Possible volcanic eruption for 9 December 2016, with an explanation of my interpretation of such charts. More
I suspect that a large eruption is being signalled by the North American Ensemble Forecast. This is a collection of recent forecasts from the Meteorological offices of Canada and Britain with my interpretation of what they mean.
You can find them for yourself at: https://weather.gc.ca/ensemble/naefs/cartes_e.html and: http://www.metoffice.gov.uk/public/weather/surface-pressure/#?tab=surfacePressureColour&fcTime=1481198400 Whilst their products are copyrighted by the makers; I doubt that fair use for health and safety even if false alarms occur will be proscribed.