Weather Synopsis – April 2, 2024

James Murakami

Tue2nd69/54Sunny day. Clear evening.
Wed3rd68/53Sunny day. Chance of low clouds developing late evening.
Thu4th61/48Mostly cloudy morning; Possible partial afternoon clearing and breezy at times; Mostly cloudy evening with a chance of light showers.
Fri5th57/47Mostly cloudy morning with a chance of showers; Partly cloudy afternoon and breezy at times. Clearing in the evening with decreasing wind.
Sat6th62/48Mostly sunny day. Mostly clear evening.


This past weekend’s storm played out generally as I expected. However, the initial passage of the cold front Saturday morning produced a different outcome than I anticipated. The front slowed down in forward progress and nearly stalled just to the east of L.A. County. That led to higher storm totals in some areas than expected (by me). UCLA wound up with 2.61 inches for the period Friday evening through Sunday (1 – 2.75 inches common in the lowland away from the mountains). For the month of March, the campus tally was 5.74 inches (12th wettest March in campus history…9.65 inches last March). For the water year to date (began 1 October, 2023 and will end 30 September of this year), the total stands at 31.18 inches (11th wettest year to date…40.35 inches or 3rd wettest season previous year). Interestingly, after have coming through an extended drought in recent years, it’s been the wettest back to back water years in UCLA history. The two year total (so far) is 71.55 inches (previous record was a 61.38 inches Oct 1996 – Sep 1998).

A moderate strength ridge of high pressure covers the state today. A marginal, off-shore flow that started yesterday has promoted noticeable, daytime warming (a far cry from last Saturday when most areas failed to reach 60 degrees). Many inland areas warmed well into the 70s today (warming near the coast more muted due to limited, off-shore flow winds…relevant wind only at higher elevations). Not much weather change is expected tomorrow. Inland areas may warm a tad more than it did today, but areas closer to the coast will probably wind up a bit cooler tomorrow (assumes sea breeze starts a little sooner than today…predicted weakening influence from high pressure aloft).

A new, Pacific trough will approach the state tomorrow. Wet weather is forecast to reach the northwest corner of the state by late in the afternoon. Areas of precipitation is likely in northern California Wednesday night into Thursday. By Thursday evening showers should reach northwest sections of southern California. The best shot as widespread, wet weather in the Southland should be Friday morning (based on today’s computer model consensus). Clearing should commence (northwest to southeast) late Friday evening or early Saturday. For a change, this weekend should be dry one though it should be slightly cooler than normal.

Like the past weekend storm, the one slated for late this week will be a cold one (snow levels may drop to 3000 feet in places for a short time). However, its projected path to southern California will be less favorable, water vapor content-wise. L.A. County rainfall in the lowlands should be mostly under a quarter inch. If the storm takes more of an “inside slider” path (i.e. mostly over land), widespread, measurable precipitation may not even occur (some model solutions lean in this direction). It would also lead to a windier system (more than currently anticipated). Cold air instability could still support isolated thunderstorms on Friday, but even such rain clouds should produce less rain than with the past weekend’s storm). Snow at resort level will probably be no more than six inches.

A different, upper level trough is forecast to arrive in the Southland early Monday. This one has a better chance at being an “inside slider” trough (more wind than wet weather). However, there is some chance at afternoon, cold air instability showers and thunderstorms (mainly over and adjacent to the higher mountains). Predicted northerly winds over L.A. County in the afternoon could direct mountain showers toward the coastal plain. At this point, this scenario is a minority model solution (i.e. low confidence in outcome verifying). In any case, cooler than normal weather should prevail in the early part of next week.

Most of the longer range models show high pressure building over the Southland by the second half of next week. This should lead to warmer than normal weather (similar to current pattern). However, there are some model solutions allowing a weak storm to reach the Southland toward the end of next week. Some of the longer range models even re-open the “storm gate” for the period after the subsequent weekend (no major storms predicted though). Of course, we’re getting into the period normally of low confidence levels.

Next issued forecast/synopsis may be on Thursday, 4 April.