| Day | Date | High/Low | Forecast |
| Mon | 17th | 71/60 | Morning low clouds; Sunny afternoon. Chance of late evening low clouds. |
| Tue | 18th | 73/59 | Chance of early morning low clouds; Otherwise, mostly sunny day. Chance of late evening low clouds. |
| Wed | 19th | 72/59 | Good chance of early morning low clouds; Otherwise, mostly sunny day. Chance of late evening low clouds. |
| Thu | 20th | 72/60 | Good chance of early morning low clouds; Otherwise, mostly sunny day. Chance of late evening low clouds. |
| Fri | 21st | 73/61 | Chance of early morning low clouds; Otherwise, mostly sunny day. Chance of late evening low clouds. |
Synopsis
Upper level low pressure covers the western states with it being strongest in the upper Great Basin region today. The various, computer models aren’t forecasting major changes with this pattern for the work week. Low level on-shore flow in southern California does undergo some changes at times. In fact, it’s forecast to go slightly off-shore tomorrow (just briefly). However, the overall pattern doesn’t change enough to significantly dilute the marine layer, let alone get rid of it (with respect to the coastal plain). Subtle day to day changes in the wind flow pattern may alter the “behavior” of the marine layer clouds on a given day, but the effect on day to day temperature changes should be minor in the coastal plain. For this week, even trends in the coastal valleys should be modest at best (due to predicted presence of the upper level trough). I’ve respected the model forecast for slight warming tomorrow (brief off-shore flow), but it’s possible that the off-shore flow will glide over the current marine layer, and no apparent weather change may occur near the coast in L.A. County. [FYI–Astronomically speaking, summer begins on Thursday (20th) at 1:50 PM]
High pressure aloft is expected to strengthen in the desert Southwest this weekend (till early next week). This should lead to moderately warmer weather for areas away from the coast. For areas near the coast, only minor warming is expected. That is assuming that the predicted, shallow marine layer doesn’t develop significant holes in the low cloud field. Should that occur, it could get several degrees higher this weekend near the coast than I currently expect (even flirting with 80 degrees at UCLA).
The longer range models show a new though weak, upper level trough developing over the West Coast. That should result in general cooling as the week progresses (most of that occurring late in the week). Slightly cooler than normal may continue for the remainder of the month. Summer heat in the coastal plain is coming, but apparently not this month, if today’s model consensus holds up. Enjoy the mild weather while it lasts.
Note: Lasting through most of September, I plan to reduce regularly, issued forecasts/synopses to once a week. The next issued forecast will be on Monday, 24 June.