| Day | Date | High/Low | Forecast |
| Mon | 2nd | 68/50 | Partly cloudy through the evening with high clouds |
| Tue | 3rd | 67/48 | Partly cloudy through the evening with high clouds |
| Wed | 4th | 65/49 | Chance of early morning fog/low clouds; Otherwise, mostly sunny day with some high clouds. Some high clouds in the evening. |
| Thu | 5th | 71/54 | Sunny day. Clear evening. |
| Fri | 6th | 77/56 | Sunny day. Clear evening. |
Synopsis
At the surface, off-shore flow continues today, but it’s been on a decaying phase for a couple days now. The off-shore flow produced, for the most part, slightly warmer weather than I predicted last week (included a smattering of 80 degree readings in some valley locales). The off-shore flow was stronger than anticipated despite being a relatively shallow system (on-shore flow high aloft promoted varying amounts of sub-tropical, high clouds. Even today, it wound up a little warmer at UCLA than I expected (peaked at 72 degrees).
The “split flow” in the Northeast Pacific jet stream also continues today. Occasional, weak troughs in the southern stream travel toward the state, but other than variable, mid/high clouds, these troughs have been uneventful, weather-wise. The jet steam is forecast to consolidate back into one unified stream by the latter half of the week. The current, rather disorganized looking trough off the state coast will migrate inland on Wednesday. This should lead to weak on-shore flow for a short period (as early as tomorrow afternoon but ending by Thursday morning). Daytime temperatures should fall back to normal or even get slightly below normal on Wednesday (latter most probable where a shallow marine layer forms). Considering how warm it got on campus today, I thought about amending Tuesday temperatures up slightly, but if the sea breeze starts as the computer models project, my forecast should be alright. Wednesday temperatures may be too low though, if the predicted, shallow marine layer fails to materialize (even a diluted one).
With high pressure aloft predicted to return over the state, warmer than normal weather should again prevail (peaking early in the weekend). The predicted off-shore flow should be a weak one (similar to the Thanksgiving weekend event). So, Santa Ana wind prone areas shouldn’t experience peak speeds above 50 mph (applicable higher mountains; lowland areas with peak gusts 35 mph). This should be in the Thursday to Friday period (off-shore flow decaying slowly thereafter though not going away entirely over the weekend). There is some chance that the models are again under predicting the maximum warmth of the upcoming off-shore flow. There is a chance that the campus area will reach 80 degrees for a day or two on Friday-Saturday.
Most of the longer range models predict high pressure aloft remaining just west of the state next week. This would promote warmer than normal weather (most or all of next week). However, a number of model runs show a few “inside slider” troughs passing through or near the Southland (first one early next week). A few model solutions depict one strong enough trough to trigger cold air, instability showers (mostly over and adjacent to higher mountains). However, as with most “inside sliders” these troughs would be more wind storms than wet storms. At this point, I’m leaning against any showers in southern California next week (assumes today’s model consensus holds true). The chief uncertainty concerns temperature and wind. Depending on which solution verifies, it could be cool and windy at times or relatively warm and breezy in Santa Ana wind prone areas (model consensus currently leans toward latter scenario but not by wide margin).
Next issued forecast/synopsis should be on Friday, 6 December.