EXPLAINER: January 2005 Archives

Winter’s grip on Chicago will relax a bit in the upcoming week with the possibility for seven consecutive days with highs above freezing. Though maximum temperatures early in the week will be capped in the middle 30s, afternoon highs by the end of the week should climb into the lower 40s resulting in a marked decline in the area’s ample snow pack.

While the Chicago area is thawing, Atlanta along with much of the Southeast is reeling from the effects of a major ice storm. At least one-quarter inch of ice accumulated in the Atlanta area Saturday, knocking out power and shutting down every interstate in the area. Air traffic was crippled as hundreds of flights were canceled and there were at least three traffic fatalities.
As January, 2005 enters the record books, the month will be remembered for its snow—the 9 days with an inch or more of snowfall, two major snowstorms and a monthly snow total that will approach 30 inches.

January 2005’s final weekend has arrived‚—and with a temperature rebound underway! Readings by Friday afternoon reached 27° here—quite an improvement over the 2° low here which tied for this winter’s third coldest. It was areas just east of the city which bore the brunt of the arctic air. Valparaiso, Ind., bottomed out at -3° early in the day—but, in Michigan, Alpena established a new record with its -16° low and Flint hit -11°. Other records included -16° at Albany, -18° at Syracuse and -27° at Watertown—all in New York state.
The Deep South was in the grip of a winter storm late Friday. Ice accumulations up to 0.5” were predicted from Atlanta and Augusta, Ga., east into the Carolinas.
Moist air running up and over the retreating arctic air mass is behind Chicago’s cloud cover and predicted snowy spells Saturday. A second system could bring some more snow early next week.

Chicagoans are getting just a taste Friday morning of the frigid arctic air mass responsible for heartstopping -30° morning lows yesterday from northern Wisconsin and Upper Michigan to interior New England. Fresh snow and light winds facilitated the temperature crash. In the Upper Midwest, readings were among this winter’s coldest, bottoming out at -32° at Petosky, -31° at Indian River, -30° at Elmira in northern Michigan while nearby Eagle River, Wis. hosted -26°. The southern flank of that bitter air mass has produced single digits in the city early Friday for only the 13th time this winter while sub-0° readings cover lower Michigan and northern Indiana at daybreak. New England is the region most directly affected by the chill. Watertown in Upstate New York recorded a record-breaking -32° low Thursday morning, “warming” to just +4° in the afternoon. Windchills in the Northeast held to -45° at some locations.

Thursday dawns with lake-effect clouds still generating snow showers and flurries over parts of the area. But, the atmospheric set-up responsible for the snowfall is to break down. Temps aloft are beginning to warm—a development which in time is to extinguish the upwelling of air critical to lake snow formation. In addition, surface winds are to change direction. Instead of blowing from the NE, a trajectory which brings them over 90-plus miles of open lake water, the flow will become SE this afternoon and evening. This dramatically reduces the air’s contact with water, shutting down the lake snow’s moisture supply.
More than 2” had fallen by late Wednesday evening at Schererville, Ind., and Beach Park (near Waukegan), while just 0.8” fell at Midway. Spotty accumulations in excess of 4” are likely in the hardest hit areas close to the lake.
Out East, hard-hit Boston recorded another 4.5” Wednesday bringing its January total to 42.2”—the greatest amount ever observed there for the month.

It hasn’t been as warm here as Tuesday afternoon’s 43° since a 47° high two weeks ago on January 13. Absent the area’s heavy snow cover, temperatures would have surged into the mid 50s! The mild spell effortlessly lopped 5” off one of the area’s heaviest late January snowpacks in years. At Midway Airport, the 14” cover Sunday shrunk to 9” by late Tuesday evening. But, the country’s real warmth Tuesday was in the Plains where new high temp records were established—among them 65° at Grand Island and 66° at North Platte—both in Nebraska.

Wednesday is to be the last day until next October 30 to produce a pre-5pm sunset thanks to lengthening days. The trend toward longer days has been ongoing for more than a month. In fact, Chicagoans now enjoy 52 minutes more sunlight than back on Dec. 21—the city’s shortest day and also the official start of winter.

-Tom Skilling

With Chicago’s 2004-05 seasonal snow tally now at 30.4” in the wake of this weekend’s big storm (11.2” at O’Hare and 12.9” at Midway), the area has exceeded by nearly half a foot the 24.8” which fell all of last snow season. January, with 24.6” of snow to date, has become the city’s 4th snowiest since 1885. Even the snow which covers the ground is turning into one for the books. The 8” of snow on the ground here late Monday is the greatest cover of snow observed on a Jan. 24 since the 24” snowpack observed in 1979. (Note: There have been more recent January dates with heavier Chicago snowpacks, among them the 18” measured in the wake of the 21.6” snowstorm Jan. 1-3, 1999 and the 11” snow cover which remained after a foot of snow fell Jan. 30-31, 2002).
The chilliest weather in 2 years gripped Florida Monday morning. Temps fell to 31° at Tampa, 33° at Orlando, and 43° at Miami. Daytime highs only reached 59° at Tampa, a reading below the 69° recorded at Rapid City, S.D.

Above-freezing temperatures today and a chance of showers tonight will start to work on the current 6-12”-plus snow cover across the region. Cold temperatures midweek will stall the process, but thawing may pick up momentum next weekend with readings well into the 30s and a strong likelihood of more substantial rains. Should this scenario occur, the snow melt combined with significant rains could create runoff/flood problems the first part of the following week. Soils are saturated and frozen down to a 6-inch depth; add warming and rain, and flood-prone areas could be in real trouble.
Meanwhile, New England will try to dig out of a paralyzing 10-20” snowfall that reached 3-foot depths in Massachusetts.
Cold air has spread into the South with hard freeze warnings in effect this morning along the Gulf Coast and most of Florida.

Northeast Illinois awoke Saturday to a heavy snow cover that was continuing to build. As the day progressed northerly winds gusting consistently over 35 miles per hour whipped and drifted falling and already fallen snow. As the storm center moved east, and winds became more east of north, the Lake Michigan “snow machine” kicked in. Bursts of snow dumped an additional 3 to 6 inches as far inland as DuPage County. Whiteout conditions along Chicago’s Lake Shore Drive forced its temporary closing late Saturday afternoon. Most of the city proper received a foot of snow with Wrigleyville reporting 15 inches. The storm raged on as it moved quickly through Ohio and Pennsylvania continuing to dump up to a foot of snow far to the north of its path. The storm was expected to further intensify off the New Jersey coast and blizzard warning were issued for a good portion of New England including New York and Boston where snowfalls up to 20 inches were forecast.

Not since the 12” in January 30-31, 2002 has a storm generated more snow here. Truly big snows are actually relatively infrequent here. Of the 2,546 measurable snows since official measurements were first archived by the National Weather Service here in 1885, only 80 have generated 8”+ accumulations--and just 20 of those have produced 12”+ totals. That means a 12” or greater snow occurs on average only once every 6 years. Should the final storm total in the current system reach one foot at O’Hare—an outcome dependent on the amount of lake snow which occurs Saturday—it would become only the fourth time in the past 26 years that a 12” snowfall has occurred here.

Final snow tallies in this storm are likely to reach 9-13”. But, another 2-4” is likely to occur inland Saturday with greater amounts possible in bursts of snowfall off the lake. That could mean totals in excess of 13”occur in the hardest hit areas close to Lake Michigan.

Periods of snow here Thursday, totaling 1.5” at O’Hare, 1.6” at La Grange, 1.7” Oak Lawn and as much as 2.5” at one location the city’s northwest side, have pushed the seasonal snow tally to more than twice the levels observed a year ago. Since the current season began, 19.2” has fallen at O’Hare—13.7” of it this month alone, well above the 11.3” full January norm. The nearly 20” on the books to date is 2.5 times the 7.6” a year ago.

Barring last minute storm track changes—a perennial possibility in the complex world of Midwest winter weather—the city may be on the way to its second +7” snowfall this month beginning this evening. Though it’s conceivable snowfall may break temporarily between the steady snows generated by the storm Friday night/Sat. morning and the lake snows due here Saturday afternoon and evening, final storm totals may reach 5-7”—heavier lakeside.
-Tom Skilling

January has hosted the Chicago area’s three biggest snowstorms—the infamous 1967 Blizzard (23.0”) and the megasnows of 1979 (20.7”) and 1999 (21.6”). Significant snow accumulations are no stranger here this time of year. Even without a truly mammoth snowstorm to its credit, the month has tallied a total of 12” of snow to date, making it one for the books. The amount is already more than the 11.3” considered normal in an entire January. The opening 19 days of the month now qualify as the 15th snowiest of any January 1-19 period since official measurements began in 1885.

Another 1-2” is predicted in Thursday’s snowy periods. But, Friday night and Saturday is the period being closely monitored for the next significant snowfall here. An accumulation of 7” or more would mark only the third time in 121 years the city has been hit by two 7” or greater snows in a single January. (The first occurred Jan. 4-6, 2005 and totaled 9.8”).
-Tom Skilling

Chicago’s winter weather has moved into a decidely snowier phase. The area recorded Winter, 2004-05’s third-heaviest snowfall overnight, the final flurries of which could linger at some locations into Wednesday’s opening hours. By late Tuesday, snowfalls with the system had reached 4.5” at International Falls and 3.8” at Duluth, Minn. to Chicago’s northwest.

The snow comes on the heels of a cold January period—one of only 23 here over the last 135 years which have produced 15° or colder daytime highs over four consecutive days.
Tuesday marked the 10th day on which temps failed to reach 20°. By this time last year, only two such days had occurred. To our north, LaCrosse, Wisconsin recorded a morning low of -7°—-its 6th straight day with sub-zero temperatures there.

Record warmth made news Tuesday in the Pacific Northwest. In Oregon, temps reached 66° in Portland and 67° at Eugene.
-Tom Skilling

Before temperatures surge into the low 20s Tuesday, Chicagoans will have shivered through 108 consecutive hours of sub-15° readings which began at midnight Thursday night/Friday morning. It’s only the 11th time since 1871 that four consecutive days in mid-January have hosted temps of 15° or lower. The past four days have averaged only 8.5°—more than 15.5 degrees below normal and the 14th coolest mid-January period here in 135 years. Monday’s 11° high was Chicago’s coldest since the 3° high a year ago on Jan. 30.
The chill plunged deep into Florida where wind chill advisories accompanied predicted upper 20° lows overnight.
Meanwhile, space weather forecasters continue monitoring a mammoth sunspot which on Monday grew to the size of Jupiter on our sun’s surface. Huge solar flares have emanated from the area of solar storminess and auroral displays continue a better than normal possibility here on Earth.

Chicago’s current cold snap will begin to ease Tuesday as temperatures creep back into the 20s after four days with highs in the 10º to 15º range as the massive arctic high pressure area that brought the cold weather moves to the eastern United States.
That arctic high brought the coldest weather in nearly a decade to portions of the northern Plains and upper Midwest. One of the coldest spots has been Aberdeen, S.D., where record weekend cold sent lows to -35º on Friday, -25º Saturday and -30º Sunday.
The price for warmer weather will be an increasing threat of snow as a series of storm systems move across the Midwest. The first system should primarily affect areas north of Chicago Tuesday night and Wednesday, but the next system arriving Thursday night should track further south and could bring several inches of snow to Chicago before it moves east of the area early Saturday.

With cold dense arctic air well entrenched across the Midwest, Chicago’s official barometer reading climbed to lofty levels Saturday peaking at 30.86” around 9 a.m. This equaled the highest barometric pressure here since February 25, 1990 falling just short of the city’s record high reading of 30.98” recorded on February 16, 1989. Despite the proximity of the arctic air, some cloudiness and a lack of snow cover have held city temps just above zero Friday and Saturday mornings, but that is likely to change as a reinforcing lobe of the arctic cold moves in today and Monday. People willing to brave the cold may be treated to a display of the northern lights tonight or Monday night, a result of increased solar flare activity this weekend.

In the longer term, the cold weather is expected to moderate by midweek, but a “clipper” type storm system may bring a round of accumulating snow by the end of the week.

Cold as it is in Chicago, the brutal core of this arctic air mass is positioned just west of the metro area where it’s producing the coldest temperatures observed in 9 years—since 1996. From northern Iowa and Minnesota west to Montana, the mercury failed to break above 0° Friday. Wind chills hovered in the bonechilling -30 and -45° range. Only the lack of a heavy snow cover across the Chicago area has prevented the coldest readings here. That’s little comfort to those who work outdoors and the chill’s grip is to strengthen as a reinforcing cold front passes Sunday morning—a system which could bring snow showers to the area.

Temps to Chicago’s west Friday reached levels not often seen in recent winters. Readings dropped to -42° at Culbertson, Mont., -35° at Aberdeen, S.D. and -33° at Brainerd, Minn. at daybreak—and remained well below 0° all day . The current cold spell is well timed. Winter’s coldest temps here occur around January 19.

Temperatures in Chicago have reached the 60s only 32 times since official observations began here 134 years ago. That means fewer than two in 10 Januarys have been as mild as Wednesday. Yesterday’s official 62° high tied a 115-year old record (set in 1890) and was the city’s warmest January reading here in 8 years—since the 64° high on January 4, 1997. A 62° reading is equal to the normal high temp here on April 25.

Powerful t-storms swept a narrow corridor of the metro area, from Kendall County northeast into Cook County Wednesday morning. But by evening, a far more substantial squall line swept into the area from the west producing driving downpours, winds which gusted as high as 64 m.p.h. at west suburban Sugar Grove Airport and cloud to ground lightning at a rate of 60 to 120 strokes every 10 minutes. Overnight rains of up to 1.50” threatened to push rivers, already swollen by Wednesday’s snowmelt runoff, to flood stage.
-Tom Skilling

For only the second time this month, thunder may accompany rainfall later Wednesday. South winds predicted to reach 75 m.p.h. just a mile above Chicago are forcing unusually mild air over the area’s extensive snow cover. Dense fog has resulted as the chilly surface cools the air, producing condensation.

Downpour generating t-storms and the prolific runoff generated as melting snows free 0.50” to 1.50” of water trapped in the area’s snowpack, threaten widespread flooding. Ice dams—the buildup of chunks of ice as above freezing temps reach area river basins—and snow-clogged storm sewers threaten extensive flooding. An incoming flood of frigid air Thursday may complicate matters by turning standing water to ice later Thursday/Thursday night. Thundery weather has occurred already this month on Jan. 1. Additional t-storms late today would mark the 10th time since 1871 that a January has produced two or more days of t-storms.
-Tom Skilling

Not since 1963 have the opening 10 days of January been cloudier. Just 3% of this area’s possible sunshine has been recorded. The period’s 1.37” of precipitation ranks 13th wettest of the past 135 years. On average, Januarys here host 43% of their possible sun. Clouds lingering in the wake of an icy overnight weather system promise a continuation of the month’s dismal character Tuesday. The storminess here pales in comparison to the downpours which have flooded southern California. Four-day rain totals have been astronomical in the mountains near Los Angeles and San Diego. By late Monday, 27.64” had fallen in Opids Camp while Beverly Hills recorded 10.57”.
Winds, originating Tuesday more than 900 miles to the south near Biloxi, Miss., head for Chicago Wednesday with 50° highs. But, arctic air likely to produce lows of -35° over the upper Midwest Thursday night, will send temps here diving more than 50 degrees to near 0° by Friday morning.

The National Weather Service has placed Northeast Illinois under a Winter Storm Watch with a strong potential for freezing rain to develop later tonight and continue into the daylight hours Tuesday. Even a very thin coating of ice could create significant travel problems, so persons anticipating a need to be out later tonight and Tuesday should be aware of potential complications and take appropriate precautions.
Warming temperatures may alleviate icing later Tuesday, but rain will probably intensify and snow melt accelerate, causing local flood problems as drainage basins and small streams overflow—especially in susceptible lower-lying areas, basements and streets.
A temperature drop of nearly 45 degrees in 36 hours will hit Thursday and Friday with falling temps Thursday and subzero wind chills likely into the weekend.

As Indiana battles the highest floodwaters in a century in the south and recovers from ice-storm related power-outages in the central and north, the first part of the week Chicagoans will see temperatures for the most part above freezing with highs in the upper 30s to lower 40s. Wednesday should see warming well into the 40s maybe even hitting 50°.

These seasonably mild readings (averaging some 15° above normal) combined with gusty winds and a good chance of rain Tuesday and Wednesday will melt/evaporate much of the snow that presently covers northeast Illinois. However a major shift in jet stream flow mid-week will open the doors to a northerly flow that will tap Arctic cold and shunt the coldest air of the winter into the Midwest the latter half of the week. The coldest air will hit Friday and Saturday with single-digit daytime highs and sub-zero overnight lows.

Chicago and environs continue to dig out from the recent 10 inch snowfall. Though Saturday’s high of only 32° will not make much of a dent, successively warmer days should substantially erode, if not eradicate, the snow pack by the end of the day Wednesday, when temperatures stretch to near 50deg. Effective snow-eating features in the upcoming warm-up include rain with dew points and nighttime temperatures above freezing.

Shortly thereafter in this high amplitude pattern, the tables turn abruptly as some of the coldest air of the season sweeps through starting overnight Wednesday. The jet stream, which has been southwesterly for more than a week, turns in from the north as the polar vortex shifts to this side of the northern hemisphere. Thursday promises to be very windy with steadily falling temperatures. By the weekend, reinforcing cold air with origins in Siberia arrives in force, when high temperatures climb only into single digits after subzero lows.

Skies cleared across Chicago by midday Thursday, after the 36 hour storm dumped 9.8 inches officially at O’Hare and 9.2 inches at Midway. Only about once every three years does a storm of this magnitude strike Chicago: the last was a 12 inch storm on January 30-31, 2002. Chicago was just one stop on the coast-to-coast storm which began last weekend in California and soon exits New England.

Downstate Illinois reported a significant ice storm. Meanwhile, fresh snow cover and clear skies allowed temperatures to plummet last night. For the upcoming week, temperatures rise slowly, with meaningful snow melt beginning Sunday and continuing until mid week. By next Wednesday or so, the tables turn and the jet stream turns northwesterly, tapping frigid Arctic air for an extended period.

By Wednesday, 4 to 8 inches of snow were reported across Chicagoland, the heaviest north and west of Chicago, with lesser amounts south of the city where precipitation began as rain before changing over to all snow.
The official O’Hare airport total should exceed 8 inches, smashing the one-day January 5 snow record of 3.1 in. back in 1991. Across central Illinois, a thick coating of freezing rain caused widespread power outages.

Lingering flurries with the system should end before noon Thursday, with a slow warm-up beginning over the weekend. By early next week, temperatures climb into the 40’s and stay above freezing overnight, averaging 15 to 20 degrees above normal and making significant inroads into melting snow. This scenario is totally out of character for Chicago, since heavy January snows are usually followed by a stiff dose of Arctic cold.

Heavy snow is no stranger to Chicago in January. The most recent one-footer was less than three years ago, Jan. 30-31, 2002. This storm has good credentials: it’s dripping with moisture and has the punch for a major storm. However, all storm elements don’t quite gather at the same time, so the surface low development and cold air fail to phase completely, and much of the storm’s moisture is spent on freezing rain or rain south of Kankakee. Nonetheless, longevity compensates, and the resulting long duration snow at Chicago may top 8 inches, with the peak of the storm late Wednesday.

This time of year, a major storm normally pulls down a mountain of frigid air from Canada, but that air is missing since the jet stream in days to come has origins in the southwest U.S. By early next week, temperatures rebound into the snow-melting 40s.

Chicago has been dodging snow and ice storms since Thanksgiving, but that may all be ending soon. A powerful upper low that plagued California and the southern Rockies with snow and more flooding rain is taking aim on the Midwest. The eventual track of the heaviest snow is still in doubt as development of the attendant surface low does not appear until noon Wednesday. To further complicate matters, some of the considerable moisture with this system is above freezing, allowing sleet, freezing rain or even rain to mix in. If the storm stays all snow, city totals could exceed 8 inches, peaking in the overnight hours of Wednesday into Thursday. The storm could span 48 hours from late Tuesday until early Thursday. Thereafter, brisk northerly winds follow Thursday, with a slow warming each succeeding day—into the low 40s by next Monday.

Rain, which moved into Chicagoland during the night, will continue through much of the day on Monday. Morning temperatures will remain at or below freezing north and west of Chicago (except along the lakeshore), which will aid in the development of some light freezing rain. During the afternoon, the area of freezing rain will expand southward before precipitation finally ends in the evening. For the days that follow, Chicago will sit on the cold side of the jet stream until late in the week, so precipitation Wednesday will likely be in the form of snow in Chicago, with an ice storm in central Illinois.
So far this season, freezing rain has been reported over many areas of the United States and Canada east of the Rockies, with several traffic fatalities a direct result of ice covered roads. In this pattern, eastern Kansas and western Missouri are vulnerable to ice storms right through Wednesday.

Ice storms are not that rare in the Midwest but are more common in other parts of the country, like the Appalachians or Ozarks. Yet Saturday, parts of Minnesota and Wisconsin are enduring a second ice storm in three days, with another three days of freezing rain or sleet possible.
This type of frozen precipitation occurs when above-freezing rain at some lower level in the atmosphere overspreads below freezing temperatures at ground level. These freezing rain events can cause significant problems for trees, power lines, and motorists. On the warmer side of the air mass, Chicago has been spared so far, but is close enough to the next ice storm to keep it in the forecast Monday.
Before that, another shot of mild air sweeps through from the south for a mild day Sunday. Thereafter, temperatures return toward normal, with rain or snow possible on most days in the upcoming week.

The last two days of 2004 saw Chicago’s thermometers hit at least the mid 50s (57° Thursday and 56° Friday)—the last time this happened was 40 years ago in 1965 when the highs on the 30th and 31st were 56° and 60° respectively.
This meteorological feat (consecutive year-end highs of 55°-plus) has occurred a grand total of only four times since 1870. These readings are 25 to 30 degrees above normal—more typical of Halloween.
While the west-to-east jet stream flow aloft will for the most part confine arctic cold air masses north of the Canadian border, it also encourages frequent passages of low pressure systems along this parallel. As a result, rain is expected to hit later today and tonight, again Monday night into Wednesday, and then again next weekend. The week ahead will see a drop off in temperatures, but readings will still average better than 10 degrees above normal.