Bitter Cold Returns
Cold temperatures reminiscent of last winter returned to the Midwest this week as polar air rushed into the Midwest from Canada (Figure 1). The closest to normal average temperatures in the Midwest were on the western fringes of the region. Even those areas were 10-15°F below normal. The coldest areas were in Kentucky and Ohio, where temperatures were as much as 25°F below normal. The remainder of the region really didn’t fare any better with temperatures 15-20 degrees below normal. Average low temperatures were below 0°F for all of Wisconsin, Minnesota, Michigan and Ohio, as well as parts of Indiana, eastern Kentucky, northern Illinois and northeast Iowa (Figure 2). Single digit average lows were seen across the rest of the region.
Wet In the South
After very little precipitation last week, two major winter storms brought large amounts of precipitation to the southern half of the Midwest this week (Figure 3). Precipitation amounts of a half inch or more were common from southern Illinois, Indiana, and Ohio and further south. Most of Kentucky saw well over an inch of precipitation this week with nearly half of the state seeing more than 1.5 inches. Isolated areas up to 3 inches were also seen in the southern fringes of the state. Farther north, Iowa and northern Illinois stayed mostly dry with minimal precipitation seen throughout most of Wisconsin and Minnesota. While lake effect snow showers brought up to a half inch of precipitation to the Lake Michigan coast and U.P. of Michigan, western portions of the state were quite dry. Luckily, the driest areas did not see much in the form of a below normal departure this week as lower precipitation amounts are expected during the winter months (Figure 4). Areas in Kentucky, southern Illinois and southeastern Missouri, however, saw 2-3 times their normal precipitation for this week (Figure 5).
Snowfall amounts were also quite high this week (Figure 6), with two major storms moving through the region. Most of the southern half of the region saw 5 or more inches of snow this week while areas in eastern Kentucky saw 12-18 inches of snow, thanks in large part to one of the largest storms in decades across the state on February 15-17. Lake effect snows along the western Lake Michigan coast and in the Michigan U.P. also dropped 5-10 inches.
Wild Week in Kentucky
Before this week, Kentucky had seen mainly 2-5 inches of snow across the state this season. During the snowstorm on February 15-17 (Figure 7), most of the state saw 8-16 inches! In most cases, this was the most snowfall in decades across the state. This prompted Kentucky governor Steve Beshear to declare a state of emergency across the entire state. It even caused the Harlan, Kentucky Police Department to jokingly issue an arrest warrant for a beloved Disney character.
All of this snow made the frigid air-mass that followed even colder. Below zero lows were seen in northern and western Kentucky on the morning of February 17th. A low of -17°F was recorded in Brandenburg, Kentucky. Yet another burst of brutally cold air came on February 19th as most of the state saw temperatures 5-10°F below zero.
And if Kentuckians thought they had seen it all, they were wrong! On February 20-22, another major system moved through the state. The system started as light snow and wintry mix before turning into rain. 1-3 inches of precipitation fell across the state, with most of that falling as rain. This melted a good portion of the snowpack across the state. Thankfully, the heaviest rain fell over areas where moderate drought is present.
Exceptionally Cold Night February 19
Near record lows gripped the Midwest on the morning of February 19 as arctic air intruded the region (Figure 8). Almost the entire region saw low temperatures below zero. Nearly all of Wisconsin and Minnesota were 10°F below zero with northern Wisconsin, Minnesota and the western U.P. of Michigan was 25-35°F below zero. The western Ohio Valley also saw temperatures 5-15°F below zero. Northerly winds accompanying this cold snap prompted wind chill advisories and warnings as wind chills of 15-30°F below zero were common across the region.
With the prevailing wind direction from the north to northwest and plenty of open water on Lake Michigan, conditions were good for lake effect snow showers on Michigan’s western shores most of this week (Figure 9). Totals of 5-12 inches were common across the western lakeshore counties with a sharp decline in totals to the east. Lake effect snow was also seen in the Upper Peninsula this week accounting for 5-8 inches of snow. However, Lake Superior is beginning to freeze completely over, which should shut off most of the lake effect snow in the U.P. in the coming weeks.
A major winter storm moved through the Midwest starting on February 20 and continuing through February 22. Heavy rain fell from southern Illinois into Kentucky as temperatures hovered just above freezing. Almost all of Kentucky saw more than an inch of precipitation, with the southern fringes of the state seeing as much as 3 inches (Figure 10). Farther north, a belt of snow fell from northeast Missouri through Ohio. Snowfall totals of 3-6 inches were common with isolated higher amounts (Figure 11). The added precipitation from this storm may help lower drought prospects across Kentucky.
With temperatures for the month 10-15°F below normal along the Great Lakes, ice cover has rapidly increased over the past few weeks. Lake Erie and Huron are almost completely ice covered, while Lake Superior has only a small portion of open water remaining. Lake Ontario, often the hardest of the Great Lakes to freeze because of its depth, has around 50% ice cover compared to only around 20% last year. On February 18th, the Great Lakes Environmental Research Laboratory estimated ice cover on the Great Lakes to be 85.4% (Figure 12). This is similar to last year where the highest extent of ice coverage was 92.5% on March 6th, 2014. Continued cold weather should add to the ice cover percentage in the coming weeks. The record ice cover percentage since records were started in 1973 was 94.7% in 1979.
When the National Drought Mitigation Center released its drought monitor for this week (Figure 13), it hadn’t included the heavy rainfall across the state on February 20-22. However, moderate drought conditions were kept across most of the state after the heavy snowfall on February 15-17 as streamflow continues to be low across the state. Deficits since November 1 have been cut into significantly due to these two major storms, but most of western and northern Kentucky continues to be 4-6 inches below normal for the winter season (Figure 14).
The Kentucky Climate Center also contributed to this report.