| Day | Date | High/Low | Forecast |
| Mon | 18th | 69/55 | Hazy sunshine remainder of day. Mostly clear evening. |
| Tue | 19th | 72/57 | Sunny day. Mostly clear evening. |
| Wed | 20th | 72/57 | Chance of some early morning low clouds; Otherwise, sunny day. Chance of late evening low clouds. |
| Thu | 21st | 70/58 | Good chance of early morning low clouds; Otherwise, mostly sunny day with some high clouds. Chance of late evening low clouds. |
| Fri | 22nd | 69/57 | Good chance of early morning low clouds; Otherwise, mostly sunny day. Chance of evening low clouds. |
Synopsis
A large, upper level trough covers much of the intermountain West today. An embedded, “inside slider” type trough passed through southern California, and that induced some off-shore flow aloft this morning (nothing noticeable close to sea level). Significant wind (at least 25 mph gusts) was restricted to higher elevations (a few reports to 50 mph early morning), but the wind flow did help disrupt the coastal low cloud field. It’s noticeably warmer today in inland areas, but warming was more modest closer to the coast (campus included).
A secondary “inside slider” is forecast to pass through the state tonight into early tomorrow. Its passage should help to re-enforce the low level, off-shore flow tomorrow. So, the warming trend should continue into tomorrow (modest in most areas due to proximity of the aforementioned, large trough). The deviation from normal temperatures should be least near the coast (diluted, shallow marine layer predicted).
By Wednesday, marginal on-shore flow may foster a return of coastal low clouds (not necessarily as a solid blanket of low clouds). Early morning low clouds should be more general across the coastal plain Thursday onward (daily clearing before late morning). Computer model consensus leans toward Wednesday being the warmest of the next several days, but I wouldn’t be surprised if the coastal plain winds up the same or even a tad cooler than it gets tomorrow (leaned today’s campus forecast that way). That should depend on how quickly the local, low cloud field returns. General but minor cooling should follow the rest of the week. Temperatures in most areas should be seasonable.
With the wind flow pattern getting mostly weaker in the Southland, subtle wind flow shifts will probably play a role in day to day weather (e.g. how the marine layer “behaves” from one day to the next). Also, we’ve reached the point in the “rainy” season when prospects for wet weather are almost nil (spotty marine layer mist being the most common form of wet weather). Today’s model consensus favors dry weather over the whole state for the rest of May (likely June too unless early season, “monsoon” moisture shows up).
Next issued forecast/synopsis should be on Friday, 22 May.