High temperatures peak today before a slight cooling trend Sunday and Monday. Locally gusty offshore winds will continue today for the passes, coastal slopes, foothills. Dense fog may return to the coastal areas Monday and Tuesday mornings before another round of weak to locally moderate offshore flow returns Tuesday through Friday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Skies are mostly clear this morning with breezy east winds gusting 25-35 mph along the coastal slopes of the mountains and below the San Gorgonio Pass. Weak offshore flow will persist through the day, and the center of an upper level high will move directly overhead. Another warm and sunny day is in store with high temperatures in the low to mid 80s across most of the inland coastal areas, valleys, and low deserts, low 70s in the high desert, and upper 50s to around 70 in the mountains. This equates to highs around 15-20 degrees above normal west of the mountains, and around 10-15 degrees above normal elsewhere.
Surface pressure gradients and offshore flow weaken on Sunday while the upper level ridge axis shifts eastward. This will allow for some cooling, especially west of the mountains, though highs will remain anywhere from 7 to 15 degrees above normal. A weak short wave moves by well to the north late Sunday into Monday, bringing more noticeable cooling for Monday. With a brief return of onshore flow and the potential for a coastal eddy to develop, dense fog may form over the coastal waters and coastal areas late Sunday into Monday morning. There is a lower but non-zero chance of low clouds and fog developing again Monday night.
An upper level ridge rebuilds by Tuesday, and northwest flow/cold air advection into the Great Basin will reestablish the surface high, driving another round of weak Santa Ana winds. High temperatures will ramp back up into the 80s west of the mountains. The warming trend continues into Wednesday as offshore flow weakens and the upper level ridge amplifies. For later in the week, ensembles are showing a closed low developing beneath the high somewhere over or off the coast of northern Baja. If this low gets close enough it could help bring temperatures down slightly the latter half of the week. The position of the low will also influence how much upper support/easterly flow we get to add to the offshore flow. As we head into Thursday, the CW3E West-WRF ensemble has a 75% chance of at least a weak Santa Ana, a 35% chance of a moderate event, and around a 15% chance of a moderate to strong event. A closed low begins to approach the West Coast Friday and Saturday with the upper high weakening and shifting east for relatively cooler weather with highs "only" 5-10 degrees above normal.
311000, VFR conditions with mostly clear skies except for FEW-SCT clouds AOA 20k ft continue through the TAF period. Breezy northeasterly winds will continue in the foothills and below mountain passes and locally into adjacent valleys through about Sun 06Z, with gusts to 20-30 kts in these areas.
No hazardous marine conditions are expected through Wednesday.
Fresh northwest swell 3-5 feet at 15-17 sec will move in late Sunday night into Monday morning, likely leading to breaking waves of 5-7 feet with local sets to 8 feet on west-facing beaches Monday into early Tuesday. Additionally, morning high tides 6-6.5 feet combined with the larger surf will possibly result in minor tidal overflow/flooding for low-lying beach lots and walkways Monday morning.
Ca, None. PZ, None.
