| Day | Date | High/Low | Forecast |
| Mon | 16th | 67/54 | Mostly sunny day with some high clouds. Some evening high clouds; Possibly breezy at times late tonight. |
| Tue | 17th | 75/57 | Sunny day; Possibly breezy at times in the morning. Clear evening. |
| Wed | 18th | 79/56 | Sunny day. Mostly clear evening. |
| Thu | 19th | 76/53 | Mostly sunny day with scattered high clouds. Scattered evening high clouds. |
| Fri | 20th | 70/51 | Mostly sunny day with scattered high clouds. Scattered evening high clouds. |
Synopsis
A marginal off-shore flow exists today (still on-shore toward the low desert at the surface), but unlike yesterday, no relevant wind in the mountains exist this afternoon (off-shore flow wind, that is). Off-shore flow aloft is expected to increase tonight through tomorrow. So, Santa Ana wind prone areas should experience increasing wind tonight, especially higher elevation locales (peaking tomorrow morning). Predicted conditions appear marginal for the campus area, but I decided to include it with this forecast. Peak wind gusts at UCLA shouldn’t exceed 30 mph (most gusts probably no higher than 23 mph), but more typical, Santa Ana wind prone areas may see gusts to 50 mph in the higher mountains (40 mph lowland spots). Although surface off-shore flow will peak on Wednesday, greatly diminished, upper air support that day should actually lead to weaker winds in most locales prone to Santa Ana winds (far from calm in some areas, however). A return to marginal off-shore flow on Thursday should lead to little, relevant wind in the wind prone locales. A return to weak on-shore flow is expected by Friday afternoon (lasting into the weekend).
High clouds were more substantial in southern California than I anticipated (partly related to a storm crossing through northern California today). Fortunately for my forecast, clouds didn’t thicken too quickly to affect my forecast maximum temperature for today. There should be much less high clouds tomorrow as high pressure aloft strengthens. Variable high clouds should return beginning late Wednesday evening or Thursday, but clouds probably won’t get as extensive as today (I think).
The developing off-shore flow should promote warmer than normal weather tomorrow through Friday (even Saturday, if some computer model solutions are right). The peak warm day should be Wednesday, but Thursday shouldn’t be much different. With the shortest daylight hours and lowest solar insolation of the year, this time of year is the least likely period for 80 degree weather (in southern California). However, the predicted high pressure aloft and surface off-shore flow could promote widespread 80 degree weather for a couple days (areas near the coast only on Wednesday, if it actually happens).
Most models show a weakening, Pacific storm passing to our north late Saturday into early Sunday. Most model solutions keep the threat of wet weather well to our north (minor to modest storm expected northern California), but a return to weak on-shore flow should bring temperatures back down to near seasonal normals in most areas (most probable near the coast on Saturday and Sunday for locales farther inland). At least for now, the models aren’t inclined to favor a return of marine layer clouds (at least, no widespread, areal coverage). That could change next week, depending on which model solution verifies.
Longer range model forecasts vary, but most show occasional storms affecting northern California next week (including a chance for a white Christmas in the northern Sierras). It’s less clear of a forecast down in the Southland. Most solutions keep most of the Southland dry next week (i.e. south of Point Conception), but some do actually predict some wet weather (sometime Monday-Tuesday period). It would be a minor to modest strength storm if the wet scenario verifies. For the time being, I’m sticking with the model consensus (dry weather with near seasonable temperatures). Of course, much could change between now and next week.
Next issued forecast/synopsis will be on Thursday, 19 December (last one for this year).