Late spring frost possible early Tuesday

Mother Nature decided to throw Minnesota another curveball on Monday, sending temperatures plunging toward the freeze mark and actually bringing a few snowflakes to parts of the north. While this isn't record breaking by any means, it feels a little unusual to be talking about freezing temperatures in the second half of May. Considering temperatures have been hovering in the 30's and 40's through the day, it's not going to take a lot for those numbers to drop to the freezing level and beyond. But, there will be many atmospheric variables working against a widespread freeze. First, the ground temperatures are now well into the 50's, which means that it will take a lot of work by the atmosphere to get surface temperatures down into the 20's and 30's. Let's face it, the Earth is a gigantic object radiating 50° temps all night. Secondly, cloud cover will likely hang around much of the night, acting blanket like to keep the lower levels of the atmosphere slightly warmer. And then lastly, winds will be far from calm. In order to get good surface cooling, winds need to calm. This allows the colder, denser air to sink all the way to the ground. This can often times snowball (no pun intended) and actually force temperatures to cool much further than they otherwise would. The image below shows temperatures around 5000 feet up at noon on Monday and will shed light on just how cold this airmass really is…

 

Just look at the funnel of cold air in the Upper Midwest with temperatures in the teens just a little above the surface. You add the brisk winds to this and it's just constantly reinforcing the cold air over the state. So just how cold will it get tonight? Well, according to our high resolution computer model, many areas north of I-94 have a pretty good chance at a frost or freeze. Check out what it is expecting for temperatures around 6am…

 

Some 20's could be found in far northern Minnesota with plenty of low 30's once you get north and west of the metro. So how accurate could this be? Well, considering there are several other models on board with this picture, it looks like it will probably be happening. Check out what a couple other models say…