Another spring storm is coming

Today certainly began as a very chilly day for mid April.  While the Twin Cities had a low of 27 degrees, Granite Falls, Minn., reported 9 degrees and an observer near Alexandria, Minn., came in with just 4.  Afternoon temperatures ran almost 20 degrees colder than normal in most areas.

There have been some signs of spring in addition to lake ice looking rotten.  The Twin Cities National Weather Service measures soil temperatures.  Its graph below shows that the warmer weather last week allowed the soil to warm, especially in the afternoons, to where crabgrass and dandelions will be able to germinate soon.  Yippee.

The usual afternoon thunderstorms have  been pushed farther south than usual today by the southward push of cold air.  The lightning plot locates the most intense storms.

Skies will be in clearing mode across Minnesota this evening.  For night owls, that presents a fine opportunity to observe a total lunar eclipse that will be visible all across the United States.

A lunar eclipse occurs when the full moon passes through Earth's shadow in space.  The moon will begin to enter the umbra, the dark part of Earth's shadow, at 12:58 a.m.  The total eclipse will last for more than an hour from 2:06 a.m. until 3:24 a.m.

During that time the moon will be dark except for some "earthshine," filtered light from Earth that can make the moon look red, orange or brownish depending on what volcanic ash and other contaminants happen to be in the atmosphere to color the light.

If that is too late for you, look for Mars in the east-southeast after sunset as it makes its closest approach to Earth this year.  It will be quite bright, reddish and easy to spot as it comes within about 57 million miles of Earth.

The big event this week will be a major spring storm.  It will drop into the US from western Canada and then slide eastward across the Upper Midwest.  Here is a look ahead from the National Weather Service office in Duluth.

Light snow should begin to fall Tuesday night, become heavier and mix with rain during the day on Wednesday, change back to all snow Wednesday night, and taper to light snow Thursday morning as it winds down.

How much snow?  That's a difficult one to answer with these April storms as the snow will be wet and often changes to rain with the warming of the day.  As of now it looks as though central Minnesota north of the metro area will be hit much harder than the Twin Cities.

A winter storm watch has been posted for late Tuesday night until Thursday morning for central Minnesota and northern Wisconsin.  This includes the Little Falls-Brainerd-Hinckley-Duluth-Two Harbors area in Minnesota and Rice Lake-Hayward-Superior-Ashland in Wisconsin. Much of that area should expect 4 to 8 inches of snow. 

An axis of heavier snow, possibly in the 8 to 12 inch range, could develop somewhere between Brainerd and Duluth-Superior.  Much of the metro area should see anywhere from less than an inch on the far south side to as much as 4 inches on the north side.

These storms, while uncommon, are not unprecedented.

On this date back in 1983 Minneapolis-St. Paul International Airport measured 13.6 inches of snow, which is a 24-hour Twin Cities record for April, brought down the roof of the Metrodome, closed the airport and resulted in mail service being cancelled.  If my memory serves me correctly, the IRS even gave us an extra day to get our tax returns in the mail.

Look for milder weather by the weekend and some actual warm weather next week.