By Meteorologist Tom Skilling
Wet snow or a wintry cocktail of precipitation, ranging from chilly rain, ice pellets and wet snowflakes, is visiting sections of the Chicago area for a second morning Wednesday. The latest burst of precipitation has arrived a bit later than Tuesday's and may last into the lunch hour before giving way to mixed sunshine and a third consecutive day of 40-degree temperatures likely to melt any snow which falls.
Wednesday's band of precipitation is to be comparatively narrow with the demarcation between mixed precipitation and all snow likely to set up between I-80 and I-88.
To the north, primarily wet snow is to fall in a comparatively narrow 20 to 30 mile wide corridor, while a band of mixed ice pellets, wet snow and possible cold rain may fall to the south--- changing to all rain from near Morris to Kanakakee and Renssalear.
Yet another impulse crosses the area Wednesday night. By that time, computer model temperature profiles paint a picture of an atmosphere which has warmed to the point rain is expected.
The disturbances behind the brief rounds of precipitation are embedded within a powerful west to east jet stream draped across the northern U.S. from the Pacific Northwest to New England. Indications are a series of impulses are likely to continue racing across the country into next week.
Return of some sun Wednesday afternoon sends temperatures into the 40s a third consecutive day
A series of factors come together late in the cold season which make it more difficult for chilly air of an intensity comparable to the heart of winter several months ago to survive the trek into and across the Midwest.
Not only is the sun traveling across the sky more directly overhead than in December, the amount of energy which is delivered in late February sun is more than twice (225 percent) as strong as when winter began Dec. 21. And, there's more of it. Wednesday will see 104 additional minutes of sunlight because of the lengthening period of daylight each day.
Mild winter has produced a rare bounty of 40+ degree days; 46 such days expected by Thursday's close, twice normal!
With 40+-degree highs predicted the next two days, the tally of 40s will grow to 46 by Thursday's close. That's nearly twice the 141 year average of 40-degree or milder temperatures through Feb. 23 and just shy of six times last winter's total of 8 days in the 40s over the same period.
Winter 2001-02 is the only other winter since 1900 with as many 40s through Feb. 23
In only 6 other winters----all but one of them occurring prior the beginning of the last century in 1900---have as many or more 40s been logged through Feb. 23. The most recent winter with a comparable number of 40s occurred in 2001-02 when 47 were on the books.
Spin-up of large windy storm over the eastern half of North America late this week to drag colder air south from Canada; Friday/Saturday here look blustery and chilly with flurries in the air
Cold air's been bottled up over northern Canada and Alaska in recent days. But the spin-up of a huge circulation with a sprawling late week/early weekend low pressure over eastern North America will drive some of that late season cold air south into Chicago and the Midwest on gusty northwest winds. Snow flurries and extensive cloudiness are likely to accompany the two day downturn before another eastbound storm shifts Chicago winds southerly Sunday---a development expected to push late weekend temperatures well into the 40s before another cold punch---potentially the chilliest in over a month--- sweeps in next Monday and Tuesday.
Storm track along southern flank of large pool of cold late season air will have to be monitored; wouldn't take much to spin up a storm in coming weeks
A huge mass of colder than normal air is to take up residence over much of the north and western U.S. next week. A vigorous jet stream running along its southern flank, and the disturbances these jet stream winds transport, will have to be monitored. It's this sort of atmospheric set-up which is capable of developing storm systems generating significant precipitation.
No such storm is yet being predicted by our models. But such systems can develop more easily than in other patterns and the Chicago area and much of the Midwest may be in line for above normal precipitation because of this atmospheric configuration.
Summers which have followed mild winters have tended to be warmer than average with increased 90-degree days
An in-house analysis of a series of mild winters---not unlike this one---continues to indicate a bias toward warmer than normal summer weather, including more 90s than usual. In 7 of 10 years we examined, summer (June through August) temperatures and 90-degree tallies each finished above normal.
Wet snow or a wintry cocktail of precipitation, ranging from chilly rain, ice pellets and wet snowflakes, is visiting sections of the Chicago area for a second morning Wednesday. The latest burst of precipitation has arrived a bit later than Tuesday's and may last into the lunch hour before giving way to mixed sunshine and a third consecutive day of 40-degree temperatures likely to melt any snow which falls.
Wednesday's band of precipitation is to be comparatively narrow with the demarcation between mixed precipitation and all snow likely to set up between I-80 and I-88.
To the north, primarily wet snow is to fall in a comparatively narrow 20 to 30 mile wide corridor, while a band of mixed ice pellets, wet snow and possible cold rain may fall to the south--- changing to all rain from near Morris to Kanakakee and Renssalear.
Yet another impulse crosses the area Wednesday night. By that time, computer model temperature profiles paint a picture of an atmosphere which has warmed to the point rain is expected.
The disturbances behind the brief rounds of precipitation are embedded within a powerful west to east jet stream draped across the northern U.S. from the Pacific Northwest to New England. Indications are a series of impulses are likely to continue racing across the country into next week.
Return of some sun Wednesday afternoon sends temperatures into the 40s a third consecutive day
A series of factors come together late in the cold season which make it more difficult for chilly air of an intensity comparable to the heart of winter several months ago to survive the trek into and across the Midwest.
Not only is the sun traveling across the sky more directly overhead than in December, the amount of energy which is delivered in late February sun is more than twice (225 percent) as strong as when winter began Dec. 21. And, there's more of it. Wednesday will see 104 additional minutes of sunlight because of the lengthening period of daylight each day.
Mild winter has produced a rare bounty of 40+ degree days; 46 such days expected by Thursday's close, twice normal!
With 40+-degree highs predicted the next two days, the tally of 40s will grow to 46 by Thursday's close. That's nearly twice the 141 year average of 40-degree or milder temperatures through Feb. 23 and just shy of six times last winter's total of 8 days in the 40s over the same period.
Winter 2001-02 is the only other winter since 1900 with as many 40s through Feb. 23
In only 6 other winters----all but one of them occurring prior the beginning of the last century in 1900---have as many or more 40s been logged through Feb. 23. The most recent winter with a comparable number of 40s occurred in 2001-02 when 47 were on the books.
Spin-up of large windy storm over the eastern half of North America late this week to drag colder air south from Canada; Friday/Saturday here look blustery and chilly with flurries in the air
Cold air's been bottled up over northern Canada and Alaska in recent days. But the spin-up of a huge circulation with a sprawling late week/early weekend low pressure over eastern North America will drive some of that late season cold air south into Chicago and the Midwest on gusty northwest winds. Snow flurries and extensive cloudiness are likely to accompany the two day downturn before another eastbound storm shifts Chicago winds southerly Sunday---a development expected to push late weekend temperatures well into the 40s before another cold punch---potentially the chilliest in over a month--- sweeps in next Monday and Tuesday.
Storm track along southern flank of large pool of cold late season air will have to be monitored; wouldn't take much to spin up a storm in coming weeks
A huge mass of colder than normal air is to take up residence over much of the north and western U.S. next week. A vigorous jet stream running along its southern flank, and the disturbances these jet stream winds transport, will have to be monitored. It's this sort of atmospheric set-up which is capable of developing storm systems generating significant precipitation.
No such storm is yet being predicted by our models. But such systems can develop more easily than in other patterns and the Chicago area and much of the Midwest may be in line for above normal precipitation because of this atmospheric configuration.
Summers which have followed mild winters have tended to be warmer than average with increased 90-degree days
An in-house analysis of a series of mild winters---not unlike this one---continues to indicate a bias toward warmer than normal summer weather, including more 90s than usual. In 7 of 10 years we examined, summer (June through August) temperatures and 90-degree tallies each finished above normal.
