981 FXUS66 KLOX 122133 AFDLOXArea Forecast Discussion National Weather Service Los Angeles/Oxnard CA 233 PM PDT Fri Sep 12 2025
.SYNOPSIS...12/208 PM.
Little change through Saturday. Steady warm each day for early next week. Tuesday through Thursday should be the warmest, with an elevated risk for heat illness for sensitive people. Humidities and shower chances rise for the back half of next week.
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.SHORT TERM (TDY-MON)...12/221 PM.
Ample sunshine today leading to a degree or two of warming compared to yesterday. Otherwise looking for little change through Saturday, with temperatures 5 to 10 degrees below normal and mostly unorganized low clouds each morning. Some sub-advisory northwest winds will impact the southwest Santa Barbara coasts and the I-5 Corridor.
High pressure aloft will increase Sunday and Monday to around 585 decameters (at 500 millibars) while onshore pressure gradients weaken closer to neutral (at 12Z). This will provide a noticeable warm up back to around normal by Monday with highs inland of the beaches between 83 and 93 degrees common. The ridging aloft should also strengthen the marine inversion and help the low clouds become a little more organized, which will moderate any warming affects along the coast. There might be a little dense fog along the Central Coast as well. On Monday, some models (like the NAM) are showing signs of a southerly surge around Point Conception, which might add up to a slow clearing day for the coastal areas of LA, Ventura and Santa Barbara Counties, and a fast clearing day over San Luis Obispo (with some offshore flow in the hills).
.LONG TERM (TUE-FRI)...12/233 PM.
High pressure aloft will amplify over the southwest United States Tuesday through Thursday. This, along with further weakening of the onshore flow, should add up to additional warming with highs inland of the coast into the 93 to 103 territory by Wednesday. This is 5 to 10 degrees above normal. Calendar day records are very high for this stretch and look safe. This would usually mean that Heat Advisories would not be a concern, but because of an influx of moisture by Wednesday or Thursday, and the associated increase of overnight low temperatures, there is a low but present 20 to 30 percent chance of some Heat Advisories over coastal and valley areas.
That moisture, which is a combination of a typical monsoonal source and remnant moisture from Tropical Storm Mario, will also bring a threat of showers and thunderstorms pretty much anywhere over the 4 county area sometime between Wednesday and Saturday of next week. Thunderstorm forecasting this far out is often a fools errand, but there are a lot of things going for this surge: 1) High model consensus of precipitable water values over 1.25 inches 2) Several models showing multiple easterly waves, and 3) A low pressure system just off the coast producing diffluent flow aloft. PoPs of 20 to 30 percent were added to most areas, with the highest chances over Los Angeles County. Holding off on thunderstorm mentioned yet, but unless something drastically changes, they will likely be added in the next day or two. If this all materializes, there will be risks of heavy rain inducing flooding and gusty winds. If you are sensitive to these threats, continue to monitor this evolving situation.
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.AVIATION...12/1950Z.
At 1919Z at KLAX, the marine layer depth was a deep moist layer up to 3700 ft.
High confidence in TAFs for KPMD and KWJF.
Low to moderate confidence in all coastal and valley TAFs. Cigs arrival tonight may be off by 3 hours and morning clearing may be off by 2 hours. Minimum flight cat may be off by 1 cat at times. There is a 20 percent chance of no cigs developing tonight at KBUR and KPRB tonight, and a a 20 percent chance of IFR-MVFR cigs at KSBA from 13Z-18Z Sat.
KLAX...Moderate confidence in TAF, BKN08-015 cigs are likely after 02Z Sat, but arrival times may be off +/- 3 hours. There is a 15 percent chance of a southeast wind component reaching 8 kt from 11Z-17Z SAT.
KBUR...Moderate confidence in TAF. Arrival of BKN005-012 cigs tonight may be off +/- 2 hours.
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.MARINE...12/137 PM.
Small Craft Advisory (SCA) level NW winds (peaking at 20-30 kts) will impact the outer waters through Sunday night. Winds will be the strongest during the afternoons and evenings, and lulls may occur during the morning hours. The nearshore waters along the Central Coast will see SCA level NW winds (20-30 kts) each afternoon and evening through Sunday night. Seas will peak around 6 to 8 feet through late Sunday.
For the inner waters south of Point Conception, SCA level WNW winds (20-25 kts) are likely across the Santa Barbara Channel Friday, with moderate (50 percent) chances Saturday and Sunday, then conditions will be below SCA levels into next week. Seas will be choppy and peak at 3 to 5 feet this afternoon and evening. Some localized NW gusts to 20 kts may occur near Point Dume and west of Catalina this afternoon and evening, then winds will trend lighter over the weekend and will be below SCA levels into next week.
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.LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zones 670-673-676. (See LAXMWWLOX).
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PUBLIC...Kittell AVIATION...Schoenfeld MARINE...Lewis/Schoenfeld SYNOPSIS...Kittell
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Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox
NWS LOX Office Area Forecast Discussion