Winter Storm — Mille Lacs, Minnesota

2020-11-10 · Mille Lacs, Minnesota

Event narrative

Several trained weather observers and local airports reported light snow Tuesday afternoon. Heavier snowfall began during the late afternoon and evening before ending toward midnight. Snowfall amounts across the county averaged around 6 to 8 inches.

Wider weather episode

On the morning of Tuesday, November, 10th, a cold front had moved across Minnesota and western Wisconsin. A 500 MB short wave that developed across the central Rockies was moving northeast across Nebraska with an intensifying 850 MB low developing across Iowa Tuesday morning. At the surface, low pressure was across northern Missouri. Initially, the 850 MB low moved northward across Iowa, and stronger warm air advection across eastern Minnesota and western Wisconsin kept the precipitation in the form of sleet, freezing rain, and some snow Tuesday morning. Farther to the west and deeper into the colder air, light snow fell but it was mostly flurries or occasionally 2-4 mile visibility in light snow.

A dry slot developed, and moved over eastern Minnesota, while the main storm system moved farther west. Once the upper low moved over southwest Minnesota, a broader area of precipitation started to develop over central Minnesota where the dendritic growth zone was maximized together with abundant moisture content and lift. Also during the later afternoon, as the short wave moved closer to Minnesota and under the influence of a developing jet couplet over the Upper Midwest, the storm system became more organized as noted with a beautiful comma-shaped upper low moving over Minnesota. This was also where several snow bands started to develop, especially over central Minnesota where the combination of the intensifying short wave and upper-level jet occurred. At the surface, the low continued to strengthen and move northeast across eastern Iowa, and into northern Wisconsin by late evening.

Just along and north of the comma-head shaped storm system was where the bulk of the heavier snowfall occurred, and it eventually produced 6-8 inches in central Minnesota, northeast into the arrowhead region of Minnesota. Farther to the south and southeast, too much mixing and not enough heavy precipitation kept snowfall amounts under 6 inches. A general 2 to 4 inches fell northwest of Mankato, to Luck, Wisconsin. Isolated areas of 5 to 6 inches across the Twin Cities metro area, northeast toward St. Cloud and Mora. Over most of south-central and southeast Minnesota, snowfall amounts of 1 inch or less occurred. Some freezing rain did occur Tuesday morning, and into the afternoon, but only isolated areas received enough to cause problems.

Source: NOAA Storm Events Database, event_id 920554. Narrative written by the NWS forecast office that issued the report.