| Day | Date | High/Low | Forecast |
| Mon | 5th | 82/64 | Mostly sunny remainder of day with some high clouds. Mostly clear evening. |
| Tue | 6th | 82/65 | Mostly sunny day with some high clouds. Some high clouds in the evening. |
| Wed | 7th | 79/64 | Mostly sunny day with scattered high clouds. Scattered high clouds in the evening. |
| Thu | 8th | 78/64 | Partly cloudy with high clouds through the evening. |
| Fri | 9th | 79/65 | Partly cloudy with high clouds through the evening. |
Synopsis
High pressure aloft was centered around the Four Corners region today. It is forecast to remain the dominant weather force in the Southwest this week (as is common for much of the summer). The high pressure center is expected to drift about, but toward the end of the week, a secondary center may reach as far west as Nevada. No major weather changes are anticipated, but a slight cooling trend is predicted for midweek (high pressure weakens slightly and allows for a little stronger, low level, on-shore flow). A rebound is probable toward the end of the week, assuming the secondary center does form over southeast Nevada. At this point, this high pressure isn’t expected to get as strong as the current Four Corners high pressure. So, the end of the week warming shouldn’t get quite as hot as it is today (UCLA high so far 84 degrees…a little over my forecast…warmest on campus since 1 November of last year…86 degrees that day).
While the latest warming trend has been greatest for well inland areas (commonly, the case), areas near the coast (near sea level within a few miles of the ocean) have warmed modestly today. Apparently, what marine layer exists (diluted so that no low clouds/fog existed this morning along the L.A. County coastline) hasn’t curbed the mixing of warmer air aloft (reason for relevant warming for locales a few hundred feet above sea level even if within a mile or so of the coast). How much of a comeback with the marine layer in L.A. County will influence the midweek cooling trend (leaning with the model consensus with just minor cooling but confidence not high). If a shallow but defined marine layer persists at the end of the week, the predicted warming trend may be absent near the coast.
A couple of disturbances late last week did promote some light showers west of the mountains (just sprinkles, to my knowledge). The flow of “monsoon” moisture aloft has varied from day to day (same applicable to occasional shallow surges of humid air from the Gulf of California into the Colorado River Valley). A couple of brief lived thunderstorms occurred this afternoon in the southern mountains (San Diego County) and eastern desert. However, for the most part, storm activity has stayed south and east of the state. Some models predict a deeper, moisture incursion late this week (reason for partly cloudy in the campus forecast), but at this point, no shower clouds are expected to get west of the mountains (predicted, upper air disturbance expected to stay too far away for influence west of the mountains). Of course, a small error in predicted wind flow could result in noticeably, different outcome.
Most of the longer range models show high pressure aloft in the Southwest giving away sometime next week (as early as the beginning of the work week). A number of model solutions show a weak, upper level trough over the state for a day or two. Slightly cooler than normal weather would result (all of the state, including interior sections). However, as we’re in the dog days of summer, high pressure aloft is expected to nose back into the region by the subsequent weekend. That should then lead to renewed warming (how much, remains to be seen).
Next issued forecast/synopsis should be on Monday, 12 August.