Early Week Menu: Cold Leftovers!

Why Does the Atmosphere Have to Use Us to Get Rid of Cold Air?

For the first half of this week, we are going to see the the atmospheric equivalent of Saturday night's pizza, three-day old bean salad, orange slices from the end of the soccer game, and french toast from yesterday's brunch. While the sun is now working its magic across the Northern Hemisphere, as high temperatures climbed into the 50's even in the Yukon and western Nunavut yesterday (see 4 PM Sunday NWS WPC North American zoom-in map), there are still pockets of the wintertime air mass in northern latitudes, like the area that produced highs in the teens, 20's and 30's from the northern Arctic Islands to the western shore of Hudson Bay. It already has been warmed to some degree, since there aren't the sub-zero readings that would be seen in January and February. But, the way the atmosphere gets rid of the cold leftovers once and for all is to send it further to the south, away from the snow cover and into the region with longer daylight, so it can be warmed up.

New Wave of Arctic Leftovers Today Through Wednesday

Behind the cold front that pushed through Minnesota late yesterday afternoon (see 4 PM Sunday NWS WPC North American zoom-in map), an upper-air low pressure system,, which marks one lobe of that colder air, is pushing southward through Manitoba and Saskatchewan (see counterclockwise circulation on the Mid-tropospheric water vapor loop from Colorado State satellite slider). That air will sweep across North Dakota, Minnesota, and Wisconsin over the next two days. Yesterday, southern and central Minnesota climbed above the 60-degree mark (see 7-day graph of St. Cloud temperatures from MesoWest), very close to where high temperatures are supposed to be, but that will have to hold us for a while.

Some Snow Accumulated to Our North Overnight

We are going to repeat similar conditions to what we saw the first part of last week. There has been some accumulating snow overnight in the Boundary Waters and the Arrowhead where between 2 and 5 inches of snow may have fallen. Parts of north central Minnesota may wake up to between a dusting and 2 inches of snow, mainly on grass (see few reports of snow on roads on the MnDOT Minnesota road reports), but the chance of accumulating snow is generally less elsewhere in northern and central Minnesota than what we saw last week.

Lots of Clouds, Some Snowflakes, But No Accumulation Expected Today

Still, the large temperature difference between the cold air aloft associated with the upper-air low and the relatively warm ground will increase the clouds seen in southern Manitoba and Saskatchewan (see Shortwave Albedo from Colorado State satellite slider) a lot of midday and afternoon clouds to develop today and tomorrow. There will be occasional snow showers, although nearly all of the snowflakes will melt on contact with the ground. However, morning temperatures will take their time climbing from the upper 20's before daybreak (see NWS Aviation Weather Center metar map) to the 30's. They will only get to the low to perhaps the middle 40's at times this afternoon. Throw in the strong northwest winds at 15-25 MPH with gusts over 30 MPH and the frequent periods of cloudy skies, and it will feel more like the 20's to lower 30's at best (see NWS Minnesota Hourly Weather Round-Up for latest).

40's Day, 20's Night (Close to Records) Through Thursday Morning

It will take until Wednesday to completely get rid of the cold air aloft. Tonight, most of the instability clouds will dissipate and the breeze will ease up a bit. That will allow low temperatures to fall back into the 20's. Tomorrow, a second lobe of the upper air low will be right over Minnesota, so we may begin with sunshine, but clouds will rapidly develop and we will again see on-and-off snow showers during the midday and afternoon. The only difference between tomorrow afternoon and this afternoon is that the northwest winds will ease up a little to 10-20 MPH, but temperatures will still be in the lower 40's and they will feel like the lower 30's. The snow showers or flurries might persist into Tuesday night. If that happens, there is a small chance for a coating of snow on grass, but that would be the only time for some accumulation. Temperatures will again be in the upper 20's to near 30, which is within 10 degrees of Wednesday's record cold low.

On Wednesday, the low finally moves through the Great Lakes, so there will be slightly fewer clouds and more sunshine. There still might be a snowflake or two, but there will be more sunny periods. With the lighter winds, afternoon temperatures in the middle 40's will feel a bit better than on Monday and Tuesday.

Back to 50's, Perhaps 60, Late Week

We finally get clean out the cold air the second half of the work week. We will get off to a chilly start on Thursday, possibly approaching the April 22 record cold low of 23 degrees, but we will see more sunshine during the day, allowing highs to return to the 50's, perhaps making a run at 60 degrees again. A weaker cool front will slip into Minnesota Wednesday night, but high temperatures on Friday should still make it into the 50's. However, our flow will still be coming from the northwest, so some cooler air could move in for the weekend, especially if an uncertain storm throws more clouds into the forecast.

April Continues Mild Cool Season Trend

So far in April, St. Cloud has continued the trend that dominated the cold season. The average temperature was more than 4 degrees milder than average, despite the coolness early last week. That continues the trend of every cold season month, except February.

The minor flooding of the Mississippi River in the Aitkin area will continue until mid-week. The Mississippi River is forecast to remain within its banks at Fort Ripley.

Detailed St. Cloud, MN, and Vicinity Forecast

Confidence Level: "While Preparing a Meal I Will Drop a Slice of Bread"

Monday 4/19/2021: Maybe some early sun, then rapidly becoming mostly cloudy, windy, and much cooler. A chance of a scattered afternoon rain or snow shower. Any snow will melt on contact with the ground. High: between 40 and 45. Winds: NW 15-25 MPH with higher gusts. Chance of measurable snowfall: 30%.

Monday Night: Perhaps an early evening snow flurry, then partial clearing with slowly diminishing wind and cooler. Low: between 23 and 28. Winds: NW 5-10 MPH. Chance of measurable snowfall: 10%.

Tuesday 4/20/2021: A sunny start, then becoming a mixture of clouds and sun with still a few afternoon snow showers. Any snow will melt on contact with the ground. Not as breezy, but still cool. High: between 40 and 45. Winds: NW 10-20 MPH with higher gusts. Chance of measurable rainfall: 30%.

Tuesday Night: Cloudy, light winds, with perhaps some snow flurries. Still cool. Low: between 25 and 30 (record cold low: 21 in 1936, 1950). Winds: NW 5-10 MPH. Chance of measurable snowfall: 20%.

Wednesday 4/21/2021: Sunny in the morning, partly sunny in the afternoon. Maybe a stray sprinkle. Still cool. High: between 42 and 47. Winds: NW 10-20 MPH. Chance of measurable rainfall: 20%.

Confidence Level: "The Bread Will Land on the Floor Jelly Side Down"

Wednesday Night: Partly clear with a bit of a late night breeze. Cool once again. Low: between 25 and 30 (record cold low: 23 in 1909, 1967, 1986). Winds: W 5-10 MPH. Chance of measurable rainfall: 10%.

Thursday 4/22/2021: Sunny, breezy, and seasonably mild. High: between 55 and 60. Winds: SW 10-20 MPH. Chance of measurable rainfall: 10%.

Thursday Night: Partly clear, breezy, and much milder. Low: between 38 and 43. Winds: SW 5-15 MPH. Chance of measurable rainfall: 10%.

Friday 4/23/2021: Morning sun, lots of midday and afternoon clouds with a chance of a scattered snow shower. Seasonably mild. High: between 53 and 58. Winds: SW 10-20 MPH. Chance of measurable rainfall: 20%.

Confidence Level: "My Sock Will Not Get Stuck to the Floor Because I Won't Step in the Jelly Spot"

Extended: Slightly cooler Saturday??? Maybe some Sunday precipitation????

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 7 Friday, 6 Friday night through Sunday, 5 Sunday night and Monday, 4 Monday night and Tuesday, 3 Wednesday.

Yesterday's High: 63°F; Overnight Low (through 3 AM Monday): 32°F
St. Cloud Airport 24-Hour Precipitation (through 3 AM Monday): Trace; SCSU Precipitation (through 3 AM Monday): TBA

Next Update: Tuesday, April 20, 2021 8 AM