Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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635 FXUS66 KLOX 132054 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 154 PM PDT Mon May 13 2024 .SYNOPSIS...12/837 PM. Quiet weather will continue the next several days with near to slightly below normal temperatures. Widespread night and morning low clouds are expected across coast and valleys as onshore flow increases. Temperatures will cool slightly through Wednesday, then warm slightly the end of the week. Gusty winds are likely across the mountains and Antelope Valley each afternoon. && .SHORT TERM (TDY-THU)...13/153 PM. Overall, 12Z models in good synoptic agreement through the period. At upper levels, weak low will slowly move southeast across the bight and into northern Mexico today through Wednesday with ridge building in from the west on Thursday. Near the surface, moderate to strong onshore flow will continue. Forecast-wise for the short term, a "May Gray" pattern will be the main story. With the weak upper low being the main player, the marine inversion will remain deep tonight through Wednesday with low clouds likely pushing into the the Santa Clarita Valley each night. Also with the strong onshore gradients, stratus dissipation will likely be slower than usual with some coastal spots remaining cloudy through the afternoon hours. For Wednesday night/Thursday, H5 heights increase which should result a bit less inland penetration of stratus and a better/quicker dissipation. Other than the stratus issues, there is enough mid-level moisture and instability to generate some afternoon cumulus buildups over the mountains today through Wednesday. However, both parameters are rather limited, so do anticipate much more than a 5-10% chance of mountain thunderstorms each afternoon. With respect to winds and temperatures, do not anticipate any significant issues through Thursday. Afternoon temperatures will exhibit minor day-to-day changes, but generally will remain at or a couple degrees below seasonal normals. As for winds, the strong onshore gradients will generate gusty southwesterly winds across interior sections, including the Antelope Valley. However, outside of the local wind tunnels like Lake Palmdale, do not expect any widespread advisory-level gusts for the area. .LONG TERM (FRI-MON)...13/153 PM. For the extended forecast, no significant issues are anticipated. The upper level ridge will peak in strength on Friday. This should result in some slightly warmer temperatures and less extensive marine layer clouds and fog. For Saturday through Monday, an upper level low will move in from the west. This will bring cooler temperatures and more extensive marine layer stratus. Also, could be enough lift to generate some drizzle Saturday night and Sunday morning. Main issue for the weekend will be the onshore winds. Latest ensemble forecasts indicate an increase in the potential for advisory-level southwest winds across interior sections, especially the Antelope Valley and the adjacent foothills. At this time, there looks to be about a 30-40% chance of advisory-level southwesterly winds and this potential will need to be watched. && .AVIATION...13/1813Z. At 1737Z at KLAX, the marine layer was 2200 feet deep. The top of the inversion was around 3200 feet with a max temp of 17 C. High confidence in desert TAFs. Moderate confidence in all other TAFs. Flight cat change timing could be off by +/- 2 hours and cig hgt could be off by +/- 200 ft. KLAX...Moderate confidence in TAF. There is a 25 percent chc of BKN025 conds 20Z-01Z. Good confidence that any east wind component will be under 5kt. KBUR...Moderate confidence in TAF. Cigs will likely clearing between 19-21Z. Cigs will have a 70% chance of returning between 04 and 06Z tonight. && .MARINE...13/137 PM. Moderate to high confidence in the current forecast. For southern outer waters, there is a 30% chance of Small Craft Advisory (SCA) winds developing during the afternoons/evenings today through Thursday. Winds will be the strongest around Point Conception and the Channel Islands. There is a 20% chance of SCA conditions for the western third of the Santa Barbara Channel during the same times. There is a 10% chance of SCA conditions across the southern inner waters, including nearshore LA and Ventura County, during the afternoons and evenings Tuesday and Wednesday. Patches of dense fog and drizzle are possible overnight and in the mornings through the period. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...Thompson AVIATION...Schoenfeld MARINE...Munroe/Schoenfeld SYNOPSIS...MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox