St. Cloud, MN Weather Forecast

Tuesday, April 20, 2021 4:05 AM

Bob Weisman
Meteorology Professor
Saint Cloud State University
Atmospheric and Hydrologic Sciences Department

Cold, Hard Facts of April

Ring Around the Lowsie

The series of upper-air lows over central Canada continue to circulate into the North Central US (see Mid-tropospheric water vapor loop from Colorado State satellite slider). That's because the larger circulation in the steering winds is one large counterclockwise circulation with the various lows caught up in it. One low is moving northeastward from Ontario into Quebec, but another one is moving southward across Manitoba and Saskatchewan. Each of these lows represents a puddle of cold air aloft. The one to our northwest has more persistent low-level clouds than the one that has gone by (see Shortwave Albedo from Colorado State satellite slider).

A Couple of Extra Degrees, A Few Less Miles an Hour, Still Scattered Snowflakes

That all means that today will be very similar to yesterday. The clear spots across Minnesota that has allowed early morning temperatures to fall well down into the 20's (see NWS Aviation Weather Center metar map) will fill in again with a lot of clouds, especially during the second half of today. With this upper air low scheduled to move into western Minnesota by late in the day, there will be more scattered snow showers during the afternoon and early evening. Any daytime snow will melt on contact with the ground since temperatures will be a few degrees above 40. Any snow flakes this evening will have a small chance to produce a coating on grass. Northwest winds won't be as strong as they were yesterday (gusts of 20-30 MPH on the NWS: Last 72 hours of St. Cloud Observations), but we will still see 10-20 MPH northwest winds. So, it will end up being only slightly less miserable than yesterday.

Cold Enough to Approach Record Lows Wed, Thu If Skies Clear Out

With the evening clouds, low temperatures will again be a little milder than they could be, since the dry, cold air could support lows well down in the 20's or even some teens. Our record cold lows for the next two mornings are in the lower 20's (21 tomorrow, 23 Thursday), relatively mild for mid-April (most record lows are in the teens). I think we will have a better shot at a record cold low Thursday, when there will be fewer clouds and the winds will be light.

Fewer Clouds, 45 Tomorrow

The large low causing the cold pockets to circulate will ease a bit to the east tomorrow, becoming centered over Lake Huron. That will allow Minnesota to only be on the fringe of the cold pool. So, we will have more sunshine mixed with clouds. There still will be a slight chance for a stray snowflake. The northwest winds will ease to 5-15 MPH and temperatures will make a strong run at 45 degrees.

Rapid Warm-Up Thursday...

However, the big low will be replaced by flow from over the Canadian Rockies. That area has been relatively mild with highs in the 40's and 50's from northwestern Alberta into the Yukon (see 4 PM Monday NWS WPC North American zoom-in map), so we will see a warm-up from the current chilly air. Highs on Thursday afternoon will be warmed by a better supply of sunshine, so temperatures will climb to near or perhaps even above 60 degrees.

...But More Friday Clouds, A Few Showers

The overall steering winds will continue to move weather systems from northwestern Canada into the central and eastern US. So, Thursday's 60-ish temperatures will have to satisfy our warm desires for a while. Friday, we will have a front hang up in Minnesota, producing more clouds and the chance for some showers. There isn't a lot of moisture with this system, so the showers will be scattered. When it isn't raining, temperatures should be able to get back into the 50's.

Another Cool Shot Saturday Won't Be Quite as Cold or as Persistent

A stronger cold front is forecast to push into Minnesota Friday night. This will bring an end to the occasional showers, but usher in cooler air. It won't be one of the leftover lodes of cold arctic air this time, so there won't be as many instability clouds dimming the sun. And, high temperatures will be in the upper 40's to near 50. There will be a strong northwest wind once again. This cool shot looks like it will be shorter-lived than the one we are experiencing now, so there could be some moderation in temperatures as early as Sunday.

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"

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 evening snow flurries. Partial clearing late at night. Still cool. Low: between 25 and 30 (record cold low: 21 in 1936, 1950). Winds: NW 5-10 MPH. Chance of measurable snowfall: 10%.

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 5-15 MPH. Chance of measurable rainfall: 10%.

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: calm early, SW 5-10 MPH late at night. Chance of measurable rainfall: 0%.

Thursday 4/22/2021: Sunny, breezy, and seasonably warm. High: between 57 and 62. Winds: SW 10-20 MPH. Chance of measurable rainfall: 10%.

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

Thursday Night: Partly clear and mild evening, cloudy with a chance of rain showers late. Breezy. Low: between 38 and 43. Winds: SW 10-20 MPH evening, S 5-10 MPH late. Chance of measurable rainfall: 40%.

Friday 4/23/2021: Cloudy, breezy, and cooler with perhaps some scattered rain showers. Not quite as warm. High: between 52 and 57. Winds: SW 5-15 MPH. Chance of measurable rainfall: 30%.

Friday Night: Cloudy with perhaps an evening rain shower, then turning breezy and cooler late. Low: between 32 and 37. Winds: SW 8-15 MPH evening, NW 10-25 MPH late. Chance of measurable rainfall: 30%.

Saturday 4/24/2021: Becoming partly sunny, breezy, and a bit cooler. High: between 45 and 50. Winds: NW 15-25 MPH. Chance of measurable rainfall: 10%.

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

Extended: Chance of a few showers Sunday???

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 8 Tuesday, 7 Tuesday night and Wednesday, 6 Wednesday night and Thursday, 5 Thursday night and Friday, 4 Friday night and Saturday, 2 Sunday.

Yesterday's High: 40°F; Overnight Low (through 4 AM Tuesday): 31°F
St. Cloud Airport 24-Hour Precipitation (through 4 AM Tuesday): Trace; SCSU Precipitation (through 4 AM Tuesday): Trace

St. Cloud Daily Average and Record Temperatures
April 20 Historical Data High Low
Average Temperatures 59°F 34°F
Record Temperatures 84°F (1980) 56°F (1985)
35°F (1928) 16°F (2013)

Next Update: Wednesday, April 21, 2021 8 AM





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Let me know what you think about this forecast and discussion by emailing SCSU meteorology professor Bob Weisman. Please note that I make the forecast, not the weather!

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