Blog: Crushed & departing? A romance novel?

[windfind]

Hi Gang,

Many times each year after a strong wind period the Bay Area and Southern California forecasts will talk about the North Pacific High being crushed against the coast by a storm and then the winds fading as the NPH departs our waters.

It is hard for words to capture these events so I have made an animation with text to try to help you visualize all this jargon.

http://blog.weatherflow.com/west-coast-wind-blog-north-pacific-high-crushed-and-departing/

This animation covers the time span from dawn today until Sunday afternoon. Be sure to watch the time base at the bottom and the wind streaks.

Mike Godsey

[windsrf]

I've always thought that high pressure areas flow into/towards low pressure areas? Is there another way to describe why the results are as you've so nicely displayed - i.e. vs. "crushed"?
Thanks in any case Mike.

[windfind]

Hi windsrf,

Yes wind flows from high pressure towards low pressure with the actual trajectory of the wind being impacted by surface friction and coriolis force.

But it is not the case that the high pressure area itself (in this case the NPH) moves towards the low pressure area (in this case the storm to the west).

The movement of high pressure systems and low pressure systems is largely determined by the movement of the upper level winds known as upper troughs and upper ridges. These upper level features steer the surface lows and high usually from west to east.

Interestingly the North Pacific High is partially an exception to this steering effect since it is usually being regenerated by descending wind that originated from the tropics. So the upper level winds mostly bump in around but do not carry it away to the east.

Hope this make sense.

Mike Godsey
iwindsurf.com/ikitesurf.com
Weatheflow.com

[windsrf]

Helpful distinction - thanks!