Dear Tom,
My mother says she remembers a terrible ice storm in Chicago that occurred on New Year's Eve. What year was that?
Kendra Rasmussen
Dear Kendra,
Chicago's worst-ever ice storm began just after 1 a.m. on Jan. 1, 1948. With temperatures hovering around freezing, a steady rain quickly coated the city with nearly a half inch of glaze. The rain became mixed with sleet, adding to the icing woes. Strong winds gusting to 60 coupled with the weight of the ice brought down trees and power lines. Several large radio transmission towers also crashed down.
Roads were so slippery that all traffic, except for emergency vehicles, was ordered off the streets. Adding to the day's misery, nearly five inches of snow fell on top of the ice later that day. In one ironic twist, a New Year's Day city ice skating championship had to be canceled due to the ice storm.
Dear Tom,
After a trip to Oahu (the island on which Honolulu is located), my parents said rainfall varies greatly from one side of the island to the other. There is even a song about the windward and leeward sides, but they have not been able to find the song. It's a long shot, but can you identify that song?
Bill Frank
Dear Bill,
The song is "Island Style" by John Cruz, who, incidentally, grew up on Oahu. The lyrics that caught your parents' attention are:
"On the Island, we do it Island Style, from the mountain to the ocean, from the windward to the leeward side."
However, the song does not refer to Oahu's climate; rather, it's a celebration of the laid-back Hawaiian life style. Because northeast trade winds dominate Oahu's climate, the northeast-facing (windward) coast and mountains are awash with 60-280 inches of rain annually, whereas the southwest (lee) coast receives only 8-15 inches.
Dear Tom,
Didn't we tie or break a record for consecutive snowy days last January?
Tim Benshoof
Dear Tim,
You are absolutely correct. Chicago recorded measurable snow for nine straight days earlier this year from Jan. 6-14. The nine day snowfall total was 18 inches with most of that falling in a two-day storm on January 9-10 that buried the city with a foot of snow. That string of nine snowy days equaled a stretch logged back in 1902, when measurable snow was observed from Jan. 29 to Feb. 6. However the total snowfall then was only 5 inches with most days getting just a dusting. You may remember that bitterly cold weather followed the snowy period last January with the mercury dropping to minus 18 at O'Hare International Airport on Jan. 16. Many suburban areas were much colder with Joliet falling to 30 below zero and Barrington to minus 23.
Dear Tom,
It seems like we haven't seen the sun in weeks. Is this December cloudier than normal? What is Chicago's cloudiest month?
Rich Bartecki Morton Grove
Dear Rich,
Even though December is the city's cloudiest month, December 2009 has indeed been much cloudier than normal in Chicago. Frank Wachowski, who tracks Chicago sunshine, reports that through Dec. 28 the city had received only 26 percent of the month's possible sunlight, far less than the normally dismal 39 percent. In fact, the city has logged a total of just 64 minutes of sun dating back to December 17. As cloudy as it's been here, there have been cloudier Decembers. December 1975 produced only 19 percent of the possible sunshine and the city's cloudiest month ever was Nov. 1988 with just 16 percent.
Dear Tom,
I see that the second full moon this month will be on New Year's Eve. Has this ever happened before?
Lucy Thomson, Lake Forest
Dear Lucy,
A New Year's Eve full moon is a fairly rare event, but it has happened many times before. The last one was 19 years ago in 1990 and the one before that occurred back in 1971. After this year's Dec. 31 full moon we will have to wait until 2028, 2066, 2104, 2115, 2134 and 2180 for repeats. By nature of the moon's 29.5-day cycle, a New Year's Eve full moon will always be the second full moon of the month. Astronomer Dan Joyce of the Cernan Earth and Space Center at Triton College tells us that the odds are that a full moon will occur twice on a particular calendar date in any 59-year period.
Dear Tom,
What was the track of the low that brought Chicago its massive New Year's snowstorm in 1999?
Matt Balitewicz, East Chicago, Ind.
Dear Matt,
The crippling blizzard that officially brought Chicago 21.6 inches of snow followed a classic heavy snow track for Chicago. It formed in southeast Colorado New Year's Day, then traveled across far southern Missouri before turning northeast across Indiana and moving into Lower Michigan. During its trek across the Midwest, the storm ingested large amounts of Gulf moisture at the same time cold air was feeding into it on its northern flank, assuring the precipitation here remained snow. With strong northeast winds, lake effect added several inches to the final storm totals. This snowstorm remains the city's second greatest, surpassed only by the 23.0 inch "Big Snow" of Jan. 26-27, 1967.
Dear Tom,
What is the preferred indoor relative humidity during the winter?
Nolan Marg
Dear Nolan,
A good rule of thumb is to try to keep the indoor relative humidity in your home at about one half of the indoor temperature. If your house is heated to 70 degrees then the humidity in the house should be about 35 percent. When cold outside air is warmed to room temperature without additional moisture, the relative humidity level undergoes a significant decrease. It is not as critical when air temperatures are above 40 degrees, but once outdoor readings drop into the 30s or lower, a house can become "desert-dry" with the relative humidity dropping below 10 percent. When this happens, static electricity flourishes and many people experience dry skin and respiratory discomfort.
Dear Tom,
What is the difference between sleet, ice pellets and freezing rain?
Jesse Starkman
Dear Jesse,
Sleet is precipitation in the form of small grains of ice. It forms when raindrops (or largely melted snowflakes), originating in warmer air aloft, fall through a layer of subfreezing air at ground level and then freeze on their way down. Sleet is referred to as ice pellets in weather observations.
Freezing rain is rain, also originating in warmer air aloft, that falls into a shallow layer of subfreezing air (usually only several hundred feet deep) at the ground and freezes upon impact to form a coating of glaze on exposed objects.
Sleet and snow always present challenges for those who must cope with them, but when it comes to creating inconvenient, damaging and even life-threatening conditions, freezing rain is in a class by itself.
Dear Tom,
What is the average daily temperature at the South Pole?
Mel Dormer Aurora
Dear Mel,
The National Weather Service maintains the Amundsen-Scott weather station located directly at the South Pole at an altitude of 9355 feet. The "warmest" time of the year there is in January, when there is 24 hours of sunlight a day and the average daily temperature climbs to about minus 20. The coldest time of the year is in July's mid-winter darkness when typical readings register about minus 76.
Current weather from the Amundsen-Scott station is always available at http://weather.noaa.gov/weather/current/NZSP.html.
The weather station at Vostok, Antarctica takes the dubious honor for recording this planet's lowest temperature, a reading of minus 129 on July 21, 1983 while the record high there is just 7.5 degrees above zero reached on Dec. 27, 1978.
Dear Tom,
What are Chicago's temperature records for the holiday period from Christmas Eve into Jan. 1? We were wondering about the mildest and coldest.
Edna Polivka
Dear Edna,
Chicago's holiday temperature extremes are mighty extreme, but that's characteristic of the city's continental climate (so-called because our climate is typical of the conditions that prevail toward the interior of continent-sized land masses -- areas far removed from the moderating influences of oceans).
Chicago's Christmas Eve (Dec. 24) temperature records are 64 degrees (1889) and 25 below zero (1983); on Christmas Day (Dec. 25), 64 degrees (1982) and minus 17 (1983) -- back-to-back years!; New Year's Day (Jan.1), 65 degrees (1876) and 10 below (1969). The nine-day averages (Dec. 24 - Jan. 1) range from 41.9 degrees (1875-76), the mildest, to 2.7 degrees (1983-84), the coldest.
Dear Tom,
What is the record snowfall rate for Chicago?
Marty Shanahan, Plainfield
Dear Marty,
On the evening of Feb. 23, 1967, less than a month after the city's 23-inch "Big Snow", Chicago was hit by a full-scale blizzard. Traffic came to a standstill as blinding snowfall reduced the visibility to zero, stranding thousands of motorists. According to Chicago climatologist Frank Wachowski the storm dropped 3.5 inches of snow at Midway Airport in just one hour, a city record. The intense storm that brought up to 6 inches of snow to the metropolitan area in just a few hours was accompanied by considerable thunder and lightning and temperatures in the teens. The snow was blown horizontally and piled into huge drifts by northwest winds that gusted to 47 mph in the city and as high as 82 mph at Ogden Dunes in northwest Indiana.
Dear Tom,
The huge snow totals from the storm in the East remind me of Chicago's paralyzing snowstorms in 1967 and 1979. Are we overdue for another?
Kate Flaherty, Lisle
Dear Kate,
Huge snowstorms are really quite rare in Chicago with only three on the books that totaled more than 20 inches in 125 years of weather records dating back to 1884. You have referred to two of them, the 23.0 inch "Big Snow" of Jan. 26-27, 1967, and the "Blizzard of '79" that brought 20.3 inches on Jan. 12-14, 1979. The city's only other 20-inch-plus storm took place nearly 11 years ago on Jan. 1-3, 1999, when a monster storm dropped 21.6 inches of snow on the Chicago area. Most of Chicago's big snowstorms generally bring about a foot of snow, and typically the city gets a storm of that magnitude about once every six years.
Dear Tom,
I just read your recent column about the snowy December 1951. Didn't the opening of the Edens Expressway take place in a major snowstorm about that time?
Howard Mason
Dear Howard,
The official opening of the Edens Expressway took place Dec. 20, 1951, during a major snowstorm that brought Chicago a three-day snow total of 7.3 inches. At 11 a.m. that day, the ribbon was cut near the overpass at Peterson and Caldwell avenues, which marked the south end of the new six-lane expressway. A dozen snowplows ran interference as a motorcade traveled 14 miles north along the highway to its northern limit at Lake-Cook Road. One of the ribbon cutters was William G. Edens, after whom the highway was named. He was a pioneer in promoting the state's first highways in 1918.
Dear Tom,
A recent column talked about all the snow in December 2000. Wasn't the rest of that winter relatively snow free?
Richard Strombom, Wheeling
Dear Richard,
You are absolutely correct. After the city was staggered by one of the snowiest months on record in December 2000, the rest of the winter turned out to be a piece of cake. More than three-quarters of the season's snowfall fell that month. At Midway Airport, where December brought a record 41.3 inches of snow, the rest of the winter delivered only 13.2 inches, bringing the final total for the season to 54.5 inches. January recorded just 2 inches, February 2.9, March 6.6 inches and April a meager 0.6 inches. At O'Hare, December snowfall tallied 30.9 inches and comprised nearly 80 percent of the city's official 39.2-inch seasonal total.
Dear Tom,
We get big snows that last a day or two, but sometimes it snows just a little bit for days on end. What is Chicago's record for the largest number of consecutive days with snow?
Todd Pierce
Dear Todd
Your observation that Chicago's largest snow storms are usually just one-day or two-day events is correct. In 125 years of snowfall records dating from the winter of 1884-85, Chicago's all-time greatest snow storm was the blizzard of Jan. 26-27, 1967, when 23.0 inches of wind-whipped snow (and 6-foot drifts) brought the city to a standstill.
However, a scan of Chicago's snowfall data also supports your contention that periods of "little snows" and flurries can sometimes go on for days. In that regard, Chicago's extreme event was the nine-day period of Jan. 29 through Feb. 6, 1902. Measurable snow fell on each of those days, but the 9-day total was only 5.0 inches.
Dear Tom,
What is the most snow we've ever had on Christmas Eve and Christmas Day?
Ellen Abbott Oak Park
Dear Ellen,
While snow on the ground Christmas Day is picturesque and idyllic, a Christmas snowstorm can be a nightmare. Such was the case back in the very snowy December of 1951, when the city was hit by a major holiday snowstorm that began late in the afternoon of Christmas Eve and ended just before noon Christmas Day, bringing an official snowfall of 8.6 inches. The city had been hit by three other snowstorms in the days leading up to Christmas and combined with this storm nearly halted holiday travel. The two-day storm dumped 4.6 inches of snow on Dec. 24 and the final 4.0 inches on Dec. 25. Chicago has recorded two snowier Christmas Days; 5.1 inches just one year earlier in 1950 and 5.0 inches in1909.
Dear Mr. Skilling,
How are icebergs formed and how many are there?
Alice Van Rosendale, South Holland
Dear Alice,
Icebergs -- thousands per year -- are composed of freshwater ice that was formed over land and eventually makes its way into the sea. This occurs in two ways. In the Northern Hemisphere, icebergs are born when glaciers terminate at the ocean and pieces break away (calve) from the parent glacier. Around Antarctica, the continental icecap in places extends out over the ocean as an ice shelf, and huge pieces occasionally break off.
In describing icebergs, The Greenland Tourism Bureau says their "... magnificence and majesty cannot adequately be captured on film -- they must be experienced firsthand! ... It also gives food for thought that icebergs were originally created in a slow transformation from snowflakes to ice during a period predating modern history."
Dear Tom,
How many days in the year do we receive snow in Chicago? I'll estimate about 25 days.
Robert Browning, Chicago
Dear Robert,
"Snow days" can be tallied in two ways, but your estimate is low either way: Snow flies surprisingly frequently around here. That's good news or bad news, depending upon your point of view.
The National Weather Service defines two kinds of days with snow: those with measurable snow (an accumulation of one-tenth inch or more on grassy surfaces) and those with mere "traces" (flakes in the air, but no accumulation).
A computer sweep of 80 years (1929-2008) of Midway Airport snow data, courtesy of Chicago weather guru Frank Wachowski, yields these surprising numbers: On average, we experience 30 days per year with measurable snow and another 34 days with traces, for an annual total of 64 snow days.
Dear Tom,
I am impressed by the fabulous graphics in your weathercasts and the magnificent colors that are used to illustrate the buildings in downtown Chicago, especially the bright red skyscraper. Are the colors real, or are they just presented to represent the various landscapes of your city?
Leigh Rainey
Dear Leigh,
The colors are real. We receive occasional questions about Chicago's unique skyline and, in particular, that imposing red structure. Because of its massive height and bright red color, the CNA Plaza Building is one of the more prominent buildings on Chicago's downtown skyline.
Rising to 601 feet and 44 stories, the CNA Plaza Building was completed in 1972 and is located at 325 S. Wabash Ave. And yes, that is the structure's actual color. It is bright red, and red figures in many interior fixtures of the building as well.
Dear Tom,
You have described December as a winter month, but in my experience here in Chicago it seems that it is a month of tremendous temperature variations with extreme cold but also surprising warmth. Am I off base?
David Witherspoon
Dear David,
Your description of December temperatures is apt. The month is decidedly wintry on balance, but it's a testament to the variability of Chicago's continental climate that huge temperature swings occur routinely in December. December's all-time temperature extremes span a range of 96 degrees, from 71 degrees (Dec. 3, 1970, and again on Dec 2, 1982) to 25 below zero (Dec. 24, 1983).
That's bad enough, but consider this: In a normal December, the highest temperature in the month will be 55 degrees, and the lowest will be 0 degrees. A normal December produces very mild and very cold temperatures.
Dear Tom,
The blizzard this week missed Chicago but it makes me curious as to the differences, if any, between a blizzard and a snow storm. Those terms are always being tossed around, but there must be a difference. Am I being picky?
Jeff Weiss, Chicago
Dear Jeff,
Meteorological jargon often finds its way into general use, but the precise definitions of terms sometimes get lost in the shuffle of news reports and commentary. You're not being picky. Meteorologically, the distinctions between a snow storm and a blizzard are significant.
A snow storm is a generic term for any storm with lots of new snow, whereas a blizzard is a special and rather rare event: a severe storm that brings sustained winds of 35 mph or higher and sufficient falling and/or blowing snow to reduce visibility to less than 1/4 mile for at least three hours. New snow is not a necessary blizzard criterion.
Dear Tom,
In 1982 I remember a very warm Christmas, then one so cold a few years later that people were afraid to shut off their cars for fear they wouldn't start. Did these both set records?
Sharon Tamura, Chicago
Dear Sharon,
You are recalling Chicago's two most memorable Christmases (in a meteorological sense) and they actually occurred back-to-back. Christmas 1982 was the city's warmest on record in an El Nino influenced winter. The maximum temperature reached a balmy record high of 64 degrees on a Christmas so mild that many people were wearing shorts and washing their cars. The very next year the bottom dropped out of the thermometer, as the mercury plunged to a record low of minus 25 on Christmas Eve, followed by the city's all-time coldest Christmas with a high of just minus 5 and a low of minus 17.
Dear Tom,
What are the city's snowfall extremes for month of December?
Nick Recchia River Grove
Dear Nick,
After some teaser light snows in November, December typically marks the real start of Chicago's snow season, with the monthly total currently averaging in the 9-10 inch range. Since snowfall records began in 1884, the city has never recorded a snow-free December, though two years (1889 and 1912) came close, each receiving just a trace of snow---an amount too small to measure). On the high side of the snow ledger, the city's snowiest December was just nine years ago (December of 2000) when the weather observation site at Midway Airport logged 41.3 inches (although the official station at O'Hare received less).
Last winter, Chicago got 21.9 inches of snow in December.
Dear Tom,
I often hear meteorologists say it's "unseasonably hot" in the summer or "unseasonably cold" in the winter. That's not correct is it?
Kirk Melhuish
Dear Kirk,
No it's not, unless the adjective was intended to be "unreasonably". Extremes of heat in the summer and cold in the winter are best described by qualifiers such as extremely, unusually, torrid or bitterly -- but not by unseasonably, which literally means out of season. In Chicago, a 70-degree day in January would qualify as unseasonably warm or mild as would a July day in the 40s best be described as unseasonably cold or chilly. When Chicago dropped to -27 degrees on Jan. 20, 1985, meteorologists used terms like "all-time record cold" or "cold as it's ever been" to describe the event.
Dear Tom,
I lived in Des Moines and remember December 2000 as being a brutal month with an excess of snow and cold. Was it as bad in Chicago?
Douglas Hanbury
Dear Douglas,
You bet it was. December 2000 in Chicago was incredibly cold and snowy. Much of the area received more than 40 inches of snow making it one of city's all-time snowiest months. The snow parade was highlighted by a major storm on Dec. 11 that brought 14.5 inches of snow to Midway Airport and 9.5 inches to O'Hare International Airport. In addition to the frequent and heavy snows, it was exceptionally cold. There were 10 days when the mercury dropped below zero including a string of six days from Dec. 20 through Christmas. The month averaged 10.6 degrees below normal and was the city's second coldest December on record, runner-up only to December 1983.
Dear Tom,
What was the weather in Chicago like on Dec. 7, 1941?
Tom Zale, Tinley Park
Dear Tom,
It was typical early December weather on Sunday Dec. 7, 1941, when news of the surprise Japanese attack on Pearl Harbor reached the Chicago area shortly after noon. Skies were overcast and temperatures were holding in the middle 30s with gusty south winds making it feel even colder. Temperatures had climbed from an early morning low in the middle 20s on the way to an afternoon high of 38 degrees. The weather was dry, though a few snow flurries would fall across the city later that evening. Temperatures remained chilly in the following week, but spiked to near 60 in a pre-Christmas warm-up. Snow was not much of a factor that month, totaling just 1.7 inches with nearly an inch falling just before the New Year.
Dear Tom,
There was a record warm spell in August 1953, and I recently read on this weather page that record highs were set in the fall. What was going on in 1953?
--Beth Swanick
Dear Beth,
For unexplained reasons, 1953 was a remarkable year in terms of unseasonable or unusually warm weather. The year hosted an unprecedented 22 new record highs, 16 of which remain in effect. The year's first record was set on May 30 with a high of 93 degrees and the final one established on Nov. 18 with a balmy 72. Most notable was a six-day stretch of record highs from Aug. 29 to Sept. 3 featuring back-to-back 101 degree days on Sept. 1 and 2. That was followed by a four-day string of record highs in the middle 80s from Oct. 19 to 22. A November warm spell produced five straight 70s, but only the 72 on Nov. 18 remains a record.
Dear Tom,
What is Chicago's biggest temperature drop in the shortest time span?
Kathy Roupas
Dear Kathy,
Having chilly Lake Michigan on our eastern doorstep makes Chicago a prime candidate for rapid temperature declines. Just before 2 p.m. on May 9, 1963, a fast-moving cold front sweeping south down the length of the lake dropped the lakefront temperature 22 degrees from a warm 84 to a chilly 62 degrees in just a minute and a half. On a longer time frame, a huge temperature drop occurred on Nov. 11, 1911, when the temperature plunged 61 degrees in just 8 hours from an unseasonably warm 74 degrees at 4 p.m. to a wintry 13 degrees at midnight. The largest 24-hour temperature drop in the U.S. took place on Jan. 23-24, 1916, at Browning, Mont., when the mercury plunged an incredible 100 degrees from 44 to minus 56.
Dear Tom,
My father told me that he had heard that there is always some snow in Chicago before Thanksgiving. For the last 40 years it seemed right. Was this year an exception?
David Levine
Dear David,
While snow has certainly been lacking so far this fall, there was a trace of snow at Midway Airport on Oct. 24 and again on Thanksgiving morning. At the city's official O'Hare site, the season's only snowflakes fell early Thanksgiving morning, though some ice pellets were observed on Oct. 16. Since 1969 your dad's rule is pretty much true with two exceptions. In 1994 the season's first flakes didn't occur until Nov. 27--three days after Thanksgiving, and in 1999 the city recorded its latest first flakes on record on Dec. 5, 10 days after the Nov. 25 holiday.
Dear Tom,
I remember getting sent home from high school during a big snowstorm about 10 years ago. Can you pin-point this storm?
Barry Waldron
Dear Barry,
The storm was most likely the major snow that struck the Chicago area on Dec. 11, 2000. Though it had been snowing all night, conditions were not too bad for the morning commute and many schools remained open. However, the snow intensified through the morning, falling at the rate of an inch an hour and blown about by strong northeast winds that piled it into huge drifts. As conditions worsened, many schools and businesses closed early creating traffic gridlock. When the storm finally subsided, Midway Airport had recorded 14.5 inches of snow while O'Hare tallied 9.5 inches. December 2000 went on to produce tremendous snowfall, with Midway eventually logging 41.3 inches, a December record.
