Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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740 FXUS66 KLOX 152017 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 117 PM PDT Tue Sep 15 2026 .SYNOPSIS...15/1157 AM. Warm but below normal temperatures will continue through Thursday, with expanding coastal morning low clouds. Temperatures are likely to increase towards the end of the week. && .SHORT TERM (TDY-THU)...15/1206 PM. Deep marine layer influence well into the coastal foothills today will expand further inland and upward into additional lower mountain slopes and interior San Luis Obispo County into Wednesday. Patchy drizzle is possible just about anywhere within the mid level cloud deck early Wednesday morning. Fog may impact lower mountain passes including lower portions of the I-5 corridor as the low clouds deepen to between 3000-4500 feet. Reverse clearing is likely where low clouds hang on longer coastal valleys and especially foothills where a few spots may struggle to clear much of the day. A weak trough briefly stalling just north of San Fransisco and the deepening marine layer will contribute to another few degrees of cooling and breezy onshore winds for the far interior. We enter a more progressive pattern Thursday and especially beyond. The trough will slide east of the region by Friday with a pop up ridge warming temperatures several degrees and approaching normal by Friday or Saturday. The marine layer will shrink in coverage and size and may undergo shrinking pains where it struggles to reform, leading unexpectedly sunny skies sometime Friday or Saturday. .LONG TERM (FRI-MON)...15/1204 PM. Not much going on in the xtnd very weak ridging moves into the area Friday and continues into Saturday hgts may approach 588 dam. Mdt onshore flow will continue to the east. There will be weak offshore flow in the morning from the north but it will turn to weak onshore flow in the afternoon. The morning offshore push should reduce (but not eliminate) the morning low cloud coverage. Look for 2 to 4 degrees of warming each day. This will lead to max temps in the 70s and lower 80s across the csts and 80s in the vlys on Saturday. Despite the warming these max temps are still 2 to 4 degrees blo normal. A weak upper low will move into the area Sunday and Monday. It currently looks to be moisture starved, although it should provide sufficient dynamics to gin up a deep marine layer and perhaps some morning drizzle or a passing shower. Although the exact weather pattern becomes more uncertain, we have fairly high confidence that benign weather will prevail into the middle part of next week. && .AVIATION...15/1728Z. At 1701Z at KLAX, the marine layer was 3200 feet deep. The top of the inversion was at 4500 feet with a temperature of 20 C. High confidence a deep marine layer bringing low clouds to all coastal and valley sites (10% chance at KPMD & KWJF). MVFR conds will dominate south of Point Conception, with IFR to MVFR to the north. There is a 15% chance of -DZ at any site with low clouds late tonight into Wed morning. North of Point Conception: 50% chance of no clearing today with IFR-MVFR conds continuing at KSBP/KSMX. Low confidence in arrival time (+/ 4 hours) and min cig height (+/- 500 ft) at KPRB tonight. South of Point Conception: 30% chance of no clearing today with MVFR-VFR cigs continuing. Otherwise arrival times may be off +/- 3 hours and some sites may see cigs remain greater than BKN/OVC022 through the period. KLAX...Moderate confidence in TAF except low confidence in clearing this morning. There is a 30% chance for no clearing of MVFR-VFR cigs, otherwise clearing time likely from now through 22Z. Cigs may remain above BKN/OVC022 through the period. Moderate confidence in any east wind component remaining below 8 kt after this morning and again late tonight. KBUR...Moderate confidence in TAF except low confidence in clearing this morning. There is a 30% chance for no clearing of MVFR-VFR cigs, otherwise clearing time likely from now through 22Z. && .MARINE...15/116 PM. High confidence in relatively light winds over the area through Thursday morning, with a return of normal outer waters (and potentially Santa Barbara Channel) northwest Small Craft Advisory (SCA) winds for Thursday night through the weekend. These winds will generate a building short period swell over all waters. Best chances for SCAs to be issued exist for the outer waters south and west of Point Sal Thursday, then SCA winds are likely to become more expansive Friday through this weekend. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...RM/Rorke AVIATION...Lewis MARINE...Lewis SYNOPSIS...RK weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox