Weather Synopsis – June 13, 2024

James Murakami

Thu13th70/56Low clouds clearing to a sunny afternoon. Chance of evening low clouds.
Fri14th71/59Chance of early morning low clouds; Otherwise, mostly sunny day. Clear evening.
Sat15th75/60Chance of some early morning low clouds; Otherwise, sunny day. Clear evening.
Sun16th72/58Chance of early morning low clouds; Otherwise, mostly sunny day. Chance of evening low clouds.
Mon17th70/57Good chance of morning low clouds but sunny afternoon. Chance of evening low clouds.


Extensive low clouds were present off of the state coast early today (extended into some coastal valleys thanks to a decent strength, on-shore flow). The numerical models continue to forecast a general decrease in areal coverage of low clouds for the next couple of days. This particularly applies to to more, well inland areas, but increasing north winds (tomorrow) over Santa Barbara County should help clear away coastal low clouds there (developing “sundowner” winds). A reversal in winds (back to increasing on-shore flow, including Santa Barbara County) is predicted for the Sunday-Monday period. Yet, another decreasing on-shore flow period should follow later next week (very weak, on-shore flow a possibility toward the end of next week…more on this in a bit).

A shallower marine layer, aided by increasing high pressure aloft and weaker, surface on-shore flow (toward the east) should promote sunnier and warmer weather (Friday-Saturday period). Moderate warming is likely for well inland areas, but sundowner winds are expected to bring noticeable warming to coastal, southern Santa Barbara County. Depending on how much mixing of dry air occurs into the marine layer from L.A. County southward, some decent warming could occur in the campus area as well (also applicable to other areas near the coast). For this forecast, I held to a modest warming for Saturday, but a purge of the marine layer could add several degrees to the current forecast (valid mostly for Saturday). On the other hand, a shallow but defined marine layer could hinder a relevant warming cycle near the coast (today is a little cooler than I anticipated).

A new, upper level trough is forecast to develop over the state as early as Sunday (separate from a weak, upper low pressure nearing San Diego from the southwest today). This should result in increasing on-shore flow (Sunday-Monday) and more extensive low clouds again (Sundowner winds should weaken and cease for early next week). There are some model forecasts showing a disruption to the low cloud field by the middle of next week. At the least, another cycle of weaker on-shore flow later next week should promote less low clouds for inland areas. Warmer weather should also follow (similar to what’s expected for the next couple of days).

Some of the longer range models do show high pressure aloft building across the desert Southwest late next week. If true, the subsequent weekend could include the coast for significant warming (potentially well into the 70s at the beaches, flirting with 90 degrees inland coastal plain, and widespread, triple digit heat further inland). This would just about coincide with the astronomical start of summer next week (20 June at 1:50 PM this year). There are still some model solutions holding onto the weakness in the high pressure aloft along the state coast. That scenario would allow for less warming near the coast (shallow marine layer maintained). For now, the warmer scenario is the model consensus.

Note: Beginning next week and lasting through most of September, I plan to reduce regularly, issued forecasts/synopses to once a week. The next issued forecast will be on Monday, 17 June.