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A record high set Wednesday with a strong heating event but not likely to repeat

Lake Cachuma sun and high clouds
Posted at 4:49 PM, Oct 19, 2022
and last updated 2022-10-19 19:49:09-04

We knew Wednesday was going to be a hot day with a lot of 90s, but the 100 (or near 100) in San Luis Obispo was a bit higher than the forecast.

The driving force of the heat event Wednesday was not only offshore flow (which keeps the influence of cool ocean waters minimalized) but also compressional heating. The latter is when high pressure and/or the airflow pattern is for sinking air. Sinking air compresses it and that increases the temperature of the air.

Thursday looks warmer than average again. This is because some of the same elements are still around that drove Wednesday's heat event, but they are not the same.

The offshore flow is still going to develop later tonight but the wind speeds don't look as high nor do I think the event lasts as long. To me, it looks like the winds should make a turn back onshore sooner Thursday. Along with more high clouds and the ridge of high pressure in a process of weakening, these are all factors that suggest the forecast should still be warm but not AS warm as Wednesday.

Later Thursday into Friday onshore winds will be much more dominant. The weekend features a trough over The West and cooler and breezy to windy weather is likely. Temperatures will be dramatically cooler, lower than average in fact with a lot of 60s near the coast with inland areas also cooling into the 70s. Temps early next week should come up from the weekend cooler high by about 5 degrees.

The longer extended forecast still looks generally mild to cool to close the month and begin November. There looks to be a series of cold fronts passing thru California but they look mostly dry to me, maybe a sprinkle or light shower but nothing meaningful at this point. In fast this weekend we'll see the first of that series of fronts, but after an offshore and dry event like today, the weekend front looks mostly dry if not entirely.