December 17, 2017

Windy California

While the Pacific Northwest is enjoying benign, moist weather, strong winds continue to hit California.  For example, here are the maximum gusts above 35 mph) for the 24-h ending 9 AM this morning (Sunday).  A number of locations both in central/northern and southern CA hit that threshold, with several exceeding 50 mph (red colors)

Southern California is particularly impressive, with 50-70 mph gusts observed both east and west of LA.  LA itself is somewhat protected by the higher section of the San Gabriel mountains.

The latest run of the high-resolution DRI/CANSAC forecasting system shows very strong winds continuing today over southern CA (see below), with sustained winds around the Thomas fire area (between LA and Santa Barbara) getting to 35-45 mph.  Which means gusts above 50 mph.

Why the winds?  The same persistent pattern with high pressure over the intermountain west, a trough over coastal California, and an offshore pressure difference that produces strong easterly and northeasterly flow.

One good thing is that Pacific Gas and Electric is FINALLY starting to think about more effective adaptation measures, above the obvious need to clear vegetation away from their powerlines.   This week they have started to talk about pre-emptive power shutdowns to prevent electrical initial of wildfires.

And they reprogrammed their breaker system, so that it doesn't keep on trying to reenergize lines that have experienced shorts.

And now the good news for California.  Two strong troughs are going to move southward into California: one on Wednesday and one on Sunday (see below).

These disturbances will bring some serious rain to the dry Golden State. Here is the ten-day total from the NOAA/NWS GFS model.   The Northwest get quite wet (5-10 inches in our mountains of liquid water equivalent), but nearly all of CA gets some.

And it looks like the worst of the wind, will soon be over for southern CA.  A major fire event is about to end over CA.


  1. Maybe some Fraser outflow next weekend too,if a disturbance rounding the ridge can develop enough and retrograde the ridge?

  2. Another winter with barely any lowland snow. Imagine that!

  3. Looks like we're in for some pretty chilly weather if the forecast hold s through Christmas...and possibly beyond? Now if only we cold get the cold and the moisture to be with us at the same time....

  4. The winds today out on Lake Washington sure didn't seem benign. In fact it was pretty rough out during the Christmas ships parade:

  5. "Another winter with barely any lowland snow. Imagine that!"

    Last winter we had almost twice the average snowfall at Seatac - 11.2" vs. 6.8". So I would say by that measurement we had lots of lowland snow in 2017!

  6. Hi Cliff,

    It looks like a deepening low is heading straight through central WA tonight. Is there enough cold air to the north to consider a lowland snow threat in Whatcom/Skagit counties? I saw the afternoon forecast discussion mentioned the possibilities of snow on the north side of the Olympic range. Curious if you see enough adiabatic cooling potential for other parts of the lowlands.


  7. Those predicted troughs never made it into central and southern CA. Both were washouts in the SF Bay Area. December is turning out to be exceptionally dry in most of CA. There are indicators of a pre-drought pattern with the persistent blocking high and PDO trends that could indicate continued lack of precipitation. La Nina seems to be entrenched. Always interested to hear a scientific explanation.


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