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By Meteorologist Tom Skilling

    Prospects that sunshine may manage to break through Saturday's thick morning clouds increase during the day. The gray open, which could produce patchy light rain or ice pellets in some areas south of the city, is the product of moisture streaming off a huge winter storm responsible for burying sections of Colorado's Front Range under a huge accumulation of snow. As much as four feet fell there Friday and wind-blown 12+inch snow accumulations extended east into portions of Nebraska.
     Any other eastbound storm with a center over southwest Missouri Saturday morning, might be expected to bring the Chicago area a healthy dose of precipitation.  But, some of this storm's energy is being deflected south in a gradually dissipating state across downstate Illinois and Indiana by what meteorologists refer to as a "blocking pattern" over the Rockies.
    Such a pattern allows some of the storm's energy to propagate eastward--but locks a pool of cold air, around which upper winds spin--producing the "lift" which creates the storm in the first place--farther west.  The result is, the initial surge of eastbound energy, responsible for clouds and precipitation, eventually shears away from its primary energy source and begins to lose strength.
    While precipitation continues for a while in such an environment, eventually, the area of rain and snow begins to shrink in areal coverage and intensity.
     It's at that point northwest upper winds coming into the Chicago area are to begin importing milder, drier Pacific air, encouraging clouds to break and daytime sunshine to emerge. The slow clearing will permit sunshine to appear first in northern suburbs then settle into other sections of the metro area Saturday afternoon as precipitation shifts downstate.


Northeast winds off Lake Michigan waters to lend Saturday a "chilly" feel lakeside

    Thursday's 39-degree high at O'Hare wasn't "warm"--but it does qualify as "mild' for this time of year.  The reading exceeded the date's "normal" high by 7-degrees.  And, while northeast winds promise a chill as they flood into the area off mid 30-degree lake waters, the appearance of some mixed sun and complete lack of snow cover bodes well for some highs in the 40s away from the lake Saturday--the 14th consecutive day of above normal temperatures!
     This process is to accelerate Sunday as the northeast flow weakens and even more sunshine follows the exit of possible early clouds. 
    By Monday, gusty southwest winds and compressional warming ahead of a southbound cold front, expected to pass late Monday night, could push temperatures within striking distance of 50-degrees in typically warmer locations.


Winter 2011-12 now the mildest to date here in 80 years
 
      Chicago's average meteorological Winter 2011-12 temperature from Dec. 1 through Friday, February 3, has reached 32.9-degrees, making this the mildest meteorological winter period in Chicago of the past 80 years!  The reading ranks 9th warmest of 141 comparable meteorological winter periods on record since 1871 and places this winter among the warmest 6 percent on record here since 1870. The temperature is 6.6-degrees milder than the long term average and over 11-degrees warmer than a year ago.


Greenland Blocking, noticeably absent thus far this season, looms big-time on latest global model runs later next week into Week #2; that's a "cold signal" for the Midwest

      The potential that winter is may still target the Chicago area with cold air has received a big boost from global computer model runs in recent days. Not one, but a suite of these forecasts are now predicting strong warming over Greenland and the North Atlantic in the next 1-2 weeks.
    The appearance of unseasonably mild air aloft there hints strongly that the winter season's first truly significant round of blocking--a "cold signal" for the Midwest--could be the harbinger of a temperature downturn of some import later next week and beyond.
    The first punch of blustery cold air is to hit behind a southbound cold front late Monday night.  But what follows late in the week and the following weekend could be significantly stronger. We'll keep you posted!


Plains & Denver area hit hard by blizzard while another snowstorm sweeps southern Alaska; Anchorage's seasonal tally tops 100 inches--twice normal; the Valdez total passes 337 inches
 
     Midwest snowfall tallies may be running far below recent years, but any snow drought is noticeably absent in the Plains and Colorado Rockies after the area was hit by heavy snows Friday.  In the Denver area, as much as 4 feet of snow buried nearby Front Slope communities.  Denver itself measured 13 inches of snow--but observers in nearby Blackhawk reported a 48 inch accumulation.
     Even more extraordinary are seasonal snow tallies being reported out of southern Alaska--a region hit by yet another snowstorm Friday. Up to 18 inches of snow was predicted in sections of the Anchorage area of south-central Alaska.  There the 2011-12 seasonal total has reached 100.9-inches--nearly twice the normal of 50.7-inches to date. Even more noteworthy is Valdez, Alaska's 337.4-inch seasonal total to date. There, normal winter snowfall through February 3 is just 199.8-inches.


Deadly European/Russian cold wave rolls on; temps dip 20-30-below; 101 dead in Ukraine alone; concerns about natural gas supplies
 
      The deadly European/Russian cold wave continued unabated Friday with concerns Russian natural gas supplies were being cut to European countries because of increased domestic usage. The death toll for the region was cited at more than 220 by some news agencies there--with 101 deaths reported in the Ukraine alone.
    Snowfall in Rome was the heaviest since the 1980s and a foot of snow is reported to have accumulated over recent days in Istanbul, Turkey. 
    Western Russian and eastern European temperatures have dropped to under 30-below zero in recent nights.

By Meteorologist Tom Skilling

January 2012 closes as it began: Unseasonably mild; Monday's 53-degree city high, mildest in 3 weeks, misses the record by 2 degrees!
 
Temperatures in Chicago Monday, which missed the 1988 record by just 2-degrees, may well top the official April-level 53-degree high Tuesday---hitting the mid 50s. The meteorological wildcard Tuesday is the speed at which clouds spread over area skies as powerful southwest winds with Gulf moisture in tow, make their way into the Chicago area. Clouds are expected to extinguish morning sunshine upon their lunchtime and afternoon arrival.

It wouldn't be surprising at all to see a few typically milder locations across the Chicago area flirt with 60-degrees.

Tuesday's predicted high of 54 at O'Hare would be 22-degrees above normal and the mildest reading here in nearly three weeks. It would also equal April 2nd's "normal" high!

The latest round of unseasonable warmth comes at the end of a month expected to finish nearly 6-degrees above normal when it ends Tuesday night at midnight.

The opening two months of meteorological winter season, which began December 1, has been this area's mildest in 78 years and has featured the fewest number of days with an inch of snow on the ground---just 7 of them---in 23 years.  

Monday's 53-degree high marked the ninth time this winter season a daytime reading has reached or exceeded 50-degrees.  Over the years, an average of only half as many 50-degree days have occurred by January's close. And just two other winter seasons over the past 32 years (dating back to the 1980-81 cold season) have produced a greater number of 50-degree or higher readings by Jan. 31: Winter 2001-02 and the 2006-07 season.
 
60-degree temperatures as close as Peru and Peoria; St. Louis and Kansas city top out at 67-degrees
 
Spring-like 60-degree temperatures weren't all that far away Monday. 60-degree highs occurred as close Peoria and the Quad Cities---each record-breaking readings.. Farther south and west, St. Louis and Kansas City topped out at 67-degrees.
 
Scope of Monday's above normal temperatures breathtaking; the mild weather across the Lower 48 extended nearly coast to coast; readings in the 60s to near 70 broke records Monday across 6 states
 
Temperatures were milder than normal from coast to coast across the Lower 48 Monday.  A Penn State meteorology department analysis of afternoon readings Monday afternoon put temperatures at nearly every weather station from eastern Montana across the Plains and into Illinois and southern Wisconsin within the warmest 10 percent of temperatures observed this time of the year from 1981 through 2010.

Highs in the 60s to around 70 established new records across 6 mid-U.S. states. Among the new record highs were:
 
70-degrees Topeka and Russell, Kansas,
69-degrees  Grand Island, Nebraska
67-degrees St. Louis
67-degrees Norfolk, Nebraska
66-degrees Joplin, Missouri
65-degrees Vichy-Rolla, Missouri
65-degrees Sioux City and Ottumwa, Iowa
63 Lamoni, Iowa
60 Peoria, Illinois
49-degrees Sisseton, South Dakota
 
 
 
January's temperatures finish 5 to 14-degrees higher than a year ago across the entire Midwest; month to finish 6-degrees above normal in Chicago
 
The uniformity of above normal temperatures in January 2012 from one corner of the Midwest to another was stunning. The region's average temperatures are to finish an impressive 6-degrees above normal upon the month's close, a departure which means this past month's temperatures have run 5 to as much as 14-degrees above January a year ago
 
 
Small earthquake hits near Illinois/Wisconsin border around 9:54 pm; prompts calls from anxious residents; USGS reports trembler only a 2.4 on Richter Scale
 
Reports that an earthquake may have occurred began arriving in our WGN/Chicago Tribune weather office and our WGN-TV news desk around 10 p.m. from a range of communities, most of them north of Chicago. There was initially NO confirmation from the U.S. Geological Survey---the agency which monitors the country's earthquake activity. 

Our check with area police departments indicated they had received scores of calls from concerned residents who had noticed the minor quake---and, sure enough, official word was soon to follow around 11 pm from USGS that a tiny quake had indeed occurred. The agency reported that a small 2.4 Richter Scale quake was measured, emanating 6.2 miles below the surface close to the Wisconsin/Illinois border 11 miles southwest of Kenosha, WI and 14 miles northwest of Waukegan.  

Such quakes are small enough to be missed by many---but others reported to us that the trembler was QUITE noticeable to them and that it had made what was frequently described as a deep rumbling sound.

Alaska shivering through month-long cold wave; Interior temps down to 66-below in recent days; Fairbanks average January temp of 26.4-below, more than 18-degrees below normal!
 
While January's abnormal warmth had dominated weather cover across much of the Lower 48, brutally cold air has gripped Alaska nearly the entire month, producing temperatures as low as 66-degrees below zero Monday morning near Ft. Yukon, Alaska and 64-below at the Kandik River COOP observation site in the state's Interior. Other lows included 60-below at Manley Hot Springs, 54-below at Nenana and 51-below at Fairbanks.

The month's average temperature of 26.4-below at Fairbanks is 18.4-degrees below normal. Farther south in Anchorage in the south-central section of the state, January's 23-degree average temperature, while cold, is nearly 4-degrees above normal.
 
End of week central U.S. storm system being monitored; rain could switch to wet snow between Friday afternoon and Saturday
 
A storm system, forecast to take shape in the Plains later this week, is being monitored as a possible precipitation producer here in Chicago. The disturbance is arrive amid colder temperatures and strengthening east to northeast winds later Friday into Saturday. It could bring drizzle or sprinkles to the area Friday morning which would build to steadier rain, mixing with ice pellets and possible snow Friday night---then possibly switching to wet snow for a time Saturday.

Many details are only beginning to come into view---but it's definitely a system we'll be watching and reporting on in coming days!
 
 
 
 

By Meteorologist Tom Skilling

    January 28 is a significant day in the annals of Chicago weather history. It's the city's coldest day of the year on average and also the date beyond which area residents begin to see an upward overall trend in temperatures. This doesn't mean all cold weather is over--far from it. Chicago's weather pattern has been known to produce wintry spells well into March and even April. But the trend is clear. Longer days and strengthening sunlight begin from this point in the season forward to nudge temperatures higher with increased frequency.
    A computer sweep of 141 years of official temperature data reveals Chicago's average January 28 temperature comes out to 22.95745-degrees while the second and third coldest days of the year here work out to be Feb. 2 (which averages 23.12766-degrees) and January 27 with an average temperature of 23.17021-degrees.  
   
 
The list of this winter's warm weather credentials keeps growing!
 
     No matter how it's examined, winter 2011-12 continues to look quite extraordinary.  The period since Dec. 1 has been the warmest here in 78 years, comes in as the 12th warmest of the 141 winter seasons on record, has produced the fewest sub-freezing daytime temperatures--just 11 of them--in four decades and the fewest days in which the ground has been snow covered in 23 years.   
    Friday's 43-degree high became the season's 33rd daytime high at or above 40-degrees, the most in nearly four decades.  By comparison, last winter had produced just three 40-degree or warmer daytime highs. 11 is the long-term average.


Days are getting longer

    Saturday will see 45 additional minutes of daylight compared to the year's shortest day back on Dec. 21st. Lengthening days contribute to warmer temperatures, though the seasonal warming process is slow.


Water levels in the Great Lakes up in part because of the mild winter

    Lakes Michigan and Huron boast water levels 7 inches above those observed a year ago according to this week's report from the U.S. Army Corps of Engineers. A number of factors influence lake levels, but among the most important are evaporation rates from the huge bodies of water. These rates soar in cold winters because temperatures above the Great Lakes decline rapidly with height in periods of bitterly cold arctic air. Such a setup encourages moisture to evaporate at a swifter pace than in periods in which temperatures above the lake are warmer.
    The warmer-than-normal winter this season has greatly diminished the loss of moisture from the lake surfaces while cutting down on lake effect snow production. The result is less water has exited the lakes through evaporation keeping lake levels higher.


The chill is on this weekend but a return to much above normal temperatures looms

    Colder air spilling into the Midwest this weekend won't be around long. A second burst of cold air threatens a new period of light snow late Saturday night and early Sunday in the wake of Saturday's sunshine. But the return of warm air isn't far behind.
    The passage of a warm front and the onset of strong southwest winds Monday and Tuesday are to send temperatures, expected to hold in the 20s Sunday, soaring into the 40s Monday and to near 50 Tuesday--a level just under 20-degrees above normal.

By Meteorologist Tom Skilling

    Snow is to follow Friday's sunshine, much of it to come down in a 6 to 8 hour period commencing just an hour or two beyond sunset Friday night. It's the first of two snowy spells likely to occur this weekend. The second hits later Saturday night into Sunday morning.
    Neither spell of snow is to come ANYWHERE close to generating the 4 to 10-inches which fell last weekend, transforming the Friday rush hour into a 5 to 6 hour nightmare for many.
    The clouds which spread back into the area Friday afternoon and evening, could send up to 6 to 8 hours of wet snow into the Chicago area Friday night.
     Snow is to commence within an hour or two of sunset Thursday evening.  A slushy half inch to two inch accumulation appears a good bet in a number of areas near Chicago Friday night, especially on grassy and colder outdoor surfaces.
  
   
This winter has produced the fewest sub-freezing days in nearly four decades

    With just 11 sub-32-degree temperatures so far this year compared to the average since 1928 of 25 at Midway Airport, this winter has seen less than half the typical number of below-freezing days in the city.  By comparison, last winter had logged a phenomenal 43-days below freezing by now.
  
   
Meteorological winter 2011-12 heads into a 47th above-normal day since Dec. 1 Friday
 
     Temperatures peek above normal Friday for the 47th time since the 3-month Meteorological season began on Dec. 1. 82 percent of this season's days have produced a temperature surplus.
  
   
Second snowy spell sweeps in Saturday night ahead of a brief rendezvous with daytime 20s Sunday
 
    A second snowy spell ahead of the weekend's coldest air is to sweep across the Chicago area late Saturday night into early Sunday.  Once again, modest snow accumulations are possible--potentially an inch or two of snow at some locations.
    The passage of that snow will allow daytime readings Sunday to settle back to the low or mid 20s amid powerful northwest wind gusts.
  
   
Strong warming follows next week; a string of 40+-degree days begins Tuesday
 
       The chill won't last long if current forecast trends prove accurate. Daytime readings are expected to bounce back to the mid or upper 40s Tuesday and peak in the 40s Wednesday and Thursday next week.

By Meteorologist Tom Skilling

Thursday's weather won't win any awards. Skies are to remain gray with a bit of drizzle---even a few ice pellets from time to time into Thursday night, though a majority of hours are likely to remain precipitation-free. But, compared to events on this date in 1967, Thursday's weather is to come off as a veritable walk in the meteorological park!

The Jan. 26-27, 1967 storm remains the area's biggest; 50,000 cars/800 CTA buses stranded on area thoroughfares
 
It was 45 years ago today that the area was descending into its worst snowstorm on record---the infamous Blizzard of 1967. The storm would cripple the city as no storm had before. Its wind, snowfall and towering drifts would lead to the abandonment of 50,000 cars on area thoroughfares and the stranding of 800 CTA buses. The storm was responsible for 26 deaths and forced school closings for days beyond the storm itself.

The snow started falling at Midway Airport, the city's official observation site at the time, at 5:02 am Thursday, Jan. 26. It was to continue uninterrupted for nearly 29 hours, then in light bursts for an additional 5 hours.

Wind gusts of 53 mph whipped the snow into drifts as high as 15 feet. While several storms have come close to producing as much snow since, none has produced an accumulation any greater than the 23 inches which fell in the January 1967 storm.
   
1967 blizzard, Chicago's biggest ever, took the city by surprise; forecasters lacked many of the meteorological tools available today
 
The blizzard hit without warning in an era before weather satellites and today's incredibly complex computer models which are run on supercomputers capable of performing 80-trillion mathematical calculations per second. It was an era in which weather maps were plotted by hand in the country's weather offices. Such an environment made it possible for a storm to  spin up before forecasters were able to grasp such systems' real intensities.

Evening forecasts the night before had predicted a 50 percent chance of rain or snow and highs in the 30s, offering no clue of the meteorological behemoth about the cripple the area. The last thing on many people's minds was a raging blizzard. After all, temperatures had hit 65-degrees with thunderstorms in the area only three days before.

We've posted actual copies of the teletype forecasts distributed by the U.S. Weather Bureau before, during and after the 1967 blizzard  on this blog and wish to thank veteran Chicago weather observer and historian Frank Wachowski for making them available to us. Frank was responsible for the official measurement of the storm's incredible 23 inch accumulation at Midway Airport.

Big snows aren't as common as many here think. Snowfalls of 6-inches or more have occurred in Chicago only 171 times over the 127 years of official observations dating back to the 1884-85 snow season.
 
Thursday to log the meteorological winter season's 46th above normal day
 
There will be no blizzard Thursday! Temperatures are predicted to peak in the upper 30s making this the 46th day of above normal temperatures since meteorological winter began 56 days ago on Dec 1.
 
Heavy rains, severe thunderstorms rake the South; storm's rains and some ice extend north into central Illinois/Indiana
 
Chicago sits beneath clouds on the north flank of a wet storm churning across the South where it's creating downpours and severe weather. The system's heavy rains made their way into downstate Illinois and Indiana Wednesday, dumping 0.68 inches on Collinsville, 0.67-inches on Hillsboro and 0.62-inches on Edwardsville.  Effingham reported 0.50 inches.

Precipitation on the storm's northernmost perimeter was falling in sub-freezing temperatures, raising the specter of icy conditions.

The storm walloped sections of Texas early Wednesday with 6+ inches of rain and some 50+ mph wind gusts. At least a half dozen reports of twisters flowed into NOAA's Storm Prediction Center Wednesday bringing to 55 the number of twister reports which have been archived for the month to date---a very active pace.
 
Cold hits in two waves this weekend; a swath of snow could precede each
 
Cold air is to dive into the Lower 48 for a brief but blustery stay this weekend. The influx of cold air is to produce a swath of snow which could reach the Chicago area late Friday into Friday night, producing a dusting to as much as an inch or two of snowfall.

A second, colder punch of air hits Saturday night into Sunday.  That may lead to a second swath of snow setting up across the area late Saturday into Sunday morning.

Temperatures are to bounce back to the 40s by Tuesday.

By Meteorologist Tom Skilling

Here are the original weather forecasts which were sent out by teletype to radio and television stations for the Blizzard of 1967 courtesy of Frank Wachowski.  The night before the forecast, the prediction was for a 50 percent chance of rain or snow. There was NO word a storm was on its way. The Blizzard of 1967 caught Chicagoans completely by surprise.  The temperature had hit 65-degrees only two days earlier.

Forecasters in that era had NO satellite imagery, NO in flight aircraft observations, hand plotted their maps and had access to an upper air forecast off  one one very simple computer model--the so-called "barotropic" model, which didn't perform well in developmental situations (like the 1967 blizzard situation) and predicted the flow pattern at only one level of the atmosphere.

Today's models which take into account atmospheric developments in up to 90 vertical layers and on a global basis, focusing on small scale features of developing storms, something forecasters in 1967 couldn't even imagine.. 2012 computer projections are run on supercomputers which can perform 80-trillion mathematical operations per second. And forecasters can look at dozens of different models to hone forecasts.





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By Meteorologist Tom Skilling

There hasn't been a milder meteorological winter here than this one in 78 years. Though this season has produced some wintry moments, last Friday's snowstorm among them, the vast majority of days---82 percent of them---have posted above normal temperatures. What's more, we could find only 11 winters of the past 141 for which official weather records exist, which have been milder up to this point in time.

Chicago's average temperature since Dec. 1 is running 32.4-degrees, well above the 141-year average of 26.8-degrees and a stunning 11.3-degrees warmer than the same period a year ago. That's a difference which suggests many Chicago area residents have required 17 percent less home heating.

To find a winter that's been milder over the Dec. 1 through Jan. 24 period, you'd have  to go back to the Dust Bowl---specifically to the winter of 1933-34 when the city's  temperature averaged 32.8-degrees.
 
 
 
A slight majority of springs following comparably mild winters have trended cooler than normal; 70 percent of summer have been warmer than the norm
 
We're often asked if winter weather tells us anything about the spring and summer season to come. To answer than, we scanned Chicago's observational record all the way back to 1871 and isolated ten winters with mild temperatures close to those observed this year. 

In 6 of the 10 meteorological springs (covering the period from March 1 through May 31), overall temperatures turned around and averaged cooler than the long term average. But an even more impressive number of summers (80 percent of them) turned warmer than the long term average.
 
Latest winter storm threatening waves of severe weather and drenching rains across the South; southern Midwest could see healthy rains
 
A wet storm, with access to an unlimited supply of Gulf moisture, is to come together from Texas into the Ohio Valley in coming days. For the second time in half a week, severe weather is threatening the South from Texas east to the Florida panhandle. It's a region hit by damaging and even several deadly twisters this past weekend into Monday.

Some studies have shown La Nina springs have a tendency to produce more "family-type" tornado outbreaks, where clusters of twisters occur. The severe weather outbreak from Arkansas to Mississippi and Alabama earlier this week is consistent with that pattern.


U.S. 2012 severe weather season off to active start; the most reports of tornadoes/severe storm into the Storm Prediction Center to date since 2008

The very young 2012 severe weather season is off to an active start. A total of 435 reports of severe weather (i.e. large hail, damaging straight-line winds, etc.) have been filed with the Storm Prediction Center (SPC) which, along with NOAA's National Climatic Data Center in Asheville, North Carolina,  maintain the country's severe weather archive.

Since 2000, only 2008 has managed to record more severe storm reports by  now. The 56 reports of twisters on the books this year at SPC is surpassed since 2000 only by the 75 tornadoes reported in January 2008.
 
Several snowy periods could occur here during the transition to colder air this weekend, beginning late Friday
 
A multi-day burst of frigid arctic air heads into the area in waves late this week into the coming weekend.  Any one of them, if fully developed, could produce several inches of snow. The first is due later Friday into Friday night---a second swings into the area just ahead of  sharp cooling predicted Saturday into Saturday night.

The arctic chill will come and go fairly expeditiously, as has been the case with previous cold spells all season.

A third period of light overrunning snow could occur Monday before temperature surge above freezing by Tuesday next week.

 

By Meteorologist Tom Skilling

Chicago's weather has moved into a quieter state likely to last until a blustery outbreak of arctic air hits this weekend. The calm follows the winter season's biggest snowstorm on Friday---then, only two days later, a rare round of downpour-generating January thunderstorms which washed much of the snow away in a matter of hours late Sunday.
  
Chicago weather records underscore how unusual January thunderstorms here are. Over 141 years of official weather observations, there have only been 53 January days on which thunderstorms have occurred---the least of any month.

By comparison, June has recorded 883 thunderstorms, July 845 and August 794.

The 0.80 inches of rain unleashed by the thunderstorms in the city at Midway Airport and the 0.61 inches at O'Hare reduced to puddles all but remnant of snow piles from the Friday storm.

Clouds are expected to break allowing some mixed sun by Tuesday afternoon. But the flood of colder air into the area on gusty northwest winds Monday and overnight is likely on Tuesday to produce only the 10th day in which temperatures have failed to reach 30-degrees this winter. There had been three times as many such days to date a year ago.
 
 
Winter continues meek compared to last year; only half  of last winter's snow has fallen
 
Despite recently colder temperatures and last Friday's snow, this winter remains demonstrably meeker than its counterpart a year ago.  Temperatures to date are running 10-degree higher than last winter's over the same span of time and snowfall has been just half as much ( 12.9 inches versus 24.7-inches a year ago).
 
Monday's 46-degree pre-dawn high one of this cold season's 32 days with highs 40+-deg; only 3 such days a year ago
 
Before the cold air hit Monday, temperatures managed to surge to 46-degrees---the 32nd time since the start of meteorological winter Dec. 1 that readings have reached or exceeded 40-degrees.

Temps at or above 40 had occurred only three times by this date
a year ago!
 
More severe weather as another Pineapple Express storm jumps the Rockies and targets Texas and the Gulf; this one stays south of Chicago
 
The 2012 severe season got off to a rip-roaring start Sunday night and Monday as severe thunderstorms sent a swarm of damaging tornadoes dancing across the South. 24 twister reports were logged by the Storm Prediction Center from Arkansas into Tennessee, Mississippi and Alabama.

A new outbreak of super-cellular thunderstorms capable of spinning up tornadoes, threatens the South Tuesday and Tuesday night with Texas at the epicenter of the area at risk.

Downpours with the latest storm sweeping acrossthe Lower 48 are predicted to be heavy Tuesday and Wednesday  from Texas north into Oklahoma, Arkansas, Missouri and, in coming days, even sections of downstate Illinois and Indiana. Some of the predicted downpours are to fall across an area which has been plagued by extreme drought for years.
 
Surge of high energy protons off largest solar storm in 7 years to shower Earth's upper atmosphere Tuesday; could activate Northern Lights
 
A mammoth solar flare late Sunday, the biggest observed in 7 years, produced an earth-bound surge of energy known as a coronal mass ejection (CME). Charged protons within this CME have already played a role in producing some spectacular northern lights displays on earth visible late Sunday in Scotland, Wales and the northern English Coast.

It takes about 36 hours for these charged particles to reach Earth---a timetable that would have them contacting earth's upper atmosphere around 9 a.m. Chicago time Tuesday morning, give or take 7 hours. These particles move at the mind-numbing speed of 5-million miles per hour.

Our astronomer Dan Joyce makes no guarantees---but says it's just possible some in the area may be able to see the Northern Lights Tuesday night, weather permitting. The best estimate among space scientists is that the energy out of Sunday's flare is only to  skirt earth but may still be capable of initiating auroral displays possible.
 
The city's coldest day historically has occurred on or about Jan. 28
 
Many ask at this time of year, which day is the city's coldest? It turns out that Jan. 28 (this Saturday) fits that bill. That's significant because average temperatures begin climbing slowly beyond that date.  
 

By Meteorologist Tom Skilling
 
Snowfall got underway early Friday and wasted no time building into the Chicago area's most challenging snowstorm of a season. The system's 4 to 9 inch snowfall and hours of quarter-mile or less visibilities were to lay the foundation for one of the area's most difficult commute periods in literally decades.

Not since the infamous Valentine Day's snowstorm of 1990, which unleashed a 10-inch accumulation of snow at the height of the evening rush hour, has a snowstorm created the level of grief Friday's did. Reports of five-hour commute times were rampant.

Make no mistake about it. The logistics of clearing snow off this area's thoroughfares---tough under the best of circumstances---become infinitely more demanding when snow removal crews must struggle to salt and plow highways and roads in gridlocked traffic.

Friday's storm, responsible for the 7.3 inch accumulation at Midway Airport, was a record-setter at the South Side site.  That accumulation blew past the 4.9 inch record for the date set in 1949.

In one fell swoop, the storm all but doubled the city's 2011-12 snow total which had been at 8 inches before the onset of Friday's snow.

The area of snowfall blossomed quickly as the storm responsible spread eastward toward the Midwest late Thursday.

Its first flurries began fluttering to earth at Midway Airport around 9:23 am Friday morning and at 10:22 am at O'Hare. Twelve hours later,  flurries had finally begun to wind down after accumulating as much as 9 to 10 inches in the hardest hit locations and 4 to 5 inches elsewhere.

The snowstorm was the biggest to occur here since last February's blizzard.
 
Area blanketed by 4 to 10-inch snows; visibilities slashed to fractions of a mile at the height of the storm
 
Snowfall is almost never distributed evenly across the Chicago area. It's one of the reasons predictions of snowfall are presented as a range of inches.

Though snow fell across the Chicago area for more than 12 hours, the heaviest accumulations occurred within a 6 to 8 hour window of time.

Preliminary snow accumulation data indicates 9.1 inches fell at Joliet; 8.2 inches at Portage, IN; 8 inches Elburn; 7.6 inches at Bolingbrook, and 7.2 inches at Peotone and Naperville. Other Friday totals include 8.0 inches at Bull Valley in McHenry County.

Lake-effect snow showers the threat Saturday
 
Snow showers and flurries are to blow from time to time off Lake Michigan Saturday, flirting with the lakeside counties of Illinois, Wisconsin and northwest Indiana.

Such snows tend to be localized. But, if you get under the heart of the so-called "lake snow plume"---the concentrated band of snow showers oriented north to south over the lake---precipitation can occur heavily for brief periods.
    
 
Swath of significant snowfall extends west into Iowa, southern Minnesota and South Dakota; local 8-inch totals there
 
This storm's snowfall wasn't limited to the Chicago area. It extended into sections of southern Wisconsin, west to Iowa, southern Minnesota and South Dakota. Up to 8 inches of snow whitened a narrow corridor there. Some of the heavier totals  totals included 8 inches at Ringsted; 7.5 inches at Maquopketa---both in Iowa--and 7 inches at Elizabeth and Mt. Carroll, Illinois. Dubuque, Galena and Waterloo, Iowa all reported 6.5-inch accumulations with Friday's storm.
 

By Meteorologist Tom Skilling

      Snow spares Friday morning's rush period but is to be in the air here by lunchtime and at its height from mid-afternoon through the evening rush hour.  The storm has every indication of becoming Chicago's biggest this season to date, with accumulations over portions of the metro area likely to surpass the 4.9 inches which fell at O'Hare and the 6 inches which fell at Midway Airport only a week ago.
    Days of snowfall projections--90 of them in all--from a suite of computer models, suggests an average of 7.3 inches will fall across Chicago, though the range in snow forecasts runs the gamut from 2.5 inches to as much as 12.5 inches.  The more modest 7-inch-plus figure has a good chance of accurately verifying since the vast majority of computer snowfall estimates in recent days have hovered around that figure.
    That the system was tapping the rush of moisture heading north from the Gulf and was undergoing rapid development late Thursday evening was evident as weather radars across the Plains began to glow a fast-expanding swath of precipitation.
    Our best estimate is that snow is to reach the city before lunchtime Friday then becomes heavy at times Friday afternoon and evening, peaking from mid-afternoon through early evening. By the time the final flakes of snow with this latest storm flutter to earth, 4 to 9 inch accumulations are expected to be widespread across the area.
 
 
Snow to fall steadily for 12 hours, then to be followed by period of lake-effect snow showers/flurries
 
    Steady snow appears likely to fall for roughly 12 hours--commencing in the city within an hour or two of 10 am and ending away from the lake around 10 pm Friday evening--but continuing as sporadic lake snow showers or flurries in lakeside counties of Illinois, Wisconsin and Indiana into Saturday.
    It's likely the bulk of this storm's snow accumulation will occur in just 8 hours from noon to 8 pm Friday evening.
 
 
Gulf's wide open; metro area to sit within the corridor of the heaviest snow totals
 
     Watching snow systems come together in the winter is fascinating. Many meteorological elements have to be perfectly aligned for big snows to occur. With southerly winds blowing from the Gulf of Mexico north into the arctic air which dominates the Midwest, there's certainly no lack of moisture. There, the similarity with many other Midwest snow-systems ends.  The storm system producing the low level southerly flow several thousand feet above the ground, propelling moisture up and over the frigid arctic air  assures Friday's storm has all the moisture it needs to produce a corridor of impressive accumulations. That corridor is to run from South Dakota across northern Iowa and southern Minnesota into southern Wisconsin, northern Illinois, northern Indiana and southern Michigan. It appears the axis of the heaviest snowfall is to extend across the greater Chicago area.
 
 
Snow system has a history of 50-inch mountain snows, huge rainfalls and  hurricane force coastal and mountaintop wind gusts across the Northwest
 
    The storm which is to generate Friday's Chicago snow has quite a history to our West.  Near Mt. Hood, Oregon, it generated 50 inches of snow--that's more than four feet--while Ketchum, Idaho reported 38.5 inches of snow late Thursday.  The storm, a by-product of the so-called Pineapple Express pattern, has generated 8.83-inches of rain at Silverton and 7.40-inches at Agness, both in Oregon.
     At Summer Lake, Oregon, winds hit 88 mph earlier this week and comparably strong winds have blasted other Western peaks.
 
 
Bitter Thursday afternoon temps and sub-zero wind chills the culmination of a 12 hour temp plunge from 28 to single digits
 
   One of the the most jarring surges of cold air in 11 months descended on the Chicago area Friday.  Temperatures during the day plummeted from 28-degrees to single digits in just 12 hours time.
    Morning lows early Thursday bottomed out as low as 30-below across sections of northern Minnesota and dropped sub-zero for a time across Chicago's northwest suburbs late Thursday, a region which shivered through 10 to 16-below wind chills in the day's gusty southwest winds.
 
 
Milder weather to follow Sunday as powerful south winds send temps above freezing while delivering rain showers
 
    A thick blanket of snow is to slow the advance of mild air into the area this weekend. But model indications of powerful southerly winds here by Sunday will be capable of mixing some milder air down to the surface, boosting Chicago temperatures above freezing in the afternoon.
 
 
Model indications of Greenland blocking late month signal a potentially frigid February open
 
     February's open may be a cold one this year.  All major computer models are developing a dome of warm air across far north of Chicago across Greenland in the 11 to 15 day forecast period.  That's a cold signal for Chicago since domes of warmth in the upper atmosphere there often force colder air into the Lower 48.