Chicago's 35th 60-degree January high temperature over the city's 142 year observational record was one for the books Tuesday, replacing the 99-year-old January 29th record of 59-degrees. The 63-degree high at O'Hare equaled the normal peak reading which occurs here on April 25.
January 60s are truly rare, having occurred in only 21 of the past 142 years. On only 10 occasions has one of those January readings reached or exceeded 63-degrees.
Tuesday's high fell just 4-degrees short of January's all- time record of 67-degrees set in 1950.
The warm, moist Gulf air behind Tuesday's "warmth" helped fuel thundery downpours which swept back into the city during the afternoon---in time for the evening commute period. So heavy was the rainfall that Midway Airport's late evening 0.95" tally had already exceeded the record for the date of 0.92" set back in 1947. Additional heavy rainfall was expected to further boost Tuesday's tally.
Standing water forced the closing of some roads across the area. Frozen ground was among the culprits. Rainfall was unable to percolate into the soil forcing it to collect or run off.
By late Tuesday, other impressive rainfall reports were pouring into our Weather Center. Rain had reached 1.55" at Carol Stream while WeatherBug rain gauges indicated even heavier totals north and west of the city. Lake Geneva, WI reported 1.82" while the measurement at Glenview surged to 1.65" with Wilmette not far behind at 1.44".
Falling temperatures to the west indicators of the weather to come
With temperatures in free-fall west of the Mississippi late Tuesday evening, there was little doubt additional big weather changes were on the way to Chicago. The wintry chill, which turned rain to snow over Iowa, Missouri and sections of Nebraska and Kansas, was headed this way.
Measurable snow's have followed 19 of city's rare 21 January 60s since 1884; predicted 1-3" totals Chicago but 4-8" toward Rockford
The transition to snow predicted Wednesday follows a well established pattern after past January warm surges.
With just 21 instances in which a January has produced one or more 60s , a total of 19 of those 21 years went on to produce measurable snowfall. Wednesday is to be the latest to join their ranks with what may become the Chicago area's biggest single snowfall of the lackluster 2012-13 snow season.
Various snowfall forecast techniques suggest the switch to snow, expected to reach the city toward midday, may lead to 1-3 inch accumulations in the city and even more to the north and west, where 4-8 inch totals are predicted toward DeKalb and Rockford, north into Wisconsin.
Return to wintry chill to be spread across four days; Chicago in line for a record 65-degree temp pullback by Friday morning
Arctic cold's on the move again, a development which will become increasingly evident to Chicagoans in coming days as temps undergo a record four-day, 65-degree temperature pullback ----from Tuesday's 63-degree high to Friday morning's 2-below minimum temperature at O'Hare. A temp drop of that magnitude would be the first of its kind here in 142 years of weather observations..
Near 0 temps and sub-zero wind chills to grip area by Thursday night/Friday morning
Friday is to dawn with single-digit and sub-zero temps and a gusty northwest wind expected to drive wind chill readings as much as 20-degrees below zero!