Friday, April 18, 2025  3:15 AM 

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

Storm Mostly Leaves Central Minnesota Drier Than Needed

That's the Problem With Getting Rain from Thunderstorms

A couple of waves of showers and thunderstorms developed yesterday and overnight across mainly south central and eastern Minnesota (set number of frames to 200 on the College of DuPage north central US radar loop). The midday storms produced some large hail in central Minnesota to our north with smaller hail reports to our south, and some wind damage in Faribault County. Since the bulk of the storm's first wave developed just to the north and east of St. Cloud and the bulk of the afternoon storms developed just to our south and east, moving through the Twin Cities and eastern Minnesota, St. Cloud did not get the expected rainfall help. Only 0.05 inch of rain was produced at the St. Cloud Regional Airport (see NWS: last 72 hours of St. Cloud observations), while Minneapolis-St. Paul International Airport picked up 0.38 inch, and Duluth got 0.47 inch. Overnight, new storms developed, mostly over southern Minnesota, producing an important 1.11 inch at Rochester. More strong storms have developed during the early morning hours along the Minnesota-Iowa border, but they will also stay well to our south. There have been some lingering light rain showers in South Dakota.

Only a Few Sprinkles Today With Little Rainfall Reaching the Ground....

All that's left from the storm over Alberta (see counterclockwise circulation on the mid-tropospheric water vapor loop from Colorado State satellite slider) will be those light instability showers. They will become more widespread as the ground gets heated by the sun, creating a large temperature difference between the ground and the middle atmosphere. However, the drier air is moving in from the Dakotas on northwest winds with dew points from the 50's seen in southern Minnesota yesterday afternoon (see green numbers on the 4 PM NWS WPC North America zoom-in map) to the upper 30's now in central Minnesota (see number at lower left on the NWS Aviation Weather Center METAR map) with lower 30's and even upper 20's in northwestern Minnesota and eastern North Dakota. So, we will likely see some rain drops at times today, but I give the showers only a 1 in 5 chance to completely wet the ground.

Missing the bulk of the showers and thunderstorms did allow afternoon temperatures to climb into the lower 70's in St. Cloud (see NWS: last 72 hours of St. Cloud observations) with some middle and even upper 70's in west central and southwestern Minnesota (set time to 18Z-20Z, 1-3 PM, on the NWS Aviation Weather Center METAR map).

...Windy, and Cooler

The persistent instability clouds seen over Manitoba and Saskatchewan (see light blue on the GeoColor satellite loop from Colorado State satellite slider) will remain over Minnesota today, so temperatures will be a lot cooler. Highs will struggle to make it to 50 degrees and the northwest winds will pick up, gusting over 30 MPH during the middle of the day (see NWS Minnesota hourly weather round-up for the latest temperatures and winds). That combination of wind and mainly drier air will also produce an elevated fire danger in parts of northern Minnesota (yellow area on the Minnesota DNR wildfire danger map will be smaller today when it is updated).

Mainly Dry and Seasonably Mild Weekend

The weekend outlook still looks good. Saturday, we will see the return of sunshine, less wind, and temperatures climbing back into the 50's. There will still be a fair amount of midday and afternoon instability clouds, but it will be very hard for more than a few drops to reach the ground. Temperatures both Friday and Saturday night will have a shot at a below freezing low, with the better chance early tomorrow morning. On Sunday, temperatures will return to the upper 50's with a shot at 60, depending on how quickly high and middle clouds move in from the south.

Sunday Night Rain Edging Closer, But Still Low Rain Chance in Central Minnesota

There is the Sunday-Monday system that is still expected to track through northern Missouri and eastern Iowa. The computer forecasts are still jumping around a bit, but are putting the northwestern edge of the significant precipitation in southeastern Minnesota. The trend over the past day has been to move the storm track a bit to the west, so south central and east central Minnesota, including the Twin Cities, are now getting more of the forecast rainfall in some projections (see Day 3 on the NWS WPC quantitative precipitation forecast). There is a small chance that some wet snow flakes could be mixed in with the rain on Sunday night with the bulk of the chance in southeastern Minnesota and Wisconsin. I am still only carrying a 1 in 5 shot at rain showers in St. Cloud, but further movement to the northwest could mean a shot at some rainfall.

Since the only batch of really cold air due over the next week will be over Minnesota today, missing the Sunday-Monday storm should allow Monday's highs to return to the 60's.

Frequent Chances for Some Rain Next Week, and a Shade Warmer Than Average

The active west-to-east flow pattern is still set up for much of next week. That will bring frequent chances for at least some rainfall, although there isn't any major northward surge of moisture that would allow really heavy rainfall (see Days 4-7 on the NWS WPC quantitative precipitation forecast). But, as we've seen, the possibility of thunderstorms means the uncertainty level goes way up.

The first chance for a few scattered storms will come on Tuesday with scattered showers and perhaps a thunderstorm both in the early morning and late afternoon.

When we aren't cloudy, temperatures will remain a bit warmer than average, but the chances of 70's will be small, since the really warm air is forecast to remain in the Central Plains.

Detailed St. Cloud, MN, and Vicinity Forecast

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

Friday 4/18/2025: Mostly cloudy with perhaps a sprinkle, windy, and cooler. High: between 47 and 52. Winds: NW 15-25 MPH with gusts over 35 MPH. Chance of measurable rainfall: 20%.

Friday Night: Clearing, not as breezy, and cooler. Low: between 28 and 33. Winds: NW 5-15 MPH evening, 5 MPH late at night. Chance of measurable rainfall: 10%.

Saturday 4/19/2025: Sunny in the morning, mixed clouds and sun with perhaps a sprinkle during the afternoon. Less windy and milder. High: between 52 and 57. Winds: NW 5-15 MPH. Chance of measurable rainfall: 10%.

Saturday Night: Clearing, light winds, and cooler. Maybe some fog. Low: between 30 and 35. Winds: light evening, SE 5 MPH late at night. Chance of measurable rainfall: 10%.

Sunday 4/20/2025: Sunny in the morning, mixed sun and clouds during the afternoon with a slight chance for a sprinkle. Continued seasonably mild. High: between 55 and 60. Winds: SE 8-15 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: Cloudy, but not quite as cool. A slight chance for a shower. Low: between 38 and 44. Winds: NE 5-10 MPH. Chance of measurable rainfall: 20%.

Monday 4/21/2025: Becoming mostly sunny, warmer, and dry. High: between 60 and 65. Winds: NE 5-15 MPH. Chance of measurable rainfall: 10%.

Monday Night: Clear early, increasing clouds late. A slight chance for a late night shower. Low: between 42 and 47. Winds: SE 5-10 MPH evening, 8-15 MPH late at night. Chance of measurable rainfall: 20%.

Tuesday 4/22/2025: Mixed clouds and sun with a chance for either an early morning or late day shower. Continued warm. High: between 60 and 65. Winds: SE 8-15 MPH. Chance of measurable rainfall: 30%.

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

Extended: Frequent, but uncertain chances for more precipitation next week??? Temperatures mainly above average???

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

Yesterday's High: 73°F; Overnight Low (through 3 AM Friday): 45°F
St. Cloud Airport 24-Hour Melted Precipitation (through 3 AM Friday): 0.05 inch; SCSU 24-Hour Precipitation (through 3 AM Friday): TBA

Next Update: Monday, April 21, 2025 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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