It's an October responsible for unusual weather which we'll not soon forget once it closes at midnight Saturday. Rain has fallen more frequently than in any October since 1925 -- on 22 days since the first of the month, 19 of them measurably.
Midway Airport's eye-catching 7.69" October total -- which includes Thursday night and Friday's 2.26" downpours -- finishes nearly three times "normal." The month's gray skies have permitted only 33% of October's possible sunshine -- a far cry from the 58% which is normal -- and the least October sun here over the past quarter century. It's among the three lowest October sun tallies since 1893. And if the wet, gray weather hasn't been enough, October's 48.9-degree average temperature comes in at 5 degrees below the long-term average, making it the 19th coolest in 139 years. It's estimated home heating may have been up as much as 21 percent over a year ago.
The wind-driven deluge Thursday and Friday -- the 2nd to drench the area in a week -- produced eye-catching totals. Early measurements from Weather Bug rain gauges ranged as high as high as 3.65" at Hebron and 3.54" at Darien. Chesterton picked up 2.74" and Kankakee County's Bonfield was swamped by 2.55" while National Weather Service CO-OP observers reported 3.10" at Portage, Ind.; 2.50" at Woodridge; 2.39" at Romeoville; and 2.26" at Oak Brook and Peotone.
State Climatologist Dr. Jim Angel of the Midwestern Regional Climate Center reports statewide rainfall in October will finish 2nd wettest since 1895. It's the wettest to occur in Illinois since 1941.
Friday's 67 degrees not enough; October the first in 92 years not to generate a 70-degree high
While temperatures and surging humidities (dew points, a measure of atmospheric moisture, surged into the mid 60s) produced a springlike feel to the air Friday and highs of 67 degrees at O'Hare and 68 degrees at Midway, the month closes at midnight as the first October in 92 years which has failed to produce a single 70-degree high. That's happened in only two Octobers over the 139-year Chicago weather record. Temperatures did reach 70 Friday at Gary!
For the second time in a week, the area is being walloped by significant rains. The October rain tally had reached 4.63" at O'Hare and 5.46" at Midway even before the current system's precipitation began Thursday, assuring the month a spot among the Top 10 wettest Octobers on the books here. The frequency with which rain has fallen the past 30 days has been stunning. The last time an October produced 22 days with a trace or more of rain occurred 84 years ago in 1925.
The waves of rainfall predicted to sweep the Chicago area Friday are a continuation of overnight downpours, some from 41,000-foot thunderstorms. They fall on saturated soils unable to absorb them. With no option but to run-off, the 1" to local 2.5" totals predicted by Friday evening will stream into area rivers threatening flooding. The Fox River near Montgomery was within 0.2 feet of flood stage even before the latest deluges arrived.
The powerful autumn storm behind Friday's downpours has established an uninterrupted flow of Gulf moisture riding 60-plus mph south winds into the Midwest just above the surface. It's a set-up which assures a nearly limitless supply of moisture to fuel Friday's waves of gusty showers and thunderstorms. Though rain won't fall continuously, when it does it may well be heavy. With dew points, a measure of atmospheric moisture, predicted to hover around 60 degrees Friday -- much higher than yesterday's upper 40s -- in combination with mild south rather than lake-cooled southeast winds, Friday should feel "warmer."
Chicago's wet storm was responsible for a half dozen twisters which dipped Thursday from Texas, Louisiana and Arkansas skies. Rainfall topped 5" near Shreveport, La., and flood watches extend over a dozen states from the Gulf north to Illinois and Indiana.
Blinding snows dominated the system's backside and halted travel over sections of 4 states from Colorado and Wyoming into western Nebraska and South Dakota. Snowfall reached 1-2 feet in Denver and up to 4 feet nearby in the mountains. An area three miles southeast of Pinecliffe, Colo., was buried by 45.8" of new snow and drifts in Wyoming were up to 6 feet tall.
Warming slated later next week -- but it may not last
Much cooler air hits Friday night into Sunday morning. Gusty west winds will add to the chill of the 50-degree Halloween Day predicted Saturday. Longer range models hint at the potential for significant warming later next week into the following weekend. The predicted "warm-up" has the look of an El Nino inspired temperature increase. But, several key cold weather indexes turn negative toward the end of the coming two weeks -- suggesting any warming may not last.
REMINDER: Daylight Saving Time ends Sunday morning at 2 a.m. Turn clocks back an hour before heading to bed Saturday night. The change means it will feel like we have an extra hour of sleep Sunday. But sunsets will move from 5:46 p.m. Saturday to 4:45 p.m. Sunday as a result of the change.
It often takes the powerful winds of a large autumn storm to sweep warm air into Chicago this time of year. That's precisely what happens Thursday in advance of the wind-driven and potentially thundery waves of rainfall expected to produce fall's 2nd heaviest rainfall here Thursday night and Friday. An average of 30 computer rainfall projections suggests 1.19" may fall before Friday closes -- but predictions range as high as 2.57". It will take only 0.6" of additional rain to push the month into the ranks of Chicago's 10 wettest Octobers on record over the past 139 years. At Wednesday's close, October's official O'Hare total stood at 4.63".
Thursday's strengthening southeast winds are predicted to gust to 30 mph by nightfall and are likely to grow even stronger at times Thursday night and Friday. They represent a key element of the approaching storm. Any thunderstorms which arrive within the storm's expansive rain shield may well be able to harness energy from the 60-plus mph winds predicted just above the surface, transferring some of that wind energy down to the surface as powerful gusts.
Before the downpours get going late Thursday night, Chicagoans are in for something of a meteorological treat. Sunshine, in short supply this month -- it's been the 5th cloudiest October on record and the least sunny in a quarter century -- should be abundant.
The day's southeast winds sweep into North Shore suburbs after a trip over Lake Michigan's cool waters. That's a development expected to restrict highs in Waukegan and Kenosha to near 60 degrees while Chicago's lakeshore reaches the mid 60s and some warmer south and southwest suburbs peak in the low 70s. The city has yet to log a 70-degree temperature this month, making it only the third October to do so since 1871.
Storm buries Colorado under 2-plus feet of snow;
threatening Plains severe weather outbreak
The storm behind Chicago's two day "warm-up" has hammered the Rockies and western Plains with the region's biggest snow this season. Totals late Wednesday had reached 35" at Pinecliffe, 28.6" near Nederland, 28.5" just outside Golden and 14" at Boulder -- all in Colorado. The area just south of Denver was under a new 11" snowpack as night fell Wednesday.
A severe weather outbreak threatens to the east in the storm's front-side warm sector Thursday. Areas from Texas north to Oklahoma, Arkansas and southern Missouri are at risk for damaging thunderstorm winds including possible tornadoes.
The last vestiges of the mega-rain producing storm which walloped the area with 2 to 4 inch rains Thursday night and Friday aren't long for the Chicago area Saturday. The cloudy, sporadically drizzly weather with which the day opens gives way to brightening skies toward midday and some welcome sunshine Saturday afternoon. Temperatures, which peaked for a time in the 60s Friday -- 61 at O'Hare and 62 at Midway -- will average 12 degrees cooler Saturday and may have trouble breaking out of the upper 40s in some areas.
October rainfall, typically just 2.71", is running twice the normal pace in the city -- but has totaled as much as 7.62" at south suburban Flossmoor, 7.28" at Hebron, Ind., and 6.79" at Glenview. All the wet weather this month makes October 2009 among the wettest of the past 139 years. The 4.15" at O'Hare is the 13th wettest to date since 1871; Midway's up to 4.80" -- and there's still a week to go. Rain has fallen on 17 of the month's opening 24 days -- that's 71 percent of them!
It was snow -- not rain -- which fell on the departing storm's backside in Minnesota and northern Wisconsin Friday. Stewartville, Minn., was hit with 4.2" while Rochester was whitened by a 3" snow pack and Eau Claire, Wis., was hit by 2".
Next wet storm could warm Chicago mid-week before a Halloween weekend temp crash
A disturbance due to sweep into the area Sunday brings clouds and a few possible mainly afternoon sprinkles -- with a better chance of showers Sunday night into Monday. But it's Wednesday and Thursday which sees a broad fetch of gusty south winds make their way into the area as a storm develops in the Texas Panhandle Wednesday and lifts into the Great Lakes Thursday and Friday, inducing warmer temperatures. The set-up could even support gusty thunderstorms Thursday.
The system's progress will have to be monitored: A bit of sunshine or a slowdown in its northeast trek across the Heartland could permit temperatures to become even warmer than the 60s now indicated to occur. Weather history shows 80 percent of the final weeks of October have produced 60s and 45 percent have hosted 70s.
What an October! Cool weather is well into its third week and still has two days to run. Gusty northeast to north winds and a steep 30-degree temperature drop in the first mile of the atmosphere set the stage for lake-effect rain showers Friday into Saturday evening before sunshine returns Sunday for the first time in more than week. The warming which follows arrives on gusty southerly winds Monday and Tuesday sending temperatures into recovery mode and boosting readings here to their mildest levels in three weeks.
Thursday's temperatures were anything but mild--and would have been at home in late November. The day's 44-degree official high equaled readings observed here for the date in 1876, 1909 and 1943--each tying as Oct. 15's coldest on record. The tenacious cold spell--which is to last into Sunday morning before breaking--produces a 19th day of below normal temperatures Friday and limits highs to the 40s for a 7th consecutive day--the most ever so early in the season. Chicago's average temperature over the month's first 15 days slipped Thursday to 47.3-degrees---the city's chilliest October open in the 133 years since 1876. Not only has it been cool---it's been cloudy and wet. Rain has fallen 10 of the past 15 days and has totaled 2.13 inches---nearly an inch (0.85) above normal. The damp weather has allowed only 38 percent of October's possible sunshine to date---58 percent is typical.
Not all of the country is shivering. South Texas broiled in unseasonable heat. Readings hit 100-degrees at McAllen and 99 at Del Rio.
Gusty downslope winds sweep Colorado during Thursday balloon episode
The 20-foot-diameter, helium-filled balloon first feared to be carrying a 6-year old as it took to the skies above Colorado Thursday afternoon, was whipped by gusty winds sweeping out of the mountains into the state's eastern Plains. These katabatic or Chinook winds gusted at times as high as 28 to 50 mph. The compressional warming they set in motion sent eastern Colorado temperatures soaring to near 70-degrees.
Cold air is hitting early this year. A subfreezing temperature -- similar to the one predicted at O'Hare Airport Saturday night and behind the freeze warnings which have been issued for the entire Chicago area -- didn't occur a year ago for another two weeks until Oct. 28. Saturday's 54-degree high is an early November level reading -- 11 degrees below normal. But the passage of a cold front, expected to shroud area skies in clouds as Saturday afternoon proceeds, is to bring snow flurries across Iowa into western Illinois before drying out -- intensifying cold air's grip on the area Saturday night and Sunday. Daytime highs are likely to rise no higher than the mid to upper 40s Sunday after recovering from the low/mid 20s across western suburbs in Sunday's predawn hours.
The onset of cold air each fall and winter is largely a function of astronomical changes. The sun set at the North Pole Sept. 22, and that region of the arctic is now in round-the-clock darkness. Days to the south -- including the Chicago area -- shrink from summer's arrival, which occurred this year on June 21, to the onset of winter on Dec. 21.
The decrease in solar energy sets the stage for cooling. It's a process which takes place most dramatically in the arctic. While Saturday is to host 3 minutes less sunlight than Friday in Chicago, the loss of daylight increases to 7 minutes farther north in Anchorage, Alaska, and to an amazing 28 minutes in the northernmost reaches of North America. It's little wonder cold air -- and eventually a reflective snow cover -- assembles fastest there.
October is off to a remarkably chilly, wet start. Temperatures have averaged 51.2 degrees -- more than 7 degrees off the long-term average. Rainfall in the wake of Friday's chilly downpours is 1.82" -- far from the 0.82" which is normal for the month's opening nine days.
Sunday's Bank of America Chicago Marathon to kick off in air 30 degrees colder than last year
Runners in Sunday's Chicago Marathon, subjected only two years ago to wilting heat which forced the race to be cut short, are likely to shiver in Sunday morning's mid 30-degree temperatures. The readings represent a 30-degree decrease from the mid 60s as the Marathon got underway a year ago and nearly 40 degrees from the ill-fated 2007 race.
Powerful winds with the first of two autumn storms predicted to impact the region this week, whipped sections of the Chicago area with gusts topping 50 mph late Tuesday. A 63 mph blast was clocked at 9:05 p.m. three miles off Chicago's shoreline at the Harrison-Dever Crib and other gusts included 54 mph at the Weather Bug wind sensor at Queen of Angels School in Chicago, 50 mph at Algonquin, and 48 mph at Glenview. The storm responsible produced modest amounts of rain here---only 0.03 inches at O'Hare and 0.27 at Rockford--but drenched the Upper Midwest with 1.74 inches at Tomahawk and 1.55 at Oconto--both in Wisconsin.
Tuesday's stormy weather comes on the heels of the area's coolest October open of the past 6 years. Temperatures over the month's opening 6 days averaged 52.1-degrees--- 7-degrees below the 138 year average and among the 7 coldest such periods since observations began in 1871. In 6 previous years with comparable cool October starts, the sub-normal temperature trend remained dominant the remainder of the month.
A powerful new early season cool surge---including a potential for the first daytime highs which fail to break above 50-degrees since April, continues a threat this weekend into early next week. The chill's arrival in the U.S. is to ignite a new round of snowfall in the northern Rockies as it sweeps out of Canada. Winter weather advisories were issued in Montana for Wednesday.
A new storm threatens parts of the area with big rains Thursday
The week's second storm may may bring parts of the Chicago area as much as 1 to 2 inches of rain---especially in southern sections Thursday into Friday morning.
The chilliest spell of weather here in over five months moves into a
9th consecutive day Tuesday---but under cloudier skies than in recent
days. Rainfall with the first of this week's two wet weather systems is
predicted to begin from the day's rapidly lowering and thickening
overcast by mid-morning and continues in waves through much of the
afternoon. A suite of the 11 most recent computer projections places
the day's potential rainfall from 0.10 inches to as much as 0.85---an
amount which comes on top of the 1.22 inches recorded here in the past
8 days---a period which has averaged nearly 5 degrees below normal.
Estimates based on temperatures since October's open suggest the cool
spell has led to home furnace use nearly 60 percent more than the most
recent 30 year average.
Gusty west winds, likely to top 30
m.p.h. at times Tuesday night, deliver a reinforcing shot of chilly
air. But, the far more significant cold surge---potentially the coolest
in more than 5 months and likely to limit high temperatures to the 40s
for the first time since last April---looms this weekend.
Wet storm system later this week could produce up to 3 times Tuesday's rainfall
A
frontal wave expected to sweep the area as the cold air approaches is
likely to produce a far wetter interlude than Tuesday's---doubling or
tripling the amount of rain to fall today.
