November 2013 will always be remembered for the tornado outbreak on November 17, 2013, that produced 25 tornadoes across Illinois based on the latest reports. Much has been written on that subject in this blog and elsewhere. While not as dramatic, November 2013 in Illinois was colder and drier than average.
The statewide precipitation was 2.6 inches, 0.9 inches below the 1981-2010 average. This is the fifth month with below-average precipitation for Illinois. Since July, the statewide precipitation has been 12.2 inches and 5.4 inches below average. That ranks as the 15th driest July-November on record. It is in stark contrast to the first half of 2013 which was the wettest January-June on record with 29.0 inches.
Snowfall was common in the northern half of the state in November. Snowfall amounts were heaviest in the northwest corner of the state and in the range of 4.0 to 4.6 inches in the Galena area.
The statewide temperature for November was 38.3 degrees, 4.2 degrees below average. While cold, it was far from the coldest November on record. That record stands at 33.6 degrees in 1976. Many places in Illinois experienced both spring-time temperatures and winter chill in November.
The warmest day of the month was November 17 as warm, moist air moved in from the south ahead of a strong cold front. This warm, moist air helped fuel the tornado outbreak. Just a week later low temperatures dropped down into the teens. For example, Chicago O’Hare Airport reported a high of 69 degrees on November 17 and a low of 11 degrees on November 24. That is a 58-degree change in temperature in 7 days.
Below are the summary maps for November precipitation accumulation, November precipitation departures, and snowfall accumulation. The outstanding features are the widespread dryness around the state as shown in the second map and the widespread report of snowfall in the northern half of the state.
Note: the word average used in the text and the word normal used in one of the maps below refers to the 1981-2010 average.