| Day | Date | High/Low | Forecast |
| Fri | 21st | 76/58 | Mostly sunny day with some high clouds. Mostly clear evening. |
| Sat | 22nd | 77/59 | Mostly sunny day with some high clouds. Mostly clear evening. |
| Sun | 23rd | 78/58 | Sunny day. Mostly clear evening. |
| Mon | 24th | 77/59 | Mostly sunny day except chance of some early morning fog. Mostly clear evening. |
| Tue | 25th | 80/61 | Mostly sunny day with some high clouds. Some evening high clouds. |
Synopsis
There’s not much to say today. High pressure aloft that started to nose into California (from the Pacific) yesterday has a firm grip on the state today. A resultant, weak, off-shore flow will continue in some form for several days (marginal off-shore flow at times) . This should continue to promote warmer than normal weather west of the mountains. Day to day temperatures changes may vary some, depending on how strong the off-shore flow gradients gets. Variations in upper air support (for off-shore flow) should also play a role. The latest, computer model forecasts show a short term peak in temperatures on Sunday (minor drop on Monday when a marginal, on-shore flow is possible). Greater warming is possible later next week when subsidence (sinking air motion) from a sub-tropical, high pressure aloft produces greater warming (some chance at isolated, valley readings reaching 90 degrees for the first time this year).
My most recent forecast over predicted high temperatures at UCLA (off by a few to several degrees, including today). Despite the presence of off-shore flow, a counter current (i.e. the sea breeze) managed to limit warming near the coast (also reason for areas of dense fog overnight to early, daylight hours). The various models do show the possibility of widespread, fog/low clouds late Sunday night into Monday morning (possible, brief, on-shore flow, albeit pretty weak). Otherwise, no relevant marine layer is forecast through most of next week. Of course, if a shallow but defined marine layer persists (doesn’t need to manifest itself as fog/low clouds), any off-shore flow air may not mix down to the ground fully. In that case, I may be overforecasting temperatures again for the campus area (more confident in greater warming for well inland areas though).
Most of the longer range models do show a weak, Pacific, upper level trough at the end of the month (a “closed” low pressure, in this case). The center of the trough is expected to travel to the south of our region when it makes landfall in northern Baja California. The model consensus doesn’t favor any showers reaching the Southland (wouldn’t rule out some sprinkles in places, however). At the least, a cooling trend should develop (falling back to near normal temperatures by next Friday). The model consensus keeps the “storm gate” open to the state through the first week of March. None of the predicted storms look impressive in terms of precipitation (a little better amounts northern California versus down here). Assuming the model consensus holds true (???), these storms would be the common, cold type systems that quickly move through the state. Even if the Southland stays mostly rain free (some model scenarios favor this), the beginning period in March should be a cool one.
Next issued forecast/synopsis may be on Monday, 24 February.