textproduct: San Diego

SYNOPSIS

Gusty Santa Ana winds will diminish today, then return on Saturday afternoon into early Sunday with the stronger gusts mostly 45 mph or less. Some patchy low clouds return tonight at the coast. High temperatures as much as 10 to 15 degrees above average for the valleys will continue through Saturday followed be a gradual cooling trend for the early an middle part of next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Tonight through tomorrow night...

Mild Santa Ana conditions continue to persist. There will be a few passing high clouds and gusty winds across some of the higher terrain and through the passes. It will still be on the mild side, with temperatures within the inland valleys and the IE getting up into the mid 80s for some areas. Gusty winds will begin to decouple and diminish going into the later evening hours. Weak offshore winds and clear skies overnight will lead to some sufficient radiational cooling, although temperatures will be slightly warmer than they were the previous night so the probability of any patchy areas of frost within the wind-protected valleys, although there still is a minimal threat for some of the higher valleys. HREF guidance is suggesting that the marine layer will begin to return later tonight into tomorrow morning, although this should be mainly confined just along the coast if it does form, and likely be spotty in terms of broken coverage. There will also be the possibility of some areas of fog as well right along the coast, and possibly within some of the inland valleys extending to around 5 to 10 miles inland for San Diego and Orange counties.

Friday through Tuesday...

Mild to moderate Santa Ana conditions will continue to diminish through this 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. Weak offshore winds overnight will predominantly keep any development of the marine layer mostly confined over the coastal waters and right along the coast through the weekend, although there will be a better surge of the marine layer going into the early half of next week with more of the fog/low clouds penetrating further into the inland areas of San Diego and Orange counties with the inversion beginning to lift and onshore flow continues to be more persistent. Looking a bit 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, which may allow for some showers to impact the region as early as Thursday of next week as the GFS deterministic model alludes to, with a cooldown also going into the end of next week.

AVIATION

160030Z...Patchy FG reducing VIS to 1/4-1SM around Point Loma and the San Diego Bay, reaching over KSAN. FG lingers off-and-on in this area through 06z tonight then develops farther north along the OC/SD county coasts 08-11z Fri, locally reducing vis/cigs below LIFR conditions. Low clouds and FG that form should begin to clear after 15Z in SD County and after 18Z in Orange County. Otherwise, VFR and clear skies for inland areas.

MARINE

Areas of dense fog have formed around Point Loma and in the San Diego Bay. More fog is expected to develop across the inner and outer waters this evening and tonight, scattering Friday morning. 40- 50% chance for fog redevelopment over the waters Friday afternoon and night. Visibilities below 1 NM observed in fog.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.