| Day | Date | High/Low | Forecast |
| Mon | 12th | 75/58 | Sunny afternoon. Mostly clear evening. |
| Tue | 13th | 79/60 | Sunny day. Mostly clear evening. |
| Wed | 14th | 81/61 | Mostly sunny day with some. high clouds. Some evening high clouds. |
| Thu | 15th | 82/62 | Mostly sunny day with some. high clouds. Some evening high clouds. |
| Fri | 16th | 82/60 | Sunny day. Mostly clear evening. |
Synopsis
Off-shore flow says it all for this week. High pressure aloft covers most of the West today, and even the Pacific Northwest states will have a reprieve from the common place, wet weather. In southern California, the warmer than normal weather that began this past weekend will continue through the week (likely extending into the MLK, Jr. holiday weekend). The windy weather in Santa Ana wind prone areas didn’t diminish as much as I expected over the past weekend. Today, however,, it was less windy today compared with yesterday (gusts over 65 in the higher mountains very isolated). Of course, most of the L.A. Basin didn’t experience any significant wind (gusts 25 mph or higher).
Today wound up a little cooler than I anticipated (afternoon a couple to few degrees lower than yesterday in many locales). Surface off-shore flow weakened some, but it shouldn’t have been enough to promote cooling west of the mountains. Apparently the weaker off-shore flow led to less vertical air mixing (i.e. subsidence). That should not be the case for the next few days. High pressure aloft is forecast to strengthen some, which should lead to better subsidence. Widespread 80 degree weather west of the mountains should prevail for at least a couple days (possibly as early as tomorrow). The center of high pressure aloft isn’t forecast to get any closer than northern California. That may be just a little too far away for temperatures to reach the upper 80s in the Southland, but isolated mid-80s is a plausible scenario (some beaches as warm as the upper 70s, if deep layered easterly wind flow occurs).
Wind speeds in Santa Ana wind prone areas may increase again late tonight/tomorrow and persist into Wednesday, but peak wind gusts should stay a bit lower than recent days. If deep layered, easterly wind flow occurs, the campus areas may be relatively calm (not common to get relevant wind with such wind flow pattern). The off-shore flow should weaken in the second half of the week but not by much. Some model forecast even predict a brief strengthening on Saturday. As with many off-shore flow patterns, most or all of the L.A. Basin shouldn’t see wind gusts reach 25 mph (under 15 mph being common place).
The longer range models continue to show a pattern shift in the jet stream location over the northeastern Pacific (a change to bring the storm track through California again). However, they’ve slowly back pedaled on when this would occur. At one time, it was supposed to occur by the 17th (this Saturday). The recent, model consensus has pushed the date back to the 21st (late in the day). Still, the chance for any wet weather reaching the Southland looks minimal at first (isolated showers on the 22nd). The first real threat of wet weather may not occur till the 24th or 25th (day earlier in northern California). Model consensus is poor on weather details, but generally speaking, no big storms are foreseen down in southern California. A return to cooler than normal weather looks likely, but whether widespread, significant rains fall (half inch or more in the lowlands away from the mountains), that is big question mark (at this time).
Next issued forecast/synopsis may occur this Friday, 16 January, time permitting.