St. Cloud, MN Weather Forecast

Spring in Central US Can Produce Any Weather

On Friday, the spring equinox, our sunshine will be up to 12 hours, but we've been in a wild weather roller coaster of temperatures for the past month (see 30-day graph of St. Cloud temperatures from MesoWest).  Here's an overview of the storm snowfall totals (set duration to 72-hour accumulation) with a NWS Twin Cities local map here. And, the weekend snowstorm changed us from a relatively rare late February and early March with no snow on the ground to the half-foot still over the Twin Cities with more over Wisconsin. 

How Much Can It Change? Look at the Range of March Record Temperatures

Note, however, that it isn't unusual for wild swings in spring weather. The St. Cloud March temperature records show this in detail. The 12 hours of sun and higher elevation mean that areas to our south, especially in northern Mexico, can approach late spring or summer high temperatures, when the air flow is warm. This happened yesterday in the Desert Southwest with highs in the 80's and 90's. The strong high pressure system over the west (see clockwise circulation on the College of DuPage North America water vapor loop) is causing sinking, compressing the air (like when you use a manual tire pump to inflate your bike tires; the outer portion of the air chamber heats up if you pump hard). And, there is additional sinking when the air passes down a mountain range, so even Alberta, Saskatchewan, and Manitoba had highs in the 50's and 60's yesterday.

On the other hand, Friday is sunrise at the North Pole and the low sun angle (plus the presence of snow) reducing the heating in cold air masses, so we still have true arctic cold right now over Greenland, northeast Canada, and the north end of Hudson Bay (see blue and white on the Alicia Bentley North America 850 mb equivalent potential temperature map). That air produced afternoon temperatures only in the minus teens, -20's, and -30's.

Where the Warm and Cold Air Come Together, Precipitation is Possible

The goal of the atmosphere is to try to undo the big north-south temperature differences by bringing colder air southward and warmer air northward. However, that temperature difference creates enough lift to produce storms. 

And, some of those storm can produce snow, if the warm air has a supply of moisture from the Gulf of Mexico and the more modest air brought down the Rockies is relatively dry (keep in mind that dew point temperatures are the lowest possible low temperature on a clear, calm night, which could turn that mild high still into a low in the 30's and 20's). So, snow is possible on the northern flank.

Today Through Saturday: A Warm Swing, Tempered by Snow Melt

During the rest of this week, we will be on the warm end of the roller coaster. The cold air already saw the mountain air rise above it, producing the light snow cover we see this morning. And, that milder air will be at about 5,000 to 10,000 feet above the ground by late today.

The main question in the forecast is whether the cooling caused by melting the snow and the lingering moisture above the melting snow will cause a lot of low clouds to hang around. It's still a bit early for the sun to be able to heat the ground when there are thick clouds in between.

Even though temperatures 1-2 miles up would clearly indicate highs in the 50's, 60's, and even 70's, I have been slowing the warm-up all week. I expect the worst combination of temperatures above freezing and light winds today and tomorrow, so I have highs only in the upper half of the 30's today and near 40 tomorrow. And, there will be a risk of dense fog during the evening, lasting through the early morning, and perhaps persisting throughout the morning.

The change I see for Friday is that the warm front stalled to our west (see NWS WPC North America zoom-in map) will push through Minnesota early in the day. That should allow some stronger southwest or west-southwest winds to develop. Those winds won't carry as much snowmelt moisture and the stronger winds will give the air a better chance to deposit some of the moisture in the middle atmosphere, breaking up the clouds. So, I have a good shot at highs in the 50's on Friday with 60's likely on Saturday.

Sunday Back to Near Average Temperatures

There will be a cooler air mass pushing into Minnesota for Sunday. At this point, the front between the air masses appears to have little moisture, so I only have a 1 in 5 chance for precipitation. However, highs will get knocked back to the 40's.

Minnesota is forecast to remain in the area where cold air is just to the north and warm air is just to the south, so the roller coaster temperatures will resume. There may be a chance for light precipitation at times, but the computer forecasts are all over the place about the track or timing of any storm.