| Day | Date | High/Low | Forecast |
| Tue | 1st | 63/50 | Partly cloudy day and breezy at times. Some evening high clouds and possibly breezy at times. |
| Wed | 2nd | 64/51 | Mostly sunny day with some clouds possible; Possibly breezy at times in the afternoon. Becoming partly cloudy in the evening. |
| Thu | 3rd | 61/49 | Partly to mostly cloudy day with a chance of showers, mainly in the afternoon. Decreasing clouds in the evening. |
| Fri | 4th | 66/50 | Mostly sunny day with some distant afternoon clouds. Mostly clear evening. |
| Sat | 5th | 70/54 | Mostly sunny day with some high clouds. Some evening high clouds. |
Synopsis
A large, upper level, low pressure trough covers much of the West today. Embedded disturbances circulating about the low pressure circulation are producing showery weather in parts of the state (particularly around and over mountainous areas). Breezy weather also prevails in some parts of the state (southern California in particular today). Additional disturbances are forecast to pass through the state tonight through Thursday. By Friday afternoon, however, the current trough should begin a noticeable, eastward motion (i.e. tranquil weather on the way).
The embedded disturbances are taking an “inside slider” trajectory through the Southland. Some isolated showers have occurred (none in L.A. County, to my knowledge). Radar data shows scattered showers moving down the state from the northwest, but a “rain shadow” effect should prevent any showers from occurring in the L.A. Basin tonight. North facing mountains, especially in the Tehachapis stand a good chance at showers (snow levels getting as low as 3500 feet). West of the mountains, areas down toward San Diego County may get some showers (mostly up against the mountains).
Wednesday should see less cold air instability showers (mountains vulnerable in the afternoon hours though). If some of today’s computer models are right, the predicted disturbance on Thursday may produce more widespread, instability showers (including isolated, afternoon thunderstorm). This disturbance is expected to take a marginal, “inside slider” trajectory, but some models produce a small, low level low pressure over the inner coastal waters. If this occurs, the current, “rain shadow” effect should be absent for much of Thursday (daytime hours). Showers should still favor areas near/over the higher mountains, but lowland areas closer to the coast might see a shower or two (wouldn’t rule out a brief-lived thunderstorm either). Confidence in widespread shower activity isn’t high (at this time), but I decided to write in a “chance of showers” in today’s forecast.
Where showers occur on Thursday, rainfall should be mostly well under a quarter inch (under a tenth inch probably most common). Where thunderstorms occur, it’s possible for rainfall to reach a half inch (assumes thunderstorm doesn’t fade too quickly). Snow levels may fall to as low as 4000 feet that day, but accumulations shouldn’t be relevant (dusting at 4000 feet, perhaps up to a couple inches at resort level).
Although there may be enough cold air instability lingering on Friday (especially if upper low pressure remains in the “neighborhood”), any mountain showers that day (afternoon hours) should be minor (short-lived and isolated in coverage). High pressure aloft should begin a warming trend this weekend. Warmer than normal weather is expected by Sunday (Saturday for more inland locales). A passing trough over northern California may temporarily halt the warming trend on Monday (maybe a tad cooler that day near the coast). For the rest of the work week, temperatures should trend upward. If some of today’s model forecasts are right, high pressure could induce widespread 80 degree weather for the second half of next week (90s in many valley locales). Cooler weather is anticipated over the subsequent weekend, but it should remain warmer than normal.
Most of the longer range models don’t show any relevant storms reaching the state after this week. April can be wet at times (mostly first half of the month), but generally, storms tend to be minor events. The chances for widespread, soaking precipitation are probably over for this rain season. However, one can never be sure.
Next issued forecast/synopsis may be on Friday, 4 April.