Friday, September 18, 2020 3:55 AM 

Atmosphere to Keep Its Chilly Hotter Through the Weekend

Bluer Than Blue (if I stay out too long)

The cooler air was entrenched in Minnesota yesterday. After a morning low of 36 degrees (see, we did make a 40 degree swing since Tuesday; see 5-day graph of St. Cloud temperatures from MesoWest), temperatures only made it into the middle 50's in central Minnesota (see 4 PM Thursday UCAR map). St. Cloud was 6 degrees too warm for the September 17 record cold high (49, set in 1929). We had patches of clearing overnight (see Shortwave Albedo loop from Colorado State satellite slider), so temperatures have dropped below freezing in Hinckley, Moose Lake, and Mora (see NWS Aviation Weather Center METAR map). There were 20's in Aitkin and again in the Iron Range and throughout the Arrowhead. Most of the St. Cloud area has seen temperatures in the middle 30's, but some patchy frost may have occurred. Further to the north and west, temperatures were back in the 40's, thanks to those middle clouds.

Last Day of October Preview for Now

We will have one last really cool day before temperatures come back to where they are supposed to be (average high of 69, average low of 42) and beyond for the weekend and into next week. Highs will climb to around 60 degrees with more sunshine and a light wind.

Return to September Norm

That high pressure area off to our east (see NWS WPC Latest North American zoom-in surface map) will push away, allowing southeast winds to become more persistent and bringing milder air into our area. I expect lows tonight to remain in the 40's. Tomorrow, we should have a near average temperature day with a high in the upper 60's to perhaps the lower 70's. The south winds will remain stronger tomorrow night, so lows will likely stay in the 50's. On Sunday, highs will climb to the middle or upper 70's.

Break Out the Disco Balls and the Platform Shoes....70's (and Even 80's) Return Sunday into Next Week

The breezy and warm weather will continue into next week with highs in the upper 70's to possibly 80's if we get a full supply of sun. We will be down to 12 hours of sunlight with the Fall Equinox on Tuesday, so we need a good strong wind and nearly all of the possible sun for temperatures to climb into the 80's. However, with the wind expected to blow overnight, we might have a low in the 60's, giving us quite the early start.

There still could be some high haze from the smoke of the western forest fires (see EPA Air Quality map).

Minnesota Protected from Wet Systems, But Tropics to Affect Texas and Possibly East Coast

With the big high pressure area over the western third of the US (see clockwise rotation centered in Colorado on the Mid-Tropospheric water vapor map from Colorado State satellite slider), it will be hard for any weather system to bring moisture into Minnesota. Instead, the east-to-west winds prevalent over the central and tropical Atlantic into the Gulf of Mexico and Caribbean Sea will continue to foster tropical systems. The cloud cluster in the western Gulf of Mexico (see Shortwave Albedo loop from Colorado State satellite slider) is a new tropical depression. This system is forecast to wander close to the Mexico-Texas border and stall with future strengthening very uncertain. At the very least, it has the potential of dumping a prolonged heavy rain along the Texas or Mexican coast.

In the western tropical Atlantic is Hurricane Teddy. Top winds are currently 130 MPH and the storm is expected to approach or pass nearby Bermuda late Sunday or Monday. The risk for major impact is increasing. Teddy will also cause dangerous tides along the Caribbean Islands, the Bahamas, and parts of the US by the weekend. The storm is expected to merge with a mid-latitude cyclone and lose its tropical characteristics next week, but is expected to be powerful with some forecasts having the storm approach eastern Canada.

Detailed St. Cloud, MN, and Vicinity Forecast

Confidence Level: "While Preparing a Meal I Will Drop a Slice of Bread"

Friday 9/18/2020: Partly cloudy, breezy, and continued cool. High: between 58 and 63. Winds: SE 5-15 MPH. Chance of measurable rainfall: 0%.

Friday Night: Partly cloudy, breezy, and not as cool. Low: between 42 and 47. Winds: SE 5-15 MPH. Chance of measurable rainfall: 0%.

Saturday 9/19/2020: Partly cloudy, windy, and returning to more typical warmth. High: between 68 and 74. Winds: SE 15-25 MPH. Chance of measurable rainfall: 0%.

Saturday Night: Partly to mostly cloudy, breezy, and warmer. Low: between 53 and 58. Winds: SE 10-20 MPH. Chance of measurable rainfall: 10%.

Sunday 9/20/2020: Partly sunny, windy, and warmer. High: between 72 and 78. Winds: SE 15-25 MPH. Chance of measurable rainfall: 10%.

Confidence Level: "The Bread Will Land on the Floor Jelly Side Down"

Sunday Night: Partly to mostly cloudy, breezy, and warmer. Low: between 58 and 64. Winds: SE 10-20 MPH. Chance of measurable rainfall: 10%.

Monday 9/21/2020: Continued partly sunny, windy, and warm. High: between 77 and 82. Winds: SW 15-25 MPH. Chance of measurable rainfall: 10%.

Confidence Level: "My Sock Will Not Get Stuck to the Floor Because I Won't Step in the Jelly Spot"

Monday Night: Partly clear, light winds, and still warm. Low: between 53 and 58. Winds: SW 5-10 MPH. Chance of measurable rainfall: 10%.

Tuesday 9/22/2020: Sunny, light winds, and continued warm. High: between 78 and 84. Winds: SW 5-15 MPH. Chance of measurable rainfall: 10%.

Extended: Chance of rain late Monday or Monday night??? Continued average to above average temperatures well into next week???

Forecast Confidence (10 - "The Rabbits Will Thump Even Though I Fed Them"; 0 - "The Rabbits Will Offer To Groom My Bald Spot"): 8 Wednesday, 6 Wednesday night and Thursday, 5 Thursday night and Friday, 3 Friday night through Sunday.

Yesterday's High: 56°F; Overnight Low (through 3 AM Friday): 37°F
St. Cloud Airport 24-Hour Precipitation (through 3 AM Friday): None; SCSU Precipitation (through 3 AM Friday): None

Next Update: Monday, September 21, 2020 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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