Tuesday’s 38-degree April 15 “Tax Day” temp the coldest here in 86 years; readings flirt with records and 21-degrees below normal

By Meteorologist Tom Skilling

Tuesday’s 38-degree Chicago high temperature would have been right at home in February. The reading equals the “normal” high here on Feb. 22.

But the frigid 38-degree reading, 21-degrees below normal, occurred on “Tax Day” and was the coldest April 15 which has been observed here in the 86 years since 1928!

Daytime highs were actually higher in much of Alaska than in Chicago and adjacent areas of Illinois, Wisconsin and Michigan—reaching levels close to 50-degrees at a number of locations across the 49th state.

Chicagoans didn’t shiver alone; records fell at a number of Upper Midwest locations; frost and freeze warnings issued for 24 states overnight

The abnormal chill wasn’t limited to Chicago Tuesday. Morning readings dipped to new records at International Falls, Minn.( 5 degrees), Sioux Falls, S.D. and Grand Forks, N.D. (11 degrees);  Watertown, S.D. (12 degrees) and at both Minneapolis, Minn. and Madison, Wisconsin (18 degrees).

Frost and freeze warnings were hoisted across 23 states south and east of Chicago—from eastern Oklahoma across much of the Deep South to New Jersey, Delaware and Maryland.

Tuesday highs averaged more than 20-degrees below normal south as far as Georgia, Alabama and Mississippi.

Only 4 other days beyond April 15 have generated daytime highs of 38-degrees or lower in over a half century at O’Hare 

Weather observations began at O’Hare in 1959. In all that time, temps of 38-degrees or lower have occurred beyond April 15 on only 4 other occasions.

Milder temps Wednesday and Thursday to yield to a chilly, new round of “NE” winds Friday

 Temps stage a modest recovery with the arrival of Wednesday’s powerful southerly winds. The “warming” may linger into a second day Thursday.  But a thermal downturn, prompted by the re-emergence of northeast winds Friday, is to render the “warming” short-lived.

Daytime highs Friday may remain in the 40s in areas close to Lake Michigan.

South winds Easter Sunday could send temps surging into the 60s

More significant warming is in the offing over the weekend—particularly Easter Sunday.  At that time, a new round of powerful southerly winds is to send temps back into the 60s.

The area logs the heaviest snow accumulation within 3 days of an 80-degree temp since records began in 1884-85

By Meteorologist Tom Skilling

Snow has historically been no stranger in Chicago during the month of April. Official snow records indicate a trace or more of snow has fallen this late in 86 of the past 129 seasons dating back to 1884-85. That’s 67% of the time.

But the amount of snow which fell Monday and the fact it occurred within 3 days of 80-degree warmth (on Saturday) and on a day which opened in the 60s is without precedent. Neither has occurred before over the 129 year term of official Chicago snow records.

Monday’s preliminary snow totals through 10 pm came in at 1.2” at O’Hare and 1” at Midway.

The 1.2” tally at O’Hare equals the  amount of snow which typically falls over the full month of April and was the heaviest official snowfall to occur here so late in a season in 3 decades.

Monday’s snow means April 2014 has become at the 5th month to reach or exceed the city’s normal monthly snowfall.

Heavier snow totals were reported late Monday evening elsewhere across the metro area including 2.5” at Wauconda; 2.1” Huntley; 1.9” Downers Grove; 1.7” Oak Brook; 1.5” Lindenhurst; 1.5” Batavia and 1.4” at north suburban Beach Park.

The 50-degree temp pullback from Saturday to late Monday is the area’s largest to occur in an April in 20 years

The 3-day temperature drop of 50 degrees, which is what occurred in Chicago between Saturday afternoon’s summer-like 80-degree high and the 30-degree reading registered late Monday, was the biggest to occur here in an April over the past 2 decades.

That shift in temperatures was the equivalent of moving from mid-June back late February-level readings in a span of just 72 hours.

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Two-steps backwards after Saturday’s 80

Saturday’s 80-degree high, occurring about two weeks ahead of schedule, was an aberration in Chicago slow-starting spring. The unusual warmth lingered into Sunday morning with highs peaking around 70 before the return of a chilly northeast flow dropped the mercury into the familiar 40s that have dominated much of this spring. What may be winter’s last hurrah is expected Monday afternoon and evening when an influx of cold air will change the lingering rain to snow before ending. Most of the snow is expected to melt on contact with the warm pavements, the some snow could whiten grassy areas especially north and west of the city.

Eclipse viewing iffy

Chicagoans ability to view Tuesday’s predawn total lunar eclipse will hinge on the rate of clearing as Monday’s rain and snow pull out of the area. Latest forecasts time the clearing to coincide with the start of the eclipse, but a lingering overcast would ruin the sky show.

Showers/thunderstorms likely – then turning colder

The warm air that provided 80-degree highs on Saturday will be departing our area Sunday. Even though this has been a long cold period dating back to last fall, we are ahead of last year on the 80-degree front. Last year our first official 80-degree high didn’t occur until the last day of April.

A cold front will slowly settle southeast through the Chicago area Sunday with a good chance of showers and thunderstorms. Ahead of the front (to the south and east) winds will be south to southwesterly with temperatures in the 70s, while behind the front (to the north) the winds will be north to northeast and temperatures in the upper 40s to middle 50s.

Heavy rains are likely Sunday night into Monday, as cold air rides northeast winds into northeast Illinois and northwest Indiana. Indications are that Monday will be a damp chilly day with occasional rain, possibly even mixed with some wet snow at times. Storm total rainfall could end up exceeding two to three inches at many locations in the Chicago area – especially to the north. Precipitation will be slow to end – probably continuing off and on Monday night, before ending early Tuesday.

Warmest weekend temps in more than 6 months lay atmospheric foundation for vigorous, possibly severe t-storms

It’s not rare to see 70s in Chicago by April 12—in fact, it’s happened in 3 of 4 years since records began in 1871.

Friday’s high was the first of 2014 to reach 70, coming 18 days beyond March 24 which has been the average date for the city’s first 70 of the season.

Saturday’s powerful southerly winds, sweeping up the eastern flank of the country’s latest spring storm, are to propel afternoon readings even higher—reaching 76-degrees.

With a 68-degree high to follow Sunday, this weekend’s daytime temps are to be the warmest of any Saturday/Sunday period since the 80 and 64-degree highs on Saturday and Sunday, October 5-6—more than 6 months ago.

Saturday’s June-level temps are to beat last year’s 45 on this date by 31-degrees

If the 76-degree high predicted Saturday afternoon verifies, it will be 18-degrees above normal and, even more impressively, 31-degrees warmer than last April 12’s 45-degree max temp.

The set of back to back 70s Friday and Saturday come 18 days earlier than a year ago

Friday’s 70-degree high and the predicted 76-degree peak reading Saturday are to be the first back to back 70-degree or higher temperatures of 2014. These consecutive 70s arrive 18 days earlier than the first two 70s appeared on the scene a year ago. Impressive rainfall numbers coming out of computer models; thundery downpours could produce 2”+ totals—the biggest in 10 months

The waves of thundery downpours likely to sweep the area later Saturday into Sunday night—then end as cold rain Monday morning amid markedly lower temperatures and strong northerly winds, may end up this area’s heaviest rain producers since last June. A suite (collection) of computer forecast models are producing 2”+ cumulative rainfall totals–with harder hit locations potentially logging some 3+” totals.

Warmest day of the year brings severe storm potential

Southwesterly winds gradually strengthen during the day Saturday, pulling warm moist air into the Chicago area. Winds will be gusting over 25 miles per hour in the afternoon, as temperatures peak in the middle 70s – easily the warmest day so far this year, the second consecutive 70-degree day (Friday’s official high was 70-degrees), and the warmest temperature since 76-degrees was recorded back last October 11. Dew-points will be on the increase, and the added low-level moisture combined with developing wind shear, a cold front approaching from the west and an increasingly more unstable air mass – all point toward a good chance of strong severe thunderstorm development over Illinois into southern Wisconsin later in the afternoon and Saturday night.

Waves of showers and occasional thunderstorm downpours should occur from Saturday night, through Sunday into early Monday. During this period rainfall could total well over two-inches at many northeast Illinois locations – perhaps even exceeding three-inches in spots. Much colder air will follow on the wings of strong north to northeast winds later Sunday into Monday – temperature drops of 25 to 30-degrees will be common.

Upcoming weekend to be area’s warmest in the 6 months since early October; back to back 70s lie ahead Saturday and Sunday

By Meteorologist Tom Skilling

It’s been long in coming!  The year’s first official 70+degree temperatures are to arrive this weekend. Saturday and Sunday are to produce a set of daytime highs we’ve not seen since back-to-back 70s occurred here on Oct. 11-12 last fall.

Highs of 74 degrees are being predicted Saturday and 71 for Sunday—unseasonably mild readings which are to be followed by plunging temperatures as winds turn northerly Sunday night.

Thursday’s 66-degree high was 2014’s 2nd warmest reading

Temps soared above 60-degrees for a third consecutive day Thursday and are set to do so for a fourth day Friday.

The day’s 66-degree high was the year’s 2nd warmest to date.

A high of 68 Friday would tie 2014’s highest reading yet—and even higher temperature would establish a new record.

Spring storm spins up over the Plains and it’s Chicago-bound; weekend’s warmth and increasing humidity to lay the groundwork for the city’s biggest rain in 10 months

Model estimates of the rain likely to accompany Sunday and Monday’s storms have surged in recent days.  An average of all available precipitation estimates puts the late weekend/Monday rain tally around 2.50 inches—but the individual computer generated totals from which that average was derived range from 1.80 to 3.39 inches.

If rainfall occurs in those amounts, the late weekend/Monday storm would be the wettest to sweep this area in 10 months.

60-deg highs extend into a 3rd consecutive day; it’s Chicago’s mildest spell in 6 months

By Meteorologist Tom Skilling

The area’s mildest spell of weather in 6 months continues Thursday.  The day is to produce the third of what is likely to become a six-consecutive day string of 60-degree or higher temperatures. Not since last October have so many 60+ degree readings been clustered together and the current mild streak may well include a 70+ degree temperature Saturday, the year’s warmest.

Warmth originating within huge air mass responsible for 90-degree highs Wednesday in the Plains 

While the ongoing warm-up marks quite a departure from the chilly temps which have dominated so much of the past 6 months, readings here in Chicago pale in comparison to the warmth observed within this air mass Wednesday over the Plains.

Highs there hit 90-degrees at Russell and Phillipsburg, Kansas and Gage, Oklahoma. Mid 80-degree temps were observed north into South Dakota. Those highs averaged as much as 20 to 30-degrees above normal and fell within the warmest 10% of a number of weather stations’ April 10 peak daytime readings.

Thursday frontal passage to set-off showers; up to 60% of the greater Chicago area could see some rain before the day’s close

Scattered showers are to grow more numerous in the Chicago area as Thursday proceeds with the passage of a modest cold front passes resulting in a wind shift to the northwest. While huge rainfalls are unlikely, as much as 60% of the region may see a shower before the day closes—though a number of dry hours are to be interspersed.

 Influx of year’s warmest air and highest moisture levels since last October to fuel powerful spring storm over the weekend; thundery downpours due Sunday

The weekend weather pattern grows far more complicated. A shower or thunderstorm can’t be ruled out at some point Saturday.  But it’s Sunday into Monday that the main precipitation is to fall.

Thundery downpours Sunday into Sunday night may be produced by storms which bubble up into strong high altitude winds. That’s a set-up which  can lead to powerful wind gusts and rainfalls in the 1 to 3” range—potentially the heaviest official tallies to occur here since late June last summer.

But even more interesting is the potential that a rush of colder air into the area Sunday night into Monday could lead to a wintry mix of precipitation—even a potential switch to snow—in sections of the Midwest, possibly including Chicago or areas close-by.  We’ll be monitoring this situation in coming days.

Measurable snow’s occurred this late in the season in 30% of years

Sticking snow’s not unheard of this time of year—even with the advent of warm weather in the days immediately ahead.

Measurable snow’s been recorded 39 of the past 129 years beyond April 10th— 30% of those years.  And April 15-16, 1961 even managed a 6.5” accumulation with 3.7” recorded April 14-15, 1980.

Temps reach 60-degrees for only the 2nd time in 2014 Tuesday; fewest 60s at this point in a season in 21 years

By Meteorologist Tom Skilling

For only the second time this year, temperatures peaked at 60-degrees Tuesday. The low tally of 60s is a testament to how cool it’s been and how few and far between the year’s warm spells have been up to now.

Not since 1993 has a year reached April 9th with just two 60-degree or warmer readings on the books.

Over the city’s 144 year observational record, only 19 years have produced 2 or fewer 60s by now—that’s just 13% of all the years that comprise Chicago’s weather archive.

String of five 60s ahead, the longest mild spell in 6 months

If forecast trends verify, Chicago temperatures warm into the 60s each of the coming six days.  The meteorological wild card governing the extent to which each day warms is, as is so often the case in spring, to be wind direction.

A flow from the east travels over cold lake water and tends to cool the lakeshore. A westerly flow, on the other hand, overpowers lake cooling and brings warmth up to area beaches.

Friday appears the first day in which easterly lake breezes may be a factor, bring cooler air ashore. But current indications  suggest those winds will be light and fairly localized, so the areas cooled would tend to be localized and relatively close to the lake.

Weekend winds may be a bit more tricky.  Indications are Saturday’s southerly flow could have an easterly component to it until a warm front crosses the area late in the day or at night. That would  produce a situation in which inland readings would flirt with 70 while shoreline and beach temps might hold in the mid 50 to low 60-degree range.

Spin-up of powerful spring storm threatening thundery downpours Sunday

 On Sunday, several models—including the respected European Center model—places Chicago in the latest spring storm’s warm sector with dew points, which reflect the moisture content of the air, headed to 60-degrees, signaling a significant flow of moisture into the area. That moist air would be able to fuel thundery downpours in the Sunday and Sunday night time frame.

6 months and counting on the chill; “NNE” winds cooling lakeshore Tuesday

By Meteorologist Tom Skilling

It’s been a long cold season in Chicago. April marks the 6th consecutive month in which temps have fallen short of seasonal norms.

Tuesday’s north/northeast flow keeps the chilly weather going another day.  But, there are encouraging signs several spells of warmer temps are in the metro area’s future, including what may become the year’s second 60-degree high Wednesday with the potential for a third Thursday.

It’s the upcoming weekend—in particular Saturday—which appears poised to produced the warmest temps over the coming week.

70-degree temps running more than 2 weeks late this year; upcoming weekend may produce 2014’s first!

What mild air there’s been in 2014 to date—-has been short-lived and in incredibly short supply.

To date, a single 60-degree temp is on the books and readings have yet to reach 70. That may well happen Saturday—more than two week late.

Weather history here indicates the average first date of a 70-degree temp at Midway Airport has been on or about March 26 and around March 24 at O’Hare.

Chicago’s lakefront generally produces the season’s first 70 later than at other observation sites in the area because of chilly Lake Michigan waters there.

Stronger sun, longer days lay the foundation for overall warming—but the chill’s not finished yet 

The foundation is being laid for the warmer days of summer. It’s just happening very slowly this year.

Sunlight pours down on Chicago an additional 234 minutes when compared to the area’s shortest day—Dec. 21, which is also the astronomical start of winter.

But not only are days longer, the sunlight which falls on Chicago is nearly 3.5 times stronger than on Dec. 21.

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