| Day | Date | High/Low | Forecast |
| Mon | 6th | 72/53 | Mostly sunny day with some high clouds. Mostly clear evening. |
| Tue | 7th | 69/55 | Sunny day and becoming breezy. Mostly clear evening and breezy. |
| Wed | 8th | 70/50 | Mostly sunny day with some high clouds; Breezy at times, mainly early. Some evening high clouds. |
| Thu | 9th | 72/48 | Sunny day. Clear evening. |
| Fri | 10th | 68/47 | Sunny day. Mostly clear evening. |
Synopsis
Happy New Year to all!
The new year started out on a dry note, and for the most part, it should last through at least mid-month. A series of “inside slider” type troughs will be passing through or near the state. The one expected to pass through southern California early tomorrow morning may turn out to be the strongest of the bunch. Others will follow at irregular intervals, some producing widespread, significant Santa Ana winds in their wake; Others not so much.
In the meantime, a marginal on-shore flow has developed late this afternoon. Relative humidity by the coast has returned closer to normal, humid readings. It wouldn’t be out of the question if patchy fog/low clouds developed by the coast later tonight (mainly south of L.A. County). However, increasing north to northwest winds (already occurring on some of the higher, northern mountain locales) should scour away any marine fog/low clouds by sunrise. After that, the next chance at a brief return of coastal fog/low clouds may be Saturday morning (next predicted, marginal, on-shore flow).
Widespread, significant wind (25 mph or higher) is expected to develop tomorrow (overnight tonight in the higher mountains first). The campus area should get breezy by mid-morning (brisk winds starting as early as sunrise). Depending on the direction of deep layered winds, the entire L.A. Basin may or may not experience a period of significant wind. Unless the winds shift to a more easterly direction quickly, windy weather is almost certain on the Westside. For most of the Southland, the peak windy period should come tomorrow evening into the early hours of Wednesday. Highest wind gusts in the mountains potentially could reach 100 mph (isolated readings…nothing widespread nor sustained). Values into the 50s will probably be more common though. For lowland areas that are prone to Santa Ana winds, peak gusts may reach 50 mph (again, isolated readings). For the campus areas, peak gusts may approach 40 mph (mid-20s to low 30s being more common during the windiest period).
Upper air support for widespread, significant wind should taper off quickly Wednesday afternoon, but relevant Santa Ana winds may not completely go away in some areas through much of next week (Saturday being most probable respite, if today’s model consensus holds true). At least, any subsequent increases in wind later this week (after Wednesday) shouldn’t approach the strength of what’s expected tomorrow (again, based on current model consensus).
Although strong, off-shore flow will occur tomorrow, prior to the “inside slider” passage early tomorrow, there actually could be some isolated, mountain snow showers (snow level about 4000 feet for a brief time on north facing slopes). The polar air following the “inside slider” should also limit warming tomorrow (starting out as a “cool” Santa Ana wind). Better warming is anticipated for Wednesday and Thursday (not anticipating any 80 degree readings Thursday but not completely out of the question). Some modest cooling is expected Friday-Saturday before another warm up on Sunday. Overall, we’re expecting a period of mild temperatures west of the mountains (for January).
It’s far from certain, but a number of the longer range, model forecasts show one or more of the “inside sliders” taking on more of an “outside” track (i.e. circulation moving over the ocean). One such scenario offers a chance of instability showers (not just for the mountains) as early as the 16th. Other model scenarios delay that till the weekend of the 18th. Of course, at this point, this is more speculation that actual forecast (model forecasts too varied at those longer range periods). Widespread wet weather is bound to occur sometime this winter in southern California. The question is “when?”.
Next issued forecast/synopsis should be on Friday, 10 January.