Rest of March – Cold, Wet; April-June – Wet According to NWS

The NWS Climate Prediction Center released their latest outlooks for March, April, and beyond. So far, March has been cooler and drier than normal. The statewide average temperature was 36.8 degrees, which is about a degree below normal, while the statewide average precipitation was 1 inch, about 70% of normal.

Rest of March: there is an increased chance that the rest of March will be both colder and wetter than normal, according to the NWS forecast that extends out to 14 days. Here are the maps for the 8-14 day period. The 6-10 day maps are nearly identical. The expected colder and wetter conditions are widespread across the Midwest.

April: the outlook for April resembles the waning stages of a typical La Niña event. The southern third of Illinois has an increased chance of being warmer and wetter than normal. There are no strong climate signals for the rest of the state.

April-June: the outlook for April-June shows Illinois and much of the Midwest with an increased chance of being both warmer and wetter than normal. That would be pretty much in line with the conditions we have seen in previous April-June periods. Seven out of the past eight April-June periods have been warmer than normal; six out of eight have been wetter than normal.

July-September: the big black hole of uncertainty in the central US is due to a lack of guidance from the models and the climate trends. The eastern half of Illinois has a slightly increased chance of being warmer than normal from July through September. There are no strong climate signals to provide any guidance for rainfall in Illinois. This is a very common situation with the outlooks for Illinois and the Midwest during summer because rainfall at this time of year is often driven by short-lived features (e.g., passing cold fronts) and local conditions (e.g., too much or too little soil moisture).

Historically, there are no strong trends in rainfall for this period. However, there is a lot of year to year variability. The same is true for the average temperature. We have noticed a decrease in the average daily high temperature in recent decades while the daily average low temperature has increased. The two trends essentially cancel each other out. However, higher nighttime temperatures can be detrimental to crops, livestock, and humans because it impedes the recovery from the daytime heat. Several studies have noted increases in summer humidity. That will be a subject for a separate post.



Record Wet February in Illinois

Highlights: Based on preliminary data, the statewide average precipitation (rain and water content of snow) was 5.0 inches for February, 2.9 inches above normal and the wettest February on record. It beat the old record of 4.4 inches set back in 2008.  Statewide records go back to 1895. The highest monthly snowfall total for the month was Aurora with 26 inches. The warmest reading was 83 degrees at Belleville on 2/15 while the coldest reading was -16 degrees at Fulton on 2/7.


Below are the precipitation maps for February in Illinois (click to enlarge). The left panel shows the observed precipitation while the right panel shows the departures from normal (1981-2010 average). Areas in the shades of red to purple received 5 to 10 inches of precipitation for the month. That’s about 3 to 8 inches above normal. Areas that received only 3 to 5 inches include far western and northern Illinois and that was still above normal for February. The highest reported monthly total was Streator with 11.45 inches, followed by Cobden with 10.88 inches.


As this figure from the Midwestern Regional Climate Center shows, several sites across Illinois broke daily rainfall records during the last two weeks.


Here are the streamflows in Illinois at the end of the month with most flows in the top 25 percent of all streamflows for this time of year. That is much better than two weeks earlier when streamflows were in the bottom 25 percent of all streamflows for this time of year. Source: USGS.  As the rains developed, many rivers and streams reached flood stage. While the smaller streams have subsided, the Illinois River remains at flood stage at the end of the month as the large amounts of water makes it’s way from the tributaries to the main stem of the river.



Below are the snowfall maps for February. While northern Illinois experienced between 10 and 25 inches of snowfall and was above normal for the month, the rest of the state saw little snow. In fact, areas south of Springfield reported less than an inch for the month. The largest monthly snowfall total was at Aurora with 26.0 inches. The second highest total was Chicago Heights with 25.5 inches.


The statewide average temperature for the month was 31.2 degrees, 0.3 degrees above average. However, the range of temperatures was impressive. The warmest daily high temperature was 83 degrees at Belleville on February 15. The coldest daily low temperature was -16 degrees at Fulton on February 7.

US Drought Monitor

Concerns about the dry fall and winter, especially in areas east of St. Louis, reached a peak by mid-February (left panel). However, these concerns were washed away by the heavy rains of over the last two weeks of the month. In fact, by the end of the month, no drought was present in Illinois (right panel). A few areas were still behind on precipitation but that may not present a problem now. Click maps to enlarge.

From Drought to Flood Worries in Illinois

Illinois has had a quite the shift in the weather pattern in the last few days with widespread rains across the state, including areas that have been dry for some time. Here are the rainfall totals for the past 7 days as of this morning (February 20th), both observed and departures from normal. In the top map, areas in yellow received between 2 and 3 inches. Many areas of the rest of the state received between 1 and 2 inches. As the bottom map shows, that’s above normal for this time of year, especially in the areas that received 2 to 3 inches of rain.

February 20, 2018 7-Day Observed PrecipitationFebruary 20, 2018 7-Day Departure Precipitation

Precipitation Forecast: And it continues to rain as I write this. Many areas in northern and central Illinois are currently in a flood watch or warning, according to the National Weather Service. And more rainfall is on the way. Here are the potential rainfall totals over the next five days. Southern Illinois could see between 5 and 7 inches while central Illinois could see 2 to 5 inches. Northern Illinois could see between 0.75 and 2 inches, depending on where you are. Continue reading

Outlook for Spring and Summer from NWS

The new outlooks for March, Spring, and Summer from the National Weather Service’s Climate Prediction Center are out.  You can click on any map to see the larger version.

Overview: The NWS says that La Nina conditions continued through January and into early February across the equatorial Pacific Ocean, as indicated by oceanic and atmospheric observations. The CPC/IRI consensus ENSO forecast indicates that La Nina conditions are expected to decay rapidly and transition to ENSO-neutral conditions during Spring. ENSO-neutral conditions are favored to persist through at least the summer.


Parts of Illinois shaded in blue have an increased chance of colder than normal conditions. This is part of a larger area of expected colder conditions that extend from the Midwest westward and is a classic La Nina signal for this region. Current climate conditions do not favor colder or warmer than normal conditions in the rest of Illinois. Current climate conditions do not favor wetter or drier than normal conditions in Illinois in March.


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Cold, Snowy, Cloudy Weather – Welcome to February

I will have to admit, February is not on my list of favorite months. It’s a good thing it’s only 28 days long. Here is the rundown for the first half of February.


The big story is the snowfall across northern Illinois. Many areas north of Interstate 80 have received between 15 and 20 inches of snow. In fact, Chicago experienced an impressive 9 days in a row with snowfall. A few stations have reported over 20 inches of snow. The largest total that I’ve seen is 24.0 inches at Chicago Heights (IL-CK-296), followed closely by Aurora (COOP) with 23.5 inches, and Somonauk (IL-DK-24) with 22.7 inches. Meanwhile, the snowfall totals dropped precipitously (pun intended) moving southward. Areas south of Springfield have received less than an inch and many locations in southern and southwestern Illinois have reported no snowfall in February.



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January in Illinois, Cold and Dry

January in Illinois was colder and drier than normal without much snow.


The statewide average precipitation (rain and water content of snow) was only 1.31 inches, 0.76 inches below normal. The largest precipitation total for the month was 4.07 inches at Rosiclare (Hardin County).

From the viewpoint of climate, January is one of our driest months of the year with an average of only two inches of precipitation. However, we don’t notice it because most of our precipitation falls as snow. It just seems like a lot until you melt it.

Most of the state received 1 to 1.5 inches of precipitation (figure below, left panel) with drier patches in northern and western Illinois, and much of southern Illinois. Overall, most of the state was within an inch of normal (right panel). Click to enlarge.


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NWS Outlook for First Half of 2018

The NWS released their new outlooks for the first half of 2018. First of all, the NWS notes that La Niña conditions continue across the Pacific Ocean and will likely persist through the rest of winter. It will likely fade this spring, leading to so-called “ENSO-neutral” conditions, which will continue through summer. “ENSO-neutral” just means that we are between La Niña and El Niño conditions, in other words, neutral.


The shorter-range forecasts out to 14 days indicate a shift in the weather pattern bringing warmer and wetter than normal conditions across Illinois. By this Sunday we could be in the 40s and 50s in Illinois (left panel, below) while the prospects of rainfall are high with potential totals of 1/2 to 1 inch over the next 7 days (right panel).

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