Friday, August 17, 2018 3:05 AM

Wildfire Smoke to Cause Ground Problems Through Weekend

N MN Air Quality Alert Through Sunday With Expansion to S MN Likely This PM

The light northwest winds have allowed the thick smoke plume in the Canadian Prairie Provinces to approach the US border (see GeoColor infrared satellite loop from Colorado State slider satellite menu). Smoke particles, which have been producing poor air quality for all in Alberta (see red dots and even dark red on the Current Fire and Smoke map from the EPA's Airnow web site), are expected to move into northern Minnesota this morning and reach the southern half of Minnesota by late in the day. That's why the Minnesota Pollution Control Agency has issued an air quality alert for the northern half of Minnesota through noon on Sunday and is expecting to issue an alert this afternoon for the southern half of Minnesota for this afternoon through Sunday. Under these conditions, seniors, kids, and people with a history of heart or breathing problems should avoid outdoor activity.

The smoke is again being produced by western Canada wildfires with a large number of them in British Columbia as well as northern Washington, Idaho and Montana. Air pollution advisories also cover parts of the northern Rockies from Washington to northwestern Montana. And, conditions are favorable for more fires (chance of thunderstorms producing lightning, but no rain) to develop today in Oregon, Idaho, and western Montana (red areas on linked map).

Warm and Sticky With Isolated PM Storms Through Tomorrow

Otherwise, we will continue to see the warm and uncomfortably humid conditions through tomorrow. Highs will be well into the 80's and have a slight chance of hitting 90. Dew points in the early morning are in the upper 50's to near 60 (see UCAR Minnesota surface chart), but will rise into the uncomfortable 60's each afternoon. The air on the sticky side could produce a few isolated late day thunderstorms. Some of these slow moving storms produced heavy rain near Faribault and Welcome yesterday (an inch and a half to 2 inches of rain) but most of us will remain dry through Saturday.

Better Chance for Sunday (esp. PM) Rain

Our best chance for rain will be on Sunday. There might be a few scattered early morning showers drifting over from the Dakotas, but our best chance for rain will be from late afternoon through the night. The system causing clouds and a few showers in Idaho and western Montana (see Shortwave Albedo loop from the Colorado State satellite slider menu) will move through Montana and push southeastward into Nebraska, Kansas, and Missouri. However, a cold front due to pass through Minnesota late Sunday could pull enough moisture northeastward to give us a decent shot at reasonable rainfall.

Behind the cool front, another shot of Canadian air will move in. This will knock highs back to the 70's to near 80. However, recent fronts have failed to drop central and southern Minnesota dew points much below 60, so we'll see if there is a major drying out. In northern Minnesota, dew points could allow low temperatures to drop into the 40's. We will also have to see how quickly we redevelop smoke problems.

The second half of next week appears to show a warm up.

Confidence Level: "I Will be Up Early to Make the Forecast"

Friday 8/17/2018: Partly sunny and very warm with uncomfortable humidity. A slight chance of an afternoon shower or thunderstorm. High: between 85 and 90 (record warm high: 94 in 1925,1934). Winds: NW 5-15 MPH. Chance of measurable rainfall: 20%.

Friday Night: Partly clear, light winds, and uncomfortably humid. Low: between 58 and 63. Winds: light NE. Chance of measurable rainfall: 10%.

Saturday 8/18/2018: Partly sunny, very warm, and uncomfortably humid. Some air pollution problems. A slight chance of a late day shower or thunderstorm. High: between 85 and 90. Winds: SW 5-15 MPH. Chance of measurable rainfall: 20%.

Saturday Night: Partly clear, warm, and sticky. A slight chance of a shower or thunderstorm. Some air pollution problems. Low: between 62 and 68. Winds: SW 5-10 MPH. Chance of measurable rainfall: 20%.

Confidence Level: "The Rabbits Will See the Light On and Want Petting Instead of Forecasting"

Sunday 8/19/2018: Partly sunny, warm, and even more humid. A chance of a late day shower or thunderstorm. High: between 82 and 87. Winds: SW 5-15 MPH. Chance of measurable rainfall: 30%.

Sunday Night: Showers and thunderstorms likely. Low: between 60 and 65. Winds: becoming NW 10-20 MPH. Chance of measurable rainfall: 70%.

Monday 8/20/2018: Cloudy with perhaps a lingering morning shower. Partial clearing and slowly turning less humid in the afternoon. High: between 77 and 82. Winds: N 8-15 MPH. Chance of measurable rainfall: 30%.

Monday Night: Partly clear and not quite as humid. Maybe some fog by morning. Low: between 55 and 60. Winds: N 5-15 MPH. Chance of measurable rainfall: 10%.

Tuesday 8/21/2018: Sunny and seasonably warm with noticeable humidity. High: between 75 and 80. Winds: NW 8-15 MPH. Chance of measurable rainfall: 10%.

Confidence Level: "The Rabbits Will Shed Information on the Upcoming Weather, Rather Than Just Fur in My Hand"

Extended: Cooler than average early next week. Warmer than average late next 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?"): 7 Thursday through Friday, 6 Friday night through Saturday night, 4 Sunday through Monday.

Yesterday's High: 84°F; Overnight Low (through 3 AM Friday): 60°F
St. Cloud Airport 24 Hour Precipitation (through 3 AM Friday): None; SCSU Precipitation (through 3 AM Friday): None

Next Update: Monday, August 20, 2018 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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