Periods of locally gusty Santa Ana winds will continue into Thursday, with weaker winds for Friday into early next week. Inland areas will continue to be unseasonably warm through Friday followed by slight cooling for the weekend. Cooling is expected to spread inland next week as high pressure aloft weakens and onshore flow develops. Some return of night and morning coastal low clouds and fog will likely have to wait for a few days.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Today was likely the warmest day of the week with inland temperatures reaching the mid 80s for some areas. Sfc pressure gradients remain offshore with -12.3 mb SAN-TPH and -4.3 mb SAN- DAG. The Santa Ana winds have weakened slightly and become a little more localized, with a handful of locations reporting wind gusts of 45-55 mph in the last hour.
From previous discussion, Expect gradually weakening Santa Ana winds through tomorrow night. There will be a few passing high clouds. Weak offshore winds, dry conditions and clear skies overnight will lead to efficient radiational cooling so some of the wind- sheltered inland areas may get close to the freezing mark again tonight, with some patchy frost being possible in those areas. It seems unlikely that low clouds will develop during the early morning hours along the coastal areas before later this weekend.
Friday through Tuesday, Mild to moderate Santa Ana conditions will continue to diminish gradually into the weekend as the pressure gradient weakens with the ridge expanding northwestward. As this occurs, the ridge axis will become more elongated and negatively tilted, which will act as a blocking pattern and keep the dry conditions persisting through the beginning of next week, with only a gradual cooldown as some troughing to the east over central CONUS does help to influence the region with cooler air advection from the north, although with the ridge still in control, along with weak downsloping winds, temperatures will remain above average. Offshore winds will predominantly keep any development of the marine layer mostly confined over the coastal waters, although there could be a return of some fog/low clouds moving in over portions of the coast and inland areas of San Diego and Orange counties beginning later in the weekend. The development of the marine layer will continue to become more prevalent going into early next week. There is also some indication with some of the deterministic models which shows possible subtropical influence from a weakening decaying wave moving up from the southern Pacific Ocean along 120W, which may bring about a slight chance of a shower/thunderstorm over the mountains of San Diego County during the afternoon on Tuesday of next week, although this is still quite far out and therefore is subject to change. Looking beyond the forecast, ensembles are still hinting a return in the chance of precipitation towards the end of next week as there begins a change in the longwave pattern with a break down in the ridge over the E Pac waters.
150400z, Clear skies and VFR conditions through Thursday evening.
Areas of east to northeast wind gusts 30-40 kts mainly in foothills and near mountain passes with corridors of gusts 20-30 kts stretching into into adjacent inland valleys until 20z Thu. Mod up/downdrafts and local LLWS in lee of mountains. Small (20-30%) chance for patchy fog development off the SD County Coast starting 03z Fri.
No hazardous marine conditions are expected through Sunday.
Ca, None. PZ, None.
