Spikes on my wind graph

I have a Vantage Pro2. I’m running WD 10.37S Build 81 I’m getting spikes on my wind graphs. There might be to or three over a 12 hr period.

The spikes show all the same wind speed. In the link below you can see three spikes extending above the regular wind data. Each of these is exactly 38.9 Km/h. I wouldn’t mid a bit of ‘noise’ in the graph, but these show up on the “Maximum Gust Today” readout, so my data is getting corrupted.

http://ve4cy.net/misc-images/spikes.jpg

I’ve noticed these spikes on the last couple of builds… Any Idea of what they are and how I can get rid of them?