A Weak El Nino Has Arrived, Another Winter Storm for Southern Illinois

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El Niño Arrives in 2015. This image shows the average sea surface temperature for February 2015 as measured by NOAA satellites. The large area of red (warmer than average) can be seen extending through the equatorial Pacific. (Credit: NOAA)

Today the National Weather Service reported that the long-awaited El Niño has arrived in the Pacific Ocean. El Niño occurs when we have above-average temperatures in the Pacific Ocean along the equator. It alters the Pacific weather pattern, which in turn alters our weather patterns over the US. The NWS forecasters say “it is likely (50 to 60 percent chance) that El Niño conditions will continue through summer. ” Due to the weak nature of this event, they are not expecting widespread or strong impacts from this event.

In other news, far southern Illinois was hit this week with another winter storm that passed through Arkansas; southeastern Missouri;  southern Illinois, Indiana, and Ohio; as well as most of Kentucky and points beyond. Some of the largest snowfall totals from this event include Grand Chain Dam with 10.0 inches and Brookport Dam with 9.0 inches.

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Winter Finishes Cold and Snowy in Illinois

The statewide average temperature for the three winter months of December, January, and February in Illinois was 26.1 degrees, 7.5 degrees below average. While cold, it was not nearly as cold as last winter’s 21.7 degrees. This winter ranks as the 30th coldest on record.

winterThis winter started off mild with an average December temperature of 33.9 degrees, 4 degrees above average.  The average temperature in January was 25.7 degrees, only 0.7 degrees below average, and the average in February was 18.6 degrees, 12.3 degrees below average. See figure to the left, click to enlarge. Last winter, all three months were well below average.

Snowfall

Snowfall was above average for the winter from December through February. Most of that fell in February. December was snow-free for most of the state except in the far west. Snowfall was common in January but below average except for a band across northern Illinois. Major snows occurred in February to bring up the winter snowfall totals across the state. Above-average snowfall occurred across northern and western Illinois as well as far southern Illinois. The maps below show the observed amounts and departure from average.

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Precipitation

map1The average precipitation for December-February was 4.97 inches, 1.85 inches below average. In fact, most of the Midwest received below-average precipitation this winter (figure left). Precipitation is a measure of both rainfall and the water content of any snow. While we received above-average snowfall, the water content of that snow was not always great. In a typical year we can get rain in winter, but not so much this winter. This kind of precipitation deficit would be a concern during the growing season. However, in winter the water demand is low.

February – 7th Coldest on Record for Illinois

The statewide average temperature for February was 18.6 degrees. That is 12.3 degrees below the 1981-2010 average and the 7th coldest February on record. By comparison, February 2014 was 9th coldest at 19.5 degrees.

Here are some amazing statistics for Chicago. February was tied with 1875 for the coldest on record, according to the Chicago National Weather Service.  The average temperature for February was 14.6 degrees, 13.1 degrees below average. In addition, it was the 10th coldest month overall on record. February snowfall in Chicago was the third largest on record with 26.8 inches, 17.7 inches above average.

Snowfall for February in Illinois was widespread and well above average. Amounts of 15 to 20 inches were common in western and northern Illinois and 10 to 15 across central Illinois and parts of far southern Illinois. This was 8 to 12 inches above average in many locations. See maps below. Click to enlarge.

Some other February snowfall totals from around the state:

  • Chicago Midway AP: 28.3 inches
  • Rockford: 14.7 inches
  • Peoria: 12.8 inches
  • Quincy Lock and Dam: 11.2 inches
  • Springfield: 22.6 inches
  • Champaign-Urbana: 12.4 inches
  • Bloomington-Normal: 13.0 inches
  • Carbondale: 6.0 inches

The statewide average precipitation (rain plus the water content of snow) for February was 1.5 inches, 0.5 inches below average. Most of the state received 1 to 2 inches of precipitation, except for far southern Illinois which got 2 to 3 inches. See the second batch of maps for precipitation and precipitation departures from average.

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