Monday, July 22, 2019  3:45 AM

Natural Air Conditioning Through Middle of the Week

Heat and Humidity Swept Out By Weekend Cold Front

The heat and humidity late in the last work week finally was swept out by a Friday PM cold front. The front did trigger scattered thunderstorms just to our north, which became severe as they pushed into Wisconsin. The thunderstorms that came through central Minnesota behind the front on Saturday also produced straight line wind damage in eastern South Dakota early Saturday morning and another bout of large scale wind damage in Wisconsin Saturday afternoon.

The blobs of overnight thunderstorms on the edge of the tropical air have now moved to Kansas, Missouri, and southern Illinois (see Shortwave Albedo satellite loop from Colorado State satellite slider). That front is going to do the same job today in the Northeast and part of the Mid-Atlantic states. So, yesterday's high of 100 in New York City, Atlantic City and parts of Connecticut will ease off. Thanks to the steering winds taking on a northwest-to-southeast flow direction from the Canadian Prairies into the Great Lakes (see Mid-Troposphere water vapor loop from Colorado State satellite slider), the relief from the heat will eventually push through most of the East Coast late in the week.

Seasonably Warm and Much Drier Sunday and Continuing into at Least Wednesday

We felt the change to seasonably warm and much drier air, as high temperatures over the weekend dropped to the 70's on Saturday and around 80 on Sunday.

Slight Chance of Isolated PM Showers

We will continue with the seasonably warm and relatively dry conditions through the first half of the work week. The only issue will be a series of low pressure systems moving in this northwest to southeast flow from Canada across Minnesota. There is one of those circulation centers early this morning over southern Saskatchewan and southwestern Manitoba (see Mid-Troposphere water vapor loop from Colorado State satellite slider). However, the much more comfortable air over us with early morning dew points in the 50's in southern Minnesota and in the 40's in northern Minnesota (see NWS Aviation Weather Center METAR map) means that moisture will be rather limited. So, there will only be a slight chance of an afternoon brief shower.

Highs will rebound from their middle 50's readings to around 80 degrees once again.

The pattern will repeat tomorrow and Wednesday with natural air conditioning dropping the low temperatures into the 50's and highs topping out near or just above 80 degrees tomorrow and Wednesday. There again will be a slight chance of a late day shower, but most of us won't see one.

Enough Wildfire Ash to Cause Haze in Central Canada

The only weather issue during this first half of the week is that the moderate concentrations of smoke have pushed into the central Canadian Prairie Provinces, so it is possible that we could see some. Much of this smoke is aloft, but ground stations in northern Alberta are now seeing enough low-level ash to kick the air pollution rating out of the green, good level. Ash is even harder to forecast than thunderstorms, so it will have to be watched.

Better Chance of Some Thunderstorms Later in Work Week?

During the latter half of the week, the new center of heat over the Southwestern US and the Central and Southern Rockies will try to push over the Dakotas and Minnesota. While the hot triple-digit temperatures will increase in the West, the hotter air won't make it to the ground. The main change will be an uptick in humidity and a slightly better chance for showers and thunderstorms on Wednesday night into Thursday morning and especially on Thursday night into Friday morning. Friday will be our best shot to see temperatures climb higher into the 80's, depending on how many leftover clouds there will be.

The early outlook for next weekend indicates that the front marking the boundary between the hot Rockies air and the cooler, Canadian air may hang up around Minnesota. At this point, there doesn't appear to be any strong weather system moving along this front, so the threat of severe weather doesn't look to be as high as it was late last week. But, we'll see.

Confidence Level: "The Bulb on That Hard-To-Reach Light in the Foyer Will Burn Out"

Monday 7/22/2019: Morning sun, mixed clouds and sun in the afternoon with a slight chance of a sprinkle. Breezy and perhaps a shade cooler. High: between 73 and 78. Winds: NW 8-15 MPH. Chance of measurable rainfall: 10%.

Monday Night: Clear and continued comfortable. Low: between 53 and 58. Winds: NW 5-10 MPH. Chance of measurable rainfall: 10%.

Tuesday 7/23/2019: A sunny start, some afternoon clouds and a slight chance for a brief PM shower. Continued seasonably warm. High: between 77 and 82. Winds: NW 8-15 MPH. Chance of measurable rainfall: 20%.

Tuesday Night: Partly clear, light winds, and continued seasonably mild. Maybe some fog by morning. Low: between 55 and 60. Winds: SW 5 MPH. Chance of measurable rainfall: 10%.

Wednesday 7/24/2019: Morning sun, afternoon partial sunshine, and a chance of an isolated shower. Continued warm, but becoming noticeably humid. High: between 80 and 85. Winds: SW 10-20 MPH. Chance of measurable rainfall: 20%.

Confidence Level: "Every Time I Try to Put in a New Bulb, the Light Fixture Will Try to Detach From the Ceiling"

Wednesday Night: Partly clear, breezy, and uncomfortably humid. A chance of a late night shower or thunderstorm. Low: between 62 and 67. Winds: SW 8-18 MPH. Chance of measurable rainfall: 30%.

Thursday 7/25/2019: Perhaps a morning shower or thunderstorm. Otherwise, partly sunny, breezy, warm, and uncomfortably humid. High: between 80 and 85. Winds: SW 10-20 MPH. Chance of measurable rainfall: 30%.

Confidence Level: "The Only Way I'll Be Able to Change the Bulb and Hold the Fixture in Place Will Be to Yell At It

Thursday Night: A chance of evening showers and thunderstorms. Warm and sticky. Low: between 62 and 68. Winds: SW 8-18 MPH. Chance of measurable rainfall: 30%.

Friday 7/26/2019: Becoming sunny, breezy, very warm, and still humid. A better chance of a late day showers and thunderstorms. High: between 82 and 88. Winds: W 10-20 MPH. Chance of measurable rainfall: 40%.

Extended: Warm and humid next weekend??

Forecast Confidence (10 - "The Rabbits Will Thump, Objecting to Me Yelling at the Light Bulb"; 0 - "I Will Be Hosting a DIY Show on Home Repairs"): 8 Monday and Monday night, 7 Tuesday and Tuesday night, 6 Wednesday, 5 Wednesday night and Thursday, 3 Thursday night and Friday, 2 Weekend

Yesterday's High: 80°F; Overnight Low (through 3 AM Monday): 57°F
St. Cloud Airport 24-Hour Precipitation (through 3 AM Monday): None; SCSU Precipitation (through 3 AM Monday): None

Next Update: Tuesday, July 23 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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