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Over the years, the University of Missouri Commercial Agriculture Program has continually added to its weather resources. The network of weather stations currently numbers 25. Horizon Point is delivering site specific, customized weather information via e-mail to subscribers. BERM and AFOSITE are two interactive Websites that integrate site-specific weather information to assist farmers in understanding how to manage their land.

In discussions, producers have repeatedly asked for more windrelated weather information. They relate to us the importance of wind for short term activities such as spraying and for long term investment decisions such as where to locate an animal feeding facility. We have organized several new wind products at http://agebb.missouri.edu/weather/windroses. Two of the new products are highlighted below.

Windroses are the most recent weather products developed by the Commercial Agriculture Program to aid in management decisions. A windrose is a graphical presentation of the average hourly speed and direction of wind at a particular location. The windrose for Novelty is shown below. It consists of 16 petals that indicate the percent of time that a wind is blowing from that direction. For example the largest petal is the one for wind blowing from the south-southwest and indicates that about 11 percent of the time wind is blowing from that direction. By looking at the windrose, you can quickly see that the prevailing wind direction is from the south and southwest.

The petals of the windrose also are composed of different colors that represent the percent of time that a wind from that direction is within a specified speed range. The petal for a south wind indicates that about 3 percent of the time the wind is between 1-5 mph; 6 percent of the time it is between 5- 10 mph and 2 percent of the time it is between 10-15 mph. The average windspeed is reported as 5.99 mph.

The windroses located on the web are produced in color and contain information about the sources of data. Some windroses use National Weather Service (NWS) data, reporting speed at 30 feet above the ground, while other windroses use the MU Agricultural Weather Station data, reporting speed at 10 feet above the ground. Wind speeds are slower at when measured closer to the ground due to frictional effects. If you use a windrose that relies on NWS data understand that the speed might be greater than you would expect because they are reporting speeds at 30 feet above the ground.

Another representation of the average hourly wind data is a chart showing the average wind speed for each hour of the day during 4 months when wind information most affects land activities such as spraying. The Novelty average wind speed graph shows a consistent rise in wind speed starting at about 9:00 a.m., peaking at 4:00 p.m. and reducing until 9:00 p.m. at which time it remains fairly consistent until shortly after sunrise the next morning. The graph shows 4 lines, one each for April, May, June and July. April's wind speed is greater than May's wind speed by about 1 mph. July has the lowest average wind speed during this 4-month period.

The hourly average wind speed reveals how difficult it is to find a good time to spray pesticides so that they don't drift. For a NWS forecast of wind speeds at your farm (specific latitude and longitude) subscribe to Horizon Point (http://agebb.missouri.edu/horizonpoint) and specify that you want to receive the wind forecasts. These forecasts give predicted wind speed at three hour increments for the next 60 hours. Using these to plan when the wind might be favorable for your specific field activities could contribute in your management decisions.

Ray Massey and Pat Guinan
MasseyR@missouri.edu
GuinanP@missouri.edu