Friday, September 12, 2014

Wind Speeds at Spanish Fork

I've had my weather station in Spanish Fork for about 18 months now. Spanish Fork is famous for it's winds, so I thought it would be interesting to see a long term wind rose for my house. A wind rose shows the frequency of wind speed in a particular direction. Below is a wind rose for March 13, 2013 through September 11, 2014.

As shown below, 23% of the time wind blows from the south-south-east. 19% of the time from the south-east, and less frequently in the other directions. This is caused by out canyon wind (but also because there is a house on both sides of the station). Still, the down-canyon wind is much more frequent than an up-canyon wind. The colors indicate the wind speed of those winds. Very rarely do we have winds that blow more than 10 mph. Most of our winds are less than 6 mph.
I was also curious about how the timing of the down-canyon wind. When does it start and when does it stop. Below is plotted another wind rose, but the coordinates, instead of wind direction, is hour. The color still shows the wind speed. Notice the more warmer colors on the right side of the graph. From this we see the strong canyon winds blow during the morning hours. They are especially strong between 3:00 and 9:00. After 9:00 the frequency of strong winds drop. I usually tell people new to Spanish Fork that the wind usually stops around 10:30 in the morning, and this graph confirms that statement. After 10:30, winds above 5 mph are fairly infrequent. Also notice the bulge of blue around 19:00 (8:00 PM). Calm winds less than 1 mph are very common. This is during the transition between up-canyon and down-canyon wind flow. 

Bottom line from this quick analysis, when someone asks about the winds in Spanish Fork, say the canyon wind tends to end around 10:30 in the morning. The evenings are pleasant with little or no wind.

One thing we can learn from this is the ideal time to water your lawn. The best time would be in the evening around 9:00 PM. Since there is little to light wind, the water won't blow onto you sidewalk.

1 comment:

  1. I've been looking for historical wind data like this for a while to plan my watering schedule. I even tried looking for hourly power generation data from the Spanish Fork Wind Farm, but couldn't find any.

    I'm not an expert, but I have heard that watering in the evening can leave the grass wet all night and cause rot. Seems the best time to water might be between 9:00 and 10:30 am.

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