As the computer models predicted, off-shore flow strengthened quite a bit overnight. However, for a time, there was some doubt. Low clouds that had stayed off-shore yesterday morning, came ashore in places late in the afternoon (just scattered low clouds at first). Low clouds and some dense fog in spots prevailed in the early evening. This hadn't been predicted by the models (at least, none that I perused). The strong, off-shore gradient, however, finally prevailed in the late evening/overnight hours.
Compared with wind speeds in the pre-dawn hours, current winds in Santa Ana wind prone areas are much more manageable. Strongest winds occurred under the 4000 feet elevation (more often than not, it's the other way around). In the Inland Empire, Marshall Peak reported a peak wind gust to 98 mph! There were other reports in other areas (L.A. County included) where reported gusts were in the 80s. UCLA didn't record any wind gust over 22 mph (11:34 AM), but in the Santa Monica Mountains above Malibu, a peak wind gust to 70 mph (4:56 AM) occurred.
The current off-shore flow should weaken further tonight/tomorrow, but a minor, "inside slider" type trough passing through Nevada tonight may promote a slight, albeit short duration, increase in wind overnight (affecting mostly higher elevations only). Still, wind speeds should be much weaker than it got earlier today (peak gusts should stay under 50 mph). Some of the models are predicting a marginal, on-shore flow on Saturday (includes a potential, coastal eddy to whip up some coastal, low clouds for a short time). This happens are yet another, significant, "inside slider" trough passes through the Southland. The passage Saturday evening should be followed by a new wind event. Model forecasts vary on the exact path for the "inside slider", but there is potential for widespread, strong winds on Sunday (greater areal coverage than this morning but not necessarily peak wind speeds). Breezy weather could include much of the L.A. County, coastal plain. For this event, peak wind gusts should occur in the more typical higher elevations above 4000 feet. In any case, winds should diminish by Monday (still some significant wind in Santa Ana wind prone areas but with less areal coverage).
The widespread occurrence of temperatures into the 70s should continue tomorrow. For many areas west of the mountains, tomorrow should be a little warmer than it got today (areas near the immediate coast may wind up the same or slightly cooler due to an earlier start of ocean breezes...weakening off-shore flow). A more general though minor cooling trend should prevail on Saturday (should still be slightly warmer than normal). A rebound in daytime temperatures may or may not occur on Sunday. The off-shore flow will be accompanied by an influx of polar air. Depending on magnitude, temperatures that day may barely reach the 70 degree mark in many locales. On the other hand, a weak influx could still permit highest temperature to reach levels similar to today (mid/upper 70s). I leaned today's campus forecast on the lower range although it has gotten a little warmer than I anticipated today.
The weather for most of next week remains in uncertainty mode. The key lies with the predicted path for a particular, upper air trough that is expected to pass through the Gulf of Alaska on Sunday. Some of the longer range models show an "inside slider" fate for the trough. Marginal, on-shore flow on Monday would promote minor cooling that day. Another Santa Ana wind event would begin sometime on Tuesday (lasting into Wednesday). Warmer than normal weather would prevail for midweek. Other models show the Pacific trough moving south over the open Pacific for a couple days. Warmer than normal weather that occurs on Sunday would continue on Monday. The Pacific trough would come ashore on Wednesday, and widespread, wet weather would occur in southern California (a decent but "run of the mill" storm). Today's model consensus leans every slightly with the latter, wetter scenario, but confidence in the forecast remains quite low (dry weather scenario more consistent with recent wind flow pattern). It may take another day or two before clarity develops with the various models.
Curiously, most of the longer range models seem to agree on a marginal storm opportunity at the end of next week. The storm would be slated mostly for northern California, but the Southland could see some minor, wet weather too (only time will tell). An optimistic feature with the latest, model forecasts is that a fair number of model solutions maintain an "open storm gate" for the state beyond the end of next week. In most years, March is the last month having relevant precipitation fall in the state. The month of April tends to be more unreliable for significant storms (very rare to have good storms thereafter).
Next synopsis should be issued on Monday, 1 March (have some business to take care on Tuesday).
UCLA Forecasts and analyses are written by James Murakami
– posted: 2021-02-25