With Sunday promising a repeat of Saturday's unlimited sunshine and mild temperatures in the middle 50s nearly 15 degrees above normal, Chicagoans are enjoying a third straight mild weekend.
While this weekend's highs in the middle and upper 50s pale in comparison to the back-to-back 70s on Nov. 7-8 and the 63-degree maximum on Nov. 14, the mild conditions will provide ample opportunity for end-of-season yard work or putting up holiday decorations. The balmy weather should last into Tuesday extending the current string of above-normal days to 21-the longest November stretch since 25 straight days were logged at Midway Airport in 1999.
Brief chill may bring snow
The warmth will not last through Thanksgiving as a cold front sends temperatures plunging late Tuesday. Showers should develop with the front and could mix with snow Wednesday as readings drop into the 30s. Thanksgiving looks to be cloudy with some flurries or mixed rain and snow possible with high temperatures struggling to reach 40 degrees.
Nighttime cooling has produced areas of low cloudiness and fog from moisture lingering in the wake of the past week's damp weather system. When temperatures lower at night, air masses grow saturated with moisture at the point readings match the dew point. It's the instant relative humidities reach 100 percent.
Despite areas of clouds, Chicago remains a safe distance from the country's major precipitation-producing weather systems over the pre-Thanksgiving weekend -- one on the Gulf Coast with big rains and another sweeping into the Rockies. It's a situation which should allow the weekend here to remain mild, further extending one of the longest spells of above-normal November temperatures on the books. Highs are to reach the 50s Saturday through Monday -- readings 10 to 15 degrees above normal and more typical of late October than November. The number of consecutive above-normal days reaches 19 Sunday, the 2nd longest such period at Midway Airport since weather records began in 1928. Only 1999 managed more -- 25 of them.
Though winds are light Saturday -- often an impediment to breaking clouds up this time of year -- computer models indicate the layer of moisture supporting Saturday morning's clouds is quite shallow. This should permit daytime heating to mix the air, dissipating the cloudiness and allowing generous sunshine to emerge. Hazy sunshine is likely to return both Sunday and Monday.
As additional evidence of how mild it's been of late, the coldest temperature recorded this fall has been 28 degrees, and the coolest daytime high this month has been 47. A vast majority of years have produced temperatures colder than each of these readings by now: 128 of the past 137 years have recorded a colder autumn low temperature by now, and only one year (1933) has seen its lowest November daytime maximum higher than this year's 47.
Changing pattern to send temps tumbling by Thanksgiving;
potential cold December open ahead
Many indicators continue to suggest large pattern changes loom over the next two weeks -- changes likely to send temperatures broadly lower over the United States. The colder air appears likely to hit in two waves -- and there may be temporary warming between them.
Cold weather surges into the Midwest on gusty winds Tuesday afternoon and Wednesday amid chilly showers. Readings may be chilly enough to allow at least some mixed snowflakes to the reach the ground with the spells of cold rain. The chilly air is likely to hold Thanksgiving temperatures near 40 degrees. Even colder air may hit next weekend and carry into December.
Friday marks the 17th consecutive day of milder than normal temperatures in Chicago--one of the five longest such spells on record in the month of November at Midway Airport. Weather observations there date back to 1928. With above normal readings expected to continue into early next week, the mild spell is on track to become this area's 2nd longest of any November. That so many above normal days have occurred is likely to surprise many Chicagoans. A heavy, week-long overcast peppered with bursts of light rain and, until Thursday, wind chill-generating gusts, have contributed to a much cooler "feel" to the air than readings alone might indicate. The month's 47.5-degree average temperature at O'Hare is the 20th warmest of the past 139 years, placing the month among the Chicago area's 14 percent of mildest Novembers. Estimates based on temperatures suggest furnace usage should be down 25 percent over typical levels up to this point in the month and 18 percent below the same period a year ago.
A stubborn low pressure responsible for five consecutive days of cloudy skies has lifted out of the area--but, moisture lingers in its wake. And, while clouds may break for passing sun in coming days, spells of overcast skies aren't likely to exit the area completely--fitting in a month which is historically the second cloudiest of the year (December is the cloudiest).
Daytime temperatures are predicted to rise several degrees in each of the next three days. But, indications of change in the weeks ahead abound. Two key cold weather indexes, which look at cold air availability in the arctic as well as the predicted buckling of the jet stream over the North Atlantic---a development which frequently ends up sending cold air spilling southward over the eastern U.S., including the Midwest---have turned negative. It's an indication of colder weather on the way. The chill appears likely to hit in bursts---the first to produce a rain-generating disturbance here late Monday into Tuesday. That push of cold air is to last through through Thanksgiving (next Thursday) and may deliver this area's coldest readings of the season to date. There are growing indications flurries or snow showers could sweep at least parts of the metro area Wednesday and Thursday. Still colder air appears a threat as December hits 12 days from now. That chilly spell could allow some sticking snow at some point in December's opening 5-days, according to several preliminary computer forecast scenarios.
West Coast hit by driving rains, huge mountain snows, 100 mph wind gusts
The storm pounding the West Coast Thursday has prompted warnings for all manner of extreme weather---from heavy rain and flooding, to mountain snows measured in feet, and high winds responsible for huge waves lashing the coastline. Gusts hit 103 mph at Rogue Valley International Airport near in southern Oregon near Medford Thursday.
Clouds cover area skies a 5th consecutive day Thursday and periods of rain are to continue. Wednesday's 0.17 inches at O'Hare made it the wettest day since late October. The day's 47-degree peak reading was the third consecutive day in which temperatures failed to escape the 40s. With a fourth day of 40s predicted Thursday, the metro area is in the midst of its longest cool spell since a set of seven consecutive 40s Oct. 10-16.
To say it's been dreary is a bit of an understatement. Chicagoans have seen only 1 percent of the area's possible sun since Sunday---and November, typically the second-cloudiest month of the year here, is showing every sign of living up to its cloudy reputation over the coming week. The sluggish storm which has spun in place all week shrouding the area under a veil of clouds, is finally to lift out of the Midwest Friday. But computer models hold a fair amount of moisture in the lowest 5,000 feet of the atmosphere in the wake of the departing storm. This is more than adequate to produce clouds and could make sunshine a comparatively rare commodity. What's more, suggestions that a wet new storm is to come together across the Midwest Monday is hardly a boon to those in search of sun. Though the details of its development aren't yet carved in stone, a number of forecast scenarios predict strengthening over eastern Iowa and Missouri Monday, leading to the onset of chilly rains in Chicago Monday night and Tuesday.
Temperatures over much of the coming two weeks remain above seasonal norms, but display a downward glide. One lobe of chilly air is likely to be drawn into the Midwest on the blustery backside of next week's storm, producing a cool Wednesday and Thanksgiving Day. It's possible mid-week cooling will be sufficient to introduce snow or rain showers. But even colder air may loom beyond that. Though temperatures are likely to moderate after Thanksgiving (next Thursday,) preliminary indications suggest December---which is just 13 days away--may open on a wintry note as even colder air descends into the Chicago area.
Historic odds of a trace or more of snow falling in November's 12 remaining days: 88 percent
The possibility of snow grows this time of year. Snowfall records in Chicago extend back 125 years to 1884. At a least a trace of snow has fallen in 88 percent of those years between now and the start of December. Measurable snow (0.1 inches or more) has fallen in the same period in 60 percent of years and an inch of snow has fallen by December first 38 percent of the time.
Chicago's weather has turned wet for the first time in over two weeks bringing to an end the driest November open in a decade. Just 0.01 inches had fallen in the city up to the time rains arrived Tuesday afternoon. Rainfall is predicted to continue in waves through Thursday totaling 0.40 to 1 inches making it the area's heaviest spell of precipitation in the 18 days since 0.81 inches fell October 30.
Northeast winds, so successful in halting the northward spread of rain Monday, proved no match for the deep-layered surge of moist air which pushed rain into the metro area by Tuesday afternoon. The most impressive area totals ranged from 0.91 inches at Rensselaer and 0.71 inches at Hebron, both in northwest Indiana---to 0.61 in De Kalb County's Sandwich. Chicago rains, while enough to wet the pavement, weren't nearly as impressive---totaling just 0.08 inches at Midway and 0.05 at O'Hare---but more was expected to fall overnight.
The stalled low pressure system responsible for the wet weather is a "cut-off low." The term originates from the fact the strongest upper levels winds, which might otherwise push such a disturbance along, become situated well to the north. Systems spin in place when this happens, unable to move very quickly. The varied barometric pressures on the storm's north side were behind Tuesday's howling northeast wind gusts which approached 40 mph here and limited wind chills to the low and mid 30s.
Areas downstate bore the brunt of storm's rainfall for a second consecutive day. Totals there were impressive. Westville in east-central Illinois' Vermillion County just east of Champaign recorded 3.23 inches of rain while Lincoln was soaked by 3.14 and Danville was hit by 2.45. To put those amounts in perspective, the entire month of November in Chicago typically sees 3.01 inches.
Alaska in the Deep Freeze; Interior temps drop under -40 degrees
Cold air has reached brutal proportions in the northernmost reaches of North America. Temperatures in Alaska dropped to -45 degrees at Tanana--in the state's Interior not far from Fairbanks Tuesday, to -44 degrees at Bettles. Open water in southern Alaska appeared to "steam" as the bitterly cold air turned water vapor immediately to ice crystals, much as happens when brutally cold air makes contact with the "warmer" water of Lake Michigan here in winter. Days continue to shorten in across the northern hemisphere assuring cold air production is just beginning in the arctic. The sun sets in Barrow, Alaska Thursday for 64 days---not to rise again until late January.
Even where the sun is still visible during the day well to Chicago's north, it sits low in the sky. At its highest point Tuesday, the disc of the sun was just 6.1 degrees above the horizon in Fairbanks compared to 29 degrees above the horizon at its peak here in Chicago. (Note: Were the sun 90 degrees above the horizon, it would be directly overhead while a sun angle of 0 degrees means the sun's disc sits below the horizon.)
Sections of downstate Illinois, including the St. Louis area, were drenched by 1 to 2-inch rains Monday at the same time a foot of heavy, wet early season snow snapped power lines near the Nebraska/northeast Kansas border just northwest St. Joseph, Missouri. Morrowville, Kansas was hit by 12 inches of snow while rainfall in the storm's mild eastern sector reached 2.01 inches at downstate Fairview Heights, Illinois and 1.62 at St. Louis. The storm responsible is behind the powerful east to northeast winds which continue to rake the Chicago area Tuesday morning and produced 30+ mph gusts here Monday. With origins in Canada, the dry low level flow proved a formidable barrier to the northward spread of the storm's rain. While northwest Indiana's Hebron recorded 0.22 inches of rain and 0.10 fell at Valparaiso---both in Indiana-- just 0.01 inches fell at Midway with a trace at O'Hare.
The wet storm, spinning in place over Missouri late Monday, is mired in an atmospheric blocking pattern which has the system, for all intents and purposes, spinning in place. Since any forward motion isn't expected to resume until late this week, it's likely the storm's impact on Chicago's weather has days to run. Computer models suggest the dry air riding Monday's northeast winds into the area is to moisten slowly allowing rain prospects to rise. Once the atmosphere becomes saturated later Tuesday and Tuesday night, the rainfall which results could linger through Thursday.
While the air is to take on an increasingly damp, raw feel, temperatures are actually running above November averages. Winds and clouds are interfering with normal nocturnal (nighttime) cooling, a development which contributes to daily temperature surpluses. Tuesday marks the 14th consecutive of above normal November temperatures---and each day over the coming 7 days appears likely to finish ABOVE normal as well.
Changes loom Thanksgiving week; signs of colder temps and more storminess
Important atmospheric changes appear to loom next week. A dome of milder than normal air is predicted to take shape over eastern Canada and the Davis Strait between Labrador and Greenland. Such a development often signals a surge of cool air into eastern North America as the continent's jet streams begin buckling. Ridging in the jet over the western Atlantic is offset by troughing in the eastern U.S. which produces northwest steering winds above the Midwest--a flow able to tap cold air at higher latitudes and tug it south. Two storm systems may be by-products of this pattern evolution and an analysis of temperatures suggests readings by the end of next week and the following weekend may dip 15 to 20-degrees below the levels predicted later this week.
Such a pattern change isn't out of line with typical late November developments. 125 years of snow records here reveals the week leading up to Thanksgiving has produced at least a trace of snow 74 percent of the time while measurable snow (0.1 inches or more) has fallen in 42 percent of all years since 1885.
Most locations received little more than a few sprinkles or brief showers late Saturday afternoon and overnight as a cold front moved through, but Chicago's long dry period that extends back to the last day in October is about to end. Low pressure is expected to develop over Missouri Monday and ever so slowly work it's way north and east through Illinois, finally weakening as it reaches Wisconsin and Michigan later in the week. Rain is forecast to move into the Chicago area possibly as early as later this afternoon and then continue overnight into Monday. The slow-moving low pressure portends an extended period of cloudiness and off-and-on showers through Thursday.
Above normal temperatures to continue
The clouds and rain ahead should cut back considerably on the range of daily temperatures with readings holding for the most part in the 40s through mid-week. So even though it will feel cool and damp to Chicagoans, daily average temperatures will be in the middle 40s, some 5 degrees above normal for mid-November. Beginning on November 4th, average daily temperatures at the O'Hare official observing site have been above normal. A warm-up is forecast the latter half of this week and seasonably mild readings could extend well into Thanksgiving week.
Rain's been a scarce commodity in November but is threatening a windy comeback. Only 0.01 inch has fallen over the past two weeks, quite a change from an October in which 23 of the month's 31 days hosted at least a trace of rain. It's been the driest open to a November in a decade.
The rain's return is likely to begin quite modestly late Saturday night as post-frontal sprinkles build to a few light showers behind a wind-shifting cold front -- pause Sunday morning, then increase in number and coverage Sunday afternoon and night. Computer model handling of the wet system's movement into next week has been stunningly inconsistent in recent days -- potentially impacted by the massive Mid-Atlantic storm responsible for three days of driving rains and punishing winds in the region. Gusts Friday peaked at 60 mph at Cape May and 58 mph at Atlantic City -- both on New Jersey's coast. Gusts hit 56 mph at Ocean City, Md., and roared across Brooklyn, N.Y., at 47 mph. Air ascends into the atmosphere on a massive scale in storms as powerful as this one, forcing upper steering winds to flow around it. Such a split in the winds at jet-stream level can have continental weather implications, slowing the eastward progression of weather features. There is little doubt the storm has played a key role in slowing mild air's arrival here in recent days -- and, now that it's here, is likely to slow its retreat until Sunday's predawn hours.
Most aggressive among a suite of computer projections sweeping rain into Chicago, then holding rainfall in place for up to 5 days (through Thursday), has been the global forecast model run by the European Medium Range Forecast Center. The model generates precipitation totals approaching 2 inches and suggests the storm responsible is to lift from New Mexico and the Texas Panhandle into southwest Missouri by late Sunday, and then into downstate Illinois Monday. There, the system stalls as the upper air low producing it separates from powerful jet stream winds which might otherwise push it along.
Wet weather would be bad news for area farmers, who in recent weeks have finally been able to make progress harvesting crops. Veteran Will County farmer John Hazzard reported late Friday that most soybeans have been harvested -- but only 10 percent of the corn crop has been taken out in the hope further drying may occur. Corn moisture is well above normal, and harvested corn must be dried at the elevators to which farmers take their crop -- a slow process because elevators are able to process only so much corn on a given day. Hazzard reports yields have been good but estimates the corn harvest may take many weeks to complete.
Weather history indicates a majority of years see at least some measurable snow between now and Thanksgiving
Frigid arctic air gripping northwestern sections of North America and responsible for subzero temperatures in northern Canada and sections of Alaska in recent weeks, has shown little inclination to pour south in any great quantity. But longer-range projections are hinting that may change -- and it could happen toward the end of the coming two weeks during Thanksgiving week. A ridge forecast to build over Greenland at that time favors model projections of jet stream buckling over North America which would bring colder air crashing into a large swath of the Lower 48. Weather records show cold air before November's close isn't unusual and that 62 percent of all years since snow records began in 1884 have recorded measurable snow between now and Thanksgiving.
It was like a scene out of the Perfect Storm on the East Coast Thursday. Torrential rains---in spots more than 9 inches of it---fell horizontally as easterly winds roared ashore up and down the Mid-Atlantic Seaboard from New England to North Carolina at speeds found only in the region's most potent storms. NOAA offshore buoys bobbed about in mountainous three-story waves as shoreline cameras captured scenes of oceanic chaos as swarms of frothy waves lapped ominously at sand dunes and buildings normally out of the water's reach---but in harm's way Thursday as relentless east winds pushed a dome of Atlantic water over the shoreline at levels not seen in 13 years. The stormy environment, a by product of Hurricane Ida's remnants interacting with a sprawling Canadian high pressure, appears to have contributed to the disappearance of three commercial fishermen off Cape May, New Jersey. A 19 hour air and sea search for them was called off at 5 p.m. Virginia Governor Timothy Keane declared a state of emergency and urged people in the hardest hit areas of his state to stay home as power lines fell and standing water closed roads. Among the areas in Virginia hard hit by flooding was the Norfolk area.
Wind speeds were stunning. A Weather Bug sensor clocked a gust of 106 mph around 11 a.m. Thursday morning on the beach at Ocean City, Maryland while another nearby captured a 91 mph gust. Winds reached 68 mph at Fenwick Island, Delaware, 67 mph at Virginia Beach and 65 mph at Norfolk---both in Virginia---and 56 mph farther north at Atlantic City.
Rainfall surged past 9 inches at some locations. Swansboro, North Carolina was socked with 9.26 inches of rain while 9.12 soaked Jones Creek, Virginia.
Paltry November rains here lowest in a decade, 5th lowest on record
The East Coast storm appears to be contributing to a slowdown in U.S. weather movement---a development which could extend the 60s predicted Friday into Saturday. And while a chilly, wet storm is predicted by models to lift into the Midwest Monday, Chicago's paltry 0.01 inches tally this month is the lowest in a November in a decade and the 5th lowest of any November over the past 139 years.
Temperatures appear likely to surge within striking distance of 60-degrees Thursday and into the mid to upper 60s Friday afternoon. Cloudiness plays a key role in the extent of daytime heating which takes place this time of year. November's lower sun angle means any interference by clouds can limit warming. The expectation that cloud cover here over the next two days will be of the high, thin variety underpins our prediction of 60-degree readings. High clouds tend to interfere less with sunlight than denser low clouds. The predicted parade of 60s may even extend into a third day Saturday before a wind-shifting cool front passes, swinging winds around to the northeast off Lake Michigan. That plus a thick, occasionally showery overcast is likely to allow a flood of cooler air into the area which, along with predicted rain Sunday, should lead to a much cooler back half of the weekend.
Highs in the 60s become less frequent from this point forward each year. An average of four 60s have occurred beyond Nov. 12 in the past 138 years. By contrast, freezing temperatures grow more numerous. Weather records reveal only 7 percent of the Chicago's 32-degree or lower temperatures have typically occurred by now.
A howling northeaster (or nor'easter) pumped 50+ mph wind gusts into sections of the Eastern Seaboard Wednesday. Gust hit 57 mph at Ocean City, Maryland. The storm--which combined the remnants of Hurricane Ida with widely varied pressures beneath the southern flank of a sprawling high draped from the Midwest to New England, produced the roaring winds which set in motion seething, white-capped surf conditions from the Carolinas north to the Delmarva Peninsula. The system's driving rains drenched a multi-state region and totaled nearly 10 inches (9.83) at Opelika, Alabama.
Far to the northwest a powerful storm in the Bering Sea sent 70 mph hour gusts across western Alaska. Forecasters warned 65 to 90 mph gusts could sweep the Turnagain Arm southeast of Anchorage in the south-central section of the state. As much as 10 to 20 inches of snow was predicted in the Susitna Valley south of the Alaska Range.
75 percent of the past 138 years have produced a colder temp by now
Chicago's coolest temperature to date has been 29-degrees recorded on Oct. 11. Three quarters of all years since 1871 have produced a colder reading by Nov. 12.
