Slightly cooler today. Patchy dense fog will continue to develop over the coastal waters and locally reach the coast this morning, becoming more widespread tonight into Tuesday morning. Warmer Tuesday through Thursday with periods of weak to locally moderate Santa Ana winds. Cooler with a return of onshore flow Friday through the weekend.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Dense fog has developed over the coastal waters and spread into the beaches in southern San Diego County. Elsewhere a few high clouds were moving in from the west. Expect dense fog to continue overnight along portions of the coast, but at this time do not anticipate fog to be widespread enough to warrant a Dense Fog Advisory. A brief upper level short wave trough moving through the region today will bring widespread cooling, though highs will remain around 5 to 10 degrees above normal.
Once the short wave passes, surface high pressure will return over the Great Basin tonight into Tuesday morning, driving another round of offshore flow. Winds likely won't strengthen enough to prevent low clouds and dense fog from returning tonight into Tuesday morning, and the HREF has a 50-70% chance of fog along the coast during this time. Even later in the morning, wind gusts below the passes and on the coastal slopes will only peak at around 25-30 mph. Otherwise it will be warmer on Tuesday as a rex block develops with an upper level high over Central/Northern CA and an upper level low off the coast of Central Baja. These systems each strengthen into Wednesday, providing a tighter gradient and stronger mid-level easterly flow over So Cal. Surface pressure gradients also strengthen during this time, leading to stronger easterly Santa Ana winds Wednesday into Thursday morning. Winds are still forecast to peak on Thursday, when the CW3E west- wrf has a 60% chance of a weak to moderate event and a 30% chance of a moderate event, slightly lower than yesterday's probabilities. We will also see a significant warm-up Tuesday and Wednesday, with highs around 15-20 degrees above normal for the coastal areas and valleys and around 10-15 degrees above normal in the mountains and deserts. Portions of inland Orange County even have around a 40% chance of exceeding 90 degrees on Wednesday per the NBM with localized moderate HeatRisk in this area. Thursday will be a couple degrees cooler as the upper high begins to weaken and shift east.
The upper low off the coast of Baja eventually becomes phased with and absorbed by a short wave trough moving into Central CA on Friday. How this low tracks into Saturday is still a bit uncertain. A small number of members from each of the global ensembles is trying to produce very light precipitation over parts of So Cal sometime in the Fri-Sat time range, but for now PoPs remain below 10%. Despite the track differences, cooler weather is a guarantee these days. Weak ridging builds in on Sunday for minor warming, then a long wave trough begins to move into the West Coast on Monday with a slight (15-20%) chance of precipitation for the mountains westward by late Monday. Ensembles remain locked into the idea of additional precipitation towards the middle of next week.
021030, Coastal areas, patchy fog with vis 0-5SM and cigs based around 200-300 feet MSL will impact KSAN and vcnty through 17Z. 30- 50% chance of these impacts at other coastal airports. More widespread low clouds and fog to more uniformly cover coastal areas after 04Z tonight into Tuesday. Bases and vis would rise a little, around 400-700 feet MSL with areas of reduced vis 1-5SM.
Otherwise, VFR conditions with SCT high clouds today and tonight.
Areas of fog with local visibility under 1 nautical mile this morning. Otherwise, no hazardous marine conditions are expected through Friday.
Surf of 3 to 6 feet with sets to 8 feet peaks today and tonight, and gradually diminishes Tuesday. A higher than average tide this morning will combine with this high surf to produce minor tidal overflow and flooding, along with strong rip currents and hazardous swimming conditions, most likely in San Diego County, through Tuesday morning. Check the Coastal Hazard Message for details on these multiple hazards.
Ca, Coastal Flood Advisory until 10 AM PST Tuesday for San Diego County Coastal Areas.
High Surf Advisory until 10 AM PST Tuesday for San Diego County Coastal Areas.
Beach Hazards Statement through this evening for Orange County Coastal Areas.
PZ, None.
