Ation and Marine Discussion,
Marine layer low clouds have filled in across the coastal basin this morning and have even spread into the Cajon Pass. Further inland skies are clear. A weak upper level low off the coast of Southern CA will move eastward today, moving overhead this evening into Monday morning. This will lead to minor cooling with high temperatures near to slightly below normal. The marine layer deepens further into Monday morning, potentially producing spotty light drizzle west of the mountains. Limited clearing is expected for the coastal areas today, and the coastal areas and far western valleys on Memorial Day. The cooling trend continues into Memorial Day as well with high temperatures around 3-5 degrees below normal for the mountains westward, and near normal in the deserts.
Ensembles continue to converge on a solution for the next upper level low midweek. This low is forecast to move through the Pac NW on Tuesday, slowly moving south through CA/NV into Thursday. This will bring more substantial cooling with high temperatures 10-20 degrees below normal inland, with the greatest departure from normal in the mountains. The marine layer depth increases to around 5000 ft, and with large-scale forcing with the trough should be plenty sufficient to produce drizzle along and west of the mountains Tuesday through Thursday during the nights and mornings. There is around a 10% chance of accumulating precipitation, though any accumulations would be light (less than 0.10"). This trough will also produce gusty onshore winds in the mountains and deserts, strongest on Tuesday and Wednesday during the afternoons into late nights. Wind gusts will generally be around 35-45 mph in these areas, with isolated gusts to 60 mph through the passes.
The upper low lifts out to the northeast on Friday, followed by generally weak troughing over the western US into the weekend. This will allow for temperatures to gradually increase to around normal next weekend. Night and morning low clouds continue (it is May Gray after all), but with less inland extent and better clearing during the day.
Near average temperatures today with below average temperatures expected Monday through midweek. Low clouds will spread into the valleys each night and morning, lingering into the afternoon at times along the coast. Increased westerly winds expected Tuesday through potentially Thursday for the mountains and deserts. Patchy drizzle or light rain possible west of the mountains each night and morning from Monday night through Thursday morning.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, Updated Aviation and Marine Discussion,
Marine layer low clouds have filled in across the coastal basin this morning and have even spread into the Cajon Pass. Further inland skies are clear. A weak upper level low off the coast of Southern CA will move eastward today, moving overhead this evening into Monday morning. This will lead to minor cooling with high temperatures near to slightly below normal. The marine layer deepens further into Monday morning, potentially producing spotty light drizzle west of the mountains. Limited clearing is expected for the coastal areas today, and the coastal areas and far western valleys on Memorial Day. The cooling trend continues into Memorial Day as well with high temperatures around 3-5 degrees below normal for the mountains westward, and near normal in the deserts.
Ensembles continue to converge on a solution for the next upper level low midweek. This low is forecast to move through the Pac NW on Tuesday, slowly moving south through CA/NV into Thursday. This will bring more substantial cooling with high temperatures 10-20 degrees below normal inland, with the greatest departure from normal in the mountains. The marine layer depth increases to around 5000 ft, and with large-scale forcing with the trough should be plenty sufficient to produce drizzle along and west of the mountains Tuesday through Thursday during the nights and mornings. There is around a 10% chance of accumulating precipitation, though any accumulations would be light (less than 0.10"). This trough will also produce gusty onshore winds in the mountains and deserts, strongest on Tuesday and Wednesday during the afternoons into late nights. Wind gusts will generally be around 35-45 mph in these areas, with isolated gusts to 60 mph through the passes.
The upper low lifts out to the northeast on Friday, followed by generally weak troughing over the western US into the weekend. This will allow for temperatures to gradually increase to around normal next weekend. Night and morning low clouds continue (it is May Gray after all), but with less inland extent and better clearing during the day.
241730z, Coast/Valleys, Inland valleys clear through 20Z Sun, with coastal locations seeing partial or intermittent clearing after 20Z. Clouds with bases 2000-2500 ft MSL, locally down to 1500 ft MSL begin to spread inland after 00z Mon, filling in the coastal basin by 10Z Mon. The locations that are most likely to see bases below 2000 ft are near mountain foothills and far inland valleys (70-80 percent chance of occurrence). Low clouds expected to clear 18-20Z Mon, with only partial and intermittent clearing along the coast.
Deserts, Mostly clear with VFR conditions.
Westerly winds could gust near 21 kt Tuesday and Wednesday afternoon in evening in the outer coastal waters by San Clemente Island. Otherwise, no hazardous marine conditions are expected through Friday.
Ca, Wind Advisory from 3 PM Tuesday to 5 AM PDT Thursday for Riverside County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
Wind Advisory from 3 PM Tuesday to midnight PDT Tuesday night for Apple and Lucerne Valleys.
PZ, None.
