Near average temperatures through the weekend with below average temperatures expected next week. Low clouds and fog will be present from the coast to 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.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Marine layer low clouds have filled in over the coastal areas and western valleys and spread into the southern and western parts of the Inland Empire this morning. Clouds will continue to push several more miles inland in the Inland Empire through sunrise, then slowly clear black towards the coast through late morning. Elsewhere skies will remain clear.
Weak troughing along the West Coast will maintain cool weather with high temperatures near to slightly below normal across the region. Low clouds will spread into the inland valleys again tonight into Sunday morning, with limited clearing at the coast Sunday afternoon as the marine layer continues to deepen. A weak upper level low will move through late Sunday into Monday, helping the marine layer deepen further and bringing greater cooling for Memorial Day, when high temperatures are forecast to be around 3-7 degrees below normal for the mountains westward, and near normal in the deserts. There is a small potential for drizzle in the morning, then parts of the coasts and valleys may remain at least partly cloudy through the day. It won't exactly be beach weather with low clouds hanging around and highs in the upper 60s.
Ensembles have come into better agreement with the progression of the upper low dropping down midweek. This closed low will move into the Pacific Northwest by Tuesday morning, digging south somewhere into CA or NV Wed and Thu before ejecting eastward late in the week. The marine layer will continue to deepen, extending into the coastal mountain slopes each morning. Depending on the track of the trough axis/vort max, we may receive light precipitation from the coasts to the mountains. A more westerly track, which would favor light precipitation, currently accounts for around 45% of the ensemble space. Even then, mean precipitation within that cluster is less than 0.10". Gusty southwest to west winds are also expected with this system midweek, though again the further west track would favor stronger winds versus a more easterly/inside track. Wind gusts in the mountains and deserts are currently forecast to be around 35-45 mph with isolated gusts in excess of 55 mph below the passes Tuesday evening, weakening slightly on Wednesday. By Wednesday, when the upper low is closest, high temperatures will be around 10-15 degrees below normal inland, and around 3-5 degrees below normal near the coast. Minor warming on Thursday as the low begins to shift east, then continued warming into Saturday with high temperatures returning to near normal.
231200z, Coast/Valleys, Low clouds based 2000-2400 ft MSL have filled in across most of the coastal basin this morning, with a few gaps in the northeastern Inland Empire. With CIGs, VIS locally reduced 3-5SM in BR in far inland valleys, and 0-3SM where clouds intersect higher terrain. Inland valleys scatter out 15-16z, coastal areas 17-18z Saturday. Clouds redevelop and push back ashore after 00z Sunday with similar bases.
Otherwise, mostly clear and VFR conditions through Sunday morning.
No hazardous marine conditions are expected through Wednesday night.
Ca, None. PZ, None.
