Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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422 FXUS66 KLOX 100711 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 1211 AM PDT Mon Jun 10 2024 .SYNOPSIS...09/856 PM. Weaker onshore flow will bring a warming trend through Wednesday as high pressure builds into the region from the east. Most of the warming will be felt away from the coastal areas where onshore flow will keep night through morning low clouds and fog in the forecast. After a brief cooling trend Thursday, widespread warmer temperatures are expected Friday through next weekend with some gusty north winds at times. && .SHORT TERM (MON-THU)...09/941 PM. The latest satellite imagery shows an upper-level trough of low pressure about 290 miles southwest of Los Angeles, while ridging aloft is building into west Texas and southern New Mexico. The trough will continue to move to the southwest away from the region and allow for high pressure to the east to expand into the area. A warming trend will take shape over the coming days as ridging aloft will weaken onshore flow and thin the marine layer depth some. Onshore flow is already weakening and the marine layer stratus coverage is much less entrenched than the last several days, partially due to the trough digging past the state to the west. Night through morning low clouds and fog will remain as a staple of the coastal and valley areas through midweek though as onshore flow will remain in place. As a result, the best warming will take place well away from the coast and outside the marine layer depth. The forecast keeps a mention of drizzle for tonight and into Monday, despite the marine layer depth thinning some. Enough dynamics from the trough continues to scrape the area through Monday morning. The dynamics could lift the marine layer deck and squeeze some drizzle. An update to forecast will be issued shortly. ***From Previous Discussion*** Tuesday expected to be the warmest of this mini heat wave with far interior areas like the Antelope Valley getting into the lower 100s (though not as warm as last week) and warmer coastal valleys near 90. Forecast highs were trimmed slightly as offshore trends have lightened the last few runs but still enough for warming in most areas. Still expecting low clouds and fog for coastal areas but clearing earlier. Models currently showing onshore flow increasing again Wednesday, however, this may be a little premature as the a majority of the ensembles show the upper low not starting to move back towards the coast until early Thursday. So it`s possible that forecast highs on Wednesday are too cool, especially inland. .LONG TERM (FRI-MON)...09/157 PM. Cooler weather on tap Thursday as the upper low moves across the area from southwest to northeast. The low has very little moisture associated with it so not expecting any afternoon showers or storms in the mountains, but some increase in cumulus clouds there is a good bet. Marine layer will be deepening as the lows treks through, possibly enough for some more morning drizzle for coast/valley areas. A significant warming trend is expected Friday and Saturday as heights rise and the air mass warms following the departure of the upper low. At the same time onshore flow to the east weakens and actually turns offshore to the north by around 3mb. The GFS is showing around 50kt of north to northwest winds near and west of Pt Conception, and 25-40 kt over the western Santa Ynez Range. Will have to monitor this situation closely through the week as these conditions could create some fire weather concerns. Elsewhere, warmer valleys are expected to reach the 90s and inland coastal areas expected to be in the mid 70s to lower 80s. && .AVIATION...10/0707Z. At 0505Z at KLAX, the marine layer was 2000 ft deep. The top of the inversion was at 4900 ft with a temperature of 19 degrees C. High confidence in KPMD and KWJF. Moderate confidence in KPRB where there is a 30 percent chc of IFR cigs 11Z-16Z. For all other sites low confidence in low cloud arrival timing but high confidence that all sites will have low clouds by 13Z. Moderate confidence in VFR transition with possible clearing occuring 1 hour earlier than fcst. Low confidence again Monday evening with regard to stratus arrival. KLAX...Moderate confidence in TAF. There is a 30 percent chc of clearing by 19Z. There is a 30 percent chc that onset of low clouds Monday evening will be as late as 08Z. No significant easterly wind component is expected. KBUR...Good confidence that low clouds will be in place at 13Z but low confidence in exact arrival time. There is a 30 percent chc of clearing by 17Z. && .MARINE...09/820 PM. For the Outer Waters, high confidence in current forecast, but low confidence on marginal Small Craft Advisories (SCA). For tonight, there is a 60-80% chance of Small Craft Advisory (SCA) level winds. For Monday through Thursday, high confidence in winds and seas remaining below SCA levels. On Friday, there is a 50-70% chance of both SCA level winds and seas. For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Localized SCA conditions focused northern areas will may continue through this evening. For Monday through Thursday, high confidence in winds and seas remaining below SCA levels. For Friday, there is a 40-50% chance of SCA level winds in the afternoon and evening hours. For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For the western half of the Santa Barbara Channel, there is a 30-40% chance of SCA level winds this evening. Otherwise, high confidence in winds and seas remaining below SCA levels through Friday for the Inner Waters south of Point Conception. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT early this morning for zones 670-676. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT this morning for zone 673. (See LAXMWWLOX). && $$ PUBLIC...Hall/MW AVIATION...Rorke MARINE...RAT/Munroe SYNOPSIS...Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox