Weather Graphs Information


The Wind Graph

Sample wind speed graph

The Wind & Gust Speed Graph plots average wind and gust speeds versus time. Wind speed direction is also shown at intervals using a pointer marker (explained above) at the top of the graph. The wind and gust speed is shown in mph (miles per hour) on left y-axis and knots on right y-axis. The wind speed value plotted point is an average of the recorded wind speeds from the previous point. The wind direction (degrees) is also averaged and the marker is rotated to the wind direction angle with the 16-point compass point label shown inside the marker. The direction marker colors are based on the Tibet cardinal colors (see image above).

Wind gusts speeds are handled a bit differently than wind speed. Wind gusts values are intended to indicate a degree of 'variance' in instantaneous wind speed. Wind gusts are based on maximum wind speed in a 5 minute period. Both wind speed and direction of the gust are recorded. A maximum gust for the day is maintained, as as the gust values resets every 5 minutes. Unlike wind speeds, gusts are not averaged. The plotted wind gusts are thus the peak (maximum) value from the previous point. This graph does not indicate the wind gust direction, whereas the the wind direction and rose graph indicate gust direction.

Two (2) horizontal lines indicated the maximum average wind speed and peak wind gust. The sunrise and sunset times are shown by vertical lines, with sun and moon icons respectively. If you are viewing the Current Conditions, a green vertical line represents current local sensor time (Mansur Bay, Neenah, WI). Times that are outside time frame of graph are not drawn. Zero (0) speed gusts are not plotted as by definition a gust must be greater than zero (0). Also plotted gust points must also meet a minimum threshold difference of 2 mph between wind average and wind gust. Lines are drawn between points, but no line will be drawn if a point is skipped.

The Direction Graph

Sample direction graph

The Wind & Gust Direction Graph plots average wind and gust direction angle (degrees) versus time. Wind direction, similar to wind speed, is an average of the recorded wind directions from the previous point. Wind gusts are peak (maximum) gusts from the previous point. This graph only plots points and does not draw lines between.

The plotted points vary in size based on the wind speed value, so a larger point is a higher speed. This allows one to see comparative strength of wind speed & gust. At first glance this graph may not seem that informative, but the relationships between average wind direction and gust directions can be seen. For a sailor, this indicates headers & lifts encountered at different points of sail. A good sailor can take advantage of headers and lifts.

The Temperature Graph

Sample temperature graph

The Temperature & Wind Chill Graph plots temperature and wind chill versus time. The graph has Fahrenheit (°F) on left y-axis and Celsius (°C) on right y-axis. Temperature and wind chill values are averaged over the interval. A minimum threshold difference of 1 °F must be satisfied for wind chill points to be plotted. A wind chill temperature over 50 °F is not plotted. Most cold water sailors use the well-know 100 °F rule which states that sum of air and water temperature must be at least 100 °F. However some hard-core sailors have been known to use 80 ° rule for the super bold. Obviously proper gear and protection is a must for these extreme conditions.

Three (3) Horizontal lines are shown on the Temperature Graph. The 2 red lines are high & low temperature. The blue line is low wind chill temperature. The low wind chill temperature is an instantaneous value and is a function of wind speed by definition, so the blue line can, and most times be, lower than any plotted wind chill temperature points. You don't really see this with high & low temperature because the temperature rate of change is relatively slow, thus the instantaneous and average values are very close. However, wind speeds (and gusts) have much higher rate of change and can exhibit a lot of variability and this can yield instantaneous values that differ significantly from averages.

The Wind Rosette Graph

Sample wind rosette graph

The Wind Speed & Gust Rosette Graph plots on a polar (radial) chart. The Rosette plots wind & gust speed and direction. The wind speed and gust value (mph) are represented by distance from center of graph and the direction angle (degrees).

The most recent points are shown darkest (100% opaque), while oldest points are most transparent. Green points indicate the latest wind speed (round), gust (square), and peak wind (square). This graph can also prove useful in analyzing wind to gust strength/direction relationships.


Weather data and summary provided for informational purposes only.