| Day | Date | High/Low | Forecast |
| Mon | 7th | 76/61 | Mostly sunny remainder of day with variable high clouds. Chance of late evening low clouds/fog. |
| Tue | 8th | 76/61 | Mostly sunny day except chance of early morning low clouds/fog. Chance of late evening low clouds/fog. |
| Wed | 9th | 76/61 | Mostly sunny day except chance of early morning low clouds/fog. Chance of late evening low clouds/fog. |
| Thu | 10th | 77/62 | Mostly sunny day except chance of early morning low clouds/fog. Chance of late evening low clouds/fog. |
| Fri | 11th | 77/62 | Mostly sunny day except chance of early morning low clouds/fog. Chance of late evening low clouds/fog. |
Synopsis
The calendar says October, but the current weather pattern in southern California is reminiscent of July. High pressure aloft covers the Southwest. There is a weak, upper level trough west of the state. It’s entraining sufficient, upper level moisture to promote variable high clouds (scattered, mostly afternoon clouds over the mountain/desert region too). In addition, a shallow but effective (in moderating coastal temperatures) marine layer is more typical of summer than early Autumn.
All the computer models predict only minor day to day changes this week in the wind flow pattern affecting the Southland. They have been predicting, on occasion, the dilution of the marine layer (favors some warming though nothing like the heat in the coastal valleys). Except for temporary, selected “holes” in the low cloud field, this marine layer has helped keep areas near the coast from warming much (certainly staying cooler than model forecasts). I’ve pretty much given up on any modest warming trend in spite of some model predictions. For today’s forecast, I wrote for a tad warmer late, work week. However, subtle wind shifts and selective, temporary dilutions of the marine layer could promote some modest warming for a day or two (not limited to late week period).
The model consensus is far from unanimous, but there is general agreement on a cooling trend (all of southern California) this weekend (lasting through Monday). A deeper marine layer should result in less fog near the coast (maybe just hazy). The magnitude of cooling is still uncertain (some model disagreement), but there are solutions favoring slightly cooler than normal weather (again, all of the Southland…not just the coastal plain) on Sunday/Monday.
Model solutions are varied for later next week (nothing unusual for model forecasts). There is one scenario depicting a weak, Santa Ana wind event (first one of the autumn) sometime in the Tuesday-Wednesday period. A return to warmer than normal weather would occur, but at this point, no triple digit heat is foreseen with this scenario (campus might see some 80 degree weather for a couple days). Other model solutions show just weak high pressure aloft. It promotes seasonable to slightly warmer than normal weather for most of next week. (weather wild card being any, possible marine layer sheltering areas near the coast from much warming). If the model consensus holds up, the entire state should see no relevant threat of wet weather next week (possibly week thereafter too).
Next issued forecast/synopsis may be on Friday, 11 October.