A cool front broke a weeklong siege of heat across southern Minnesota Friday, delivering temperatures expected to be near normal Saturday after eight days of intense conditions, including a pair of triple-digit highs and dew points in the 70s.
Saturday's predicted high of 83 will be a cool splash compared to Friday's peak of 102. An afternoon dew point of 62 might even feel comfortable enough for some residents to stick their noses back outside.
The cool front arrived dramatically, dropping the Twin Cities temperature from 100 at 5 p.m. to 82 at 7:30 p.m., and touching off a brief thunderstorm. The official Twin Cities rainfall during that storm, measured at the Minneapolis-St. Paul International Airport, was 0.09 inch.
The 102-degree peak Friday, though 2 degrees short of the record for the date, was the second high over 100 this week and made 2012 the first year since 1988 to see more than one 100-degree reading. There were four that year, though even that was a far cry from the nine in 1936.
The Twin Cities temperature was expected to drop to 68 by 6 a.m. Saturday.
Clouds and rain kept temperatures in the low 60s across much of northern Minnesota through the day. But Winona, in the southeast, also hit 102.
Another line of storms, moving across the north and west metro areas, triggered severe thunderstorm warnings late Friday. The heat wave brought the Twin Cities eight straight days with highs of 90 or better, the longest since eight-day runs in 2006 and 2005. The record is 14 straight in 1936.
Despite the steady heat, there were only scattered disruptions to the region's electricity supply system. Xcel Energy spokeswoman Mary Sandok said the timing helped, with a midweek holiday that probably reduced residential as well as business demand for air conditioning. In general, a less-than-robust economy also suppresses demand, she said.
Nevertheless, Sandok said the utility had planned for a spike in demand last week by buying more power.
The week's peak demand of 9,480 megawatts, reached Monday, was a hair below Xcel's service-region peak of 9,544 megawatts, set during another heat wave last July. Xcel serves 1.6 million customers in parts of Minnesota, Wisconsin, the Dakotas and Michigan.
The National Weather Service is predicting highs in the 80s for the Twin Cities through next Friday.
Since 1873, there have been 65 days on which the high temperature in the Twin Cities has been 100 degrees or higher. Two came in the past week. Thirteen years have seen multiple triple-digit highs.
Those years, and the number of above-100 days they contained: 1894: Two. 1901: Three. 1931: Seven. 1933: Two. 1934: Five. 1936: Nine. 1940: Four. 1941: Two. 1947: Four. 1949: Two. 1955: Two. 1988: Four. 2012: Two.
Bill McAuliffe 612-673-7646