September is running nearly 3 degrees warmer than average, and that mild trend will linger for the next 4-5 days, through the middle of next week. Every computer run this week has looked more and more optimistic for our weekend weather. As much as we need a good, long, soaking, the trend is for the "cut-off low" forming over the Plains to be pushed farther and farther south and west of Minnesota, leaving us partly sunny, hazy, and August-like! We should salvage a pretty decent weekend, dry, hazy sun most of the weekend - Sunday still appears to be the sunnier, drier, warmer day statewide. If the sun is out for at least 3-4 hours we stand a good chance of hitting the 80 degree mark, a good 10 degrees above average for mid September.
This taste of August will hang on into Tuesday, a "back-door" cool front spreading showers into town late Wednesday and early Thursday will introduce a cooler, more typical September airmass into the state later in the week, daytime highs in the 60s from Thursday into the weekend. Light jacket weather is likely about 5-8 days out, but no frost, nothing I'd call a cold front. As you'll see from the long-range guidance below the odds of lukewarm weather returning are pretty high for the third week of September. It was a cool summer, maybe we'll make up for lost time (and degrees) and salvage a milder than average autumn! At this point NOTHING would surprise me....
7th Coolest Meteorologist Summer since 1895. That was the story for Minnesota, South Dakota and Wisconsin; in Michigan it was the 5th coolest in 115 years. A persistent trough of low pressure, a "wrinkle" of unseasonably chilly air stuck over the Plains and the Great Lakes states pumped a steady stream of cool, Canadian air into the United States much of the summer, especially July. The lower 48 states averaged .4 degrees F. cooler than average, but as you can see on the NOAA graphic the Midwest took the brunt of the cool fronts - meanwhile record heat gripped Florida, Texas and Washington.
WRF/NMM Model Forecast valid 7 pm Saturday evening. This graphic shows predicted rainfall from 1 pm to 7 pm today, showing scattered (mainly PM instability) showers south and west of the Minnesota River. Right now the models keep St. Cloud and the Twin Cities dry - although we can't rule out a fleeting shower, especially between 3 pm and 7 pm, the bulk of the showers should stay over southwestern counties, where 2-4 hours of rain is possible.
Obvious tornado, right? Not so fast. This image, taken near Greenville, Mississippi, shows an apparent tornado, but there was no obvious rotation, no debris. For an unusual slide show that will leave you scratching your head, click here. For more information on this bizarre cloud formation, and how and why it formed, click here for an enlightening article. A possible "downburst", coupled with unusual outflow boundaries from severe thunderstorms nearby, produced this extremely ominous cloud formation. You could certainly forgive residents of Greenville for thinking a tornado was imminent!
CPC, Climate Prediction Center Outlook through September 25. Temperatures are forecast to be considerably milder than average through the third week of this month across much of the west, as well as the northern tier states, including Minnesota. All bets are off for the end of the month, but it's probably safe to say that an extraordinarily early frost across Minnesota in mid September is highly unlikely.
Paul's Weekend Weather Outlook
Today: Partly sunny, slight chance of an afternoon shower/T-shower (vast majority of the day should be dry). Winds: SE 5-12. High: near 80
Tonight: Patchy clouds, a touch of fog possible. Low: 57
Sunday: Warm, hazy sunshine, lake-worthy. Winds: S 5-12. High: 82
Monday: Plenty of sun, warm, more like mid August. High: 81
Tuesday: Sunshine much of the day, still unusually balmy for mid September. High: near 80
Wednesday: Clouds increase, PM showers, possible T-storms. High: 75
Thursday: Showers taper, cooler with gradual clearing. High: 69
Friday: More typical of September. Mix of clouds and sun. High: 67 (low dipping into the 40s).
Saturday (September 19): Possibly the better day, partly cloudy, comfortably cool. High: 69
Sunday: More clouds, slight chance of showers or sprinkles, cooler. High: 65