Dear Tom,
I remember fall of 1954 being very rainy as I rode my bike to school every day. Didn't it rain for 11 days in a row?
---Mel Dormer, Aurora
Dear Mel,
Undoubtedly you are recalling October 1954, the city's all-time wettest October. Chicago recorded rain on 21 days that month. While it didn't rain 11 days in a row, rain fell on 11 of 12 days, Oct. 8-19. The only rain-free day was Oct. 13.
The month's precipitation totaled 12.06 inches, buoyed by two excessive rainfall events. Heavy thunderstorms Oct. 3 brought nearly 4 inches of rain that flooded basements and viaducts.
That event was dwarfed by 6.72 inches of rain that inundated the area Oct. 9-11, with some locations receiving more than a foot of rain. Massive flooding followed with damage in excess of $25 million.
By Meteorologist Tom Skilling
Chicago's Lake Michigan shoreline water temperature did something Friday it took another three weeks to occur a year ago--it hit 60-degrees. It marks the first time this season the lake water has made it to 60-degrees. A reading that warm didn't occur until June 14 last year.
Trends in lake water temperatures often mirror what's happened in the atmosphere which surrounds it in preceding weeks and months. This spring's abnormally mild temperatures have clearly played a role in producing the "warm" readings this early! The current 60-degree temperature is an impressive 10-degrees warmer than the water temperatures observed at Chicago's shoreline a year ago.
The Army Corps of Engineers released other lake-related news Thursday. It reported Lake Michigan's water level has dipped 2 inches below the level observed on this date in 2011. Lighter than normal overall precipitation over the lake's 45,000 square mile drainage basin, covering sections of four states, appears to have played a role in this development. While basin rainfall is running slightly above normal this month, April precipitation came in at just 68% of normal.
2012's warmest weekend ahead; Friday's 84-degree high to become the 13th with an 80+ temp this year--more than three times last year's tally
A weekend of remarkable warmth for so early in the season is ahead of us. Though southeast winds will limit warming to some extent on area beaches in coming days, temperatures elsewhere in the metro area will surge to unseasonable summer levels--peaking at 84-degrees Friday and close to 90 Saturday.
Friday's high marks the 13th day this year that temperatures have reached or exceeded 80-degrees--more than three times the 3 days at or above 80 which were on the books at the same point a year ago.
31 states headed into the 80s Saturday
The warmth won't be limited to the Chicago area or the Midwest. Daytime highs Saturday are predicted to reach or exceed 80-degrees over all or parts of 31 states.
Southeast to south winds will bring modestly cooler temperatures to the beaches in coming days. From Friday to Sunday afternoon, peak beach and lakeshore readings are likely to hold to the 77 to 86-degree range.
Meteorological spring season, with under 2 weeks to run, averaging 51.4-degrees--much warmer than a year ago
The clock is ticking on the 2012 meteorological spring season which runs from March through May. Chicago's temperature since March 1, has averaged 51.4-degrees--6.6-degrees warmer than the 44.8-degree spring temperature which had been reported up to this date last year.
Incoming "dome" of warm air produced 90s to Chicago's west Thursday
Temperatures within the dome of warm air, building to the west and expected to send Chicago temperatures higher as it translates east in coming days, were eye-catchers for a second consecutive day Thursday. Some of the warmer readings observed Thursday included 99-degrees at Madison, 96 Granite Falls, 92 Redwood Falls--all in Minnesota--93 Sioux City, Iowa and 95 at McCook, Nebraska.
Humidity build-up and unseasonable warmth sets the stage for possible thundery late weekend storms
The warm, moderately-humid atmosphere predicted to be in place by Sunday afternoon or evening, is likely to produce thunderstorms, some capable of gusty winds, downpours and possibly hail.
While an average rain tally, generated from a suite of computer rainfall forecasts, comes out to 0.60-inches, some of the individual computer rainfall forecasts from which that average was derived, ranged from as little as 0.19-inches to as much as 1.41-inches.
European Center's global model building second dome of unseasonable warmth across the Midwest later next week into the following weekend
One of a number of forecast trends it's going to be fascinating to follow is an aggressive prediction of warming across the Midwest put forth by the European Center's widely-regarded operational and ensemble models. Such a warm-up would follow a period of cooling early next week. The forecast of renewed warmth appears to hint at some "real" heat later next week into the following weekend. We'll keep you posted on this development in the days ahead.
By Meteorologist Tom Skilling
A decidedly warmer weather pattern takes shape in coming days. It's a warm-up which will dominate Chicago's weather through the weekend, propelling Saturday afternoon highs well into the 80s. That's a temperature level which hasn't been equaled in the 8.5 months since an 89-degree high on Sept. 3 last year. Saturday's predicted 88-degree high, and the 86-degree peak reading on Sunday, will make this the area's warmest weekend of 2012. The rising temperatures are to be accompanied by strong southerly winds and increasing humidities.
Warming a big change after Wednesday's 21-degree temperature pullback
The change to warmer, more humid weather will be quite noticeable. It comes in the wake of quite a sharp temperature downturn.
Wednesday's 65-degree high represented a 21-degree plunge from Tuesday's July-level 86. The day's cool northeast winds chilled the city's lakeshore locations and beaches even more. There, temperatures struggled to hit 60-degrees---a 26-degree plunge from 24 hours earlier.
The warm-up comes in a meteorological spring during which 78 percent of days have posted temperature surpluses
The predicted warm-up comes in a season which has been dominated by mild air. Since March 1, 78 percent of Chicago's daily highs have been above normal.
May is running a temperature surplus of nearly 6 degrees, and is the eighth consecutive month to average above normal.
Influx of Gulf moisture could ignite thunderstorms as early as Sunday afternoon
Dew points, meteorologists' favored measure of atmospheric moisture, surge to the mid 60s by Saturday afternoon---readings which reflect a level of moisture common on the Gulf Coast.
Daytime heating, combined with cooling aloft, as an upper disturbance rides into the area Sunday, could set the stage for a late weekend eruption of thunderstorms. New forecast data brings storms into the area earlier than initial indications. The updated scenario would have storms erupting as early as Sunday afternoon and evening---and in potentially greater numbers Sunday night.
An average of a suite of computer rainfall projections generated by the supercomputers of at least four meteorological forecast centers over the past three days, suggests around 0.73 inches of rain may occur in the late weekend storms. But spring rains rarely fall evenly, varying widely across the area. AT least some forecasts produce rains exceeding 2 inches.
Another warm spell mid and late next week?
One of the most interesting forecast developments in the longer range has been the suggestion of a formidable second surge of warmth which could sweep into the Chicago area the second half of next week. Temperatures at that time could exceed this weekend's predicted readings, which would assure a warm close to May 2012. Stay tuned!
By Meteorologist Tom Skilling
Tuesday's summer-level warmth is history Wednesday. A thundery, frontal passage late Tuesday evening cleared the way for markedly cooler north to northeast winds to sweep into the area overnight.
Temperatures surged Tuesday to 86 at O'Hare, tying the year's 2nd warmest temperature and putting a 14-degree surplus onto the book here. But, that warmth has exited the area, giving way to readings limited to the mid to upper 60s Wednesday---and in the low 60s at lakeshore locations.
Tuesday's 86 compares to 46 recorded May 15 a year ago; May 2012 almost 6-degrees warmer than 2011
The 86-degree high observed Tuesday was 40-degrees warmer than the chilly 46-degree peak reading observed May 15, 2011. The opening half (15 days) of May 2012 is running 5.7-degrees warmer than the same period a year ago.
Madison, Wisconsin ties 86-degree Tuesday record
Northwest of Chicago, Madison, Wisconsin recorded an 86-degree high Tuesday, tying its record for the date.
Thunderstorms, towering to 43,000 ft, rake the area Tuesday; 40+ mph gusts hit southern Wisconsin
The thunderstorms which flared along a southbound cool front late Tuesday, produced some impressive wind gusts across sections of northern Illinois and southern Wisconsin.
Doppler radar scans indicated the storms' cloud-tops reached heights of 43,000 ft.
Janesville, Wisconsin was hit by 46 mph storm gusts while Racine's Batten Airport, Oconomowoc and Mineral Point---all in Wisconsin---reported 45 mph gusts.
Wind damage occurred in sections of west-central Illinois late Tuesday. Gusts as high as 65 mph hit a mile north of Kewanee, Il while Bettendorf, Iowa reported 54 mph gusts.
Rains limited, but storms set the stage for rainbows
Rainbows---in a number of cases "DOUBLE rainbows"-----provided an eye-catching finish to Tuesday evening's storms in many sections across the Chicago area. The beautiful displays occurred as sunshine passing through suspended raindrops broke into the array of colors which make up sunlight.
Year's warmest temperatures on the way this weekend; Saturday/Sunday highs could to within striking distance of 90-degrees
Tuesday's warmth was impressive---but the warmth expected to re-surge this coming weekend into the area is likely to produce even higher temperatures. Readings could flirt with 90-degrees for the first time this year here in the city.
Another unseasonable warm surge indicated by models the middle and end of next week
Not only are temperatures to rebound this weekend, a second surge of unseasonable warmth appears a good bet later next week.
By Meteorologist Tom Skilling
Nothing scuttles spring warmth faster in Chicago than a wind shift off the lake. That's what's happened overnight. A frontal passage has turned winds northeast off lake waters which boast an an average temperature of 52-degrees.
The day's lack of sunshine won't help matters. Together, the northeast winds and heavy, occasionally light rain-producing overcast are to translate into a 14-degree pullback in Saturday's temperature---even more along Lake Michigan where shoreline air temperatures are to struggle just to hit 60-degrees.
Friday's 78-degree high ranks as May's third warmest
Friday's glorious sunshine and gusty southwest winds combined to produce Chicago's warmest temperature in over a week. The high of 78-degrees was 9-degrees above normal and the third warmest daytime reading of May 2012.
Sun's return for Mother's Day (Sunday) key to new temperature rebound; Chicago highs first likely to reach 80 Tuesday
While the weekend's off to a less than spectacular meteorological start, the good news is nicer weather's ahead for Mother's Day (Sunday) and the coming week.
Warm temperatures are to surge into Chicago in two distinct waves---the first to produce Monday 70s and the potential for the city's first 80 in nearly two weeks on Tuesday---and a stronger surge of warmth with elevated humidities in tow late in the week extending into next weekend. That warmup may be the strongest since the record-breaking 80+-degree spell which occurred in March.
Year to date average of 43.4-degrees the warmest in 142 years of observations here and 7.7-degrees above normal
Chicago is in the eighth consecutive month of above normal temperatures with little sign the overall trend is to abate. 2012's year- to-date average temperature of 43.4-degrees is a stunning 7.7-degrees above normal and ranks as the warmest observed for that period over the city's 142-year observational record dating back to 1871.
75 percent of summers following the 20 warmest Jan. 1 to May 11 periods have been warmer than normal
Though this year's temperature has no analog to offer guidance on where temperatures may be headed as we move toward meteorological summer (the three- month June through August period), a review of Chicago summers following the 20 warmest Jan. 1 to May 11 periods should make hot weather enthusiasts hopeful. 15 of those 20 summers---75 percent of them---produced above normal temperatures.
The bias toward a warmer than average summer weather regime is one which has shown up with some consistency in other in-house statistical studies we've run in our search for "signals" on what the coming summer may hold for us.
Daylight will continue its seasonal expansion for another 40 days; another 44 minutes of daylight on the way
A seasonal increase in daylight has been underway now for nearly 5 months, since the Dec. 21, the shortest day of the year. Over that time, we've picked up 321 additional minutes of daylight. We'll continue to see the daily roster of sunlight increase for another 40 days---right up to June 20, date of the summer solstice and also the year's longest day. Over that period, another 44 minutes of daylight will be added.
Warming to come in two surges next week interrupted briefly Wednesday by lake breezes
A decidedly warmer pattern is predicted to take shape over much of the Lower 48 in the coming week---a development likely to establish above normal temperatures from coast to coast, for all intents and purposes, by later this week.
The warmth is to come in two waves---separated by the passage of a weak cool front mid-week, which is to usher a bubble of high pressure into Chicago which may allowing the development of temperature- reducing, mid-week lake breezes.
Ahead of the mid-week high, temperatures may hit 80-degrees Tuesday. Any pullback in Wednesday's temperatures won't be extreme. And 80s are likely to stage a comeback Thursday into the following weekend, with an influx of humid Gulf air for the NATO Summit. An isolated thunderstorm seems possible Friday---but more significant thundery rains could begin to blossom late next weekend or the start of the following work week.
By Meteorologist Tom Skilling
The return of sunshine Thursday and Friday is to boost temperatures well above Wednesday's sub-par 60-degree high. That reading was the first below normal temperature of May----and it looks likely to be the last for a while, though a modest temperature downturn Saturday may include cooling northeast winds on area beaches.
May's 61.8-degree average temperature through Wednesday at the official O'Hare site is 6.1-degrees above normal. It's the warmest May open here in 11 years and 8.8-degrees warmer than the same period a year ago. It places this month's opening 8 days 19th-warmest of any May here since the official observation record began in 1871.
Sunlight delivers more than four times the energy in May that it did in December
The ease with which temperature are able to warm this time of year is, in part, a product of stronger sunlight. May sun delivers an average of 465 Langleys of energy in Chicago compared to the 107 Langleys which arrive in December sunlight. (A Langley is the amount of energy which sunlight is required to deliver to a surface one-square centimeter in size to raise the temperature of a single gram of water one degree Celsius).
Temps to push well into the 70s Friday---but the warmest temps follow brief weekend downturn next week
While afternoon temperatures Thursday are likely to post a 9-degree increase over Wednesday's peak reading of 60, even warmer readings are expected Friday, buoyed by the arrival of strong southerly winds, the generous sunshine predicted to occur and a bit of compressional warming likely to take place ahead of an approaching cool front.
Winds converge along fronts. This leads to compression of the air there---and compressing a gas leads to heating. It's more than possible highs Friday could flirt with 80-degrees before the front sags south across the area, potentially provoking a shower or thunderstorm in several locations Friday night into Saturday night.
Warmth not limited to Chicago; May temperature surpluses on the books from one end of the Midwest to the other
May's not only been warm in Chicago, where temperatures to date are running 6.1-degrees above normal---but significant temperature surpluses are showing up in nearly every section of the Midwest. Among the Midwest cities reported May surpluses to-date are: Des Moines (+11.0 degrees), St. Louis (+12.4-degrees); Evansville, Ind. (+12.9-degrees); Omaha, Neb. (+11.6-degrees), Indianapolis (11.1-degrees) and Kansas City, MO +10.1-degrees.
Pattern developing next week has an early summer look to it; could bring 80s to the area the second half of next week in time for the start of the NATO summit here
Decidedly warmer weather is to make a move on the Midwest and the Chicago area next week. If current forecast trends hold up, the warmest readings are likely to occur in the back half of the week---in time for the open of the NATO Summit here. It wouldn't be surprising to see some 80+-degree temps before next week ends.
Other than a few Friday night/Saturday showers/t-storms; precipitation forecasts remain conservative through next work week
The big rains of the past month are history for the time being. Other than a shower or t-storm in spots Friday night and a small portion of the metro area Saturday and possibly Saturday night, the lack of rainfall predicted over the coming 10 days represents a stunning change from the wet weather of recent weeks. An average of the rainfall forecasts off a suite of computer forecast models for the coming 7 days comes to just 0.14 inches.
By Meteorologist Tom Skilling
There hasn't been a warmer meteorological spring in Chicago at any point in the city's 142 year observational record. Temperatures since the season began March 1 have averaged 53.3-degrees---an astounding 9.6-degrees warmer than the long term average and an equally astonishing 10.4-degrees above the same period a year ago.
With only three weeks remaining until the meteorological summer season gets underway June 1, it's hard to see how the 2012 March through May period will loose a grip on its ranking as the city's warmest.
The previous warmest spring occurred 35 years ago during 1977 with a seasonal average of 50.3-degrees. Before that, spring 1921 held the record as the warmest with a 49.7-degree average.
NOAA's National Climatic Data Center (NCDC), the official archive for the country's meteorological and climatological data, indicates Chicago isn't alone with its warmer than average temperatures. On the heels of an extraordinarily mild winter, temperatures across the Lower 48 since Jan. 1 have produced the country's warmest average temperature for any such period since 1895.
The average temperature across the Lower 48 since January began comes in at 45.4-degrees, a reading 5.4-degrees above the long-term average.
Highs of 70 and 80-degrees and warmer have run at twice to three times the normal pace since March 1
An examination of the Chicago area's warmest temperatures this year indicates there have been 20 days with highs 70-degrees and warmer---more than twice the long term average of 9 such days. And, when it comes to 80-degree and warmer readings to-date this meteorological spring, the tally is at 10-days---more than three times the average of 3 such days!
Cool pool aloft and "lift" generated by nose of strong jet stream winds support scattered shower development Wednesday
The atmosphere remains unstable Wednesday, i.e. in a cloud producing mode.
A chilly pool of air aloft plus the approach of a strong band of jet stream-level winds---a feature which, along with the faster than usual decline of temperature with height, is likely to encourage air to rise, cool and produce clouds and scattered showers, is behind expectations that Wednesday isn't likely to remain completely rain-free.
Much drier weather regime in place; 7-day computer rainfall estimates average 0.10"---under 3 percent the pace of rainfall the past two weeks
No repeat of this past weekend or last week's heavy rains are in sight through next week. Spotty bursts of precip--most of it light--are likely Wednesday before sunshine returns Thursday and Friday. There's another chance of a few showers or possible thunderstorms Saturday. Otherwise, an ensemble of rainfall projections out to 14 days is yielding an estimate of 0.10".
Punch of warmer air to arrive on gusty southwest winds late week
Temperatures are headed into the 70s Friday as gusty southwest winds take hold.
First glimpse of next week's NATO summit weather has warm, humid look to it
The first forecasts for the period of the NATO summit, which begins late next week, suggests warm, humid air may well take charge of Chicago's weather.
By Meteorologist Tom Skilling
Dense fog shrouds much of the Chicago area as Tuesday dawns, having formed within the waterlogged underbelly of an air mass which has been saturated by a series of drenching thundery downpours the past 5 days. The five day stretch has produced rains of 2.89 inches at O'Hare, 2.56-inches at Midway Airport, 2.46-inches at National Weather Service Forecast Office in southwest suburban Romeoville, and 4.15 inches in the Wilmington area of western Will county.
Fog forms when humid air is cooled to saturation---i.e. the point at which the air's relative humidity reaches 100 percent. That's the threshold which has been reached late overnight.
By late Monday evening, fog formation was underway in earnest and, by midnight, visibilities had already dropped to 1/8 mile at O'Hare and Midway airports and 1/4 mile at Lansing, Joliet, and Kankakee.
The 2.98 inches on the books just 7 days into the new month makes this the wettest May open since 3.28 inches fell over the same period in 1945.
Thundery weekend rains produce local 4"+ totals; spawn brief touchdown of Iroquois County's first twister---a small one---since June 21, 2010
Weekend rainfall exceeded 4 inches to the south of Chicago at Hebron, Indiana (4.60-inches) as well at Marseilles (4.43").
Dazzling lightning displays accompanied each of the the storms----but so too did powerful straight-line winds. The storms were behind the weekend's jumbo tallies, which amounted to more than a month's worth of rain across the metro area's southernmost counties.
Rainfalls to Chicago's south included Watseka's 3.98", Crown Point, Indiana's 3.87", the 3.40" reported at Streator and the 2.51" which fell at DeMotte, Ind.
The deluges reversed what seemed for a time to be an ongoing spiral toward summer drought.
Rain and flooding weren't the only issues hoisted on Midwesterners in and around the Chicago area by this past weekend's storms. Powerful winds, reports of hail and the touchdown of a small tornado in downstate Iroquois were issues as well.
A preliminary report issued late Monday by a National Weather Service Storm Survey team dispatched to Iroquois County to asses storm damage, concluded a small twister, following a 1.5 mile path roughly 100 to 200 yards across and estimated to have produced 85 to 95 mph winds, touched down 2.5 miles east of Watseka and remained on the ground just 6 minutes, becoming the first Iroquois County twister reported since 2010. The Weather Service's post survey report indicates:
"MANY OF THE ACCOUNTS FROM CITIZENS NEAR THE DAMAGE AREA MENTIONED SEEING ROTATION WITHIN THE CLOUDS AT SOME POINT...ALTHOUGH THERE WERE AREA REPORTS OF WIDESPREAD DUST AND APPARENT WEAK GUSTNADOES IN ADVANCE OF STRONG WINDS AND ZERO VISIBILITY WITHIN HEAVY RAIN SOON AFTER THAT. THERE APPEARED TO BE STORM INTERACTION BASED ON RADAR IN THIS AREA THAT HELPED TO DEVELOP A TORNADO NEAR THE FRONT EDGE OF THE STRONG WINDS."
The team reports the small twister was embedded within a narrow 3-mile-long swath of 100 mph straight line winds responsible for producing their own damage. The swath of straight-line winds roughly paralleled U.S. 24.
Chicago's monthly rainfall already 81 percent of a full May's total
Chicago's May rainfall has reached 2.98-inches, an amount equivalent to 81 percent of May's normal 3.68 inches.
Sun's emergence to fuel scattered but gusty shower development Tuesday afternoon---some of it potentially thundery
Scattered gusty showers are to develop Tuesday afternoon with the emergence of sunshine and the warming it induces. This warming will encourage air to ascend into an incoming pool of cool, unstable air aloft. These showers will tower aloft into a 100+ mph jet stream and may transfer some of that wind energy back down to the ground as powerful gusts.
Big rains are over for a time; just 0.20" forecast over the coming 7 days, giving the area a chance to dry out
Beyond spotty Tuesday afternoon and nighttime showers, a few of which could spill over into early Wednesday, the big rains are over for the time being. The consensus of a suite of computer models is that just 0.21 inches of rain may fall in the coming 7 days, an amount just a fraction of rains the past seven---and a modest enough amount to allow drying to take place.
Daytime 70s to return late week; models hinting at warmer pattern late in the two week forecast period
Late week temperatures are likely to return to the 70s Friday with early indications of a warmer pattern taking shape in the 11 to 15 day period overall.
By Meteorologist Tom Skilling
It's been a wild night across the Chicago area with blinding rains which have submerged a number of area intersections. Hail the size of golfballs has pelted a number of locations as nearly non-stop lightning has arced earthward from 10-mile-high thunderstorms. The thundery weather follows the year's muggiest day to date--humid air heated by mid 80-degree temperatures 20-degrees above normal and more typical of July than early May. O'Hare's official 86-degree high was the year's second warmest reading and the warmest "max" here in six weeks.
We're posting a number of spectacular storm photos we've been sent online with plans to use more of your photos on our television segments Friday. MANY THANKS to so many of you for sharing storm photos with us!
These storms haven't been all bad! The heaviest rainfall they've generated has fallen across a swath of Illinois which arguably had been home to the state's least impressive rainfall tallies. It was a region in desperate need of the moisture.
With the degree of warmth and the sultry humidity levels which preceded Thursday's late-day storm eruption, it's little wonder such active weather was able to form. Early reports put Morton Grove at the epicenter of the heaviest rains with nearly 2 inches measured there--but rainfall reports are preliminary and new measurements likely to arrive in coming hours will shed more light on just how much rain has fallen.
Oak Lawn among the areas drenched by Thursday evening's cloudburst
In just an hour's time, 2.70 inches fell at Oak Lawn Thursday night--a truly phenomenal rate of rainfall. And, Oak Lawn wasn't alone. Flooding closed roads at Howard and Western in Evanston, on Dempster between Ozark and Waukegan roads, and on King Drive at Garfield and Ogden Avenue between Joliet and Lawndale.
Veteran observer and Chicago climate guru Frank Wachowski reported 0.85 inches fell in just 15 minutes at Midway Airport while O'Hare recorded 1.31 inches--the heaviest to fall there in 6 weeks--with radar tracking new rains likely to increase that total late Thursday.
Non-stop thundery downpours, accompanied by near continuous cloud-to-ground lightning discharges, "trained" (occurred in repetitive waves) across a corridor of Iowa and Illinois, extending from near Ottumwa, IA east to Lafayette, Streator and Kankakee--all in Illinois. Totals there are likely to be impressive. There are preliminary Doppler estimates of some 4 to 6 inches totals--and it wouldn't be surprising to see higher tallies in some spots when morning rain gauge reports arrive.
What's happening tonight in Illinois and portions of the Chicago area looks like a repeat performance of the repetitive waves of t-storms which lambasted sections of central Wisconsin and Michigan Wednesday night leading to numerous reports of 3 to 5 inch rains.
Temps by Friday afternoon are to dive to levels 30-35 degrees below readings Thursday once a lake-enhanced cold front passes Chicago and ushers full fetch NE winds into the city--a set-up which will send readings diving from the mid 60s to low 70s in the morning into the 50s in the afternoon.
New rains/t-storms due Sunday into Monday
While rains are to ease Friday into Saturday, tapering to sporadic sprinkles or a bit of drizzle, a new storm system is to tap the same humid air mass behind Thursday night's storm outbreak and bring new rains to the area Sunday and Sunday night.
By Meteorologist Tom Skilling
A new temperature record is on the books in the wake Wednesday's extraordinary near 20-degree 24-hour temperature surge. The 80-degree highs Wednesday at O'Hare, Midway and the Lakefront, bring to NINE the total number of 80-degree or warmer temperatures to date this year in Chicago. The previous record for early season 80-degree and higher temperatures occurred 35 years again in 1977 when 8 days with highs at or above 80 occurred through May 2.
Year's second warmest temp to date predicted Thursday
An even warmer temperature and still higher humidities are predicted Thursday. The day's forecast high of 86-degrees is 6-degrees shy of the 1955 record of 92 for the date but comes in 20-degrees above normal. It moves to TEN the number of 80-degree and higher readings which have occur thus far this season.
Winds are to shift off Lake Michigan in coming days, so prospects we'll extend the 80-degree streak beyond today are dim.
Chicago at risk for severe storms as temps warm
Adding heat to Thursday's moisture-rich atmosphere threatens to fuel vigorous thunderstorm growth of the variety observed well to Chicago's west and northwest Wednesday. There, thunderstorms towered to heights of nearly 50,000 ft. and produced hail and gusty winds.
With an inch and a half of evaporated water in the atmosphere and storms reaching high into the atmosphere where they can tap wind energy in the jet stream and transfer it down to the surface in their wind gusts, severe weather is a real possibility later Thursday into Thursday night. The Storm Prediction Center has outlooked the Chicago area for possible severe storms during that period.
Meteorological spring's rain to date just 73 percent normal; predicted rainfall over coming week to average 2 to 3 times---or more---of the long-term average
With just 73 percent of the area's possible rain on the books since meteorological spring got underway March 1, additional rainfall would be welcome if it doesn't get out of hand. Soils are still drier than they should be going into the growing season and a moisture recharge would be timely.
Influx of Gulf moisture on gusty southwest winds pushes air's moisture content to a new 8 month high; heightens the risk of thundery downpours
Averaging estimates of potential rainfall for Chicago off a suite of computer models in recent days yields an average of more than 2-inches (2.12-inches) of rain over the coming 5-days. That's well over twice the "normal" level of rainfall here for the period (0.81 inches).
As always in warm season rain events, a huge spread in rainfall totals is likely. Rain doesn't fall evenly. Some areas are drenched this time of year; others are bypassed by the heaviest downpours.
The potential exists for a few of the harder hit areas of northern Illinois and Indiana into southern Wisconsin and Michigan to receive far greater totals.
