THE GREATEST 48 HOURS OF WEATHER....
January 24th, 1967 marks the anniversary of one of the most remarkable weather events in Iowa history. 51 years ago an unprecedented tornado outbreak exploded over southeastern Iowa and portions of Missouri, Illinois, and Wisconsin. There were at least 13 tornadoes in Iowa with many of these producing significant F2 or F3 damage. To this day, these are the only January tornadoes ever reported in Iowa.
Two tornadoes struck Lee County resulting in 10 injuries, and one of those tornadoes produced F3 damage that killed a young child west of Fort Madison. Another tornado produced F4 damage just across the border in northeastern Missouri before entering Davis County. Later that evening, a strong cold front swept across the state and by the 26th, snow fell across about the southern half of Iowa with snowfall amounts ranging up to 13.5 inches at Burlington, less than two days from the significant tornado outbreak in the same area.
Here's the surface pattern showing 60s in SE Iowa and teens in the NW corner of the state. Dewpoints in SC Iowa ahead of the advancing surface low approached 60 degrees...remarkable for January and no doubt the catalyst for tornadic supercells.
The incredible turn of events makes this one of the most extraordinary 48 hours of weather in Iowa history.
While the warm side of the storm was unprecedented, so too was the wintry side which spun up in less than 24 hours. In Chicago where the high reached 65 the 24th, thunderstorms ushered in the cold front that dropped temperatures to levels cold enough to produce snow. With plenty of moisture and warmth just to the southeast, snow broke out as a new low pressure wrapped up over southern Illinois. For a number of hours snow fell at the rate of 2" per hour. By the time it ended, 23" had piled up for an all-time record 24 hour snowfall in Chicago.
Here's some excerpts from an article produced by the NWS in Chicago.
Snow began on Thursday morning, January 26th but most people made it to work and school without much trouble. But by noon about 8 inches was already on the ground and O’Hare Airport was shut down. Some businesses and schools released employees and students early. The commute home, even for those who started early, was a nightmare. Many workers did not get home, or arrived very late. Many stayed at work or in hotels. By Friday morning the city was at a standstill. The airports and local transportation were shut down. In the city of Chicago 20,000 cars and 1,100 CTA buses were stranded in the snow. People walked to stores to clear the shelves of bread and milk. Helicopters were used to deliver medical supplies to hospitals, and food and blankets to stranded motorists. Expectant mothers were taken to hospitals by sled, bulldozer and snow plow. At least a dozen babies were born at home. Looting became a problem on the west and near south sides of the city. Another problem in the aftermath of the storm was low supplies of heating oil. Trucks couldn’t get access to buildings.
By Saturday the 28th, Chicago was beginning to dig itself out. Commuter trains were running and CTA buses were operating most lines. The city sent a workforce of 2,500 people with 500 pieces of equipment out to clear the streets. Iowa, Wisconsin and Michigan sent heavy equipment to help with the snow removal. But the thousands of abandoned vehicles hampered the clean up. Snow was hauled by dump truck to the Chicago River. O’Hare finally opened around midnight Monday, allowing people who had been stranded for days to finally get home. Most schools didn’t reopen until Tuesday. By then most transportation was back to normal.
By the time it was over, 60 people were dead and there was an estimated $150 million in business losses (about $904 million in 2006 dollars). The 1967 snowstorm probably caused the biggest disruption to the commerce and transportation of Chicago of any event since the Great Chicago Fire of 1871.
On Wednesday January 25 a cold front had moved through the upper Midwest replacing the balmy 60 degree weather of the previous day with more seasonal readings. A strong 1032mb (30.48 in) high pressure center was over the prairie provinces of southern Canada. A vigorous upper level trough was moving across the southern Rockies causing a low pressure area to form at the surface near the Texas Panhandle. By midnight of Thursday January 26 the high was building into the northern plains states while the low, now at 1008mb (29.77 in) continued to develop and move east to Oklahoma. During the day Thursday the upper trough moved through the mid and lower Mississippi Valley and an upper level low began forming near the Missouri/Arkansas border. The surface low moved through Arkansas and western Tennessee and Kentucky, reaching south central Indiana by midnight Friday. The low deepened rapidly to 997mb (29.44 in) as it moved to Indiana.
Dew points in the 50s to lower 60s over the southern plains and Gulf Coast states fed the storm with ample moisture while the Canadian high pressure, now centered over Lake Superior and southern Ontario, kept cold dry air pouring into the Great Lakes. The strong pressure gradient between the high over the upper Lakes and the deepening low over the Ohio Valley caused winds to howl off Lake Michigan. This produced severe blowing and drifting of snow as well as causing lake effect enhancement of the snowfall.
On Friday the upper low continued to form and move northeast to northwest Ohio. The surface low occluded and deepened to 990mb (29.23 in) as it lifted northeast across Lake Erie and into southeast Ontario, Canada by Friday night. By this time the snow had ended in Chicago and winds shifted to north northwest and began to subside.
The Forecast for Chicago 1967: