Based on the official data, the statewide average temperature was 44.5 degrees, 8.1 degrees below normal. It was the second coldest April on record, only beaten by 43.1 degrees set in April 1907. Our statewide records go back to 1895. Normal refers to a specific benchmark, the 1981-2010 average. See the longer explanation here.
Here are the temperature departures from normal look like across the Midwest. Areas in green are 1 to 9 degrees below normal, while areas in icy blue are 9 or more degrees below normal. The lowest temperature reported in Illinois for April was -1 at both Avon and Lincoln on April 2. At the other extreme, we did reach into the 80s at times during the month. The warmest reading was 86 degrees at Kaskaskia on April 13.
As of this morning, the statewide average precipitation in Illinois was 0.34 inches. That makes it the second driest October on record. However, the forecast for Tuesday will move us down in the rankings. In the meantime, here is where we stand for dry Octobers:
October has been both warmer and drier than average so far for Illinois.
Temperatures have run 1 to 2 degrees above average in Illinois and across most of the Midwest (first map). This follows close on the heels of a September that is now considered the 8th warmest on record at 70.4 degrees according to NCEI.
Meanwhile, precipitation has been largely missing in action in October (map below). The areas in gray across Iowa, and parts of surrounding states indicate almost no measurable precipitation has fallen. It’s hard to tell on this map because of the scale, but most of Illinois has received less a tenth of an inch for the month so far. The statewide average is 0.05 inches. Continue reading “October Warm and Dry So Far in Illinois”
January 2015 in Illinois was cooler and drier than average. The statewide temperature was 25.4 degrees, 1 degree below average and the 53rd coldest on record. However, it was not nearly as cold as last January when the average temperature was 19.3 degrees and ranked as the 16th coldest on record.
The statewide average precipitation for January 2015 was 1.53 inches, 0.5 inches below average. Because of dry weather in November, December, and January, the US Drought Monitor introduced “D0” in northern and western Illinois. As I explained in an earlier post, this is not a great concern yet because of the low demand for water in winter but we are watching the situation.
Snowfall ranged from less than an inch in the far south to 10 to 15 inches north of Interstate 80 (first map). That results in above-average snowfall in the northern half of the state and below-average for the southern half (second map). However, this was far less snow than January 2014 (last map) when most of the state was covered with 10 to 25 inches of snow. Continue reading “January 2015 in Illinois – Cool and Dry”
The US Drought Monitor introduced their D0 “abnormally dry” category across northern and western Illinois (first map). Should we be worried? We have been running about 2 to 4 inches below average on precipitation this winter (second map) – that’s both rainfall and the water content of any snow. The good news is that the demand for water is very low in winter. Therefore, the impacts on soil moisture, stream flows, and lake levels so far have been minimal.
Snowfall across the central US has been slightly below average so far this winter and stands in stark contrast to last winter. However, the impact on soil moisture, rivers, and streams has been minimal.
Here is an example of snowfall differences. At Chicago O’Hare airport the snowfall total for this winter through January 14 is 13.7 inches. Last year through this date it was 35.0 inches and the 1981-2010 average is 14.2 inches.
In the first map are the snowfall departures for this winter. All the areas in tan or beige are up to 10 inches below average. That includes almost all of Illinois, Minnesota, Iowa, Missouri, Indiana, and Kentucky, as well as large portions of the Dakotas, Nebraska, Kansas, Wisconsin, Michigan, and Ohio. Areas in green are above average and include a small area in far southern Illinois and another around Moline. Snowfall is above average across upper Wisconsin and the Michigan UP. Continue reading “Quiet Winter for Snowfall across central US”
Based on preliminary data, the statewide average temperature for May in Illinois was 63.9 degrees. That is 1.2 degrees above average and the first month to be above average in Illinois since October 2013.
The statewide average precipitation for May in Illinois was 4.26 inches, just 0.34 inches below average. Below is a map of precipitation throughout the state. This is a radar-based product that is adjusted with rain gauges, resulting in higher resolution than a rain gauge network and more accuracy than a radar-only precipitation measurement. Sometimes hail can mislead the radar into calculating higher rainfall rates. That may have been the case in southern Champaign County, for example.
Some of the heaviest rainfall totals from the CoCoRaHS network for May occurred in Cook County, including Burnham-Hegewisch (IL-CK-82) with 7.64 inches and Homewood (IL-CK-64) with 7.58 inches.
The area of concern for May was the large section of blue across western and central Illinois, representing rainfall totals of only 1 to 3 inches. There are some smaller patches of blue in southern Illinois and far northwestern Illinois as well. One of the drier locations in west-central Illinois was Roseville (IL-WR-2) with only 1.32 inches with all 31 days reported. The US Drought Monitor list parts of western Illinois as “abnormally dry”.
Plots of Temperature and Precipitation
Here are the time series plots for temperature and precipitation departures for each month of 2013 and 2014. In the first plot, one can clearly see the string of very cold months from November 2013 to April 2014. On the second plot, the dryness of late last summer shows up. While March of this year was dry, it was counterbalanced by a wetter than average April.
Winter’s grip on Illinois is slowly releasing. However, we remain cold and dry for March. The statewide average temperature for March 1-16, 2014, was 30.3 degrees, which is almost 8 degrees below average. The good news is that the average, or normal, temperatures are climbing rapidly through the month. As a result, being 8 degrees below average in mid-March is still warmer than this winter. The NWS Climate Prediction Center 6-10 and 8-14 day forecasts show the below-average temperatures to continue through the end of March.
Besides the cooler temperatures, another concern at this point is the below-average precipitation (in shades of yellow and orange) for March so far. This is true not only across Illinois but much of the Midwest.
Below are the 90-day precipitation departures from average. Above-average precipitation (shaded in green) can be found in IL, IN, OH, and MI, due for the most part to our generous snows and a few rain events. However, parts of southeastern IL are 1.5 to 3 inches below average. This is part of a larger area of dryness covering Missouri and parts of KS, OK, and AR. Of course this pattern could change quickly as we get out of winter and into spring. A few good spring rains could erase most of this deficit. In the meantime, we will be watching this area closely.
The U.S. Drought Monitor just increased the drought coverage in Illinois to 100 percent. In addition, the area of D2 “severe drought” expanded in eastern Illinois and east of St. Louis and along the Illinois-Wisconsin border.
The statistics for July so far (July 1 – 11) show why the drought has worsened so quickly. The statewide average precipitation was 0.5 inches, just 37 percent of what we would normally receive in the first 11 days of July. The statewide average temperature during this time was 83.1 degrees, 7.5 degrees above normal.
The table that accompanies the map has some interesting statistics. A year ago at this time there was no drought in Illinois thanks to an exceptionally wet spring and early summer. And this year started out with no drought in Illinois. Even three months ago only a small part of southern Illinois (5 percent) was considered in a moderate drought.
The U.S. Drought Monitor is a joint effort between NOAA, USDA, and the National Drought Mitigation Center. They do consider local input on drought impacts. If you have any impacts – text and/or picture – that you would like to include for consideration, please contact me at firstname.lastname@example.org – thank you.
The Illinois State Water Survey has been monitoring the soil moisture at 19 sites around the state. The soil moisture is measured with probes set at specific depths at each site. It is reported as the fraction of water in the soil by volume. Most of the non-sandy soils in Illinois can hold up to 30-40 percent water by volume in the spaces between the soil particles.
Current observations in the driest areas of the state show significant declines at 2, 4, and 8 inches since early March. At the Peoria site, in the heart of the dry area, the fraction of water in the soil is only 15 percent at 2 inches, 18 percent at 4 inches, and 22 percent at 8 inches. The 20-inch depth has remained unchanged at 32 percent. By comparison at the end of April of last year, the fraction of water in the soil at those depths were all in the 35-40 percent range.
We are in the process of getting these data online in the next few weeks. Stay tuned.
U.S. Drought Monitor
The latest U.S. Drought Monitor map for Illinois shows an expanded area of D0 “abnormally dry” weather across the central part of the state between Interstates 70 and 80. A small area of D1 “moderate drought” is located in the area centered on Logan County. Another small area of D0 is in southeastern Illinois.