By Meteorologist Tom Skilling
Days continue to lengthen and changes in the sun angle are resulting in the arrival increased energy from the sun across the Midwest. These facts plus the presence of bare ground in the Chicago area, over which air heats more efficiently than would be the case with a snow cover, help explain how temperatures continue above normal, even at times, such as Wednesday, in which the air flowing into the area has an arctic connection.
But as any long term residents of the Midwest will tell you, concluding that wintry weather is behind us in early February is all too often a fool's errand. Historically, more than a third of Chicago's seasonal snow has fallen beyond Feb. 8---and there's little reason to believe this year will be much different, particularly with a more active pattern being advertised by computer models for next week and the week after.
Active patterns don't always guarantee snow---but they DO signal periods in which the systems which cross the area warrant special observation. Current model projections take at least three storm systems, any one of them capable of affecting the Midwest at some point in the next two weeks, across the Lower 48. These projections put the systems' so-called "rain/snow lines"----the demarcations between liquid and crystalline-form precipitation---close enough to be of possible concern.
One, two---or even all three of these systems could disappear with the arrival of newer data when future computer forecast cycles are run. But, in more than one forecast cycle over the past few days, these systems have shown up which tends to lend them an air of credibility for the moment. Stay tuned.
Tuesday's flurries: Chicago's first in 9 days; Lower 48 snowpack has shrunk to cover just 25 percent of country, half a year ago
Tuesday saw the first flurries which have fluttered to the ground here in 9 days. They melted right away in the above freezing air and upon hitting the "warm" ground.
Some clouds in lakeside counties early Wednesday may still be capable of a few flurries. But, Chicago's cold season snow stats remain anemic---a trend which extends to many corners of the Midwest and even to the country as a whole.
NOAA, parent agency of the National Weather Service, indicated snow coverage across the Lower 48 Tuesday was just over 25 percent. Nearly half of the country was covered by snow at this time a year ago.
Midwest 2011-12 seasonal snow tallies almost universally down
The milder than normal winter across the Lower 48 has cut into snow production in a majority of sections of the Midwest. A review of current seasonal snow tallies indicates Chicago's 13.9-inches to date is just 60 percent of normal while Milwaukee's 15.5 inches, Green Bay's 15.6 inches and Madison's 17.5 inches are each roughly half normal. Other sub-par seasonal snow totals to date across the Midwest (with the percent of "normal" snowfall they represent indicated in parenthesis after the snowfall totals) include: 8.5 inches Peoria (just 51 percent normal), Indianapolis 6.9-inches (37 percent), Des Moines 14.7-inches (66 percent) and St. Louis 3.8-inches (32 per cent).
Sun to emerge Wednesday delivering an 18th consecutive day of above normal temperatures; gusty SW winds, Pacific-origin air could see temps surge to the low 40s Thursday
Sunshine emerges after some lingering lake clouds flirt with lakeside counties into Wednesday morning. The returning sun is expected to push the day's temperature into the mid 30s---a level "above normal" for an 18th consecutive day.
Even milder temperatures are possible Thursday ahead of a frigid late week/weekend cold snap expected to hit with wind and snow showers Friday into Saturday morning.
Warming Thursday may benefit from a bit of "compressional warming", as the southbound cold front predicted to bring colder air to the air, produces a pile-up of air as the front's northerly winds converge with the gusty, mild west winds predicted to dominate Chicago's weather Thursday. Compressional warming in the past here has been known to push air temps as much as 6-degrees warmer than might otherwise be the case----sometimes more!
Week's second blast of arctic air to hit amid gusty winds, falling temps and snow showers Friday
The chill predicted to hit on strong northerly winds Friday is already building across east and northern Canada. Once it sweeps into Chicago Friday, the trajectory (or direction) of those winds ought to introduce some lake moisture to snow flurries and snow showers expected to accompany the downward spiraling Friday/Friday night temperatures. Enough snow could fall to dust the area.
Saturday could tie as winter 2011-12's second chilliest day
Saturday temperatures may be hard-pressed to rise out of the lower 20s. If true, the day could tie as Chicago's second coldest of the winter 2011-12 season!
Days continue to lengthen and changes in the sun angle are resulting in the arrival increased energy from the sun across the Midwest. These facts plus the presence of bare ground in the Chicago area, over which air heats more efficiently than would be the case with a snow cover, help explain how temperatures continue above normal, even at times, such as Wednesday, in which the air flowing into the area has an arctic connection.
But as any long term residents of the Midwest will tell you, concluding that wintry weather is behind us in early February is all too often a fool's errand. Historically, more than a third of Chicago's seasonal snow has fallen beyond Feb. 8---and there's little reason to believe this year will be much different, particularly with a more active pattern being advertised by computer models for next week and the week after.Active patterns don't always guarantee snow---but they DO signal periods in which the systems which cross the area warrant special observation. Current model projections take at least three storm systems, any one of them capable of affecting the Midwest at some point in the next two weeks, across the Lower 48. These projections put the systems' so-called "rain/snow lines"----the demarcations between liquid and crystalline-form precipitation---close enough to be of possible concern.
One, two---or even all three of these systems could disappear with the arrival of newer data when future computer forecast cycles are run. But, in more than one forecast cycle over the past few days, these systems have shown up which tends to lend them an air of credibility for the moment. Stay tuned.
Tuesday's flurries: Chicago's first in 9 days; Lower 48 snowpack has shrunk to cover just 25 percent of country, half a year ago
Tuesday saw the first flurries which have fluttered to the ground here in 9 days. They melted right away in the above freezing air and upon hitting the "warm" ground.
Some clouds in lakeside counties early Wednesday may still be capable of a few flurries. But, Chicago's cold season snow stats remain anemic---a trend which extends to many corners of the Midwest and even to the country as a whole.
NOAA, parent agency of the National Weather Service, indicated snow coverage across the Lower 48 Tuesday was just over 25 percent. Nearly half of the country was covered by snow at this time a year ago.
Midwest 2011-12 seasonal snow tallies almost universally down
The milder than normal winter across the Lower 48 has cut into snow production in a majority of sections of the Midwest. A review of current seasonal snow tallies indicates Chicago's 13.9-inches to date is just 60 percent of normal while Milwaukee's 15.5 inches, Green Bay's 15.6 inches and Madison's 17.5 inches are each roughly half normal. Other sub-par seasonal snow totals to date across the Midwest (with the percent of "normal" snowfall they represent indicated in parenthesis after the snowfall totals) include: 8.5 inches Peoria (just 51 percent normal), Indianapolis 6.9-inches (37 percent), Des Moines 14.7-inches (66 percent) and St. Louis 3.8-inches (32 per cent).
Sun to emerge Wednesday delivering an 18th consecutive day of above normal temperatures; gusty SW winds, Pacific-origin air could see temps surge to the low 40s Thursday
Sunshine emerges after some lingering lake clouds flirt with lakeside counties into Wednesday morning. The returning sun is expected to push the day's temperature into the mid 30s---a level "above normal" for an 18th consecutive day.
Even milder temperatures are possible Thursday ahead of a frigid late week/weekend cold snap expected to hit with wind and snow showers Friday into Saturday morning.
Warming Thursday may benefit from a bit of "compressional warming", as the southbound cold front predicted to bring colder air to the air, produces a pile-up of air as the front's northerly winds converge with the gusty, mild west winds predicted to dominate Chicago's weather Thursday. Compressional warming in the past here has been known to push air temps as much as 6-degrees warmer than might otherwise be the case----sometimes more!
Week's second blast of arctic air to hit amid gusty winds, falling temps and snow showers Friday
The chill predicted to hit on strong northerly winds Friday is already building across east and northern Canada. Once it sweeps into Chicago Friday, the trajectory (or direction) of those winds ought to introduce some lake moisture to snow flurries and snow showers expected to accompany the downward spiraling Friday/Friday night temperatures. Enough snow could fall to dust the area.
Saturday could tie as winter 2011-12's second chilliest day
Saturday temperatures may be hard-pressed to rise out of the lower 20s. If true, the day could tie as Chicago's second coldest of the winter 2011-12 season!
