By Meteorologist Tom Skilling
A chill's returned to Chicago--but for a comparatively brief stay. The brief incursion of arctic air is to hold highs to the 30s Wednesday in a month dominated by unseasonably mild 40-degree or warmer highs.
Tuesday's 41-degree high marked the 17th day this month to reach or exceed 40-degrees, hardly a common occurrence. And, while 40s take a break Wednesday, current indications are they return for December's final days Thursday, Friday and Saturday. If true, the month of December 2011 will close midnight Saturday night with twenty 40-degree or milder daytime highs to its credit. That's a comparatively rare achievement. Only 11 other Decembers here since 1870 have managed to host that number of 40s--the greatest among them involving 26 days at or above 40-degrees in 1923 and 25 in 1877 and 1889.
Morning chill the coldest here in 18 days after string of 17 consecutive above normal days
Clearing skies and plunging dew points, indicating a drop in atmospheric water levels, have permitted overnight temperatures to drop into the teens over a good part of the Chicago metro area away from the city. When air dries, it's able to cool more quickly, a development which has allowed readings to slip to the low and mid teens in the coolest locations of the Chicago area. The chill follows 17 straight days which have posted temperature surpluses here.
Just one sub-freezing temperature to date versus 20 a year ago; only a handful of years have had so few sub-32-degree days
While quite a chill has settled over the area, only one-day this season has managed a sub-freezing daytime high. It occurred on December 10 when Chicago's official max temp only made it to 27-degrees.
The area's observational record reveal 13 sub-32-degree readings typically occur this month. By this time a year ago, 20 sub-freezing daytime highs had occurred in Chicago.
December's milder than normal temperature trend has reached to every corner of the Midwest
Mild December temperatures aren't limited to Chicago. The warmer than normal weather has extended to every corner of the Midwest.
While Chicago has posted a 7-degree surplus for December to date, Green Bay, WI is running 7.3-degrees above normal and Milwaukee is home to a 6.6-degree December surplus.
The story is the same at other locations too. Peoria has a +5.7-degree-surplus on the books this month while Indianapolis has warmed 5.6-degrees above its historic thermal benchmark. Other December temperature anomalies include a 3.5-degree surplus at Marquette, MI: and 5-degree surplus at Des Moines, IA. Traverse City, MI is 6.6-degrees above normal while South Bend is running 5.1-degrees above normal.
Powerhouse 208 mph Pacific jet stream sending a series of windy, downpour-bearing fronts into the Pacific Northwest and western Canada
The Pacific Northwest and western coastline of British Columbia, Canada are preparing for an onslaught of wind-driven rainfall--and at higher elevations, heavy accumulations of snow! Measurements of a powerhouse jet stream draped across the Pacific and headed for the West Coast indicate 208 mph winds at jet airplane cruising altitude.
A jet of this strength is not an everyday occurrence and it is propelling a series of wet storms toward the West Coast, a development expected to douse the Pacific Northwest with driving rains and high winds.
A chill's returned to Chicago--but for a comparatively brief stay. The brief incursion of arctic air is to hold highs to the 30s Wednesday in a month dominated by unseasonably mild 40-degree or warmer highs.
Tuesday's 41-degree high marked the 17th day this month to reach or exceed 40-degrees, hardly a common occurrence. And, while 40s take a break Wednesday, current indications are they return for December's final days Thursday, Friday and Saturday. If true, the month of December 2011 will close midnight Saturday night with twenty 40-degree or milder daytime highs to its credit. That's a comparatively rare achievement. Only 11 other Decembers here since 1870 have managed to host that number of 40s--the greatest among them involving 26 days at or above 40-degrees in 1923 and 25 in 1877 and 1889.
Morning chill the coldest here in 18 days after string of 17 consecutive above normal days
Clearing skies and plunging dew points, indicating a drop in atmospheric water levels, have permitted overnight temperatures to drop into the teens over a good part of the Chicago metro area away from the city. When air dries, it's able to cool more quickly, a development which has allowed readings to slip to the low and mid teens in the coolest locations of the Chicago area. The chill follows 17 straight days which have posted temperature surpluses here.
Just one sub-freezing temperature to date versus 20 a year ago; only a handful of years have had so few sub-32-degree days
While quite a chill has settled over the area, only one-day this season has managed a sub-freezing daytime high. It occurred on December 10 when Chicago's official max temp only made it to 27-degrees.
The area's observational record reveal 13 sub-32-degree readings typically occur this month. By this time a year ago, 20 sub-freezing daytime highs had occurred in Chicago.
December's milder than normal temperature trend has reached to every corner of the Midwest
Mild December temperatures aren't limited to Chicago. The warmer than normal weather has extended to every corner of the Midwest.
While Chicago has posted a 7-degree surplus for December to date, Green Bay, WI is running 7.3-degrees above normal and Milwaukee is home to a 6.6-degree December surplus.
The story is the same at other locations too. Peoria has a +5.7-degree-surplus on the books this month while Indianapolis has warmed 5.6-degrees above its historic thermal benchmark. Other December temperature anomalies include a 3.5-degree surplus at Marquette, MI: and 5-degree surplus at Des Moines, IA. Traverse City, MI is 6.6-degrees above normal while South Bend is running 5.1-degrees above normal.
Powerhouse 208 mph Pacific jet stream sending a series of windy, downpour-bearing fronts into the Pacific Northwest and western Canada
The Pacific Northwest and western coastline of British Columbia, Canada are preparing for an onslaught of wind-driven rainfall--and at higher elevations, heavy accumulations of snow! Measurements of a powerhouse jet stream draped across the Pacific and headed for the West Coast indicate 208 mph winds at jet airplane cruising altitude.
A jet of this strength is not an everyday occurrence and it is propelling a series of wet storms toward the West Coast, a development expected to douse the Pacific Northwest with driving rains and high winds.
