Thursday, February 19, 2009
This mornings visible satellite showed a unique pattern of snowfall across the Upper Mississippi Valley. After some review of the features present and some collaboration with forecaster's at the NWS in Davenport, IA, it seems as if a very small mesoscale wave produced enhanced lift in a banding effect as noted by the multiple parallel lines almost evenly spaced. It also looks as if the fetch was ideal for the band furthest to the west to have some river enhanced moisture in NE IA and SE MN. Thus, this band furthest to the west is brighter than the others due to its enhanced snowfall. Not a single model picked up on this very tiny mesoscale feature. One good reason to leave a chance of precip in your forecast!