| Day | Date | High/Low | Forecast |
| Thu | 9th | 72/59 | Becoming partly cloudy with high clouds in the afternoon. Partly to mostly cloudy evening. |
| Fri | 10th | 68/58 | Mostly cloudy through the evening. Slight chance of afternoon light showers. Chance of evening light showers. |
| Sat | 11th | 67/57 | Partly cloudy with a slight chance of light showers. Partly to mostly cloudy evening with an increasing chance of rain. |
| Sun | 12th | 64/54 | Good chance of morning rain, mainly early; Partly cloudy afternoon and evening, and possibly breezy at times with a slight chance of showers. |
| Mon | 13th | 65/53 | Partly cloudy day and possibly breezy at times by afternoon. Becoming mostly clear in the evening. |
Synopsis
While fine details of expected weather remained to be defined, the numerical models started agreeing on an approaching, “cut-off” low pressure (for a time). Widespread, wet weather was supposed to reach L.A. County by Saturday morning. Well, that unity started falling apart yesterday. Now, most of the models aren’t even enthusiastic about widespread, measurable rainfall in the Southland (valid tomorrow through Saturday morning). The predicted, “cut-off” low pressure is forecast to be fairly weak when it passes through the Southland (satellite imagery already showing a disorganized circulation). Some light showers may still begin tomorrow morning north of Point Conception, but a relevant chance of showers in L.A. County probably won’t occur till late tomorrow evening or during the pre-dawn hours of Saturday. Storm totals away from the mountains should be well under a tenth inch (maybe, quarter inch maximum rainfall around some of the mountains). Snow levels shouldn’t drop below 6500 feet, and nothing more than a dusting is probable at that elevation (higher elevations might be able to get an inch or so of “wet snow”.
Earlier this week, some model solutions showed a decent strength, cold, “cut-off” low pressure following on the heels of an earlier “cut-off” (the one expected tomorrow evening). That scenario now looks to be the probable outcome. A period of showers and possibly isolated, brief-lived thunderstorms are expected in L.A. County sometime late Saturday evening into Sunday morning (possibly lingering into early afternoon, depending on the slowness of the predicted, “cut-off” low pressure). Some areas, especially around/adjacent to the mountains, may experience brief, heavy intensity showers (even without thunderstorms). Some model solutions even keep the “cut-off” nearby into Monday morning. So, some showery weather is possible well into Monday, if this scenario plays out. However, showers should be to the east and south of L.A. County by sunrise Monday (reason I decided to omit mention of showers for that day).
Due to the predicted, showery nature of the storm, rainfall in the lowlands will likely be quite varied. Storm totals away from the mountains should be in the quarter to three quarter inch range (over an inch possible if thunderstorms occur). Snow levels could fall to as low as 5000 feet on Sunday though it should be closer to 6000 feet for much of the storm period. A few to several inches of snow at resort level are probable by Monday afternoon.
A return to mundane, mostly sunny weather is expected for Tuesday-Wednesday next week. Some model solutions show a weak trough reaching the state by next Thursday. It looks too weak to pose a relevant threat of showers, but I wouldn’t rule out marine layer induced drizzle/light showers in some locales (assumes a defined marine layer forms by that time). Regardless, no significant warming cycle is anticipated next week (for now, expecting near seasonable temperatures most of next week, including subsequent weekend).
Next issued forecast/synopsis should be on Monday, 13 April.