Temps look warm mid-week but a pattern change is in sight

Posted at 4:00 PM, Nov 13, 2018

Plenty of high clouds today as the ridge of high pressure is allowing upper level moisture to stream thru. This cloud cover should dissipate a little as we go into Wednesday but there will still be some, we can call it partly cloudy. Unfortunately these are not the kind of clouds that produce rainfall, however I do see a pattern change coming. More on that later in this story.

High clouds in the Templeton skies by Cecil Horton

NE winds return tonight into Wednesday morning, locally gusty in some of the coastal passes and canyons but generally under 20mph. These winds will turn back onshore in the afternoon and come up to about 15mph.

This looks to be the pattern Wednesday and Thursday and a little weaker Friday before turning more dominantly onshore Saturday into next week.

Highs Wednesday should be in the upper 70s and some lower 80s for the coastal valleys with inland valleys in the mid 70s and beaches also in the mid 70s. Wednesday should be the warmest day of the week, it is largely dependant on the offshore winds but the amount of high clouds are also a factor. It’ll take mostly clear skies to stretch into the 80s I think. Thursday looks similar but probably about 4 degrees cooler across the board. Friday also sees another 2-5 degree temp drop as the ridge starts to break.

Weekend temps look to be in the lower 70s for most with some beaches dipping into the upper 60s.

Interior valley overnight lows will freeze again tonight and again Wednesday night before coming up a little warmer than freezing for the balance of the forecast.

OK, back to the million dollar question: rain prospects. The good news is that models continue to advertise a pattern shift right around Thanksgiving. The details of systems do however change from run to run. Currently the Tuesday afternoon run likes a weaker splash and dash front on early Thanksgiving but followed quickly by a much stronger low Friday thru Saturday with significant potential for moderate to heavy rain kicking out Sunday the 25th.

Saturday 11-25th rain potential from American GFS model

I need to make clear only the broad brush elements are lining up run to run at this point: rain, basic timing, and a series of impulses. What isn’t lining up is rain amounts and specific locations of low pressure centers which guides where the heaviest potential may fall. That said, all runs indicate that should this basic pattern develop that some could see more than 1″ of rain and with recent burn scars we’ll also need to assess rain rate for potential debris flows. Plenty to watch down the road, also with all the heavy travel also anticipated.