Monthly Temperature and Precipitation for 2015 in Illinois

How things are shaping up in 2015? The outstanding features so far are the extremely cold February and the extremely wet conditions in southern Illinois while dry elsewhere.

Monthly Temperature Departures from Average

Blue means colder than average, red means warmer than average. Temperature departures from average tend to cover very large areas, making the statewide average temperature departure a good indicator of conditions around Illinois.

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Monthly Precipitation Departures from Average

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Seasonal Outlooks for Illinois

Last week, the Climate Prediction Center released their outlooks for February and beyond. There is nothing exciting to report for Illinois. Both the outlook for February and the 3-month outlook for February-April have us in “EC” or equal chances of above, below, and near-average temperature and precipitation. See map below (click to enlarge). That’s not bad news – it means there are no increased risks of a colder than average winter.  Continue reading “Seasonal Outlooks for Illinois”

NWS Outlook for November and Winter

Today the NWS Climate Prediction Center has released their latest outlook for November and this winter. Below are the maps for November temperature, November precipitation, December-February temperature, and December-February precipitation.

For Illinois, November temperatures have equal chances (EC) of being above, below, or near-average. November precipitation is rated as EC except for the northeast quarter of the state, which has an increased chance of below-average precipitation. This is part of a larger area with increased chances of below-average precipitation across the Great Lakes region.

The category of EC is a little hard to interpret. Basically, it means that there are no consistent indications that conditions could be too warm/cold/wet/dry. Sometimes I call it a neutral forecast.

For December-February, the traditional winter months, Illinois has equal chances (EC) of above, below, and near-average temperatures. However, Illinois has an increased chance of below-average precipitation.

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When Is Fall? Astronomical, Meteorological, Climatological?

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The Quad – University of Illinois in fall color.

No doubt today (September 22) will be announced as the “first day of fall” because of the fall or autumnal equinox. However, that concept refers to the date when we get equal amounts of daylight and dark.  I don’t think it was ever intended that this astronomical event would be the start of fall. In fact, this equinox would be the start of spring in the southern hemisphere. So to be fair to everyone we should call it the September equinox and leave fall out of it.  😉

Climatologists and meteorologists prefer to use calendar months to define the four seasons in the US. For example, fall would start September 1 and end on November 30. Not only is this more convenient, because you can use monthly data, but it lines up better with the typical or average temperature pattern for Illinois. Unfortunately, the meteorologists would describe this three-month period as “meteorological fall”. However, I would argue it is “climatological fall” since we are looking at long-term average to determine the season.

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