St. Cloud, MN Weather Forecast

Wednesday, August 16, 2017 7:00 AM

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

Another Wet Slap in the Face

Overnight Storms Still Off to Our South and West

We did eke out a decent supply of sunshine yesterday, although clouds were leaning on our western doorstep both in the morning and afternoon (see infrared loop from College of DuPage Satellite and Radar Menu). Some of the high and middle clouds even produced a few drips of rain in western Minnesota. However, large blobs of showers and thunderstorms developed overnight further to the west in South Dakota and especially in Nebraska. That's because there is more than one low pressure system in the large mass of clouds, one with a counterclockwise circulation in Saskatchewan, another one in Utah, and a more subtle one that moved across Colorado and into Nebraska (see water vapor loop from College of DuPage Satellite and Radar Menu). Computer analysis actual shows a fourth one in western North Dakota. So, we have several areas of showers and thunderstorms early this morning, one in central and eastern North Dakota, and a more widespread and stronger area from Nebraska into south central South Dakota (see NWS Upper Mississippi Valley radar loop). The Nebraska storms have produced scattered severe weather, including a tornado in western Nebraska and some spotty large hail and wind damage in Nebraska and southern South Dakota. The heavy rainfall rates have also produced some flash flooding in central Nebraska.

Heavy Rainfall Potential, Especially This PM and Overnight

This wall of low pressure systems will continue to move into south central Canada and the Plains, respectively. The trend of the southernmost system producing the strongest thunderstorms will likely continue today as the Colorado and Utah systems move towards Nebraska. Since these storms to our south will tend to cut off the flow to any storms further north, any rainfall this morning in Minnesota will likely remain spotty. However, the overall trend will be to push more and more humid air northward into Minnesota and Wisconsin as the day goes on. That means showers and perhaps a few thunderstorms will become widespread in Minnesota this afternoon and overnight. These storms will be slow moving, and the air fueling them will be very humid, so some storms could produce some small stream and urban flooding. There is the potential for much of Minnesota to see 1-3 inches of rain between midday today and midday tomorrow. The August 16 record rainfall in St. Cloud is 2.07 inches, set in 1983.

Painfully Slow Improvement Tomorrow

The trend in the forecasts has been to slow down the progress of the last storm, which will drift across Minnesota tonight, but not exit central Minnesota until the second half of tomorrow. While we won't be able to keep up the heaviest rainfall rates into the morning, expect on and off rainfall to continue late tonight and through the first half of tomorrow. The storm system will finally push into Wisconsin tomorrow afternoon, so any rain will become more spotty and there is actually a chance of seeing some brightening skies in the afternoon.

All of the clouds today will not help our temperatures feel anything like mid-August. At nearly mid-month, the average St. Cloud temperature has run more than 4 degrees below average and that will go down over the next two days. If we can stay dry this morning, we could see temperatures rising from the early low 60's (see UCAR Minnesota surface chart) to the low to middle 70's. Most likely, during our rainfall, readings will be stuck in the 60's and that goes for this afternoon, tonight, and tomorrow. We will only have a shot at 70 degrees tomorrow afternoon if the skies brighten. The high temperature for mid-August is still supposed to be near 80 degrees, but we won't get there.

Next Rain Chance (Not As Much): Late Friday

The very active weather pattern will likely continue through early next week across the North Central states as a series of low pressure systems move from the eastern Pacific across southwestern Canada and the Northwest US, arriving in the Plains about a day or two apart. The next system is due to push into Minnesota late Friday afternoon. The only piece of good news is that this next storm won't have access to nearly as much moisture as the one spending the next two days moving through Minnesota, so the rain potential is less. That means we could actually see some sunshine, after a foggy start, on Friday morning and into a piece of Friday afternoon. However, the cold front from this storm will touch off scattered showers and perhaps a thunderstorm Friday afternoon into Friday evening.

Weekend??? Sure..That Will Be a Thing....

The above is the closest statement I can make about the weekend forecast. A storm system will move through the Canadian Prairie Provinces late Saturday night into Sunday morning. This will set the stage for scattered showers and thunderstorms as more humid air gets pumped over slightly cooler and drier air near the ground. It appears that these storms could be scattered around late Saturday afternoon and Saturday evening. Then, the current timing shows the cold front coming through first thing on Sunday morning, so there could be some scattered storms late Saturday night and early Sunday morning. Like the storm forecast to come through on Friday evening, this Sunday system won't have that much moisture with it, so the chance of storms will be scattered. So, I'll bet on partly sunny skies Saturday through middle afternoon with less than a 50-50 chance for showers and thunderstorms late Saturday into Saturday evening. I'm giving central Minnesota a 50-50 shot at showers and thunderstorms Sunday morning, both before and after sunrise.

That cold front will hang up somewhere near the Minnesota-Iowa border, so there could be new storms forming Sunday afternoon. Many of those will be to our south, so I am going for a fairly warm day, but we could end up with about a 1 in 3 chance for rain.

Solar Eclipse Viewing Outlook? Well...

It's still 5 days away and in this active weather pattern, so I could be easily surprised in the timing, number, and even most likely areas for storms. However, it appears that Minnesota and parts of Plains to our south, where the solar eclipse will be complete, could at least have at least a chance for showers and thunderstorms on Monday. Did I say this forecast is shakier than my smartphone on vibrate setting?

Solar Eclipse Hype

NASA has about everything you'd ever want to know about next Monday's eclipse here. Professor Elisha Polomski, SCSU's resident expert on astronomy and eclipses, recommends the safe viewing glasses and tips from the American Astronomical Society. Remember that, at best, central Minnesota will only have 80-90 percent of the sun covered (if we are clear), so it won't be safe to view the eclipse here without eye protection or a projection method.

Gert? Git......

Hurricane Gert can be seen on the eastern edge of the US satellite view (see infrared loop from College of DuPage Satellite and Radar Menu), as well as on the University of Wisconsin SSEC Satellite viewer. It has now turned to the northeast and is headed out towards the open Atlantic. It could strengthen a bit today, but will eventually become a part of the front system to its north.

d, but is in the western Atlantic (blob of clouds southeast of the Carolinas on the with top winds of 75 MPH. However, this storm is already curving northward and is expected to stay out in the Atlantic.

Confidence Level: "I Can Turn on the Computer"

Wednesday 8/16/2017: Mostly cloudy with rain or showers likely, especially in the afternoon. Heavy downpours possible. Cool again. High: between 67 and 72. Winds: SE 10-20 MPH. Chance of measurable rainfall: 90%.

Wednesday Night: Rain likely. Localized flooding possible. Low: between 60 and 65. Winds: E 10-20 MPH evening, becoming NE 8-15 MPH in the early morning hours. Chance of measurable rainfall: 90%.

Thursday 8/17/2017: Cloudy with occasional rain or drizzle through the morning. Mostly cloudy in the afternoon with perhaps a few peeks of sunshine. Continued breezy and chilly. High: between 67 and 72. Winds: NW 10-20 MPH. Chance of measurable rainfall: 50% in the morning, 20% in the afternoon.

Confidence Level: "I Can Remember Where I Wrote Down the Password and Type It In Correctly"

Thursday Night: Partial clearing, breezy, and a shade cooler. Maybe some dense fog by morning. Low: between 54 and 58. Winds: NW 5-15 MPH. Chance of measurable rainfall: 10%.

Friday 8/18/2017: Some early fog, then becoming a mixture of sun and clouds with a chance for late day showers and thunderstorms. Fairly humid. High: between 74 and 78. Winds: NW 5-15 MPH. Chance of measurable rainfall: 50%.

Friday Night: A chance of evening showers and thunderstorms, then partial clearing with perhaps some some dense fog by morning. Low: between 58 and 63. Winds: light SW. Chance of measurable rainfall: 50%.

Confidence Level: "After 5 Minutes of Boot Up Time, I Can Remember Why I Turned on the Computer"

Saturday 8/19/2017: Any fog dissipating early, then partly sunny, warm, becoming breezy and humid with a chance of a scattered late day shower or thunderstorm. High: between 76 and 82. Winds: SW 10-20 MPH. Chance of measurable rainfall: 30%.

Saturday Night: A chance of evening showers and thunderstorms, then partial clearing, breezy, and humid. More scattered showers and thunderstorms possible in the pre-dawn hours. Low: between 64 and 68. Winds: SW 10-20 MPH. Chance of measurable rainfall: 40% evening, 50% in the early morning hours.

Sunday 8/20/2017: Maybe an early shower or thunderstorm, then mixed clouds and sun, warm and still quite humid. A few scattered afternoon showers and thunderstorms possible.Still breezy and humid. High: between 76 and 82. Winds: SW 10-20 MPH. Chance of measurable rainfall: 50% in the morning, 30% in the afternoon.

Extended: A chance of afternoon showers and thunderstorms Monday????

Forecast Confidence (10 - "Will more of your hair fall out, Bob?"; 0 - "Will the winning PowerBall Numbers be encoded in your lost hair, Bob?"): 6 Wednesday through Thursday, 5 Thursday night and Friday, 4 Friday night, 3 Saturday and Saturday night, 1 Sunday, 0 Monday.

Yesterday's High: 78°F; Overnight Low (through 7 AM): 62°F
St. Cloud Airport Rainfall (through 7 AM Wednesday): 0.22 inch; SCSU Precipitation (through 7 AM Wednesday): 0.03 inch

August 16 Historical Data High Low
Average Temperatures 80°F 56°F
Record Temperatures 100°F (1950) 76°F (1937)
60°F (1979,1980) 42°F (1992)

Next Update: Thursday, August 17, 2017 8 AM (or as needed)





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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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