Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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716 FXUS66 KLOX 201933 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 1233 PM PDT Mon May 20 2024 .SYNOPSIS...20/228 AM. Low clouds will continue through the morning will better clearing in the afternoon. Breezy onshore winds will continue this afternoon and evening. More sunshine with slight warming is expected Tuesday and Wednesday as onshore flow weakens. Then cooler with increasing marine layer clouds again the latter half of next week. && .SHORT TERM (TDY-THU)...20/1151 AM. Overall, 12Z models in good synoptic agreement through the short term period. At upper levels, a broad cyclonic flow will persist across the area, but with a gradual increase in H5 heights. Near the surface, moderate to strong onshore gradients will persist with some weak northerly offshore gradients each evening. Forecast-wise for the short term, no impactful sensible weather is expected. Main challenge will be the behavior of the marine layer stratus. Currently, the inversion is in the 2500-3500 foot range. With a gradual increase in H5 heights through Wednesday, will expect the inversion to become a bit more shallow. So, will still anticipate stratus pushing into the lower coastal slopes tonight and Tuesday morning, but only into the coastal valleys Tuesday night and Wednesday morning. For Wednesday night and Thursday, looks like the stratus will make a renewed push inland to the lower coastal slopes. Other than the marine layer stratus, skies should remain mostly clear through the period. As for temperatures, will expect a warming trend for all areas Tuesday and Wednesday with rising thicknesses and less marine influence. So, coastal valley areas will experience temperatures in the 70s through Wednesday. For Thursday, temperatures will drop a few degrees for all areas. As for winds, the onshore gradients will continue to generate some gusty southwesterly winds across interior sections this afternoon and evening. Currently, Lake Palmdale is reporting 50+ MPH wind gusts. So, a WIND ADVISORY is in effect for the western Antelope Valley foothills until 900 PM this evening. For Tuesday, the winds look to diminish noticeably, but will increase again on Wednesday and Thursday. So, will need to monitor the potential for advisory level winds across interior sections Wednesday and Thursday. .LONG TERM (FRI-MON)...20/1201 PM. For the extended, models and their various ensembles are in decent agreement through the period. A broad upper level trough will persist over the area Friday/Saturday, but a rather flat upper level ridge will begin to build on Sunday/Monday. Forecast-wise, marine layer stratus will continue to be the main challenge through the period. For Friday/Saturday, expect the marine inversion to remain rather deep, with stratus pushing into the coastal slopes and slow afternoon clearing. This significant marine layer pattern and upper level trough will keep all areas a few degrees cooler than normal through Saturday. Also, moderate to strong onshore gradients will keep the potential for some advisory level southwesterly winds across interior sections each afternoon and evening, especially in the Antelope Valley foothills. For Sunday/Monday, increasing H5 heights will help to smoosh the marine inversion, with decreasing inland penetration each night. Also with rising thicknesses and less marine influence, a warming trend can be expected for all areas. && .AVIATION...20/1932Z. At 19Z at KLAX, the marine layer was 3500 ft deep. The top of the inversion was at 5000 feet with a temperature of 13 C. Good confidence in desert TAFs. Moderate confidence in clearing times (may be off by 2 hours) with low confidence the return of low cigs (may be off by 3 hours). There is a 10-20 percent chc of no clearing at coastal sites, highest across the Central Coast this afternoon. KLAX...Moderate confidence in TAF. There may be a 1-2 hour period (20Z-22Z) where low clouds are intermittent before VFR prevails. KBUR...Moderate confidence in TAF. VFR conds could arrive as late as 22Z. && .MARINE...20/917 AM. High confidence in Small Craft Advisory (SCA) seas and/or northwest winds continuing over the offshore waters from the Central Coast to San Nicolas Island through at least Tuesday and likely beyond. There will likely be brief and slight lulls each morning. There is a 30 percent chance of SCA for the western Santa Barbara Channel each evening. SCA conditions are unlikely elsewhere. Fairly large seas will continue as a result, with short period dominant seas over most nearshore waters. A long period south to southwest swell will peak through Monday with heights of 2 to 4 feet. This will create larger than usual breaking waves nearshore as well as some stronger currents near most harbor entrances. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect until 11 PM PDT this evening for zones 87-362-366. (See LAXCFWLOX). Wind Advisory in effect until 9 PM PDT this evening for zone 381. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Thompson AVIATION...Munroe MARINE...Kittell/RM SYNOPSIS...MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox