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

Monday, June 24, 2024 4:30 AM

Prepared by Bob Weisman, SCSU Meteorologist and Professor Emeritus

One Dry Day!

We had no rain in St. Cloud since 3-4 PM Saturday (seeNWS: last 72 hours of St. Cloud observations). And, we actually had a good supply of sunshine yesterday after the early low clouds and fog broke up (seeShortwave Albedoloop from Colorado State satellite slider). That allowed high temperatures to climb into the low to middle 80's (see4 PM Sunday NWS WPC North America zoom-in map).

But Flooding Issues Continue...

Flooding problems continue, especially from southern Minnesota into South Dakota and Iowa (see river gauges at flood stage, orange, moderate flood, red, or major flood, purple, on theNWS National Water Prediction Service Twin Cities area map). Flood warnings continue across southwestern and south central Minnesota and along the Crow, Minnesota, Cannon, and Mississippi Rivers (from the Twin Cities downstream; see light green areas on theNWS Twin Cities watch-warning map). And, flooding continues in northeastern Minnesota (green areas on theNWS Duluth watch-warning map).

The flooding issues are clear when you look at the rainfall. Minnesota Public Radio ran alist of 3 day rainfallfrom Thursday through Saturday. During the past week, more than 5 inches of rain fell (red) from eastern South Dakota across to Red Wing and the southern Twin Cities area. There were 10-15 inches (cyan) in southeastern South Dakota and southwestern and south central Minnesota, and even 15-20 inches (blue-purple) near Sioux Falls (on theNWS Minnesota National Water Prediction Center rainfall chart, uncheck all the River Gauge categories, and set the Hazards to 'Do Not Display,' then select 'Precipitation Estimate' from yesterday and select 7 days). Meanwhile, the St. Cloud area has been drier, but still picked up between an inch and an inch and a half of rain (middle green color). An inch a week is what is typically needed to keep crops and lawns in good shape.Northeastern Minnesota's problems can be seen in the14-day totals, with more than 6 inches of rain from the Iron Range through the Boundary Waters. of Nearly all of Minnesota, except the north central and west central, has seen more than 5 inches of rainduring the past 30 days.IowaandSouth Dakotahave shared in the flood issues.

Road Advisories and Detours (including I-29 in Extreme SE SD)

Minnesota Hwys. 1 and 61 in northeastern Minnesota, and several state roads in the Minnesota River Valley and southern Minnesota continue to have flooding issues (seeMnDOT Minnesota road reports) with some roads being detoured. There are also issues insoutheastern South DakotaandIowa(travel not advised in northwestern Iowa). I-29 is closed from Sioux City northward into South Dakota.

Drier Interlude to Continue....

However, yesterday was the first day of a drier period. This does not mean we will be completely thunderstorm-free. However, the only decent chance for thunderstorms between yesterday and Thursday morning will be late this afternoon and this evening and, even then, showers and thunderstorms will not be nearly as widespread as they have been for most of the past month.

Except (Maybe) Late Today

The atmosphere irritant that will cause the chance for storms today is the low pressure system moving from British Columbia into Alberta (see counterclockwise circulation on theMid-tropospheric water vapor loopfrom Colorado State satellite slider). That system will pull the cold front in southern Saskatchewan and eastern Montana (seelatest NWS WPC North America zoom-in map) through Minnesota late this afternoon and early this evening. The NWS Storm Prediction Center has rated the threat forsevere storms in Minnesota at category 2 out of 5with threats for large or even very large hail, straight-line damaging winds, and perhaps even a tornado. However, the percentage threat (mouse over 'tornado,' 'wind,' and 'hail') is lower than we'd usually see in soupy air (2% for tornado, 15% for hail and wind). That's because any thunderstorms that develop will have to fight a plume of warm air aloft.

Stifling Low-Level Humidity To Our West, Which Will Return Today

This is because there has been a subtle change in the overall North American weather pattern. The rain from the storms that hit southern Minnesota hard has pushed into the east from New England to the Appalachians (seeShortwave Albedoloop from Colorado State satellite slider). There is still the large clockwise circulation over the western half of the US, which is the subtropical high pressure area centered over east Texas (seeMid-tropospheric water vapor loopfrom Colorado State satellite slider). The severe heat and humidity (highs in the middle and upper 90's and even a couple of 100's, Arkansas and Georgia on the4 PM Sunday NWS WPC North America zoom-in map) from eastern Oklahoma and Kansas into Florida with dew points in the tropical upper 60's and 70's (even some upper half of the 70's, which is hurricane-like humidity, on theUCAR hourly dew point chart) continues from the Lower Mississippi Valley to the Carolinas and Florida. That's the air mass that has produced all of the heat problems.

But, Hot Air Above the Ground Will Keep Any Late Day Thunderstorms Scattered

But, the deep moisture fueling the heavy rainfall is pushing off the East Coast. There are the typical showers and thunderstorms on the fringe of the hot air, last night in Saskatchewan and Manitoba into North Dakota with only a few storms in Montana and Iowa (seeShortwave Albedoloop from Colorado State satellite slider). That's because the stream of warm air riding over the top of the drier air northeast of the warm front has a plume of very warm air aloft (dark yellow areas denote 700 mb temperatures, about 10,000 feet up, warmer than 15°C (59°F) in the northern and central Rockies on the most recent 700 mb Plymouth State College Continental US map). This has produced a difference even at the ground, since areas with highs over 100 degrees yesterday from the Nebraska Panhandle and west Kansas into western Texas had dew points in the lower 50's or lower; see4 PM Sunday NWS WPC North America zoom-in map). The plume of warm air aloft is overlapping the western edge of the steamier air further to the east. Since thunderstorm development actually depends on the temperature falling as fast as possible in the lowest 20,000 feet of the atmosphere, thunderstorm areas are few and far between.

Scattered Storms Are Likely to Produce Scattered Severe Weather

The plume of warm air aloft means that only a few scattered storms will develop, at most late this afternoon and tonight. Having fewer storms often means that the ones that develop have a better chance for producing severe weather, but fewer people experience that severe weather. The NWS Storm Prediction Center also notes in its outlook that the area with the largest severe weather threat is mainly an 'either-or' outlook. If storms develop during the afternoon, they would most likely be most severe near the warm front, which would tend to affect northern and central Minnesota. If the storms hold off until the evening hours, the strong storms would more likely develop at the cold front, which would mean more of a severe weather threat for southern Minnesota. The scattered storms also mean that heavy rainfall will be less widespread with the only half inch rainfall contours (green on the Day 1NWS WPC quantitative precipitation forecast) is in northeastern Minnesota and the St. Croix River Valley. Wisconsin has heavier amounts since the isolated storms tend to merge as they continue eastward during the nighttime hours.

Most Likely Weather-Related Issue: Most Sultry Day of Summer So Far in West Central and Southern Minnesota

Either scenario means that there are very few warm front clouds during the early morning hours (seeShortwave Albedoloop from Colorado State satellite slider) and clouds would likely be suppressed during the day until thunderstorms develop, so we should again have a good supply of sun. Since there is plenty of low-level moisture nearby, dew points will return to the uncomfortable upper 60's and Florida-like lower 70's. That means hotter temperatures with highs in the upper half of the 80's in most of central and parts of northern Minnesota with heat indices in the low to middle 90's (seeNWS Minnesota hourly weather round-upfor the latest temperatures, dew points, and heat indices of 90 or higher). 90's are most likely in the Minnesota River Valley and parts of southern Minnesota with heat indices in the 95-105 range. That's why the National Weather Service has a heat advisory in effect for the western half of the Minnesota River Valley, west central, and southwestern Minnesota (orange areas on theNWS Twin Cities watch-warning map). This is thenorthern edge of the heat advisorythat covers all of the hot weather area southward to Texas and east to the Florida Panhandle. Today has a good chance to be the most serious hot weather day we've seen so far this summer.

Drier With More Sunshine Tuesday and Wednesday(Three Out of Four Ain't Bad?)

I've now spent the previous 6 paragraphs describing why today's threat of thunderstorms will be rather small. But, the rest of my theme is that we are likely on a dry streak that will keep us rain-free 3 of the 4 days from Sunday through Wednesday. The Alberta low will likely intensify enough to turn our steering winds around to running from northwest-to-southeast. That will push the extreme heat and humidity to the central or even Southern Plains and allow Minnesota to tap the air mass in the central Canadian Prairie Provinces. While high temperatures are still warm (80's were common in southern Alberta and Saskatchewan yesterday on the4 PM Sunday NWS WPC North America zoom-in map), the air is drier with current dew points in the 50's (yellow) and a few upper 40's (green on theUCAR hourly dew point chart). As that air moves over Minnesota tonight and tomorrow, it will pick up more moisture from our wet ground, but I think that we should see dew points go back to the merely noticeable upper 50's instead of today's upper 60's and lower 70's.

Tomorrow's highs will remain well up in the 80's (perhaps 90 in a few spots) as a strong northwest wind mixes the atmosphere well. That will also allow a lot of sunshine. The winds calm down on Tuesday night, so areas of fog are likely. The fog should dissipate early on Wednesday with cooler highs in the upper 70's to perhaps the lower 80's.

Rain Chances Maybe Thursday, Uncertain Chance Thursday Night and Friday

This dry period won't be prolonged, but it will look good after the frequent rain we've seen since mid-May (11 Maydays from May 15 on and13 June dayswith measurable rainfall so far; total measurable rain on 24 of the past 40 days). By Thursday, the next storm system from the busy northeastern Pacific (see all of the low centers, spinning counterclockwise to the south of Alaska on thePacific mid-tropospheric water vapor loopfrom Colorado State satellite slider) will reach the British Columbia coast. This will begin to pull the very warm and still sticky low-level air northward. It will take a while for the really steamy stuff to get this far north, but there will be more clouds and some scattered rain showers on Thursday, mainly in the afternoon.

Eventually, the continued flow of moisture as this low pushes into the Canadian Prairies will trigger a more widespread thunderstorm threat in the Northern Plains and/or the Canadian Prairie Provinces. It's uncertain this far out where the best chance for heavy rain might be, but there is that potential, at least nearby, in the Day 4-7NWS WPC quantitative precipitation forecast). While rain isn't guaranteed, any significant rainfall in northeastern Minnesota, southern Minnesota and adjacent Iowa and South Dakota will be a problem (see Days 4-5 on theNWS WPC Excessive Rainfall Outlook).

Detailed St. Cloud, MN, and Vicinity Forecast

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

Monday 6/24/2024:Mixed clouds and sun, warmer, and turning oppressively humid again. A slight chance of a morning shower. A few scattered late day showers and thunderstorms.High: between 85 and 90.Heat indices between 92 and 97. Winds: SE 10-20 MPH in the morning, 15-25 MPH with higher gusts in the afternoon.Chance of measurable rainfall: 20% in the morning, 30% in the late afternoon.

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

Monday Night:Steamy with a chance of scattered showers and thunderstorms, especially during the evening or around midnight. Severe weather possible in those scattered thunderstorms. Partial clearing with decreasing humidity late at night.Low: between 63 and 68.Winds: SE 10-20 MPH evening, NW 15-25 MPH with higher gusts late evening through early morning, NW 5-10 MPH towards dawn.Chance of measurable rainfall: 40%.

Tuesday 6/25/2024:Sunny and quite warm, breezy, but turning drier.High: between 85 and 90.Winds: NW 10-20 MPH.Chance of measurable rainfall: 0%.

Tuesday Night:Partly clear, breezy, and not quite as warm. Areas of dense fog possible by morning.Low: between 53 and 58.Winds: N 5-15 MPH, diminishing late at night.Chance of measurable rainfall: 10%.

Wednesday 6/26/2024:Some early fog, then becoming sunny to partly cloudy the rest of the day. Noticeably humidity and not quite as warm. A slight chance of an afternoon sprinkle.High: between 77 and 82.Winds: NW 5-15 MPH.Chance of measurable rainfall: 10%.

Wednesday Night:Clear during the evening. More clouds or fog late at night. Still noticeable humidity.Low: between 55 and 60.Winds: light evening, SE 5 MPH late.Chance of measurable rainfall: 10%.

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

Thursday 6/27/2024:A lot more clouds with a chance of a scattered shower. Noticeably to uncomfortable humidity.High: between 70 and 75.Winds: SE 10-20 MPH.Chance of measurable rainfall: 30%.

Thursday Night:A better chance for showers and thunderstorms. Uncomfortable humidity.Low: between 60 and 65.Winds: SE 10-20 MPH.Chance of measurable rainfall: 50%.

Friday 6/28/2024:Mostly cloudy with scattered showers and thunderstorms. Continued humid.High: between 75 and 80.Winds: S 8-15 MPH.Chance of measurable rainfall: 40%.

Extended:Cooler Saturday?? Perhaps a few scattered showers??? Dry Sunday???

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

Yesterday's High: 84°F;Overnight Low (through 4 AM Monday): 60°F
St. Cloud Airport 24-Hour Melted Precipitation (through 4 AM Monday):None; SCSU 24-Hour Precipitation (through 4 AM Monday): None

Next Update:Tuesday, June 25, 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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