Weather Synopsis – May 29, 2024

James Murakami

Wed29th67/56Low clouds clearing late morning; Sunny afternoon. Even low clouds returning.
Thu30th68/57Morning low clouds likely but sunny afternoon. Chance of evening low clouds.
Fri31st68/58Morning low clouds likely but sunny afternoon. Chance of evening low clouds.
Sat1st June67/57Morning low clouds likely but sunny afternoon. Chance of evening low clouds.
Sun2nd67/57Morning low clouds likely but sunny afternoon. Chance of evening low clouds.


The current, weather pattern affecting the state isn’t that unusual except for its regularity. Ridges of high pressure aloft get regularly replaced by weak troughs (wet weather only in Washington state with recent troughs). Even when high pressure covers the state, low level forces of on-shore flow predominate, especially in southern California. For Southland residents near the coast, “May Gray” has been unusually persistent. None of the numerical models predict significant changes for at least a few days. So, barring an unexpected, widespread intrusion of dry air aloft into the low cloud field, more of the same can be expected.

I’ve set the forecast more or less on auto-pilot, but subtle day to day changes in the wind flow pattern may alter the “behavior” of marine layer, low clouds on any given day. Unlike farther inland, a shallower marine layer isn’t expected to induce relevant warming (on-shore flow predicted to remain too strong for more significant warming near the coast). Some of the model forecasts show the marine layer deepening again for the weekend. This should promote more persistent low clouds in the coastal valleys and modestly lower temperatures (relative to yesterday), but the “May Gray” weather should continue in the coastal plain.

High pressure aloft is forecast to build back into the state next week, but a number of model forecasts maintain a healthy, low level, on-shore flow. The resultant weather may be continued, persistent low clouds near the coast. Temperatures near the coast might edge upward but only a little (no better than reaching seasonal normals). More significant warming is probable for more well inland areas. Valley locales may get a little warmer than previous warming cycles (maybe isolated 90 degree readings by the second half of the week?)

A number of the longer range forecasts show a sub-tropical, upper low pressure developing west of Baja California late next week. If this low pressure taps into sub-tropical moisture, a risk for instability showers and thunderstorms would occur (by subsequent weekend). The chief threat for showers would occur around the mountains. At the least, variable mid/high clouds could move into the Southland. There’s also a chance that the atmospheric instability could help disrupt the local, low cloud field. The result would be mostly sunny weather and noticeable warming extending to the coast. This is still speculation, however. Much could change with the model forecasts in the coming days.

NOTE: No forecast will be issued next week (3 – 7 June). The next issued forecast/synopsis may be on Tuesday, 11 June.