A cool, damp week is underway

Monday began with a little rain across central Minnesota and snow farther to the north. Three inches of snow fell around Brainerd and Garrison while five inches was reported in Moose Lake. Although the small amount of precipitation will not do much for the soil moisture or lake and stream levels, it did dampen the dried vegetation and reduced the wildfire danger in the short term.

Areas of rain continue to train eastward across central Minnesota, to the north of the metro area and also across the far south. National Weather Service radar has been tracking all of it.

Unsettled weather will continue through the remainder of the work week. Areas of rain and snow will redevelop over Minnesota tonight with the rain in the south and the snow in the north. In between, temperatures will fall below freezing north of the metro area and allow the rain and drizzle to change to freezing rain.

The National Weather Service has posted a freezing rain advisory for parts of central Minnesota for tonight from midnight until 7 a.m. Tuesday. Light icing amounts of up to around a tenth of an inch are possible, mainly on easily-cooled surfaces such as wires, railings and vehicles. Cities in the advisory include Elk River, Cambridge, St. Cloud, Little Falls and Alexandria.

Tuesday should bring more rain to the south and snow in the north. The NAM model shows one forecast of the precipitation type at 1 p.m. Tuesday.

The colored lines across the map are various forecasts of "critical thickness" — that is, forecasts of where the boundary between rain and snow might be at that time. Of course, forecasting is much more complicated than this, but it gives a quick estimate that the rain/snow transition zone has a good chance to be somewhere in that tangle of lines. The purple colors represent the average relative humidity in a representative cloud layer.

Tuesday will be a chilly April day with highs just from the upper 30s to mid 40s. That is about ten degrees colder than normal.

Wednesday will not be much of an improvement as highs will be mainly in the 40s.

A larger, slow-moving weather system is scheduled to arrive from the southwest Wednesday night and hang around into Friday. Precipitation should be mainly rain. Thunderstorms are possible in southern Minnesota on Thursday and could include some small hail. Then this weather system might end with a burst of wet snow Thursday night into Friday to remind us that winter can last into April.

Precipitation amounts are difficult to forecast but one model of this week's totals includes a small area of heavier precipitation in east central Minnesota. Most of the stronger storms will pass to the south of our state. The heaviest forecast amounts by Saturday morning are from eastern Iowa to Pennsylvania and down the Mississippi River to the Memphis area.

While we benefit from welcome moisture this week, much of the Southwest is in an expanding area of critical fire danger due to warm temperatures, low humidities and gusty winds, especially during the afternoon when stronger winds mix down to the surface.