Sunday, August 20, 2017 4:30 AM

Storms to Be Fewer and Further Between, Then Major Drying Out Much of Next Week

Central Minnesota managed a drying out day yesterday without much in the way of high and middle clouds (see infrared loop from College of DuPage Satellite and Radar Menu) and slightly lower dew points. Highs climbed into the seasonable upper 70's to lower 80's (see 3-day loop of high temperatures from NWS/University at Albany). Overnight, the next storm system pushed through the Canadian Prairie Provinces, but the bulk of the showers and thunderstorms developed further to the south along the northern fringe of much more humid air. So, showers and thunderstorms have concentrated from Nebraska into Iowa (see NWS Upper Mississippi Valley radar loop).. There are a few scattered storms moving through central South Dakota, but the deeper moisture supply is being cut off by the storms to our south, so these SD storms will limp into western Minnesota this morning with leftover clouds and a few sprinkles.

Maybe a Scattered Morning Shower, then Afternoon Sun

We are still on track to have a cold front come through Minnesota this morning, so there will be a chance of a scattered shower or thunderstorm this morning, but I give us only a 1 in 3 shot at storms. For the rest of the day, truly drier air will be working into northern and central Minnesota, so we should end up with a good supply of sunshine. Highs will again climb into the middle or perhaps upper 70's. More showers and thunderstorms will develop this afternoon near the cold front, but that will likely be in southern Minnesota, Iowa, and Wisconsin.

Slight Chance of Early Monday Storms, But Good Chance of Seeing Midday Eclipse

There still is a shade of uncertainty about clouds and the chance for showers and thunderstorms tonight and tomorrow. The bulk of the storms will be off to our south from eastern Nebraska into Iowa, northern Missouri, Illinois, and Wisconsin. Unfortunately, that means more clouds in the area where the sun will be completely covered during tomorrow's midday eclipse. The new information shows a small chance that a few of the storms could get to central Minnesota late tonight or early tomorrow, but that's still only a 1 in 3 chance. The main question is whether the clouds will break up enough by midday to allow us a good view of the partial eclipse. I'd say central Minnesota has more than a 50-50 shot of partly clear skies during the middle portion of the day.

Finally Drying Out Much of Next Week

Overall, a drying trend will be beginning tomorrow afternoon as Canadian air begins to work its way into Minnesota, allowing us relief from not only the rainfall, but also the humidity that has lingered, even when there hasn't been any rain. That will help with the bumper crop of mushrooms in my back yard as well as the mold in my bird seed.

The first wave of cooler air will move in for Tuesday. There may be a big enough temperature difference between the relatively cool air aloft and the ground to generate some scattered afternoon rain showers, but it will generally be dryer and cooler with highs only in the middle 70's. Even that small chance of showers should disappear by midweek, so highs will be in the 70's with more sun. Early mornings could be foggy with lows actually getting down into the 40's.

More Eclipse Details

This NASA site has all the information you'll need for eclipse viewing, including how to be safe watching the sun, if we have sunshine midday on Monday. If we are sunny, remember that the sun will not be completely covered, so it will never be safe to look directly at it. The National Weather Service will be taking all kinds of extra days, launching extra weather balloons and flying research airplanes along in the path of the moon's shadow. Even with the current forecast, it appears that there still could be good viewing in Wyoming, Kansas, and Missouri. The University of Wisconsin's Space Science and Engineering Center will also be displaying satellite imagery, so you can watch the moon's shadow move across the earth's surface on Monday.

Confidence Level: "I Can Turn on the Computer"

Sunday 8/20/2017: Maybe an early shower or thunderstorm, then partly sunny, warm, and uncomfortably humid. A slight chance of scattered afternoon showers and thunderstorms. High: between 74 and 78. Winds: SW 5-15 MPH, becoming NW 10-20 MPH by midday. Chance of measurable rainfall: 30% in the morning, 20% in the afternoon.

Sunday Night: Partly clear, breezy, and cooler. Cloudy late at night with a chance for scattered showers and thunderstorms. Low: between 54 and 58. Winds: NE 10-20 MPH. Chance of measurable rainfall: 30%.

Monday 8/21/2017: Mixed clouds and sun with a shot at seeing the eclipse. A chance of a late day shower or thunderstorm. Breezy, and a shade cooler. High: between 74 and 78. Winds: NE 8-15 MPH. Chance of measurable rainfall: 30%.

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

Monday Night: Clearing, breezy, cooler and less humid. Low: between 50 and 55. Winds: N 5-15 MPH. Chance of measurable rainfall: 10%.

Tuesday 8/22/2017: Sunny in the morning, a lot of afternoon clouds, breezy, and less humid. A chance of a late day shower or thunderstorm. High: between 72 and 76. Winds: NW 8-15 MPH. Chance of measurable rainfall: 30%.

Tuesday Night: Partly clear, less windy, and cooler. Areas of fog possible by morning. Low: between 46 and 52. Winds: NW 5-15 MPH, diminishing late. Chance of measurable rainfall: 10%.

Wednesday 8/23/2017: Morning sun, afternoon clouds, breezy, and cooler. High: between 70 and 75. Winds: NW 8-15 MPH. Chance of measurable rainfall: 10%.

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

Wednesday Night: Clear, light wind, and chilly again. Areas of fog possible by morning. Low: between 45 and 50. Winds: SE 5 MPH. Chance of measurable rainfall: 10%.

Thursday 8/24/2017: Sunny and pleasant. High: between 72 and 77. Winds: SE 5-15 MPH. Chance of measurable rainfall: 10%.

Extended: Finally drying out with a streak of sunny days in the middle to late week.

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 Sunday through Monday, 5 Monday night through Wednesday, 3 Wednesday night and Thursday.

Yesterday's High: 79°F; Overnight Low (through 4 AM): 62°F
St. Cloud Airport Rainfall (through 4 AM Sunday): None; SCSU Precipitation (through 4 AM Sunday): None

Next Update: Monday, August 21, 2017 8 AM (or as needed)

Links

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!

Are you interested in studying meteorology? If so, go to the Atmospheric and Hydrologic Sciences Department home page.