I have used the following for my buienradar widget:
I used the template node and used an iframe.
No need for triggering anything. You can use the history and the forecast parameter to select the timeframe that needs to be shown.
<IFRAME SRC="https://image.buienradar.nl/2.0/image/animation/RadarMapRainNL?height=170&width=165&margin-left=100&extension=gif&renderBackground=True&renderBranding=False&renderText=True&history=3&forecast=5&skip=1" NORESIZE SCROLLING=NO HSPACE=0 VSPACE=0 FRAMEBORDER=0 MARGINHEIGHT=0 MARGINWIDTH=0 WIDTH=100% HEIGHT=100%></IFRAME>
