WGN Weather Center Blog

7.5 HOUR SNOW EVENT ENDS
The snow has ended across the Chicago area after bringing most of the city a 2-4" snowfall in just a little under 8 hours. The snow began around 8 a.m. this morning and had ended by about 3:30 p.m. Many locations in the southern portions of the metropolitan area experienced a rain/snow mix or a period of rain at the tail end of the storm. Heavier amounts of snow in the 3-5" range fell northwest of the city towards Rockford.

Some area snowfall totals
Mundelein 4.3"
Arlington Heights 2.9"
Midway Airport 2.4"
Downers Grove 2.4"
Oak Brook 2.4"
O'Hare 2.2" (official city total)

Posted by wgnweather at 4:34 PM | Permalink | TrackBacks (0)

SNOW TO END THIS AFTERNOON AFTER 2-LOCALLY 6 INCH TOTALS

The snow arrived right on schedule this morning, beginning across the area around 8 a.m. Just before 1 p.m. a little over two inches had accumulated at Arlington Heights while Frank Wachowski, the Midway observer reported 1.9". The storm is moving out of the area at a fairly rapid pace and it appears that the snow will be ending during the afternoon. The storm's fast departure will limit total snow accumulations putting final amounts in the 2-5" range. The snow has been a bit heavier to the north and west where 3- 4 inches have already accumulated in the Rockford area and a few locations far northwest of the city may wind up with 6 inches.

Posted by wgnweather at 12:49 PM | Permalink | TrackBacks (0)

DECEMBER'S SECOND MAJOR SNOWSTORM PACKS A WALLOP

The weekend snowstorm is almost history. Skies have cleared from the Chicago area west while the last vestiges of lake-effect snow are exiting Porter County in northwest Indiana. The early stages of the storm arrived in waves beginning pre-dawn Saturday. The storm really got it's snow-act together Saturday evening as the low pressure system began to intensify as it moved up the Ohio Valley from western Kentucky to central Ohio.

At Midway, weather observer Frank Wachowski reported that snow fell at the rate of one inch per hour for eight consecutive hours beginning Saturday evening between 7-8 p.m. until 3 a.m. Sunday. The snow then began to taper off and ended there around 7 a.m. Frank's snowfall totaled 10.1 inches. This storm, the area's second major snow system this month, produced more snow than 3-8" totals the December 4-5 storm did.

At Arlington Heights snowfall was about 5 inches. The new snow lies atop an ice-crusted 4 inch
residual snowpack making the total snow depth here around 9 inches.

While the Chicago area is digging out, this storm is now spreading its arsenal of heavy snow and ice to the northeast where areas from the lower Great Lakes to New England are expecting more than a foot of snow. South of the heavy snow, the precipitation will transition to ice and then to rain.
Steve Kahn WGN Weather Center Meteorologist

Posted by wgnweather at 9:53 AM | Permalink | TrackBacks (0)

Well, the Alberta Clipper really did a number in the Arlington Heights area. Snowfall as of 6 a.m. this morning totaled 7 inches. The snow began Tuesday afternoon around 3 p.m. but was quite light until about 6 p.m. By mid evening 2.5" had fallen, but it was still snowing steadily and the snow continued overnight, obviously picking up in intensity. Only a few flurries are falling at 7:40 a.m. but radar indicates that some lake effect could move in later this morning.

Posted by wgnweather at 7:35 AM | Permalink

A GUIDE TO FORECASTING AND UNDERSTANDING THE DIFFERENT TYPES OF WINTER PRECIPITATION

Today's winter storm brought a variety of winter precipitation to the Chicago area with snow, sleet and freezing rain all occurring. Tonight as surface temperatures rise above 32º, rain will fall. This graphic that originally appeared on the Chicago Tribune weather page on January 3, 2005 helps explain what kind of vertical temperature profile in the lower 2 miles of the atmosphere is needed to produce the various types of winter precipitation.

Posted by wgnweather at 6:01 PM | Permalink | TrackBacks (0)

WINTER STORM UPDATE

ICY CONDITIONS EXPECTED TO DEVELOP THIS AFTERNOON AND EVENING ESPECIALLY IN AREAS NORTH AND WEST OF THE CITY

Cloudiness has been thickening and lowering across the Chicago area this morning as the winter storm approaches. Temperatures have also been on the increase, rising into the middle and upper 20s by mid-morning. However dew points remain low, ranging from the single digits to the teens across the metropolitan area.

Radar returns are increasing as a strong southwesterly flow brings a slug of moisture into the area, but due to the initial dryness of the atmosphere it will take several more hours for it to moisten to saturation and allow the precipitation forming in the clouds to reach the ground.

Morning upper-air reports show warm air moving in aloft, so the precipitation here is likely to fall as sleet and freezing rain instead of snow. At the 5,000-foot level, temperatures are already near or above freezing with the warming continuing, Preciptation has begun in Iowa and Missouri with most locations reporting sleet and/or freezing rain.

We expect precpitation to move into the Chicago area from the southwest during the afternoon. There may be a brief flurry of snow at the onset, but that should quickly transition into sleet and freezing rain.

The most critical time for icing conditions should be from about 3 to 9 p.m. Temperatures should continue to rise slowly, though readings may drop back a few degrees when preciptation begins due to cooling from evaporation. Areas in the city and close to the lake should experience the least amount of icing as warmer air moves in from Lake Michigan with the most serious icing expected west and north of the city.

Readings should climb above freezing early tonight, allowing the the ice and glaze to melt. By Sunday temperatures could be approaching the 50-degree mark. Temperatures will crash in the storm's wake Sunday afternoon with a period of snow flurries expected.

Updates will be posted as necessary this afternoon and evening.

--By Steve Kahn, WGN-TV Weather Center Meteorologist

Posted by wgnweather at 9:45 AM | Permalink

So far August, 2007 has brought an unprecedented 13.25" of rain to my Arlington Heights rain gauge. Yesterday's storms were as prolonged and intense as any that I can remember. The neighborhood is littered with large branches and limbs after winds of 70+ m.p.h. roared through yesterday afternoon. Standing water is everywhere and retention basins are brim-full after the unrelenting downpours.

As Tom Skilling mentioned last night on his TV weathercast and also on this morning's Tribune weather page, the severity of yesterday's storms in terms of the vast expanse of the metropolitan area that was affected is one of the greatest in memory.

The scope of the damage brought back memories of a derecho that swept the Chicago area in similar fashion 42 years ago across the midnight hours of August 26-27, 1965, but that storm was a "hit-and-run" job and not part of a week-long siege of deluges like the region is currently experiencing.

That memorable storm will be revisited as the subject of the main feature on Monday August 27th's Tribune weather page and on this blog .

Partially submerged bench on Monday August 20 when monthly rainfall stood at 10"+
Photo by Steve Kahn

Same bench on Friday August 24 with monthly rainfall now at 13.25".
Photo by Steve Kahn

Snowy egret surveys the flooded Lake Arlington shoreline
Photo by Steve Kahn

Posted by wgnweather at 8:42 AM | Permalink | TrackBacks (0)

FLOATING AWAY AS AUGUST RAINFALL EXCEEDS 10 INCHES
As I gaze upon my lush yard that currently resembles the Amazon rain forest I think back to parched, dry appearance it had just a few weeks ago. August continues to amaze me with its recent penchant for producing heavy rainfall here.

August 2007 rainfall in Arlington Heights IL
4th .05"
5th 1.70"
6th .50"
7th 2.13"
8th .59"
9th .09"
12th .37"
14th .42"
15th .09"
18th .11"
19th 2.94"
20th 1.10"

Monthly total to date for August 2007 10.09" with undoubtedly more to come!

Waterlogged yard after more than 10 inches of rain
Photo by Steve Kahn

HIGH WATER AT LAKE ARLINGTON

Partially submerged bench illustrates the high water level at Lake Arlington after recent heavy rains.
Photo by Steve Kahn

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Springtime in Chicago
Wednesday's 4 inch snowfall transformed our greening yard and budding bushes back into a winter wonderland.

Photo by Deanna Kahn

Photo by Deanna Kahn

Posted by wgnweather at 6:07 PM | Permalink | TrackBacks (0)

HEAVY SNOW IN ARLINGTON HEIGHTS

As of 10.25 a.m. this morning more than 11 inches of snow had accumulated in Arlington Heights . Light snow is still falling, but the storm is definitely winding down. Total snowfall here should top out at around 1 foot.

Steve Kahn WGN-TV/Chicago Tribune Meteorologist

Posted by WGN Webmaster at 7:23 AM | Permalink

Starting winter with a bang
It was like the middle of winter this morning with near zero visibility in heavy snow, temperatures in the lower 30s. The high for the day in Arlington Heights was only 37º and late this afternoon, hours after the snow ended, snow was still nearly 1.5" deep in shaded areas in my back yard.

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"WOKE LAST NIGHT TO THE SOUND OF THUNDER"

Talk about coincidences! Back in the 1970s and 1980s it seemed that Chicago was frequently in the path of numerous derechos—fast moving clusters of thunderstorms that formed during the evening in the northern Plains or Upper Mississippi Valley on the northern edge of a dome of intensely hot air. These storms would then move into the Chicago area at speeds approaching 60 m.p.h., arriving during the pre-dawn hours with torrential rain, hail and damaging winds. Detroit rocker Bob Seger's 1976 song "Night Moves" is one of my all-time favorites. The last verse of the song begins with the the line "I woke last night to the sound of thunder" and it has always reminded me of those late night derechos.

Well, Bob Seger has been on a long hiatus from the music scene and it's been a long time since late-night derechos have swept into Chicago. After more than 10 years Seger is finally releasing a new CD this September, and as if to mark the occasion, around 4 a.m. last Thursday morning as storms swept into the Chicago area, I once again "woke to the sound of thunder".

The last verse of "Night Moves" by Bob Seger

I woke last night to the sound of thunder
How far off, I sat and wondered
Started humming a song from 1962
Ain't it funny how the night moves
When you just don't seem to have as much to lose
Strange how the night moves
With autumn closing in..

(Night Moves by Bob Seger Capitol Records 1976)

Posted by wgnweather at 6:27 AM | Permalink

Nick Liveris shares these beautiful urban sunset shots taken just before 8:30 p.m. Thursday evening, June 22, from Dearborn and Maple Streets in Chicago's Gold Coast.

Posted by wgnweather at 4:48 PM | Permalink

THIRTY YEARS AGO

On duty in the midst of a tragedy—Sinking of the Edmund Fitzgerald

Thirty years ago during the early evening hours of November 10, 1975, I was on duty as an aviation forecaster at the Chicago office of the National Weather Service. I was teamed with Lead Forecaster, the late Jim Vermoch, and we analyzing the 6 p.m. CST surface weather map. An intense storm system was moving through the upper Great Lakes and storm warnings for winds in excess of 55 m.p.h. were posted for Lake Superior. Earlier in the day strong winds had been blowing out of the east piling up huge westward moving waves on the lake, but now in the early November darkness howling west winds often reaching hurricane force (74+ m.p.h.) were creating monstrous waves in the opposite direction.

About 7:30 p.m. the "Green" phone, an internal hot-line used for forecast coordination, rang. I answered the call and found myself speaking to the Coast Guard duty officer in Sault Ste. Marie, Michigan. He told me that he believed a ship on Lake Superior had gone down that evening during the storm. He thought it was named the SS Fitzgerald. I relayed the information to Jim Vermoch and we quickly made calls to the Meteorologist-in-Charge of the office, Ray Waldman and to our regional headquarters in Kansas City, Missouri. At that time, neither of us had any idea of the magnitude of the marine tragedy that was unfolding before us.

The next morning all the horrific details of the tragedy were becoming available. A large iron ore carrying vessel, the Edmund Fitzgerald had disappeared in Lake Superior 17 miles northwest of White Fish Point, and it was almost certain that all 29 men on board had perished.

As they say, the rest is history.

Posted by wgnweather at 8:33 PM | Permalink

WGN WEATHER TEAM STORMS WRIGLEY

On Wednesday afternoon August 24 Tom Skilling and the WGN/Chicago Tribune weather team were bestowed the honor of singing Take Me Out to the Ball Game during the seventh inning stretch of the game between the Cubs and the Atlanta Braves. The weather was spectacular with plenty of sunshine, comfortable temperatures in the 70s and a refreshing northeast wind blowing in from center field. Unfortunately a fine pitching performance from Mark Prior went to waste as a late inning rally allowed the Braves to defeat the Cubs 3-1.

Aside from that, it was a wonderful day, one that none of us will ever forget- singing the seventh inning stretch at Wrigley Field.

The Weather Team warming up before the game.
L to R: Paul Dailey, Tom Valle, Tom Skilling, Steve Kahn, Nelson Taruc, Bill Snyder

The Whole Gang
L to R: Deanna Kahn, Steve Kahn, Diane Dailey, Paul Dailey, Tom Skilling, Jeanne Valle, Tom Valle, Cara Hansen, Nelson Taruc, Bill Snyder, Liz Valliyil

Tom autographing a baseball for a Cubs charity auction

Tom being interviewed on WGN Radio by Pat Hughes and Ron Santo

Talking with Ron and Pat between innnings

Tom warming up in the singer's bullpen

Waiting to sing

Are you ready Cub Fans? A one a two...

One, two three strikes you're out

Posted by wgnweather at 5:37 PM | Permalink

SEVERE THUNDERSTORM STRIKES ARLINGTON HEIGHTS MONDAY EVENING

Monday evening a severe thunderstorm packing winds to about 60 m.p.h., torrential rainfall and lots of thunder and lightning raced through the northeast portion of Arlington Heights. Rainfall totaled .92" which fell in blinding torrents in a span of just 15 minutes. This morning the streets are littered with twigs, leaves and small branches which succumbed to the storm's strong, gusty winds. The lightning during the storm was intense with many cloud to ground strikes. One clap of thunder was so loud that our whole house shook. I was sure that it had hit close by and this morning I discovered what had happened. A large tree in nearby Wildwood Park had been struck with a large limb split open and nearly severed from the tree.

A tree in Wildwood Park struck by lightning in Monday evening's storm.

Burn marks where lightning bolt hit

Another close-up view of burn marks

Posted by wgnweather at 12:43 PM | Permalink

IT'S OFFICIAL-- FIRST CHICAGO 100S IN SIX YEARS--TEMPS STILL CLIMBING

At 1:08 p.m. this afternoon the city's official thermometer at O'Hare Airport reached 100º. This is Chicago's 61st official 100º day on the books and the city's first since the high of 101º reached on July 30, 1999.

Midway Airport observer Frank Wachowski reported a high of 103º
so far this afternoon that was recorded at 1:45 p.m. CDT. With brisk west southwest winds, there is also no lake cooling with Northerly Island also reaching a high temperature of 100º. With several hours of peak heating ahead, it is likely that readings will surge even higher.

The record high temperature for today is 105º recorded in 1934 and is also Chicago's all-time official record high.

Posted by wgnweather at 1:42 PM | Permalink

WHAT IS A GUSTNADO?

A possible gustnado caused considerable damage in portions of Lake County Illinois early Wednesday afternoon near the town of Wildwood as a line of severe thunderstorms raced through the area. The gustnado typically forms along the leading edge of a thunderstorm outflow boundary called a gust front. Below is a feature from the Chicago Tribune weather page archives done several years ago explaining this unusual meteorological occurrence.

Posted by wgnweather at 4:43 PM | Permalink

MCDONALD CREEK- BONE DRY

The drought of 2005 is taking its toll. Since May 1, I have measured only 1.5 inches of rain at my house, and more than half of that fell in just 30 minutes during one heavy thunderstorm on the 4th of July. Area soils are parched and cracked and unwatered area vegetation is severely stressed and in some cases dying.

Having lived in the northeast part of Arlington Heights for more than 35 years and frequently crossing and viewing nearby McDonald Creek, I have never ever seen it bone dry like I did today on my daily walk around Lake Arlington. After a torrential rain McDonald Creek can be a raging torrent, but usually it is a lazy, low flow creek. However, today for the first time in my memory, McDonald Creek is totally dry, another casualty of the increasingly severe Drought of 2005.

A view of McDonald Creek

McDonald Creek as seen from the west bridge leading to Lake Arlington

Posted by wgnweather at 11:34 AM | Permalink

WELCOME RAIN COMES AT A PRICE

A severe thunderstorm struck the Arlington Heights area just before 1:30 p.m. on a warm and humid 4th of July afternoon. The quick hitting storm brought substantial rainfall to the area with .83" falling in a short period of time. Monday's rain was more than the .61" that fell here in the entire month of June in this parched area hard hit by this year's drought.

Though the rain will help plants in the short-term, the long term moisture outlook remains dim, with dry weather expected the rest of the week and the specter of more 90º-plus heat looming for the weekend.

The severe thunderstorm was accompanied by wind gusts estimated at between 50 and 65 m.p.h. Minor tree damage was scattered throughout the area, but some substantial tree damage occurred in the Scarsdale section of Arlington Heights.

4th of July tree damage in Arlington Heights

More damage from Monday afternoon's storm

Posted by wgnweather at 11:33 AM | Permalink

NORTHERN LIGHTS ILLUMINATE CHICAGO'S SKIES LAST NIGHT

Chicagoans were treated to a dazzling display of the aurora borealis or northern lights early Sunday morning, following a strong solar flare on the sun on Friday May 13. The display was visible across much of the United States with reports of sightings as far south as southern California. According to NASA scientests, last night's aurora storm was caused by a coronal mass ejection (CME) propelled in our direction by an M8-class explosion near sunspot 759 that left the sun on May 13. Eighteen hours later it reached the Earth's atmosphere sparking the bright auroras.

Though far from a certainty, it is possible the aurora may be visible again tonight, especially in Canada, Alaska and areas north of Chicago.

One of our viewers Al Degutis took some spectacular pictures of the aurora from Woodstock and was kind enough to allow us to post them on our weather blog.

Posted by wgnweather at 11:25 AM | Permalink

Photo by Al Degutis

Posted by wgnweather at 11:22 AM | Permalink

COLD AIR FUNNELS
Cold air funnels were reported late Tuesday afternoon in Rockford and near DeKalb. Here is an archived Ask Tom Why from 2001 explaining the meteorology behind the formation of a cold air funnel.

May 25, 2001
Dear Tom,
What are cold air funnels? Jeff Peterson, Huntley, IL

Dear Jeff,
A cold air funnel is a funnel cloud that does not develop in a typical severe weather environment. These funnels tend to form when there is large slow moving low pressure system in the upper atmosphere, similar to the one currently anchored over the Midwest. These cyclonic (counterclockwise) systems generate a lot of vorticity (spin) that enables the funnels to form. Cold air funnels get their name from the pocket of cold air aloft associated with these systems. The cold air produces a very unstable air mass, enabling towering cumulus clouds to rapidly grow into the showers and thunderstorms that produce these funnels. These funnels are weak and short-lived and usually do not touch down. Those that do reach the ground become weak tornadoes (winds often 50 m.p.h. or less) that generally produce only minor damage.

Posted by wgnweather at 7:07 PM | Permalink

Lake Arlington in Arlington Heights after today's 1.5 inch snowfall

Memories of a White St. Patrick's Day-- March 17, 1965 in Madison, Wisconsin

Today's white St. Patrick's Day in portions of the Chicago area brought back memories of a St. Patrick's Day in 1965 when I was an undergraduate meteorology student at the University of Wisconsin in Madison. It had snowed hard all night and about 6 inches of snow was on the ground at 6 a.m. on March 17. The forecast called for another 6 inches of snow with storm totals of more than one foot expected, so the university canceled classes for the day. Well, by 8 a.m. the snow had ended and skies cleared after a snowfall total of only 6.9". With no classes to attend, partying began early making for a very memorable St. Patrick's Day. That same storm system brought 3.7" of snow to Chicago, but much of the precipitation here fell as rain.

Steve O'Kahner WGN-TV/Chicago Tribune Meteorologist

Posted by wgnweather at 5:05 PM | Permalink

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

Posted by wgnweather at 1:45 PM | Permalink

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

Posted by wgnweather at 3:47 PM | Permalink

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

Posted by wgnweather at 12:03 PM | Permalink

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.

Posted by wgnweather at 8:33 AM | Permalink

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!

Posted by wgnweather at 3:20 PM | Permalink

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

Posted by wgnweather at 6:53 PM | Permalink

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.

Posted by wgnweather at 6:51 PM | Permalink

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

Posted by wgnweather at 5:11 PM | Permalink

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.

Posted by wgnweather at 6:19 AM | Permalink

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

Posted by wgnweather at 6:39 PM | Permalink

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

Posted by wgnweather at 4:55 PM | Permalink

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

Posted by wgnweather at 5:48 AM | Permalink

Sunday's earthquake and following tsunamis were great tragedies. Here are three archived Ask Tom Why questions dealing with tsunamis and seiches.

July 28, 1998
Dear Tom,
Could an earthquake in Lake Michigan cause a catastrophic tidal wave to hit Chicago like the one that happened at Papau, New Guinea?
MTM, Bartlett

Dear MTM,
There is no known historical precedent for a tsunami even remotely close to the magnitude of the Papau, New Guinea, event on the Great Lakes. The probability of such an event here has to be considered exceedingly low. says Guy Urban, geophysicist at the Palmer, Alaska, based West Coast and Alaska Tsunami Warning Center.
Urban does add that several catastrophic, rare and rather improbable occurrences would be required to set up a tsunami here. He�s quick to point out the near impossibility, absent careful modeling of such an event, of even beginning to speculate on the dimensions of such a wave. Only a direct asteroid strike, a huge thermonuclear explosion beneath the lake or a massive earthquake might initiate one, and while not impossible, the odds are not high.
Copyright � 2004, WGN-TV

March 18, 2003
Dear Tom, When and where was the most recent destructive tsunami? Shaqueda Green

Dear Shaqueda,
Tsunamis are ocean waves generated by undersea earthquakes, landslides or volcanic eruptions. They can be only a few inches high in the open ocean, but steepen and rise as they approach shallow water, reaching heights of 200 feet in extreme cases. Last year on Sept. 8, an earthquake with a Richter scale magnitude of 7.6, centered off the coast of Papua New Guinea, generated two tsunamis with heights up to 7 feet that caused two fatalities. The most recent devastating tsunami also struck Papua New Guinea, occurring on July 17, 1998, following a 7.1 magnitude earthquake. The resulting 30- to 50-foot-high wall of water struck a 25-mile stretch on the island's north coast, killing nearly 3,000 people.
Copyright � 2004, WGN-TV

May 17, 2004
Dear Tom, I once read that a tsunami wave hit Chicago in the 1950s. Did this actually happen? Anne Violante

Dear Anne,
On June 26, 1954, the Chicago lakefront was hit a 10 foot wall of water called a seiche (pronounced saysh) that swept eight unsuspecting fishermen off the Montrose Harbor pier to their deaths. While a tsunami or seismic sea wave is generated by underwater earthquake or volcanic activity, Chicago's 1954 seiche was caused by line of thunderstorms racing southeast across Lake Michigan at speeds in excess of 50 m.p.h. The cold downdrafts of air flowing out of the thunderstorms caused a rapid rise in air pressure that pushed a building bulge of lake surface water toward the southeastern shore. This surge of water then reflected back to the Chicago shore as a large wave, taking nearly 90 minutes to make the return trip.
Copyright � 2004, WGN-TV

Steve Kahn

Posted by wgnweather at 4:45 PM | Permalink

The recent cold snap has taken its toll on the water temperature of area inland lakes. This morning after a frosty low of 20�, Lake Arlington, a 50-plus acre man-made lake in the northeast section of Arlington Heights, was almost totally ice-covered for the first time the season.

Note: If you look closely, you can see ducks standing on the ice.

Posted by wgnweather at 4:38 PM | Permalink

An annual celestial spectacle. the Geminid meteor shower will peak tonight and Monday night and will be visible in the Chicago area away from the bright lights of the city if skies are clear. Clouds are expected to limit viewing tonight but current forecasts give hope for at least some clearing on Monday night. However, star gazers will have to brave strong gusty winds and chilly temperatures tonight. Winds should be much lighter on Monday night, but temperatures are expected to be well below freezing.

GEMINID METEORS: The 2004 Geminid meteor shower is underway. Midnight sky watchers this weekend can expect to see bright meteors shooting out of the constellation Geminid--at least a few per hour. Rates will increase many-fold on Dec. 13th when the shower peaks.
Space Weather News for December 11, 2004 http://spaceweather.com
Because this meteor shower has such a broad peak, a good display is possible twice: on Monday morning, Dec. 13th, during the dark hours before sunrise and again on Monday evening, Dec. 13th, especially during the hours around midnight.

Posted by wgnweather at 11:55 AM | Permalink

With 4 inches of snow on the ground at 6:00 a.m. Thanksgiving morning, Chicago officially recorded its 10th White Thanksgiving (1 inch or more of snow on the ground) since snowfall and snow depth records began in Chicago 120 years ago in late 1884. This morning's 4" snow depth was the third greatest, surpassed only by the 8 inch snow depths recorded on Thanksgiving morning in 1895 and again in 1975.

Here is the complete list of Chicago's White Thanksgivings
Nov 28 1895 8� on the ground
Nov 26 1903 1�
Nov 27 1947 3�
Nov 24 1949 1�
Nov 23 1950 2�
Nov 27 1975 8�
Nov 23 1989 2�
Nov 28 1996 1�
Nov 28 2002 2�
Nov 25 2004 4"

A very Happy Thanksgiving to all!
Steve Kahn WGN-TV/Chicago Tribune Meteorologist

Posted by wgnweather at 11:50 PM | Permalink

With December 3, the average date for this area's first 1 inch or greater snowfall rapidly approaching, and THAT four letter word starting to show up in the weather forecasts, it seemed like this was a good weekend to gas up the snowblower (just in case)!

Posted by wgnweather at 9:13 PM | Permalink

Blown out Windows
Sixty four years ago today southwest winds with speeds as high as 65 m.p.h. swept across the city during the afternoon hours producing damage estimated at $1.5 million. There was widespread damage to trees, power lines, large signs and buildings including countless windows blown out by the high winds.

My grandfather Joseph Frank operated a mirror and glass store on Wells Street in Chicago and in the wake of that storm all of his other business was put on hold as he spent many long days replacing the broken windows!

Steve Kahn

Posted by wgnweather at 4:34 PM | Permalink

Photo taken Sunday evening November 7 by Marty Eisses at Route 59 and I-88 in Naperville

Posted by wgnweather at 11:54 PM | Permalink

Dazzling Display Across the Area

If you can get outside tonight in a relatively dark area, you may be treated to one of nature's greatest spectacles- the aurora borealis- more commonly called the northern lights. They are seen infrequently in Chicago, about once every two years, so tonight is a great chance to view them.

This is an Ask Tom Why question from a few years ago explaining the northern lights.

Dear Mr. Skilling:
Why do some northern lights show color and at other times they shine only white? I've seen the northern lights many times but have witnessed only on rare occasions the colors so often associated with them.
Linda Turkovich, McHenry, Ill.

Dear Linda,
The northern lights (aurora borealis) are one of nature�s most spectacular shows. The light of the aurora is caused by a stream of electrons emitted from the sun (the �solar wind�) reaching the atmosphere of the earth and colliding with atmospheric gases. Auroral colors are determined by the energy levels of the incoming electrons as well as the density and composition of the atmosphere they are passing through. When struck by the electrons, these gases become excited and emit a characteristic color.
Nitrogen tends to give off a green color, while oxygen emits both red and green hues. Since our atmosphere is 78% nitrogen, green is the most common auroral color, and frequently in weaker auroras this green appears as the �whitish� color you describe. An exceptionally energetic aurora may be predominately red, and some auroras tend to appear purple or bluish just before dawn when sunlight strikes the top of the auroral rays in the high atmosphere hundreds of miles above the observer.

Copyright � 2004, WGN-TV

Steve Kahn

Posted by wgnweather at 11:26 PM | Permalink

Do it While it's Warm!

Take advantage of this beautiful "bonus" weekend to get your yard ready for winter, bring in that outdoor furniture, disconnect the hoses, etc. Temps will plunge by the end of the week with overnight lows falling into the lower 20s and daytime highs remaining in the 30s. Trust me, it's a lot better to do these annual chores in weather like today's!!

Steve Kahn

Posted by wgnweather at 11:14 AM | Permalink

WEATHER IN SYNC WITH THE CALENDAR
As if on cue from the calendar the weather turned very November-like today-dreary, damp and chilly. Through 3:45 p.m. rainfall in Arlington Heights totaled .75" making the day a total wash-out. With temperatures hovering in the middle and upper 40s and a gusty east/northeast wind there is a raw feel to the day. Darkness is already descending over the area even though sunset is still an hour away! Looks like a good night to curl up by the fireplace!

-Steve Kahn WGN-TV

Posted by at 4:15 PM |