EXPLAINER: November 2006 Archives

A good part of the Chicago area is threatened by its heaviest early season snow accumulations in nearly three decades—perhaps the heaviest early snow in all 122 years of snow observations here if totals exceed 7.8” at O’Hare. Thunder and lightning and the snowbursts which accompany them are a distinct possibility Friday morning and could put snow down at rates of up to 2-3” an hour. Though this storm’s final snow tallies will be inextricably linked to the length of time in which precipitation fell in a form other than snow, the heaviest totals—most likely to pile up in areas just west and north of Chicago—could reach or exceed 14”.

Chicago pavement temps fell more than 15° in Thursday’s chill. It’s a development which will make the vigorous snows which fall amid near blizzard 30+ m.p.h. wind gusts through Friday morning’s rush hour more of a challenge to clear.
--By Tom Skilling, WGN-TV Chief Meteorologist

The Chicago area, which has just closed the books on an unseasonable six-day spell of 60s, now appears threatened by one of its biggest early season snowstorms since the infamous winter of 1978-79. That’s the season which began with a 7.8” snow December 1 and concluded the area’s heaviest total ever-89.3”.

As with any complex winter storm—especially the first major snow producer of the season—track adjustments could shift the axis of heaviest snowfall. But, Chicago appears near the zone of this system’s most intense meteorological action Thursday night through much of Friday morning. Thursday’s rainy spells mix with ice pellets and some snow at times as the air here continues to cool. But, its overnight snow turns heavy over all but eastern sections of the area. Though Streets and Sanitation reports road surfaces between 48-54°, snow intensity should permit accumulation.
--By Tom Skilling, WGN-TV Chief Meteorologist

Wednesday opens in the 50s—more than 10° warmer than the normal high this time of year. The abnormal late season warmth and full expectation this afternoon’s high will become the 6th consecutive 60° late November reading—something which hasn’t happened in 78 years of weather observations at Midway Airport—are but the latest developments in what has amounted to an excursion through meteorological never-never land. But, a definitive break in this pattern is in sight and hits with an arctic front’s passage late Wednesday evening. The cold air it ushers into Chicago is the same air mass which has slashed Great Falls, Montana’s temperature 78° in just the past week.
Tuesday’s Midwest highs included records-among them 67° at Moline and 66° at Des Moines. Chicago’s 54° low Tuesday morning exceeded the previous warm nighttime minimum for the date (48°) set 90-years ago in 1916.
--By Tom Skilling, WGN-TV Chief Meteorologist

After shivering in an unseasonable chill most of the fall season, Chicagoans, who enjoyed a fourth 60-degree day Monday (at Midway Airport) find themselves on the precipice of a late season temperature record. The 60s predicted Tuesday and Wednesday would produce the longest late season string of 60s ever observed at the South Side site. Records there extend back 78 years to 1928. Until now, a string of five 60s in late November 1998 has been the longest at Midway.
Temperatures at these levelsare a rare commodity at this time of year. Only 3% of the city’s high temperatures in the final week of November and first week of December have reached or exceeded 60°.
Scattered rains the next two days become heavier Thursday. A suite of computer forecasts puts rainfall here at 2.50”. On only two occasions since 1870 has the city received 2” or more of precipitation in November’s final 11 days.
--By Tom Skilling, WGN-TV Chief Meteorologist

Mild moist southerly flow will strengthen early this week, with cloudy skies and a slowly increasing chance of significant rain. If forecasts are accurate, highs the first four days of the week will average nearly 20 degrees above normal. Precipitation is in the forecast every day of the work week, probably peaking just in advance of and in the wake of a cold front Wednesday and Thursday. Latest atmospheric models indicate a cold frontal passage in the Chicago area sometime Wednesday night and a subsequent slow movement east, allowing time for a dynamic low pressure development in Ohio Thursday. The progress of colder temperatures into northern Illinois could slow, extending the period of post-frontal rains through a good portion of Thursday. If the low forms in Ohio by Thursday evening, cold northwest winds will strengthen, and rain will change over to wet snow in Chicago. Some snow accumulation could then occur in Chicago on Friday morning.
--By Paul Dailey, WGN Weather Center Meteorologist

Mostly southerly winds will prevail into Wednesday, accompanied by a persistent cloud cover. The primary jet stream flow aloft will slowly migrate south early this week, and the southern edge of cold Canadian air will creep south with it. A strong reinforcing pool of chilling arctic air—the coldest of the season thus far—is poised to drop into the northern Plains Tuesday and follow a cold front into the Midwest later Wednesday. Before the cold front arrives, the southerly flow will keep feeding moisture from the Gulf of Mexico up the Mississippi Valley. All signs point to a nearly saturated air mass over northern Illinois and southern Wisconsin just prior to the cold front’s arrival. Strong thunderstorms could erupt with 1-inch-plus rains later Tuesday night and Wednesday. Chicago highs are expected to average about 15 degrees above normal into Wednesday; and then under very cold high pressure, run nearly 15 degrees below normal the last couple days of the work week.
--By Paul Dailey, WGN Weather Center Meteorologist

Friday’s 62° high at Midway was the city’s mildest temperature in 15 days and may not be the area’s last 60°-plus reading. Five other years since 1928 have hosted 60° or milder temperatures at the South Side observation site on Nov. 24. From this date forward, 60° warmth is—at minimum—on borrowed time. But at least two additional 60° highs appear within striking distance in the mild spell expected to hold here another five days. Sunday is the first—but strengthening southerly winds in advance of a powerful approaching autumn storm make Tuesday an especially strong candidate for a 60° reading—that one potentially the last of 2006.
Gulf moisture rides Saturday’s south winds into the area, contributing to cloud formation and mild temperatures expected to send this final weekend of meteorological autumn into the record books nearly 18 degrees above normal. As the air mass nears saturation this afternoon, several showers or isolated t-storms may form.
--By Tom Skilling, WGN-TV Chief Meteorologist

Mild weather’s in firm control the next five days. That’s a bit of an accomplishment since so many natural elements conspire to deny us warmth this time of year. For instance, sunlight in late November delivers only 21% of the energy it did in June, when the sun’s rays were strongest and highest in the sky—72° above the horizon at midday compared to just 28° today (Nov. 24). And not only is the sunlight weaker, there’s a good deal less of it. Friday will host 5 hours and 39 minutes less daylight than back in late June as summer officially began.
It’s little wonder only 3.2% of highs in the final week of November and first week of December have reached or exceeded 60° since 1870 while only 16% have risen to 50° or higher.
Thursday’s O’Hare high of 58° was the mildest Thanksgiving high here since 1998. While sunny here, Plymouth, Mass.—site of the first Thanksgiving celebration in 1621—was whipped by 50 m.p.h. winds and drenched by 2” of rain.
--By Tom Skilling, WGN-TV Chief Meteorologist

Only nine Chicago Thanksgivings in the past 136 years—just 7% of them—have produced a 60°+ high. A 60° high Thursday would not only be 17° above normal, 20° warmer than a year ago (the area had recorded 1” of snow a day earlier) and more typical of late October—it would also make this the warmest Thanksgiving since the 61° high in 1998.
Chicago sits on the east side of a record-breaking warm air mass which pushed the mercury to 74° at both Imperial and Valentine, Neb. Wednesday. New warm temperature benchmarks were established at least 20 cities across 6 states. The warmth comes only two days beyond late-arriving reports from Orlando of Florida’s first November snow flurries since 1912.
The powerful storm which lashed the Carolinas north to the mid-Atlantic Wednesday produced 82 m.p.h. gusts at Alligator River, NC and 6.39” of rain at Cape Hatteras.
--By Tom Skilling, WGN-TV Chief Meteorologist

Floridians aren’t accustomed to cold weather, especially this early in the season. Miami’s 63° afternoon high—a reading far short of the normal 80° high—was balmy compared to the 52° reading observed there late Tuesday evening. A colder air mass hasn’t occurred this early in the season across south Florida in the 38 years since 1968. Authorities opened shelters across the state to offer refuges from the abnormal chill which was expected to approach or break low temperature records early Wednesday. Tampa struggled to 59° Tuesday, Orlando struggled to 57° and Daytona Beach topped out at just 54°. Each of these readings were eclipsed by highs Tuesday in the Plains—including the record-breaking 69° at Rapid City, S.D. and Hastings, Neb.
It was snow which made news in eastern Georgia and South Carolina. Thunder accompanied the snowfall in Charleston, S.C.—a first for the city. Snow has not fallen any earlier there.

--By Tom Skilling, WGN-TV Chief Meteorologist

North winds die off today and shift to the southwest later tonight, marking the end of the recent cold spell and the beginning of a warm-up that should send high temperatures well into the 60s Wednesday and Thanksgiving Day. In fact, tomorrow’s highs may not miss the 60° mark by much, and Friday afternoon’s readings could also come close.
While two consecutive days with 60°-plus temperatures in the last 10 days of November are not that unusual (16 occurrences in 136 years of data), three consecutive 60°-plus days have occurred only three times before in Chicago (the latest 40 years ago in 1966), and four consecutive 60°-plus days have been observed only twice.
Travelers across the nation this week should encounter favorable weather conditions in all but the Pacific Northwest and along the Mid-Atlantic seaboard, where heavy rains are expected. On Thanksgiving Day, over half of the continental United States may see highs in the 60s or 70s.
--By Paul Dailey, WGN Weather Center Meteorologist

Until a bit of sun broke through the clouds Friday—all two hours of it—the latest stretch of dreary, gray November skies had blocked all sunlight for four consecutive days. November has rarely served as a repository of sunny days in Chicago, and this year’s no different. It’s just been cloudier than most. Instead of the 40% of possible sunshine considered typical, this November has received just 25% of its possible sun—the cloudiest since 1992. That makes Saturday’s additional mixed sun (until clouds fill back in this afternoon) especially welcome.
With two weeks remaining in meteorological autumn, this 12th weekend of fall is to be the area’s chilliest yet. November is running 7.4° behind a year ago, and temperatures here since Sept. 1 are now 6.4° chillier than last year.
Lake-effect showers Saturday night and Sunday will fall into a shallow layer of air “warmed” by Lake Michigan’s 46° waters. This could lead to a mix of light rain, snow and sleet near the lake—trending toward more snow inland.

The 45 m.p.h. gust which swept O’Hare at 9 a.m. Thursday morning in the midst of the 36 consecutive hours of high winds, is the second strongest since meteorological autumn began Sept. 1. A 48 m.p.h. gust there nearly two months ago on September 22 remains the season’s strongest. Winds hit 52 m.p.h. Thursday at Chicago’s perennially windy Harrison-Dever Crib three miles off the Lake Michigan shoreline and reached 49 m.p.h. at Waukegan. The dome of water which piled up in the persistent NNE flow boosted lake levels at the Calumet Harbor NOAA lake level measurement site 22” above levels observed in calmer winds three days earlier. But, wind velocities had declined so rapidly late Thursday that lake levels had already pulled back 12”.
Sporadic cloud breaks are likely to offer Chicagoans glimpses of sun Friday and Saturday. But cold air and NNE winds predicted late Saturday threaten lake-effect snow showers into Sunday.

--By Tom Skilling, WGN-TV Chief Meteorologist

Howling winds—the kind which invert umbrellas and make walking a challenge—rake the metro area Thursday, gusting to 50 m.p.h.—a velocity at which damage can begin to occur. These gales are buffeting a vast region over which November’s 2nd major storm, and easily its most intense, is draped. The same powerful updrafts which lift and cool inflowing Gulf moisture generating clouds and precipitation while producing low barometric pressures, drive huge wind fields like Thursday’s.
Rain falls vigorously at times from Chicago east into Indiana Thursday. The range in precipitation totals across the metro area is likely to be stunning. Some sections of northern Indiana are likely to see 2-3” amounts while Chicago and its immediate western suburbs may measure 0.40” to 1.10”. Farther west, amounts should decline rapidly.
--By Tom Skilling, WGN-TV Chief Meteorologist

Wednesday morning’s gray but otherwise sanguine weather masks the approach of November’s second major storm in less than a week. By late Wednesday night, NE winds—expected to strengthen slowly but steadily during the day—are likely to be gusting to 40 m.p.h. at times, delivering rain nearly horizontally. The gale force winds are likely to churn Lake Michigan into a sea of whitecaps and could build waves 8-10 ft. tall by Thursday. Though computer models have been all over the charts on the storm’s track in the past few days—a development typical with intense systems boasting backside upper winds as powerful as those observed with this storm—systems often follow a track west of the one initially predicted. If true, much of the Chicago area is in for significant precipitation. Rainfall estimates suggest water equivalent storm totals may average 0.71” in the metro area-but could exceed 1” at some locations.

--By Tom Skilling, WGN-TV Chief Meteorologist

Chicagoans rise to another damp, gray November day Tuesday. The month is historically the city’s second cloudiest of the year. But this November has been especially cloudy with only 32% of its possible sunshine on the books—half the sun in the same period a year ago and well below the monthly normal of 40%. It’s a development which continues to take a toll on Chicago temperatures.
November, like predecessors September and October, is running cooler than normal and a stunning 9.5° colder than the opening days of November a year ago. If the trend continues, this will mark the first time in over two years—since June, July and August in 2004—that three consecutive months have posted temperature deficits.
Monday’s 43° reading was the 15th daytime high since September 1 to finish below 50°. There had been only two such days by this date a year ago.

--By Tom Skilling, WGN-TV Chief Meteorologist

Chicagoans know that lengthy periods of genuinely inclement weather—three or four days, or more—can occur in any season around here, but they are far more frequent and certainly more dismal in November than at other times of the year. It’s bad enough that November is a cloudy month (only December is cloudier), that its days shorten (by nearly an hour) and that the trend of temperatures is sharply downward (we lose 12 degrees).
It’s worse, though, when a powerful storm system heads into the area and stalls—and that is forecast to happen this week. Jet-stream energy entering the Pacific Northwest today surges to the Midwest by Wednesday, then persists.
This stubborn pattern will deliver clouds, wind and precipitation on no fewer than five days this week. And if that isn’t dreary enough, it gradually turns colder, and three days of rain end with two days of wet snow and flurries.
--By Tom Skilling, WGN-TV Chief Meteorologist

No sun, no moon,
no morn, no noon;
No dawn, no dusk,
no proper time of day;
No warmth, no cheerfulness,
no healthful ease.
No comfortable feel in any member;
No shade, no shine,
no butterflies, no bees,
No fruits, no flowers,
no leaves, no birds—November!

“No!” --A poem by British poet and humorist Thomas Hood (1799-1845).
Thomas Hood certainly did not have Chicago in mind when, in 1844, he composed that description of dismal November weather in Britain, but it is unfortunately apropos to the conditions expected here by midweek.

A powerful and slow-moving storm system, accompanied by copious, wind-driven rain and chilly temperatures will descend on the area Wednesday and continue through Thursday, not abating until Friday—as wet snow.

--By Richard Koeneman, WGN-TV Meteorologist

For five lightning-punctuated hours centered on Friday evening’s rush-hour, wind-driven downpours pounded the Chicago area, unleashing the heaviest November calendar-day rainfall in 11 years. Thunderstorms are no strangers this time of the year. Sixty-two percent of Novembers since 1970—23 of the past 37 years—have hosted thunderstorms. But, the prolific lightning in Friday’s storms was exceptional. At the height of Friday’s storm, 160 cloud-to-ground strokes were observed in a single 15-minute period within 200 miles of Chicago. Doppler radar scans revealed a number of cloud tops exceeded 45,000 feet. Pea-sized hail which accompanied the storms actually covered the ground in several locations, among them Bolingbrook. Friday’s rain fell as wind chills hovered in the 30s and winds howled as high as 50 m.p.h.
The northern flank of the same storm buried sections of Iowa, Minnesota and Wisconsin under more than a foot of snow.
--By Tom Skilling, WGN-TV Chief Meteorologist

There’s been a sea change in Chicago’s weather. Friday’s markedly colder temps, strengthening winds and incoming rains make that abundantly clear to area residents treated on Thursday to the city’s latest occurring 70° in 7 years. It’s likely to be a while before such warmth returns.

Since 1928, three of four years have produced no additional 70s beyond Nov. 11. Just one 70° high has occurred this late or later in the season in the past 15 years.

Such warmth will be the last thing on Chicagoans’ minds any time soon. The upcoming weekend is to be the chilliest here in 9 months (since March 4-5). It’s likely many suburban residents will watch as temperatures plummet into the teens Saturday night and Sunday morning—the coldest nighttime lows there since last February.

Southward plunging arctic air by late Thursday had slashed record warm mid-week high temperatures by more than 30° over a huge swath of the Midwest.

-Tom Skilling

The unseasonably mild air in place Thursday morning has only hours to run. A cold front settles south across the city mid-morning and by lunch time, NNE winds should have temperatures in the first stages of a downward spiral likely to carry readings through the 50s. It’s a cool-off which marks the end of the area’s brief flirtation with mild air in a remarkably chilly autumn season. In only four years since official records began here in 1871 has Chicago’s average temperature since Sept. 1 been colder. Feedbacks from the season’s sub-par temperatures are everywhere. Lake Michigan is running 8° cooler than a year ago while temperature data suggests home heating may have surged as much as 72% over the same period a year ago. Days with 70° or warmer highs are down 37% while chilly sub-50° days since September’s open have surged from one a year ago to 11 this year.

-Tom Skilling

It’s not easy for the atmosphere to produce a 70° temperature this time of the year. Days are shorter, clouds more extensive (November is the city’s 2nd cloudiest month) and the sun traverses Chicago skies farther and farther south with each passing day, reducing the amount of energy that sunlight delivers. It’s no accident only 47 of the 11,097 temperatures above 70° at Midway Airport since observations began there in 1928 have occurred beyond Nov. 8. Complicating chances for such warmth Wednesday are fog and clouds trapped beneath a temperature inversion—an atmospheric set-up in which warm air aloft extinguishes the normal vertical mixing of air which might eradicate clouds. Though 10 states as close as Nebraska and South Dakota hosted near 80° highs Tuesday-readings 30° above normal-the lack of significant sunshine here Wednesday will inhibit the warm air’s eastward expansion. -Tom Skilling

The weather’s cooperated nicely with Chicago-area voters in each election since at least 1996, sparing the area extremes of temperature and significant precipitation. Tuesday may wind up this area’s best Election Day of all in terms of weather. Though haze and cloudiness will be extensive, precipitation is to remain downstate, and computer models predict drying above a thick low cloud deck—a process expected to scour several sun-blocking mid and high level cloud decks out of Chicago skies. Thus, even though low clouds may hang on, the effect of eliminating clouds above may be to allow skies to brighten. And, air may sink just enough to open holes in the low overcast over at least sections of the metro area this afternoon.
The addition of some sunlight—no matter how limited—would allow temperatures to reach the 60s for the first time in eight days and could make today the mildest Election Day of at least the past six.
While mild here, downsloping Santa Ana winds sent Los Angeles temperatures soaring to a record-breaking 95° high Monday. And, compressional warming as winds descend into the Plains from the Rockies are to produce 80° highs as far north as South Dakota Tuesday.
--By Tom Skilling, WGN-TV Chief Meteorologist

After last week’s early season chill, Chicagoans can gear up for a return of mild weather that should dominate the entire week ahead. The first five days of November averaged nearly 10 degrees below normal, but that deficit should quickly erode as temperatures surge here this week. After a second straight day in the 50s on Monday, readings should climb into the 60s on Tuesday (Election Day) and continue through Friday with the distinct possibility of a record or near-record high in the lower 70s Wednesday.
The mildness here is due in part to a westerly jet stream, bringing mild Pacific air across the nation. While Chicago reaps the benefits of this pattern, it’s producing major weather problems in the Pacific Northwest where the moist flow off the Pacific is expected to produce up to 10 inches of rain as it moves upslope into western Washington and Oregon. Flood watches have been posted along with high wind watches as winds up to 60 m.p.h will lash the area.
--By Steve Kahn, WGN Weather Center Meteorologist

A westerly jet stream will spread a mild Pacific air mass across the nation this week, replacing the arctic air that brought an early season cold snap to Chicago. Last week’s sub-40º high and snow flurries will be quickly replaced by highs in the middle 60s as soon as Election Day, and September-level maximums bringing near-record warmth flirting with the 70º mark look like a good bet for the rest of the week. Beyond that, an inevitable new surge of arctic air will try to make inroads into the central United States by next weekend.
That next cold surge could set the stage for the development of would could turn out to be a classic November storm, the type that brings the “Gales of November” to the Great Lakes, snow to the Upper Midwest and thunder and possible severe weather to the South. Some infamous storms during this time of year include the Nov. 11, 1940, Armistice Day storm and the Nov. 9-10, 1975, storm that sent the Edmund Fitzgerald to the bottom of Lake Superior.
--By Steve Kahn, WGN Weather Center Meteorologist

This 10th weekend of meteorological fall 2006 is to rank among the season’s three coolest to date. But hidden by Saturday’s clouds and afternoon showers are major changes in the atmosphere which are likely over the next four to five days to generate a temperature turnaround that may challenge some of November’s largest. The current cold spell bottomed out with Friday morning’s 21° low at O’Hare (teens were observed in many suburbs, including 14° at west suburban Sugar Grove and Rochelle). If current forecast trends verify, a 72° Wednesday high is in the cards here—a stunning 51-degree increase in just five days. That’s only 3 degrees shy of November’s record of a 54-degree five-day surge observed in 1887.
The wintry early season blast of recent days generated 16” of lake-effect snow Friday in Grand Marais in Michigan’s Upper Peninsula while sending 30s south into the Florida Panhandle and prompting freeze warnings across seven Southeast states.
--By Tom Skilling, WGN-TV Chief Meteorologist

The first teens of autumn 2006 greeted many Chicagoans as Friday dawned, making this the coldest morning since Feb. 26—more than eight months ago—when the mercury bottomed out at 16° at O’Hare.
Friday promises the new month’s sunniest weather to date, a development which lays the foundation for a significant warming trend in the coming week. But, the day’s predicted 44° high is still 10 degrees below normal and 26 degrees behind last year’s 70° high on this date. The predicted temperature turnaround comes not a moment too soon for many after Thursday’s 34° high—a reading 20 degrees below normal. Only six years on record since 1871 have had a daytime high that cold or colder so early in autumn. Thursday’s 30 m.p.h. wind gusts limited wind chills to just 18-24°.
Frigid air plunged into the Deep South overnight, prompting frost and freeze warnings across nine states including Alabama, Georgia and Mississippi.
--By Tom Skilling, WGN-TV Chief Meteorologist

There’s been nothing typical about this fall’s weather to date. The cold has hit early and surprisingly hard this year. The snow flurries which fall from incoming clouds and Thursday’s predicted 34° high—a reading equal to Chicago’s normal Dec. 17 high temperature but 32° colder than the same date a year ago—only underscore the unusual pattern in which we find ourselves. The air mass over Chicago, which only 24 hours ago sent snow flurries through the air in eastern North Dakota 750 miles to the northwest, is so cold that sub-zero readings will hover just 9,000 feet above ground level here.

The chill to date places fall 2006 among Chicago’s seven coolest since 1871. In terms of daytime temperatures, only one other November in the past 50 years has opened with highs colder on the first and 2nd day of the month than Wednesday’s 42° and the predicted 34° today.

-Tom Skilling