa Barbara Southwest Coast and Western Santa Ynez Mountains, as well as locally gust winds across the eastern portion of the mountains. While the general trend across high resolution models shows a slight decrease in winds tonight, there remains a 50-70% chance of northwest winds tonight gusting at 35 to 50 mph. A Wind Advisory has been issued from 4 PM this afternoon through 3 AM tomorrow morning for the Santa Barbara Southwest Coast and adjacent mountains. Marine layer cloud coverage this morning was confined to west- facing Santa Barbara County, and currently clouds are dissipating quickly. Weak onshore pressure gradients, increasing 500 mb heights, and clear skies, set the stage for a few degrees of warming today across the region. ***From Previous Discussion*** Three days of uneventful weather on tap for Srn CA. At the upper levels a very warm upper high will slide over the CA/Mexico border and into New Mexico today and Friday. On Saturday a cool (at least for mid August) will approach the CA/OR border and this will push hgts down. At the sfc there will be weak to moderate onshore flow to the east and weak occasionally offshore flow in the N/S direction. Today and Friday will be very similar days. The lack of an eddy or any other source of low level lift will really suppress marine layer cloud formation and skies will be mostly clear over the next 48 hours. The only exception will be the western portion of SBA county where there will be some morning low clouds. The SW tip of LA county has a chc of some low clouds as well. Almost all areas will see 3 to 5 degrees of warming today with the only the LA/VTA county coasts excluded. Most of the vlys will be a few degrees above normal today while the coasts and the interior will be a few degrees blo normal. One notable exception will be the SBA south coast where a N to S offshore push across the county will boost temps 5 to 10 degrees above normal. Look for another 2 to 4 degrees of warming on Friday everywhere except the SBA county south coast and the VTA county cst/vlys where a little better W to E onshore push will bring a few degrees of cooling. It will be noticeably cooler on Saturday. The approaching upper low will lower hgts. In addition the lower hgts and better onshore flow will bring more marine stratus to the coasts in the morning. The lower hgts, deeper marine layer and stronger onshore flow will all conspire to lower max temps 2 to 5 degrees. Most max temps will come in 2 to 4 degrees blo normal. The N to S offshore push across SBA county produced low end advisory level gusts last evening and will likely produce another round of advisory level Sundowner gusts tonight into early Friday morning. The strongest gusts will occur near Gaviota. The upper level flow pattern is not conducive to monsoonal flow and the threat of afternoon convection is low - well under 10 percent. .LONG TERM (SUN-WED)...15/312 AM. Mdls and ensembles have come into better agreement for the xtnd fcst. During the period big 598 dam upper high will slow push to the west moving from the TX panhandle to western NM. Hgts over Srn CA will climb from 590 dam to 594 dam. The sfc pressure pattern will not change much during the period with weak to moderate onshore flow to the east and weak onshore flow to the N in the afternoon followed by weak offshore flow to the S in the early mornings. There will be little in the way of marine layer clouds as the extra high hgts will keep the marine layer smooshed to under 800 ft. In addition there will be not be any low level lifting mechanisms that would help to generate clouds. Max temps will be the main talking point of the xtnd fcst with a 4 day warming trend on tap. Max temps will climb 1 to 3 degrees per day Sun through Tue with perhaps a degree or two of additional warming on Wed. By Wed the only 70s will be right at the beaches with 80s and lower 90s across the rest of the coasts. The vlys will see max temps in the 90s to 102 degrees. There will be plenty of triple digit heat across the far interior and lower mtn elevations as well. These max temps are 3 to 6 degrees above normal. While rather warm these temps are a few degrees below critical heat advisory thresholds. The flow pattern on Tue and Wed is mildly conducive to monsoon flow. Only a few ensembles pick up on any flow and right now the chc of afternoon convection remains less than 10 percent. Still days 6 and 7 are a ways off and this fcst could change. && .AVIATION...15/1752Z. At 1653Z at KLAX, the marine layer was 700 ft deep. The top of the inversion was 2400 ft with a temperature of 24 Celsius. High confidence in CAVU TAF for KPRB, KBUR, KVNY, KPMD, KWJF. High confidence in TAFs for LA coastal sites. There is a 10% chance for brief MVFR cigs/vsbys between 12 and 16Z at KLAX and KSMO, and a 20% chance at KLGB. Moderate confidence in TAFs for remaining coastal sites. There is a 40% chance KSMX becomes VLIFR at any point between 06Z and 16Z due to cigs/vsbys. Arrival of cigs at KSMX may be off by +/- 2 hours from current fcst. There is a 20% chance of IFR-LIFR cigs/vsbys at KSBP between 10 and 14Z. There is a 30% chance KSBA and KOXR remain VFR thru the period. KLAX...High confidence in TAF. There is a 20% chance of cigs>010 from 12Z to 16Z. No significant east wind component. KBUR...High confidence in CAVU TAF. && .MARINE...15/936 AM. For the offshore waters from the Central Coast to San Nicolas Island (the outer waters), high confidence in Gale force wind gusts through late tonight, with the strongest winds occuring in the late afternoon through late evening hours. High confidence in Gales subsiding late tonight, with SCA level winds thru at least the weekend. For the nearshore waters of the Central Coast, moderate confidence in SCA level winds and/or steep seas through late tonight, with strongest winds in the afternoon and evening hours. Chances of SCA conditions are lower Friday, and even lower through the weekend. For the Santa Barbara Channel, high confidence in SCA levels winds over the far western portion this afternoon thru late night. Moderate confidence in conditions remaining below SCA level tomorrow, but higher chances over the weekend. In the Eastern portion, high confidence in conditions remaining below SCA level thru the weekend. For the waters off of Los Angeles and Orange Counties, high confidence in conditions staying under SCA levels through the weekend. With a shallow marine layer, high confidence in dense fog with visibilities under 1 mile effecting the Central Coast waters through at least tomorrow morning. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory in effect from 4 PM this afternoon to 3 AM PDT Friday for zones 349-351. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 5 AM PDT Friday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Friday for zone 650. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Rorke/Schoenfeld AVIATION...Lewis MARINE...RK/Lewis/Lund SYNOPSIS...RS/KL weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox