Friday, April 19, 2024  2:40 AM

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

A Hint of Winter (Plus 20 Degrees)

Minnesota Spring, So Weather Can Do Anything

April, like all spring and fall months in Minnesota, can produce just about any weather. The huge rain is shown merely by looking at today's St. Cloud records. While the average high is a pleasant 56 degrees and the average low flirts with freezing at 33 degrees, the April 19 high has been as warm as a July-like 89 and a barely above freezing 33 degrees, which means it was cold enough to snow. Yes, there has been snowfall with the record a ridiculous two feet in 1893.

Yesterday, temperatures nosed down below average for one of the few times this April (see 30-day graph of St. Cloud temperatures from MesoWest). Note also the 90-degree range between our warmest high (85 on April 13) and our coldest low (6 on March 23 when we had snow on the ground) during the past 30 days. The high only reached 49 degrees (see NWS: last 72 hours of St. Cloud temperatures). The afternoon clouds combined with winds that gusted up to 35 MPH produced a wind chill in the 30's. The clouds were produced by a large area of cold air aloft centered near the upper air low on the Manitoba-Ontario border (see Mid-tropospheric water vapor loop from Colorado State satellite slider). This is frequent fall and early winter pattern as we get colder air mass, passing over ground that was recently warmer. In our case, the strong April sun quickly produced the 80 degree temperature difference between the ground and the middle atmosphere. There was a stable layer aloft, so we didn't see many strong light showers (set number of frames to 200 on the College of DuPage north central US radar loop).

Even Cooler, Windier, and More Showery Than Yesterday

With the cold air pocket closer to us this morning than yesterday morning, we have a better chance for those instability showers to be more widespread today and possibly heavier. If they occur during midday or afternoon, they will drop rain, but there might even be a clap of thunder and some scattered small hail. Some of the precipitation could also be snow (note the snow reports under those showers in northern Minnesota early this morning; see NWS Aviation Weather Center METAR map). In central Minnesota, the chance of seeing snow flakes in those showers would be best if the showers linger into the evening as ground temperatures fall back into the 30's. The showers will be brief and not everyone will get one (I have a 50-50 chance).

Temperatures will continue below average, topping out in the middle to upper 40's. And that annoying wind will be around, probably a bit stronger than yesterday. The northwest breeze will blow at 20-30 MPH with gusts over 40 MPH possible (see NWS Minnesota hourly weather round-up for latest wind speeds and gusts), especially in the vicinity of any showers. The wind chill will be in the 30's.

St. Cloud Area Earth Day Run: Cool (OK), But Breezy (Unfortunately)

It now appears that the upper-air low will move far enough to our east to reduce the instability clouds tomorrow and Sunday. Given more sunshine, Saturday's high will climb to about 50 degrees with Sunday's high near 60. The winds will stay up Friday night and Saturday, the one annoying factor for Earth Day runners early Saturday morning. They will blow at 10-20 MPH. Otherwise, it will be cool for runners (but uncomfortable for spectators without a coat) with temperatures rising through the 30's to near 40 by late morning and it will be sunny.

Get Those Delicate Plants Covered If You Forgot It Was Still April

The National Weather Service has freeze warnings in effect for those who enjoyed our warm days so much that they forgot it was April in Minnesota. Delicate plants should be covered or brought inside, since the chance for a near or sub-freezing low is even better the next three nights than they are this morning, where temperatures could get that cold in the southern half of Minnesota (see NWS Aviation Weather Center METAR map).

Back to Warmer PMs Sun and Mon

The return to above average temperatures should happen on Sunday and Monday afternoons. After a chilly start in the 20's on Sunday morning, highs will have a shot at 60 degrees. On Monday, we may see another 30-degree low, but afternoon highs will climb into the 60's.

In areas that haven't picked up as much rain, especially northern and western Minnesota, the warmer temperatures will produce very low humidity, so the fire danger will again be elevated to extreme. The green-up in central and southern Minnesota will reduce this problem.

Next Chance of Rain: Late Monday? Tuesday? (Won't Be a Repeat of Deluge Earlier This Week)

The next storm arriving from the Pacific Ocean will push into Minnesota on Tuesday. There is still some spread in the timing of this system, but it looks like the cold front will come through late Monday or Monday evening. That will produce a chance of some showers, but it won't be as wet as the system earlier this week. We might have some scattered Tuesday showers under the cold air pocket (or if the system moves more slowly). Still, I'm not willing to drop high temperatures out of the upper 50's to near 60. At this point, Wednesday looks to be a sunnier day, but we'll see.

Detailed St. Cloud, MN, and Vicinity Forecast

Confidence Level: "The Bugs Are Waiting for Me to Mow the Lawn"

Friday 4/19/2024: Morning sun, more midday and afternoon clouds with a few scattered showers. Perhaps a thunderstorm or some brief hail. Even windier and a shade cooler. High: between 43 and 48. Winds: WNW 20-30 MPH with higher gusts. Chance of measurable rainfall: 50%.

Friday Night: Perhaps a lingering early evening sprinkle or flurry, then partial clearing, still breezy, and colder. Low: between 27 and 32. Winds: NW 10-25 MPH evening, 8-15 MPH after midnight. Chance of measurable precipitation: 20%.

Earth Day Run Forecast (6-10 AM Sat): Breezy and chilly with a good supply of sun. Temperatures rising through the 30's to near 40. Winds: NW 8-15 MPH near sunrise, becoming 10-20 MPH by mid-morning. Chance of measurable rainfall: 10%.

Saturday 4/20/2024: More sunshine, fewer clouds, not quite as windy, and a shade milder. High: between 47 and 52. Winds: NW 10-20 MPH. Chance of measurable rainfall: 10%.

Saturday Night: Clearing, light winds, and colder. Fog possible in the early morning hours. Low: between 23 and 28. Winds: W 5-10 MPH evening, 5 MPH late at night. Chance of measurable rainfall: 10%.

Sunday 4/21/2024: Mostly sunny, finally light winds, and much warmer. High: between 57 and 62. Winds: W 5-15 MPH. Chance of measurable rainfall: 10%.

Confidence Level: "Extra Bugs Will Come From Every Home on the Block to Hover Around My Head"

Sunday Night: Mostly clear evening, some high clouds late. Chilly again with some fog possible. Low: between 30 and 35. Winds: SW 5 MPH evening, 5-10 MPH late at night. Chance of measurable rainfall: 10%.

Monday 4/22/2024: Sunshine through high clouds during the morning. Windy and warmer. A chance of a late day shower. High: between 60 and 65. Winds: S 15-25 MPH with higher gusts. Chance of measurable rainfall: 30%.

Confidence Level: "Enough Bugs Will Fly into My Mouth to Throw Off My Diet"

Monday Night: Cloudy with a chance of showers or thunderstorms. Not as cool. Low: between 37 and 42. Winds: SW 5-15 MPH evening, NW 5-15 MPH late at night. Chance of measurable rainfall: 40%.

Tuesday 4/23/2024: Mostly cloudy with a chance of scattered showers. Breezy and not quite as warm. High: between 55 and 60. Winds: N 10-20 MPH. Chance of measurable rainfall: 30%.

Extended: Uncertain chance for showers Tuesday and perhaps Wednesday??? Continued seasonable April temperatures???

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

Yesterday's High: 49°F; Overnight Low (through 2 AM Friday): 36°F
St. Cloud Airport 24-Hour Melted Precipitation (through 2 AM Friday): None; SCSU 24-Hour Precipitation (through 2 AM Friday): TBA

Next Update: Monday, April 22, 2024 6 AM

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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