High pressure will continue to dominate the region over the next week, bringing warmer than average weather with minor day to day changes. This will keep the marine layer thin, leading to low clouds and fog near the coast, where the fog may be locally dense over the next couple of nights/mornings.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
A 585 mb high centered near the San Francisco Bay Area continues to bring another warm day out there as highs reach into the 70s and 80s across the lower elevations away from the coast. The marine layer remains very thin (a few hundred feet), where dense fog remains at portions of the beaches. Though the fog will be intermittent during the afternoon, a Dense Fog Advisory is now in effect for the coastal areas through late Saturday morning. Some areas within a few miles of the coastline will see visibility below 1/2 mile at times. The depth of marine layer is not expected to change very much into the weekend as the area of high pressure maintains its presence, so dense fog will continue to linger near the beaches over the next few days. This synoptic pattern will also contribute to minimal changes in temperatures through the weekend as well, with highs continuing near 5-10 degrees above average near the coast and 15-20 degrees above average for inland communities. A few sites like Lake Elsinore, Palomar Mountain, and Borrego Springs will be close to breaking their daily record highs for the day today.
The ridge over the West will start to become not as amplified by early next week, shifting the center of the high to our southwest off the coast. This will continue the dry and warm weather and patchy fog by Monday and Tuesday. The ongoing active troughing pattern in the Gulf of Alaska and off the Pacific Northwest will begin to weaken this area of high pressure by the middle and end of next week. This will bring greater onshore flow and subtle cooling to our region, but dry weather will continue. Long-range ensemble models increase chances for the trough to push further south, where chances for precipitation may increase toward the Christmas holiday.
122145z, Coast/Valleys, FEW-SCT low clouds (based near 300ft MSL) present across the southern San Diego County coastal areas while coastal Orange County is seeing more BKN clouds along the beaches. Clouds/fog are expected to re-increase in coverage and push ashore later this afternoon into this evening, with CIGs anticipated along coastal TAF sites by 03-04z Saturday, eventually filling in 5-10 miles inland by 06-09z. Bases will be similar to this morning, about 100-200ft higher, sitting around 200-500 MSL. VIS restrictions generally 1/2-2SM at sea level with full obscurations of 0-1SM in FG expected along coastal mesas and locally within inland valleys. While some VIS restrictions improve after sunrise, low clouds and fog scatter out by 17-18z for San Diego County, with Orange County seeing clouds linger until 18-20z.
Mountains/Deserts, SKC and VFR conditions expected through Saturday morning.
Low clouds/fog have largely scattered out across the waters with some patches lingering along the immediate coasts. These clouds/fog are expected to re-increase in coverage and become more uniform later this afternoon into this evening. Visibility reductions to 1 NM or less expected in these low clouds and fog. A Marine Weather Statement is in effect until noon Saturday for the impacts from fog and contains more details. Conditions expected to improve late Saturday morning. Otherwise, no hazardous marine conditions are expected through Wednesday.
Ca, Dense Fog Advisory until 10 AM PST Saturday for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
