St. Cloud, MN Forecast and Weather Discussion (2024)

Wednesday, June 19, 2024 4:00 AM

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

Several Roads Closed in North Central Minnesota and the Arrowhead

Three waves of thunderstorms hit Minnesota yesterday. The first wave came through central and southern Minnesota during Tuesday's early morning hours. By sunrise, the leftovers from those storms were in northeastern Minnesota (set number of frames to 200 on theCollege of DuPage north central US radar loop). At the same time, showers and thunderstorms that developed closer to the low pressure system in Montana and the eastern Dakotas (seeMid-tropospheric water vapor loopfrom Colorado State satellite slider). paraded across northern Minnesota during the morning. Some of those early morning storms produced damaging wind and large hail in northwestern and north central Minnesota (set time to 36 on theNWS Minnesota local storm reports map). Those storms spent all day moving across northern Minnesota. Then, in the afternoon, new showers and thunderstorms developed near the Minnesota-Dakotas border and pushed eastward in the late afternoon and evening hours. But those storms ended up producing heavy rainfall over the portions of north central and northeastern Minnesota which had received heavy rainfall earlier. Radar estimates have shown that between 3 and 5 inches of rain has fallen in these areas. So, there was widespread flooding (orange dots on theNWS Minnesota local storm reports map) from north central Minnesota to the North Shore. The rain has finally moved out of northeastern Minnesota during the early morning hours, so water will recede. However, MnDOT was reporting several state roads closed by flooding between Grand Marais and Grand Rapids (seeMnDOT Minnesota road reports). This water will move from overland areas into local streams and rivers, so flooding will be more concentrated there as today goes on. The National Weather Service in Duluth has aflood warningout from north of Brainerd and Duluth to the east of International Falls, then the rest of the Arrowhead until 4 PM today. As this water drains out,northeastern Minnesota's waterfall state parkswill havemuch higher flow that normal. River currents will be strong and more than the usual amount of trails, especially on solid rock, will be wet and slippery. This will continue for several days.

Both a Rain and a Humidity Break Today

However, we will get our one-day reprieve from thunderstorm chances. The late day round of showers and thunderstorms developed along the cold front extending from the Montana low (see4 PM Tuesday NWS WPC North America zoom-in map). That fronthas pushed through the state overnight. Replacing the tropical air mass with dew points in the 70's (set time to 18Z-21Z, 1-4 PM on theNWS Aviation Weather Center METAR map) has been much drier air from the Dakotas, with dew points in the far more comfortable 40's and even 30's (green and blue areas on theUCAR hourly dew point chart). With all of the rainfall in Minnesota, we may not see dew points get to the lower 40's, since any warming during the day will allow water on the ground to evaporate. Still, we will see far more comfortable conditions instead of yesterday's heat indices over 90 (temperatures in the middle 80's with those oppressive dew points; see 1-4 PM on theNWS Minnesota hourly weather round-up).

Oh, and the sun will return. There are some lingering clouds in North Dakota in the cooler air (seeShortwave Albedofrom Colorado State satellite slider). There have been even some lighter rain showers in northeastern North Dakota and northwestern Minnesota (see last 48 frames ofCollege of DuPage north central US radar loop), as one small low moves northeastward from North Dakota towards southeastern Manitoba and western Ontario (seeMid-tropospheric water vapor loopfrom Colorado State satellite slider). So, the rain showers will stay away from the bulk of Minnesota. And, there will be enough drying to allow the sun to break through for a lot longer than during the past couple of days.

Best Chance for More Significant Rainfall Thursday and Friday Nights (Lingering into Following AM)

However, the drier conditions won't last. Minnesota will undergo another surge of the very warm and sticky air between Thursday and Saturday. The risk of severe thunderstorms will be relatively small withjust conventional thunderstorms, mainly Thursday night, and perhaps a few storms producing hail Friday morning in northern Minnesota andFriday night in southern and central Minnesota. The main threat will be another round of significant rainfall (see Days 2-4 on theNWS WPC Excessive Rainfall Outlook). Although these outlooks haven't quite nailed where the heaviest rainfall will be, any significant rain on top of the already saturated ground, especially in north central and northeastern Minnesota, will aggravate the flooding potential (see Days 2-5 on theNWS WPC quantitative precipitation forecast).

My best guess is that the most favorable time for showers and thunderstorms will be late Thursday night into Friday morning and again Friday night into Saturday morning. That's when there appears to be the best surge of the tropical air over the leftovers of today's cooler and drier air. Showers and thunderstorms may be possible as early as late tonight and tomorrow morning as the first wave of stickier air moves northward, but the drier air near the ground will prevent a lot of the rain from reaching the ground. Much of central and southern Minnesota should be in the tropical air at the ground on Friday. That would produce a lull in the thunderstorm activity if the warm front has moved to our north. Most likely, we will have another day like yesterday with mostly cloudy skies and stifling humidity.

Less of Storm Chance Saturday PM?

At this point, it appears that the next cold front will be pulled by a storm now on the Oregon-California coast (seeMid-tropospheric water vapor loopfrom Colorado State satellite slider). That front is forecast to come through during the middle of Saturday or in the early afternoon, so the bulk of the storms could be over by midday. However, eastern parts of Minnesota would have a better chance of seeing redeveloping showers and thunderstorms on Saturday afternoon.

Not as Humid Sunday, Perhaps a Few Showers?

Minnesota will be out of the steam bath by Sunday, but the computers cannot agree on the strength or movement speed of the Oregon-California low. The pocket of cold air aloft could linger over parts of Minnesota during some part of Sunday, which would keep a lot more clouds around and some scattered showers, but the rain shouldn't be as heavy as on Thursday night or Friday night.

"Turn Around, Don't Drown"

In summary, the main weather-related threat will be the flooding on-going in northern Minnesota today and the potential for more flooding from thunderstorms Thursday and Friday nights. There isn't much to be done about flash flooding during the heavy rains. When all of that water gets into rivers and streams, some people ignoring the signs closing off roads and try to drive across moving water. The problem is that your vehicle will float in sufficient water and then you will lose complete control of the vehicle. So, obey any road closures (as currently noted on theMnDOT Minnesota road reports).

Through 4 AM, the St. Cloud Regional Airport has picked up another 0.13 inch since early yesterday. The June total rainfall is 5.47 inches, more than double the average of the first 17 days (2.10 inches) and over an inch and a half above theaverage for all of June (3.75 inches)

Detailed St. Cloud, MN, and Vicinity Forecast

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

Wednesday 6/19/2024:Mixed sun and clouds, much drier, and a bit cooler.High: between 70 and 75.Winds: NW 5-15 MPH.Chance of measurable rainfall: 10%.

Wednesday Night:Partly clear during the evening, thicker clouds late at night. Low humidity. A slight chance for a late night shower.Low: between 52 and 57.Winds: E 5-10 MPH.Chance of measurable rainfall: 20%.

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

Thursday 6/20/2024:Thickening clouds with a chance of afternoon showers and thunderstorms.Cool with relatively low humidity.High: between 68 and 73.Winds: E-SE 8-15 MPH.Chance of measurable rainfall: 40%.

Thursday Night:Cloudy with perhaps an evening shower. A better chance for showers and thunderstorms late at night. Heavy downpours are possible. Turning more humid.Low: between 58 and 63.Winds: SE 8-15 MPH.Chance of measurable rainfall: 30% evening, 60% after midnight.

Friday 6/21/2024:Some lingering morning showers and thunderstorms. Warmer and uncomfortably humid the rest of the day. Perhaps some afternoon sun. Also a chance for a late day shower or thunderstorm.High: between 78 and 83.Winds: SE 8-15 MPH in the morning, S 10-25 MPH in the afternoon.Chance of measurable rainfall: 50% in the morning, 30% in the afternoon.

Friday Night:Breezy, warm, and sticky. Showers and thunderstorms possible with a better chance late at night.Low: between 60 and 65.Winds: SE 8-15 MPH, becoming SW late.Chance of measurable rainfall: 30% evening, 50% in the early morning hours.

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

Saturday 6/22/2024:Warm and sticky with a good chance of showers and thunderstorms in the morning and midday. Maybe some clearing in the afternoon.High: between 75 and 80.Winds: SW 8-15 MPH, becoming NW 8-15 MPH in the afternoon.Chance of measurable rainfall: 50%.

Saturday Night:Partly clear evening and turning less humid. Some clouds with perhaps a light rain shower late.Low: between 55 and 60.Winds: N 8-15 MPH.Chance of measurable rainfall: 20%.

Sunday 6/23/2024:Mixed clouds and sun with perhaps a scattered shower. Drier.High: between 80 and 85.Winds: SW 8-15 MPH, becoming NW 8-15 MPH in the afternoon.Chance of measurable rainfall: 50%.

Extended:Turning more humid again and possibly warmer by Monday with another round of showers and thunderstorms Sunday night???

Forecast Confidence(10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"):8 Wednesday, 7 Wednesday night, 5 Thursday, 4 Thursday night through Friday night, 3 Saturday, 2 Saturday night and Sunday.

Yesterday's High: 85°F;Overnight Low (through 3 AM Wednesday): 62°F
St. Cloud Airport 24-Hour Melted Precipitation (through 3 AM Wednesday):0.13 inch (0.79 inch since Monday); SCSU 24-Hour Precipitation (through 6 AM Tuesday): 0.63 inch

Next Update:Thursday, June 20, 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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