13 January 2012

I was looking at the graphical forecast wind conditions for the times over the next couple of days when I expect to be outdoors and things didn't look right. The barbs on the direction/strength indicator weren't matching up with the plotted strength even allowing for the granularity of the wind barbs.

I was thinking a long barb was 10 mph and a short barb 5. I went searching the web and found this NOAA site that gives some basic information on the graphical forecasts that I haven't come across before. It says 10 & 5 mph respectively for the long and short barb a and 50 mph for a flag.

But on further search I found this NOAA site on synoptic charts. It says 10 & 5 but that the units of measure are expressed in knots. That seems to bring the barbs into alignment with the plotted values but using two units of measure for the same point make the chart confusing.

I am going to have to make another chart relating wind barbs, wind speed in mph and knots, and the Beaufort Scale. Hopefully there will be some correspondence there.