WEATHER KAHNNECTIONS: January 2005 Archives

Nearly a foot of snow fell in downtown Chicago Saturday. This shot was taken from a Loop roof deck Sunday morning.

Photo by Jay and Jodi Kahn

After a final brief burst of heavy snow in the past hour, it appears that the snow is finally over in the northwest and far north suburbs. As the storm moves on the east preparing to clobber the major cities of the Northeast with a full blown nor'easter, upper-level winds over Lake Michigan are shifting from the northeast to the north allowing the lake effect snow bands to shift south and head for the south end of Lake Michigan. While the snow is ending in northern sections, this scenario means several more hours of lake effect snow for areas near the south end of the lake and many more hours of snow for northwest Indiana.

Total snowfall as measured at my home in Arlington Heights was just over 12 inches. Eight inches fell overnight from the storm itself and another 4+ inches fell today from lake effect snow.

January snowfall here now totals 27.7 inches with more than a week to go in the month. The January 4-6 storm brought more than 11 inches of to this area and this latest event a little more than 12 inches.

Steve Kahn WGN-TV/Chicago Tribune Meteorologist

Right now, the eastern portion of the Chicago area is in midst of a classic lake effect snow event. When a band of heavy snow moves in the visibility drops to near zero and the snow falls at a rate of 1-2 inches per hour. After about 15 or 20 minutes the band passes through, the snow becomes quite light and the visibility improves to 2 or 3 miles. At times there is even a hint of some sun trying to break through the snowy overcast.

In Arlington Heights snowfall from the storm system itself totaled about 8 inches as of 7 a.m. this morning. Now with the additional lake effect, another 3 or 4 inches of snow have fallen with the storm total here approaching one foot. Northeast winds are becoming strong and gusty and blowing and drifting is starting to become a serious problem.

At noon the radar indicated that these lake effect snow bands extended at least as far north as Green Bay, Wisconsin, so periods of lake effect snow should continue well into the afternoon hours until the snow bands finally pull east of the area.

Steve Kahn WGN-TV/Chicago Tribune Meteorologist

Well, part one of this storm is history. Eight inches of new snow is on the ground in Arlington Heights this morning and a massive snow removal job awaits. For the record, it is always easier for a forecaster to clear "forecast" snow than a "surprise" snow.

It doesn't look like this will be the end of the snowstorm. Lake effect snow is reving up in eastern Wisconsin this morning and shortly after daybreak Milwaukee reported the visibility near zero in heavy lake effect snow squalls. It looks like another snow removal effort will be needed this afternoon after part two of this storm-the lake effect portion- comes to an end.

The early afternoon sunshine has faded and lowering and thickening cloudiness is overspreading the city. The barometer is falling and there is a growing sense of urgency and anticipation knowing what is about to happen. Snow has already begun to fall in southwest Wisconsin and far northwest Illinois and should reach Chicago after dark. By this time Saturday, a lot of snow is likely to be on the ground and it will be badly blown and drifted about by strong winds.

Meteorologists have conflicting feelings about these storms. They know that a storm of this magnitude will cause trouble and hardship for millions of people and unfortunately probably take a few lives. Yet, it is their storm. They have watched it develop and evolve over many days, while putting all of their meteorological expertise on the line in trying to correctly forecast it and warn the public. They want to be right, but being right will mean big trouble.

Well, as stated before, the weather will do whatever it wants, no matter what the forecast is so...

Let the snow begin!

Once again Chicago is under the "snow-gun". Winter storm watches have been posted for the entire metropolitan area from late Friday through late Saturday as another winter storm, this one dubbed an "Alberta Clipper" because of its speed and origin in the western-most Canadian prairie province, takes aim at the city.

Alberta Clippers tend to move southeastward along the boundary between cold arctic air and milder Pacific air. These storms usually don't produce excessively large snowfalls because they lack Gulf of Mexico moisture, but they frequently are accompanied by strong winds which cause a lot of blowing and drifting of the snow.

WEATHER PAGE ARCHIVES
For some background material on the Alberta Clipper, we are attaching an Ask Tom Why question from 2002 along with a Tribune weather page feature from several winters ago that highlighted this type of snowstorm.

March 4, 2002

Dear Tom, What is an “Alberta Clipper”?
Thomas Sporer, Glenview

Dear Thomas, An Alberta Clipper is a fast-moving storm originating in western Canada (usually in or near the province of Alberta) that speeds southeast into the Plains and Midwest, often accompanied by significant snowfall. Because these storms develop in an area characterized by low temperatures and little moisture, the snow has a low water content usually in the snow/water ratio range of 20:1. The storms are frequently accompanied by strong winds and poor visibility, and are followed by falling temperatures. The storm generally produces a short-duration snowfall of less than six inches. The term Alberta Clipper came into use in the early 1970s after the publication of a paper on Midwest snowstorms by the chief of the Milwaukee weather office, Bill Harms, and premier snow forecaster the late Al Morrison.
Copyright © 2005, WGN-TV

When I first started my career with the Weather Bureau in 1962 we used to disseminate a type of winter weather warning that, for unknown reasons, is no longer in use today. It was called a Cold Wave Warning and was issued when a large drop in temperature was forecast to occur in a short period of time, ultimately sending readings to near or below zero. Tonight would be a perfect time to use it as current readings in the upper 50s are expected to plunge to zero or below by early Friday.

In addition to a Cold Wave Warning, a Pothole Watch would probably very appropriate to issue at this time. Chicago area motorists will soon be paying the price for this rapid freeze-thaw-freeze cycle we are currently in. As temperatures plunge the next 36 hours the rapid refreezing of all the water from the rain and melting snow will undoubtedly give rise to a new generation of potholes in the near future.

Just when it appeared to be all over, the last vestiges of the snowstorm brought a quick one inch burst of snow to Arlington Heights between 7 and 7:30 a.m. this morning bringing the storm's total snowfall to just over 11 inches. Melted down, the snow contained .97" of water giving an 11.5:1 snow to rain ratio, typical for a Chicago snowstorm with temperatures in the upper 20s.

Here is a breakdown of the 36 hour storm at my home.

Date Snowfall/Water Equivalent
January 4th 0.8" snow/.07" water
January 5th 7.4" snow/.63" water
January 6th 3.2" snow/.27" water

Storm Total 11.4"snow/.97" water

The season's first major snowstorm has come to an end and a potent one it was. The snow began around 8 p.m. Tuesday night January 4 and ended in the early morning hours of January 6, a duration of more than 30 hours.

Total snowfall at my home in Arlington Heights was about 10 inches with drifts as high as 2 feet.

Light to moderate snow continues to fall across the metro area this evening with visibilities reduced to less than one mile in most areas.
The heaviest snow appears to be falling in a band across areas from West Chicago through O'Hare to Wheeling and Northbrook where visibilities are the lowest- down to about 1/2 mile.

At 6 p.m. a deepening low pressure center was located over southwest Indiana east of Evansville, and radar and satellite data showed the heaviest snow falling across areas from southeast Nebraska across southern Iowa to northern Illinois all the way to Chicago. It appears that significant snowfall will continue across the Chicago area for several hours.

TOTAL STORM SNOWFALL IN INCHES THROUGH 6 P.M.

ARLINGTON HEIGHTS 5.8
O'HARE AIRPORT 4.8 (OFFICIAL CITY TOTAL)
MIDWAY AIRPORT 4.7

Steve Kahn WGN-TV/Chicago Tribune Meteorologist

More snow to come!

Precipitation associated with the winter storm began falling across the Chicago area around 8 p.m.Tuesday evening. with northern portions of the metropolitan area receiving snow while southern sections experienced an icy combination of freezing rain, sleet and snow. The precipitation continued through the night with much of the area waking up to a 1 to 2 inch snow cover this morning.

Throughout today snow was generally light and intermittent across the area with about another 1 to 3 inches of accumulation. Driven by strong northeast winds gusting to 30 m.p.h. snow piled into 1 foot high drifts in some areas. Through late afternoon storm snow totals ranged from 3 to 5 inches, impressive for this meager snow season to date, but hardly worthy of a major storm.

This evening, however, the storm is showing signs of intensifying and the city and suburbs may be in store for a night of heavy snow that will bring snowfall to the 6 to 12 inch totals advertised in earlier forecasts by Thursday morning.

Updates on the storm will continue through the evening.

Stay tuned!!

Steve Kahn WGN-TV/Chicago Tribune Meteorologist

This is the meteorologist's Superbowl! This is crunch time. A major winter storm is bearing down on the Midwest and the Chicago area and the weatherman's job is to warn everyone about what will happen and get it right.

These are the times of sleepless nights, hours spent in front of the computer painstakingly "Einsteining" the various atmospheric models, looking for that one bit of information that will reveal the storm's correct path to the forecaster.

By Thursday it will all be over, some areas will be digging out from more than a foot of snow. Other locations will be trying to recover from the ravages of a major ice storm, residents faced with a loss of heat and power and impossible travel conditions, while other places will get nothing more than some rain.

As usual the Chicago Metropolitan area sits near the elusive and hard to predict rain-snow line. Another two days of anguish lie ahead as the storm moves in, does its thing and then departs.

How will it all pan out? Time will of course tell and as usual, the weather will win again- no matter what is forecast!

Stay tuned!!

Steve Kahn