Heavy Snow in Iowa, February 21, 2010

A storm system moved out of the southern Rockies and across far southeast Missouri during the day on the 21st into the early morning of the 22nd. Iowa was on the northwest edge of the system with snow falling over the southern third of the state. The snowfall was limited over Iowa by three factors. The first was a strong push of dry air in the low levels during the day on the 21st. Surface dewpoints fell into the low to mid teens F. under the influence of the drier air. The second factor was the development of convection to the south of the state as the low approached. This had the effect of cutting off moisture inflow from the south. The final factor was the development of a strong dry slot with the storm system. The dry slot moved over Iowa before the the deformation precipitation development was able to become established. The upshot was that snowfall was limited to 4 to 5 inches in most locations. A narrow band of heavy snow formed over south central Iowa late on the 21st. A snowfall of 6 inches was reported in Lucas County at Chariton. This was the only location that reached a snowfall total of 6 inches in a 12 hour period.