| Day | Date | High/Low | Forecast |
| Fri | 4th | 66/51 | Sunny day. Mostly clear evening. |
| Sat | 5th | 74/54 | Mostly sunny day with some high clouds. Some evening high clouds. |
| Sun | 6th | 76/56 | Mostly sunny day with some high clouds. Some evening high clouds. |
| Mon | 7th | 72/56 | Mostly sunny day with some high clouds. Some evening high clouds. |
| Tue | 8th | 75/58 | Mostly sunny day with some high clouds. Mostly clear evening. |
Synopsis
A cold, upper level trough promoted some showers and brief-lived thunderstorms yesterday afternoon. They occurred mainly around the higher mountains and adjacent, coastal valleys. Some shower clouds survived long enough to bring sprinkles/light rain to parts of the L.A. County, coastal plain late in the afternoon (included UCLA, based on radar imagery). Rainfall was mostly a tenth inch or less, but where thunderstorms occurred, some totals between a quarter and two-thirds inch were recorded.
The aforementioned trough now is over Arizona and moving eastward slowly. Still, sufficient atmospheric instability remains to support isolated mountain showers and a brief-lived thunderstorm or two (showers over Tehachapi Mountains pretty weak but a couple decent cells noted on radar in San Diego County, as of this writing). Today should be the last day of any wet weather in southern California. High pressure aloft will build into the state over the weekend. It should be the dominant weather influencer in the Southland for most of next week.
A weak, marginal, off-shore flow should promote noticeable, daytime warming in most areas tomorrow. Further warming is anticipated on Sunday, especially if some deep layered, easterly wind flow occurs as some computer models project (coastal valleys warming warming well into the 80s; Inland coastal plain could reach 80 degrees). A leveling off or even slight cooling (relative to Sunday readings) is expected on Monday. A passing, upper level trough should temporarily weaken the Southwest high pressure (enough to allow some wet weather over the northern third of the state on Monday). The warming trend should resume on Tuesday. The peak warm day should be on Thursday (widespread 90 degree weather probable in the valleys Wednesday-Thursday). Cooling should develop by Friday though it should be minor at first.
I am currently expecting that areas near the coast will be much warmer than normal for much of next week. The one thing that could spoil this forecast is if a shallow, but effective marine layer develops. Even if it’s just a diluted marine layer (no widespread low clouds/fog), temperatures near the coast (UCLA included) likely wouldn’t reach 80 degrees. It would be more like typical, late spring weather where it infrequently gets quite warm in the valleys but remains mild near the coast (thanks to marine layer).
Most of the longer range models show a new, upper level trough reaching the West Coast over the subsequent weekend. A defined marine layer should form by that time even if none occurs earlier in the week. So, a return to seasonable or even slightly cooler than normal weather is expected (12-13 April). Depending on how strong the trough ends up, the marine layer could deepen enough to promote spotty, early morning mist/drizzle (13th). However, the days of getting significant precipitation are probably over for southern California (this rainy season). No relevant threat of wet weather is foreseen for the remainder of the month (May and June aren’t known for relevant rainfall). Of course, Mother Nature may correct me at some point.
Next issued forecast/synopsis may be on Monday, 7 April.