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By Meteorologist Tom Skilling

A good portion of the coming weekend is to remain rain-free--perfect for outdoor activity. But NOT 100 percent of it. There's concern that at least some showers associated with an eastbound disturbance expected to track from Kansas across downstate Illinois and Indiana, may affect sections of the Chicago area by Saturday afternoon and night.  Peak areal rain coverage is expected to include up to 30 percent of the area and rainfall is not likely to be continuous---but it could be a factor for those planning outdoor activities.
         
Meteorological summer, with less than two weeks to run, now ranks as Chicago's 22nd warmest of the past 140 years; 67 percent of its days have finished above normal!
 
The clock is ticking on meteorological summer here. The three month season runs through the end of August. It's been a warm summer. The season's average temperature for the June 1 through August 18 period has been 74.3-degrees, making this the 22nd warmest summer season on the books in 140 years of official observations dating back to 1871. That temperature is 2.7-degrees warmer than the long term average. 67 percent of the daytime high temperatures the over past two and a half months have averaged "above" normal.
  
Towering thunderstorms pound western Midwest/central Plains; Omaha raked with 100 mph gusts, 3-inch hail and blinding rains; airport closed
 
The blistering heat,  which has covered the southern Plains and had been unabated for months, fueled a powerful eruption of thunderstorms late Thursday across sections of 5 states. At one point, Doppler scans placed the system's highest cloud towers to an altitude of 72,000 ft.

The storms hit Omaha, Nebraska with particular force generating 100 mph gusts and rain so heavy visibilities were slashed to 10-12 ft. Hail 3 inches in diameter pounded the area, striking a Southwest Airlines pilot standing in the skyway outside the company's planes. He was transported to the hospital and was said to be conscious when he arrived.

17 flights were cancelled by Southwest and Eppley Airfield was shut down after two waves of severe weather swept through. Those on the ground wanted to examine critical equipment to make sure there had been no serious damage

One Plains storm cluster unleashes windshield-smashing hailstones, some 4.25 inches in diameter; nearly 200 hail reports filed with the Storm Prediction Center

Among the reports from Thursday's storms were 64 mph gusts at Red Oak, Iowa and hail 4.25 inches in diameter which broke car windshields near Bloomfield, NE. Power poles were snapped by the force of the storms' winds at McFall, MO.  
 
Chicago heads into the year's 71 st day of 80s---well ahead of the average of 53
 
Chicago's predicted 85-degree high Friday will bring to 71 the number of 80 degree or warmer days in 2010---well above the long term average of 53 to date.
 
Arizona thunderstorm "outflows" provoke new round of dust storms; Phoenix hits record 112-degrees before being  swept by dusty 70 mph gusts
 
A series of thunderstorm-outflow-induced dust storms swept southern Arizona again late Thursday. Phoenix, where the day's high of 112 degrees established a new record, recorded 70 mph wind gusts which lifted dust high into the air cutting visibilities to near 0.

By Meteorologist
Tom Skilling

2011 tornado and severe weather reports across the Lower 48 running at 2 to 3.5 times last year's pace

The young 2011 severe weather season is continuing to produce severe weather reports filed with NOAA's Storm Prediction Center (SPC) at 2 to 3.5 times last season's pace. While only 714 reports were on file at SPC this time last year, 2,523 had been logged by late Tuesday.

By Meteorologist Tom Skilling

Meteorological winter 2010-11, which began December 1 and reached its mid-point heading into this past weekend, has yet to produce an official sub-zero temperature in Chicago---yet it is running nearly 2-degrees (1.7-degrees) colder than the same period a year ago. The 22.1-degree average temperature for the December 1 through January 18 period is 5.1-degrees below the long term average and makes the season the 22nd-coldest of the past 140 winters. Estimates based on temperatures to date suggest furnace usage is 4 percent ahead of a year ago and 8-percent above the most recent 30 year average.

Abysmal lack of sunshine here the past 8 days; Chicago's logged just 10 percent of its possible sun; full U.S. sun tally's been lacking too
 
If you're susceptible to SAD---Season Affective Disorder---a form of depression brought on by winter's short days and lack of sunlight, the past 9 days (since Tuesday, January 11) have no doubt been especially rough. The period has logged only 10 percent of its possible sunshine, we're told by veteran National Weather Service observer Frank Wachowski---a total of just 7.9 hours.

Under the best circumstances, a typical January is not one of Chicago's sunnier months. But this month's abysmal 10 percent tally falls far short January's average of 43 percent of its possible sun. That means Chicago area residents have seen less than a quarter of January's typical sunshine.
 
Frigid late week arctic cold blast may prove winter's most intense but thankfully brief
 
Temperatures across a huge swath of Canada and Alaska failed to break above zero Tuesday. The chill there has been reinforced over the past week by a cross-polar surge of air of Siberian origin. The frigid Canadian daytime readings Tuesday came on the heels of overnight readings 30-below and lower which stretched nearly 2,000 miles from Interior Alaska to the shores of Hudson Bay.

By late Tuesday evening, the southern flank of the gargantuan cold air pool had sagged into the Dakotas, northern Nebraska, sections of Montana as well as much of Minnesota and Iowa, where temperatures had dropped sub-zero. Readings at perennial cold spot International Falls, Minnesota, which sits astride the Canadian border, had tumbled to -20 degrees by late Tuesday evening.

A tentacle of that vast reservoir of bitterly cold air is to ride northwest steering winds even more deeply into the country's mid-section Thursday night and Friday. It's flirtation with the Chicago area Friday and Friday night may well produce the city's coldest official high of any winter day thus far this year--colder than the 16-degree maximum recorded Dec. 12.  And nighttime lows well inland late Thursday night and ahead of incoming clouds Friday night, are to dip to single digits and, at the coldest inland locations, below-zero!
 
Bear's game chill Sunday predicted at seasonable levels--but will there be snow?
 
A more moderate brand of cold follows Friday's frigid blast. Weather for the Bears/Packers match-up appears at this distance likely to hover around 25-degrees at kick-off time and may include modest easterly winds off Lake Michigan. The big question revolves around a disturbance expected to track toward the area Sunday into Monday. Timing of the system will be critical in determining whether it spreads a shield of snow toward or into the area Sunday afternoon. The model consensus suggests that's a fair bet---but stay tuned. We'll keep you posted as Sunday grows ever closer.

The break in heat and humidity is welcome---but temporary. Temperatures will be creeping higher Saturday and into the 90s Sunday, Monday and Tuesday of next week.