Day | Date | High/Low | Forecast |
Mon | 27th | 57/44 | Partly cloudy remainder of day. Scattered clouds in the evening. |
Tue | 28th | 59/45 | Partly cloudy at times, but generally sunny day. Scattered clouds in the evening. |
Wed | 29th | 60/46 | Partly cloudy morning; Mostly sunny afternoon. Scattered clouds in the evening possible. |
Thu | 30th | 60/46 | Morning low clouds but mostly sunny afternoon. Some high clouds in the evening. |
Fri | 31st | 62/48 | Mostly sunny day with some high clouds. Some high clouds in the evening. |
Synopsis
An upper level, low pressure brought widespread, though variable, storm totals to southern California. It was centered over the southeast corner of the state early this afternoon. The showery nature of the storm had been expected to produce variable storm totals, but it varied more than I expected. On the low end were totals of a quarter inch or slightly less. On the high end, a spot in Santa Barbara County (Coal Oil Point near Goleta) recorded 2.33 inches of rain (nearly stationary thunderstorm contributed to high amount). An upper end total around 1.75 inches was more common though (not restricted to locales around the mountains). The areal wide, average rainfall (west of the mountains) appeared closer to 0.67 inch. Snow fell as low as about 2500 feet for a short time (dusting). Snowfall totals that I’m aware of also varied quite a bit. It ranged from a couple inches (about 3000 feet elevation) on the low end; about 17 inches on the high end (Mount Baldy area). [FYI– The UCLA auto-gauge storm total of 1.94 inched is probably too high, based on past history. I will be making a manual measurement on Tuesday…expecting total somewhere around 1.25 inches, plus or minus a quarter inch, based on some surrounding area recordings.]
Most shower activity in the Southland has ceased, but the aforementioned circulation should remain close enough (predicted to be over Arizona) to permit some instability showers to form over the southern mountains tomorrow afternoon (nothing significant expected though). There may even be some cloud build-ups over some mountains on Wednesday afternoon, but no threat of instability showers are expected by then (assumes low pressure weakens and makes some progress across Arizona). The interior sections should, otherwise, return to mostly clear weather by midweek.
Although high pressure aloft will nose into northern California by midweek, no full fledged, low level off-shore flow is predicted (some northeasterly winds occurring today in some valley locales are associated with the aforementioned, upper level low pressure). The overall, low level, wind flow pattern actually favors a marginal, on-shore flow (weak but full fledged, on-shore flow by Thursday). Most of the numerical models predict sufficient, low level moisture remaining to support variable low clouds through Thursday (maybe even into early Friday). I’m unsure whether any widespread, low cloud overcast will develop for the next couple of days (early morning hours could start out clear in many areas). The best chance at widespread low clouds may occur on Thursday, especially if a coastal eddy forms. Regardless, no drizzle/light rain is anticipated from these, predicted low clouds.
By the weekend, some models show weak off-shore flow developing (Friday being the transition day). That may be when temperature rise to slightly above normal levels west of the mountains. High pressure aloft over southern California certainly should get strong enough for warmer than normal weather (different story over northern California where wet weather should occur). The uncertainty is whether a full fledged, off-shore flow prevails. No widespread, significant winds in Santa Ana wind prone areas are expected. So, daily ocean breezes in the coastal plain could limit the warming there. In addition, variable high clouds may hinder the expected warming this weekend (associated with a sub-tropical jet stream).
Looking further out in time, there are some model solutions showing a minor rain threat reaching the Southland on Tuesday or Wednesday next week. Other storm threats could occur late next week. Most of the longer range models show an “open gate” for storms to affect northern California (most solutions don’t show anything major, however). It’s less clear if the tail ends of these storms will bring about widespread, relevant precipitation to southern California. Some model scenarios show just “inside sliders” (more wind storm than wet storm).
Next issued forecast/synopsis may be on Friday, 31 January.