| Day | Date | High/Low | Forecast |
| Mon | 3rd | 69/57 | Mostly sunny with some high clouds after low clouds clear late morning. Chance of evening low clouds/fog. |
| Tue | 4th | 70/57 | Morning low clouds likely but mostly sunny by afternoon. Good chance of evening low clouds. |
| Wed | 5th | 68/56 | Morning low clouds likely but mostly sunny afternoon. Chance of evening low clouds. |
| Thu | 6th | 70/56 | Chance of some morning low clouds; Otherwise, mostly sunny day. Mostly clear evening. |
| Fri | 7th | 74/58 | Sunny day. Clear evening. |
Synopsis
A weak, upper level low pressure passed through southern California yesterday. It didn’t do much in terms of changing daytime temperatures from the day before. So, I wasn’t anticipating any relevant day to day change for today (another weaker disturbance passing by…reason for today’s high clouds after low clouds cleared away). Well, today wound up a little warmer at UCLA than I expected (maxed out at 72 degrees). Apparently, there was a little more vertical air mixing early this afternoon than what the computer models predicted (quickly dropped back to expected values later on).
All the models show high pressure aloft to our south will expand northward tomorrow. Only minor temperature changes are anticipated for most areas west of the mountains (smallest changes for areas near the coast). Considering that it got warmer than I forecast for today, I thought about amending tomorrow’s forecast high. However, the marine layer depth isn’t forecast to change in any relevant way (same goes for predicted, on-shore flow strength). The increasing high pressure aloft may actually lead to less vertical air mixing. That, in turn, might produce less warming tomorrow than what occurred today. In the end, I left the forecast unchanged from the preliminary, morning edition.
A storm is expected to bring wet weather to northern California on Wednesday (modest soaker for the Sierras). Some of the models show light showers getting as far south as western Santa Barbara County. With the exception of a chance for spotty, early morning mist/drizzle, no wet weather is anticipated over L.A. County. Another minor threat is possible for the northwest corner of the state around Friday, but the rest of the state should be high and dry (lasting through the weekend).
The models predict high pressure will build over southern California Friday into the weekend. A number of model solutions favor at least a marginal, off-shore flow development (Friday through most of weekend). There is potential for widespread 80 degree weather for the inland coastal plain and valleys (no 90 degree weather is forecast at this point). The extent of warming closer to the coast is more uncertain. A marginal, off-shore flow this past Saturday produced less warming near the coast (campus included) than I expected (marine layer influence). Since the models forecast at least a diluted marine nearer the coast, I stayed conservative for warming at UCLA on Friday. Potentially, it may get several degrees higher (low to mid-80s a possibility over the weekend).
There is unusually good agreement with the longer range models for wet weather next week. Of course, there is the usual disagreement on weather details such as timing and magnitude of wetness. The various models show multiple storms passing through the state next week (some show the “storm gate” open to the state into the subsequent week). The earliest the first storm may reach the Southland is Tuesday evening (sometime Wednesday is current consensus though). This one looks to be a minor rain event (snow levels stay mostly above 6500 feet). A second, colder storm is expected by the end of work week (light showers possible as early as Thursday). Model forecasts vary greatly on how wet the storm may be when it reaches southern California (anywhere from minor to major). Other than being seasonably cold (snow levels dropping to 5000 feet), it’s too early to gauge confidence on how wet it may get late next week. The same applies to any other storms that may follow over the subsequent weekend and beyond (there are some model solutions showing just “inside slider” type storms (more wind than wet weather).
Next issued forecast/synopsis should be on Monday, 10 November (planning two issued forecasts next week).