| Day | Date | High/Low | Forecast |
| Fri | 16th | 66/57 | Low clouds clearing to a mostly sunny afternoon. Return of evening low clouds likely. |
| Sat | 17th | 65/55 | Possible partial afternoon clearing; Otherwise, mostly cloudy day. Partly cloudy evening. |
| Sun | 18th | 68/53 | Some morning low clouds; Otherwise, mostly sunny day. Mostly clear evening. |
| Mon | 19th | 74/56 | Sunny day. Clear evening. |
| Tue | 20th | 80/60 | Sunny day. Clear evening. |
Synopsis
A weak, upper level trough exists over the state today. One additional trough will pass through the state tomorrow before high pressure becomes the dominant, weather force on California (the Southwest, in general). Until that time, slightly cooler than normal weather will continue.
The predicted trough for tomorrow will be an “inside slider” type. It will be more a wind storm than rain storm (mainly interior sections…more so than today). Marine layer clouds may produce patchy mist early tomorrow. The various computer models show a better chance at marine layer induced drizzle or light showers late tomorrow afternoon or early evening. However, that threat should be confined to the western Inland Empire southward into San Diego County (west of the mountains). Even where wet weather occurs, rainfall should be no more than a few hundredths of an inch accumulation.
The chief weather uncertainty (to me) is whether any clearing of low clouds occur tomorrow. A deep marine layer may promote little clearing tomorrow until the trough passes through L.A. County (not predicted till late in the afternoon). There is a chance that afternoon clearing will occur over the ocean and coastal locales first (reverse clearing). While I don’t show it in this forecast, the afternoon sea breeze may blow briskly in places (strong on-shore flow predicted).
High pressure will begin to build into the state on Sunday. Mostly sunny weather should prevail that day. By Monday, some northerly winds should promote warmer than normal weather across most of the Southland (at the least, back to seasonable levels). The warming trend should pick up steam on Tuesday. Last week, there were some model solutions showing the center of high pressure aloft staying too far away from the Southland for strong warming. Recent model runs now favor a sub-tropical ridge located closer to southern California (located to the south). So, most of the Southland could experience warmth next week similar to what occurred over the previous weekend (some triple digit readings in the valleys a possibility). Closer to the coast, there is some chance of a lingering, shallow but defined marine layer sticking around. That would greatly limit the warming trend near the coast (campus included). At least for this forecast, the model consensus shows this scenario as unlikely. However, I’m not inclined to predict another 90 degree day at UCLA anytime next week (mid-80s, at best).
High pressure should weaken late next week, but no prominent trough is currently forecast for the end of the week. If this holds true, temperatures should lower through the subsequent weekend, but it should remain warmer than normal for most of the Southland. The immediate coast might be the exception (back to normal levels with possible return of fog).
Next issued forecast/synopsis may be on Monday, 19 May.