785 FXUS66 KLOX 061158 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 458 AM PDT Sun Aug 6 2023 .SYNOPSIS...06/454 AM. It will remain hot across inland areas today, but with seasonal highs near the coast. A cooling trend will begin Monday, with additional cooling expected Tuesday and with an increase in low clouds and fog in coastal and possibly valley areas. There is a slight chance of showers during mid week as the remnants of a tropical system move north over the eastern Pacific. Otherwise, cooler than normal temperatures are expected the remainder of next week. && .SHORT TERM (TDY-TUE)...06/412 AM. Just some subtle differences on satellite this morning compared to this time on Sat morning. North of Pt. Conception, the low cloud field was not quite as solid on the Central Coast and was not as extensive in the Santa Ynez Valley. In addition, clouds were a bit farther from entering the SLO portion of the Salinas Valley, and there is a chance that will not happen this morning. South of Point Conception, the cloud pattern looked fairly similar. Another eddy circulation was beginning to send clouds into coastal sections of L.A. and Ventura Counties, and though the marine layer was a bit more shallow than it was on Sat morning, some clouds will probably squeak into the San Gabriel Valley. Gusty winds reached advisory levels through and below passes and canyons of the eastern Santa Ynez Range and the adjacent south coast of SBA County, and Montecito Hills reported wind gusts to 55 mph and a relative humidity of 10%. Thankfully, the winds have diminished some, so the advisory was allowed to expire. Onshore pressure gradients between KLAX and KDAG were about the same as they were yesterday morning, which are weak, but not as weak as they were forecast to be. Still, expect skies to clear quickly in all areas today, and by mid morning it should be mostly sunny just about everywhere. The temperature forecast for today remains rather difficult. In general, the day should start off a bit warmer than it did on Sat, but really not by much. The marine layer is a bit more shallow, but also not by much. Onshore gradients are forecast to become stronger this afternoon then they were on Sat. In addition, there is very slight cooling forecast at 950 mb. Overall, expect temps to be generally similar to those that were recorded Sat, with maybe a bit of warming above the coastal plain due to the slightly shallower marine layer. Believe the current Heat Advisories will work out, but it probably will be a marginal event. A broad trough will move into West Coast tonight and Mon which will knock heights down a bit. It looks as though a fairly good eddy circulation will develop tonight. Expect more in the way of night through morning low clouds and fog in coastal areas, as well as in the Santa Ynez and San Gabriel Valleys. Onshore flow will also increase, and there will be some cooling at 950 mb Mon. Clearing mat be a bit slower Mon. There should be several degrees of cooling just about everywhere Mon, and certainly no heat products will be needed. Temps have been lowered some in the current forecast, but they may have to be lowered a bit more in subsequent forecasts. Some gusty winds are likely in the Antelope Valley and through the Highway 14 Corridor. The trough along the West Coast will deepen a bit Mon night and Tue as the upper level reflection of a then weakening Tropical system Eugene lifts northward through the eastern Pacific. The marine layer will continue to deepen, with night through morning low cloud and fog pushing into the valleys. Clearing will be slower Tue, and max temps will be lower, down to below normal levels. Gusty winds will once again affect the Antelope Valley and the Highway 14 Corridor. .LONG TERM (WED-SAT)...06/452 AM. As a trough digs through the eastern Pacific the southerly flow on its eastern side will capture the upper low associated with what will be the remnants of Eugene (it will not still be a tropical system then) and will lift it northward toward the area Tue night through early Thu. Increasing south to southwesterly flow aloft will transport moisture and mid and high level clouds into the region Tue night and Wed. The EC in particular shows the atmosphere becoming especially moisture laden, with ensemble precipitable water values near 1.8 inches, and several members showing values of 2.0 to 2.2 inches. Some of the GFS ensemble members, and many of the EC ensemble members show measurable rain across the region, primarily Wed into early Wed night. Even the deterministic run of the EC shows measurable rain in many areas Wed, while the GFS is mostly dry, with a slight chance on Thu. There really are just too many indicators to ignore the threat of showers for the forecast, so have added slight chance of showers for most of the forecast area for Wed and early Wed night. Honestly, the threat could be as early as late Tue night and could continue into Thu, but decided to pick the most likely time period based on the current guidance. Thunderstorms may also have to be added to the forecast at some point as well. And with the very high precipitable water values (potentially over 200% of normal), the threat of at least briefly heavy showers cannot be ruled out. Obviously, it would be cooler on Wed with all the cloud cover, but will likely be rather humid. The upper reflection of the tropical system will become absorbed into the trough off the West Coast on Thu and a large upper low will linger there through Sat, so expect cooler than normal weather through that period. As for the stratus pattern, it will be disrupted by the moisture, and exactly when it reorganizes is very much in question. The other issue for this upcoming week will be the south to southeast swell generated by Eugene which could bring elevated surf to south facing beaches and to portions of Catalina Island this week. && .AVIATION...06/1130Z. At 1100Z, the marine inversion at KLAX was based at 900 feet. The top of the inversion was 3400 feet with a temperature of 27 degrees Celsius. For valley/deserts sites, high confidence in 12Z TAFs as CAVU conditions are expected. For coastal sites, low to moderate confidence in 12Z TAFs due to uncertainties in the behavior of the marine layer stratus. For sites currently clear, there is a 40% chance of IFR/LIFR conditions developing 12Z-16Z. KLAX...Low confidence in 12Z TAF. There is a 50% chance that VFR conditions will persist this morning. For tonight, moderate confidence in return of CIG/VSBY restrictions, but low confidence in timing (could be +/- 3 hours of current 10Z forecast). No significant easterly wind component is expected. KBUR...High confidence in 12Z TAF as CAVU conditions are expected through the period. && .MARINE...06/127 AM. For the Outer Waters, moderate to high confidence in current forecast. Small Craft Advisory (SCA) level winds will continue across all the Outer Waters today, but will gradually diminish south to north tonight and Monday morning. From Monday afternoon through Wednesday, high confidence in winds and seas remaining below SCA levels. On Thursday, there is a 50-60% chance of SCA level winds. For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. There is a 50-60% chance of SCA level winds this afternoon and tonight. For Monday through Thursday, high confidence in winds and seas remaining below SCA levels. For the Inner Waters south of Point Conception, high confidence in current forecast. Today through Thursday, winds and seas are expected to remain below SCA levels. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory in effect until 8 PM PDT this evening for zones 38-88-342>345-348-351>353-356>358-369>372-374>376-378-379. (See LAXNPWLOX). PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Monday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Monday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zone 673. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PDT this afternoon for zone 676. (See LAXMWWLOX). && $$ PUBLIC...DB AVIATION...RAT MARINE...RAT SYNOPSIS...DB weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox