It’s official—and NO surprise! April 2013's now Chicago's wettest on record; Tuesday's rains take out the previous 66 year old April heavy rain benchmark


Tuesday marked April 2013′s 11th day of measurable rain. The day’s 0.61″ rain accumulation was enough to put this month’s  8.45″ tally (late Tuesday night, with rains still falling) into the record books as the wettest April to occur over Chicago’s 143-year observational record.


The previous record for most April precipitation here — 8.33″—was retired after a 66 year run dating back to 1947.


The new 8.45″ monthly total is more than 9 times  (939%) the amount of rain which had fallen during April’s opening 23 days a year ago (0.90″) and 2.5 times the full month’s 3.38” “normal” total.


April’s trended cloudier and chillier than typical


Rain hasn’t been April 2013′s sole attribute. The month’s been noticeably cloudier than many of its predecessors, having allowed only 41% of it possible sun. A “normal” April generates 52% of its possible sun.


It’s also been a cool month averaging more than 3-degrees below normal.


From 60-degrees to snowflakes in a single day; Tuesday undergoes a  20-degree afternoon temp pullback  


Tuesday brought the weather of two seasons to Chicago. The day dawned mild and springlike—an anomaly in a month which has produced cooler than normal daytime temperatures15 of its first 23 days—65% of them. But, the day was to watch the “warmth” evaporate as a 20-degree temperature drop ensued in the wake of a cold frontal passage which shifted winds northerly and set the thermal pullback in motion.


Late-winter level temperatures had taken hold by nightfall and reports of wet snowflakes began arriving in our weather office.


Big changes to milder weather loom late week


A huge pattern change is to lift Chicago out of the throes of chilly air before this work week comes to an end.


Vigorous south/southwest winds Friday start the process and deliver temperatures which surge well into the 60s. But even warmer weather is to follow later in the coming weekend—including very possibly the first string of consecutive 70-degree temperatures which has been logged here in six months.


First series of consecutive 70-degree or warmer days to kick off Sunday


If atmospheric conditions unfold as expected, Sunday, Monday and Tuesday next week may each host 70-degree highs. Monday appears likely to be the warmest with mid 70s not out of the question.