After such nice weather in October and most of November, real winter weather arrived in Illinois for December. The statewide average temperature for the first 14 days of December was 22.0 degrees, 10.6 degrees below normal.
The statewide average precipitation is 0.83 inches, 0.5 inches below normal.
Snowfall has been widespread across the state in early December. Snowfall totals range from less than an inch in far southern Illinois to over 10 inches in northwestern Illinois. See map below for snowfall totals for December 1-14, 2010.
Winter Preparedness Week
This is Winter Preparedness Week (November 14-20, 2010). As I write this, a major winter storm is moving through Minnesota and Wisconsin, so it is never too early to start preparing for winter conditions in Illinois.
Winter Storm Preparedness Guide
The Illinois Emergency Management Agency has teamed up with the National Weather Service and the American Red Cross to develop a Winter Storm Preparedness Guide (pdf). It provides information on winter storms, forecast terminology, and how to plan at home, work, school, and while on travel.
Having survived 50 winters in Missouri and Illinois, here is my short list of things to consider:
- be alert to the current weather and forecasts – my family and I spent one Christmas Eve in a hotel in Springfield IL because I underestimated the snowfall and overestimated the ability of other drivers to drive in the snow;
- dress appropriately – invest in a good coat, warm gloves, boots, hat, and scarf, you will be better prepared (and happier) in cold and snowy conditions;
- be flexible in your travel plans – go early, stay later, or don’t go at all to avoid severe winter weather;
- be prepared to be stuck at home for a few days – keep up stocks of food, water, and any medications;
- be careful with heaters and fireplaces – many home fires and carbon monoxide poisonings have been the result of improper operation of space heaters, fireplaces, or using inappropriate devices such as barbecue grills. Trust me on this one – my father-in-law was the fire chief so I heard all the stories.
History
As a historical footnote, the concept of a winter preparedness week started at the Illinois State Water Survey in response to the severe winters of the late 1970s and early 1980s. It was done in partnership with the Illinois Department of Energy and Natural Resources and the Illinois Emergency Management Agency. Winter preparedness week was expanded through the National Weather Service, beginning around 1990.
Frost in Illinois
Frost is defined as ice crystals that form on a freezing surface as moist air comes in contact with it. Farmers, landscapers, and gardeners are interested in frost in both spring and fall. However, frost is usually not measured directly at weather stations. Instead, we choose dates when the air temperature crosses the threshold of 32°F.
The Midwestern Regional Climate Center keeps tabs on what places have hit 32 degrees so far this fall. Click to enlarge.
Frost Climatology
The average date ranges from October 7 in far northern Illinois to October 21 or later in far southern Illinois (see map below). The actual date varies from year to year. For tender plants in the fall, subtract two weeks from the average date to protect against an early frost.
Although 32°F is the temperature traditionally used to identify frost, visible frost can be seen on the ground and objects when temperatures are slightly above 32°F. This occurs on calm, clear nights that allow cold, dense air to collect near the ground. Under these conditions, the temperature near the ground actually can be a few degrees cooler than at the 5-foot height of the official National Weather Service thermometer.
Open, grassy areas are usually the first to experience frost, while areas under trees are more protected because the trees help prevent the heat from escaping. Homeowners can protect tender plants by providing this same type of protection if they cover their plants when a frost is expected. Plants near heated buildings sometimes are spared too. Those living in the country tend to see frost earlier in the fall than those who live in town, because of the many warm buildings and trees in town may ward off frost in some cases.
Cold February Wraps Up a Cold Winter
CHAMPAIGN, Ill. – Based on preliminary data in Illinois, the statewide average temperature for February 2010 was 25.1 degrees, 5.1 degrees below normal. Snowfall for February was above normal. Amounts ranged from 6 inches in southern Illinois to over 18 inches in the Quad Cities and Chicago areas.
The cold February, along with colder-than-normal temperatures in December and January, made this the 19th coldest winter on record. The 3-month average temperature was 25.3 degrees, 2.9 degrees below average. Winters in the late 1970s were still much colder with a virtual tie between the winter of 1977-1978 at 19.6 degrees and the winter of 1978-1979 at 19.9 degrees.
Winter snowfall totals (December—February) ranged from about 45 inches in northeast Illinois to just under 15 inches in southern Illinois. This was 1 to 3 inches above normal for southern Illinois to over 10 inches above normal in northern and western Illinois. Wintertime precipitation, both rainfall and the water content of snow, measured 7.04 inches and was 0.35 inches above normal.
The latest National Weather Service outlook for March calls for an increased chance of below-normal temperatures in the southern two-thirds of Illinois. It also calls for an increased chance of drier-than-normal conditions for the month. See the Climate Prediction Center page.