High pressure aloft begins to weaken today and onshore flow returns. Temperatures will moderate near the coast as marine air spreads inland but record-setting heat will continue for many inland areas today. The cooling trend will continue through Monday, but with daytime temperatures remaining above seasonal averages. There will be stronger and gusty west winds each afternoon and evening for today and Monday in the mountains and deserts. Gusts of 35 to 45 mph are likely in the wind-prone areas. Dry and a little warmer for Tuesday through Saturday of next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Tonight through tomorrow night,
Currently as of 2 am this morning, there are some low clouds forming up right along the Point Loma area, and just south of North Island, as well as just off the coast of Carlsbad. These clouds will continue to develop going into the early hours of this morning. There may also be some patchy areas of fog (possibly dense in some locations) right along the coastal slopes and within some of the inland valleys.
High pressure dominates the region, although this is beginning to weaken now with an approaching trough that will pass by to our north through tomorrow. The tightening of the surface pressure gradient is going to allow for there to be some strong and gusty winds across the higher terrain by later this afternoon, as there could be some gusts approaching 50 mph or greater through some of the mountain canyons and passes. Onshore flow will also become more prevalent going into the afternoon hours, which will help to advect in more low level moisture from the west and allow for there to be better coverage of the marine layer filling in by later this evening and throughout the overnight hours into tomorrow morning.
For tomorrow, as the through moves into California to the north, it will allow for much cooler air to be advected in from the northwest behind the system, so high temperatures will be notably cooler for that reason and much closer to where they should be for this time of year. The marine layer will also continue lift and thicken tonight, and there may be some possible areas of light drizzle along portions of the coastal slopes and inland foothills during the early morning hours tomorrow, otherwise the only significance with this low to the north will be the increased winds and return of cooler temperatures. Winds will be gusty again during the afternoon, although these will begin to subside by later in the evening.
Tuesday through early next week,
After passage of the trough on Monday, there will be some weak ridging moving in its wake over the region, and this will allow for a brief and gradual warming from Tuesday through Wednesday, until another shortwave moves north of the region on Thursday and helps to reinforce some slightly cooler temperatures. High pressure conditions will remain in place throughout the work week, and then there will begin a shift in the longwave pattern as ensemble members have been alluding to in recent days with a deepening trough going into the upcoming weekend. There is also growing confidence that this could become cut off as deterministic solutions suggest, which may allow for there to be a slight chance of precipitation going into early next week.
011130z. Coast, Patchy fog has been staying offshore this morning with a few clouds around 200-700 ft MSL wafting in along the coast. There is still a 20-40 percent chance of periods of vis 1 SM or less in FG/BR and intermittent VV002 between 12-16z mainly for the norther half of Orange County. Any low clouds/FG present will clear 15-17z. VFR conditions will prevail for much of the period with a higher chance of low clouds and fog developing after 06Z Mon. Low clouds around 400-800 ft MSL with a 40-60 percent chance of vis 1 SM or less in FG/BR after 07Z Mon along the coast and inland 10-15 miles.
Elsewhere, VFR with SKC-FEW250. Winds will begin to increase after 20Z in the mountains and deserts with gusts up to 20-35 knots with locally higher gusts in the mountain passes.
Northwest winds increase over the outer waters this afternoon creating hazardous conditions for small craft. Peak gusts of 20 to 25 kt are expected, with seas of 4 to 7 ft. Strongest winds and highest seas will be in the outer waters near San Clemente island. Winds and seas will decrease Monday night into early Tuesday.
Ca, None. PZ, Small Craft Advisory from 4 PM this afternoon to 9 PM PST Monday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
