Warm, Wet, and Active Spring

March was warmer and wetter than average across the state, continuing the pattern from winter. The preliminary statewide average March temperature was 43.5 degrees, 2.20 degrees above the 30-year normal and the 28th warmest on record going back to 1895. Preliminary statewide average total March precipitation was 3.96 inches, 1 inch wetter than the 30-year normal and tied for the 34th wettest on record.

Data are provisional and may change slightly over time

Persistent Warmth in March

Much like the first two months of 2020, March temperatures were consistently above the long-term average.

The first two months of the climatological winter season were much warmer than average, with very few cold air incursions. The plot below shows the March daily average temperature as a departure from average in Rockford. Since the start of 2020, over 70 percent of days in Rockford have been warmer than the long-term average. This has caused 2-inch and 4-inch soil temperatures to generally remain above freezing over this time, according to observations from the Illinois Climate Network (https://www.isws.illinois.edu/warm/soil/).

Average temperatures in March ranged from the high 30s in northern Illinois to the low 50s in southern Illinois. Temperatures ranged between 1 and 5 degrees above the long-term average. The statewide average March temperature was 43.5 degrees, which is 2.20 degrees above the 30-year normal and tied for the 28th warmest on record. March marked the fourth consecutive month with statewide average temperatures above the 30-year normal. By comparison, the first three months of 2019 were all 1 to 3 degrees below the 30-year normal, considerably cooler than 2020 so far.

The warm weather in March resulted in three daily high maximum temperature records and seven daily high minimum temperature records being broken across the state. The few cold, cloudy days we had in March also resulted in six daily low maximum temperature records and one daily low minimum temperature record being broken across the state. The long-running station in Carbondale was only 1 degree away from its all-time March high minimum temperature record on March 28, thanks to a strong mid-latitude warm sector bringing warm air from the south. Multiple stations in southern Illinois recorded daily maximum temperatures at or over 80 degrees during the last week in March. At one of these stations, Fairfield in Wayne County, this was two weeks before the average first 80-degree day based on the long-term record.

The highest temperature recorded in the state in March was 81 degrees in Alexander, Pope, and Hardin Counties, while the lowest temperature was 8 degrees in Jo Daviess, Knox, and Whiteside Counties.

Storms Bring Heavy Rain to Northern and Southern Illinois

Frequent precipitation persisted from February into March for the southern part of the state. Most areas south of Interstate 64 received over 6 inches of total precipitation in March, and some areas received over 8 inches. This represents between 150 percent and 200 percent of normal March precipitation in southern Illinois (see map below). Most stations in southern Illinois received 50 percent or more of their total March precipitation in one 24-hour period between March 20 and 21, thanks to a series of storms that tracked across the region.

One-day precipitation totals reached 4.50 inches in Clay County, which set the all-time March one-day precipitation record at the station in Clay City and broke the previous record by over three-quarters of an inch. Other large one-day totals from the March 20 storms included 3.85 inches in Mt. Vernon in Jefferson County and 3.55 inches in Olney in Richland County. With these one-day totals subtracted, March 2020 was very close to March 2019 total precipitation in southern Illinois; however, because of this event, most areas in southeast Illinois received between 1.5 and 2.5 times the amount of March 2019 precipitation this month.

Although March precipitation totals in northern Illinois were not as generous as those in the south, northern Illinois was not averse to very large one-day precipitation totals. A series of storms that moved through on March 28 generated between 3 and 4 inches of precipitation in a less than 24-hour period for a stretch of Illinois between the Quad Cities and the western suburbs. One CoCoRaHS observer in Prophetstown in Whiteside County recorded 5.34 inches on this day. Unfortunately, the heaviest precipitation missed the longer-term COOP stations in the region, but the storm did manage to break the all-time March one-day precipitation total in DeKalb.

Total March precipitation ranged from over 8 inches in far southern and southeast Illinois to just over 2 inches in central Illinois. These totals ranged from over 200 percent of average March precipitation in southeastern and northern Illinois to just over 75 percent of average March precipitation in western Illinois. Most of central Illinois received between 75 percent and 125 percent of average March precipitation. This combined with above average temperatures allowed soils to dry a bit across central and western Illinois.

Last month was the wettest March on record at Rock Island Lock & Dam 15, with 6.17 inches recorded. The wettest place in the state last month was Clay City with 8.31 inches.

Overall, the preliminary statewide average total March precipitation was 3.96 inches, exactly 1 inch more than the 30-year normal and the 34th wettest on record. Although the March average does not reflect the 5- to 6-inch differences in precipitation between central and northern/southern Illinois.

Most of the northern half of the state experienced measurable snowfall last month. March totals ranged from around 6 inches in northeast Illinois to just over one-tenth of an inch along the Interstate 70 corridor. A winter storm on March 22 and 23 accounted for the vast majority of snowfall in the northern part of the state, with one-day totals exceeding 6 inches in Grundy County. Morris in Grundy County was the snowiest point in the state in March, with just over 7 inches of total snowfall.

March total snowfall departures mimic the spatial patterns for the entire winter season. Most areas of western, northwest, and west-central Illinois had totals within 5 inches of the long-term average, whereas most counties south of Interstate 70 as well as counties in the Chicagoland metro area have experienced 5 to 10 inches below average snowfall since the first snow of the season.

Severe Weather

Illinois experiences severe weather and storms in all calendar months, but March often begins the unofficial severe weather season. This last month we had numerous severe weather and storm reports, ranging from snowstorms to large hail and a few tornadoes. Trained spotters reported 2-inch hail in both Williamson and Vermilion Counties last month, with many more reports of 1.5- to 1.75-inch hail across southern and central Illinois. The AWOS station in Hyde Park in Cook County recorded a 61 mph non-thunderstorm wind gust on March 29. Finally, multiple tornadoes were reported in Illinois last month in southern and west-central Illinois, including three tornadoes between Peoria and the Quad Cities on March 28. One of these, an EF-1 tornado, developed just a quarter mile east of the Peoria International Airport, according to the Lincoln National Weather Service https://www.weather.gov/ilx/032820Tornadoes).

 Outlooks

Short-term 8-14-day outlooks from the NOAA Climate Prediction Center show strongly elevated odds of both above normal precipitation and above normal temperatures across the state.

Longer-term 30-day outlooks are similar to the 8-14 day outlooks, with continued elevated chances of warmer and wetter conditions across the state for April.

Heavy precipitation in northwest and southern Illinois, combined with continual snowmelt in the Upper Midwest has continued the threat of flooding along most major rivers in Illinois. Currently, gauges along the Mississippi, Ohio, Illinois, and Wabash Rivers are at or above minor flood stage, with nine gauges in moderate flooding, according to the National Weather Service River Forecast Center.

Mt. Carroll reclaims the title for the record minimum temperature in Illinois

Mt. Carroll reclaims the title for the record minimum temperature in Illinois

Champaign, Ill., 3/6/19: An Arctic outbreak in late January 2019 led to widespread bitterly cold temperatures across much of the Upper Midwest, including Illinois. On the morning of Jan. 31, the cooperative weather observer at Mt. Carroll, located in Carroll County, reported a temperature of -38 degrees.

After a comprehensive review, the State Climate Extremes Committee (SCEC) unanimously voted to validate the -38 degrees reading as the new official state record minimum temperature. This committee ensures that the observation is meteorologically plausible, is within a range that the reporting instrument can detect, and that the instrument is in proper working order.

Brian Kerschner at the Illinois State Water Survey represented the Illinois State Climatologist Office as a member of the SCEC, along with delegates from the National Weather Service (NWS), the Midwest Regional Climate Center (MRCC), and the National Center for Environment Information (NCEI).

The previous minimum temperature record for Illinois was -36 degrees set in Congerville, located in Woodford County, on Jan. 5, 1999. The coldest temperature prior to the Congerville record, -35 degrees, was also set at Mt. Carroll in January 1930, and was later tied with Elizabeth in February 1996.

The Mt. Carroll station is a traditional daily observing station located in northwestern Illinois. It has been in service, with minor interruptions, since 1895, and has been observing temperatures since 1897. It is operated by the City of Mt. Carroll and attended by staff at the city’s water treatment plant.

You can view the final report on the NCEI website here: https://www.ncdc.noaa.gov/extremes/scec/reports

A complete list of current state records can be found here:
https://www.ncdc.noaa.gov/extremes/scec/records/IL

Mt. Carroll coop weather observation site
Feb. 1, 2019.
Photo: NWS Quad Cities WFO

 


Media Contacts: Brian Kerschner (217) 333-0729, Fax: (217) 244-0220, statecli@isws.illinois.edu

Editor: Lisa Sheppard (217) 244-7270, sheppard@illinois.edu

Contrails and Cloudiness

contrail1
Photo by Jim Angel, Champaign, IL, January 28, 2015.

This morning we had a brilliant display of airplane contrails, enough to significantly increase the cloudiness (as if we needed more cloudiness this winter). Despite rumors to the contrary, airplane contrails are just the byproducts of burning jet fuel at high altitudes where the air is very cold and dry. The basic chemistry involves combing a carbon-based fuel and oxygen to produce CO2 and water.  CH4 + 2O2 –> CO2 + 2H2O

It’s the same process you see on a cold morning with car exhaust. The water vapor exits the exhaust pipe and condenses when it hits the colder air temperature, resulting in a white fog.

There have been some studies (mentioned below) to suggest that airplane contrails can lead to regional increases in cloudiness over time. As a result, in certain regions the daytime highs may be lower and the nighttime lows higher. In other words, a reduction in the range of daily temperatures. Continue reading “Contrails and Cloudiness”

Fort Armstrong Weather Records (1820-1836)

This semester a University of Illinois Department of Atmospheric Science student, Lauren Graham, worked to make available scanned images of the weather records for Fort Armstrong that cover the period 1820 to 1836. Fort Armstrong was located at the present-day Rock Island Arsenal. The original records were maintained and scanned by staff at the Rock Island Arsenal Museum.
These are the oldest official weather records that I have been able to find for Illinois. The records contain daily temperature readings taken at 7 am, 2 pm, and 9 pm, as well as comments on the weather. My favorite is a note in the first month about a “violent hurricane” on July 21 1820 (see image below). I’m sure it was not really a hurricane but either a tornado or severe thunderstorm with high winds.
Here is the press release of the story.
Here is the Fort Armstrong page containing the images and preliminary analysis.
The plans are to introduce more analysis of these data over the summer.

Fort Armstrong, July 1820. Note the comment on July 21 about the “violent hurricane”. Click to enlarge.

New Climate Normals for Illinois

The new 1981-2010 climate normals are available for Illinois. You can find them through a station list or a Google Map on my homepage.
Climate normals are 30-year averages that are updated every 10 years in the U.S. The National Climatic Data Center produces the climate normals for the US. By settling on a standard averaging period, users are able to compare climate conditions between two or more locations.
By updating every 10 years, the climate normals can reflect data from newer stations as well as reflect any changes to the climate.  One impact of switching from the 1971-2000 to the 1981-2010 climate normals was that the cold, snowy winters of the 1970s fell out of the calculations. As a result, the new normal snowfall has dropped a little in most places. For example, the new normal annual snowfall is 3 inches less in Champaign-Urbana.
The National Climate Data Center has a climate normals page dedicated to the new climate normals and frequently asked questions.

Snowfall Totals from around Illinois

The winter storm of February 1-2, 2011, will be remembered by many in northern and central Illinois. The National Weather Service (NWS) did an excellent job of producing forecasts and warnings on this storm. In the aftermath, we have began collecting the snowfall measurements from a variety of networks. Rather than list all the data here, I have provided some links to data sources.
Snowfall totals and some maps provided by NWS offices are available here:

Here is a preliminary look at snowfall totals across the Midwest. Snowfall amounts in excess of 12 inches extend from Oklahoma, into Missouri, the northern half of Illinois, and on into northern Indiana and southern Michigan.

Experimental Hour Snowfall Analysis
Preliminary snowfall totals map for the February 1-2, 2011 storm (NWS image).

And zooming in on northern Illinois.
Snowfall totals for the February 1-2, 2011, event in northern IL (NWS image).

Short-Term Weather Lore Holds a Kernel of Truth

Before the Internet, The Weather Channel, and NOAA radios, our ancestors relied on nature to tell its tale of upcoming weather. Moss growing on the south side of trees and squirrels hiding their nuts deep underground were thought to foretell a severe winter ahead.
Some natural prognostications like these are grounded in truth, given our current knowledge of meteorology, but others are purely fiction, according to State Climatologist Jim Angel of the Illinois State Water Survey at the University of Illinois at Urbana-Champaign.
Short-term weather forecasts based on nature observations are more likely to be accurate than long-term seasonal predictions.  In fact, there may be some merit to the notion that bad weather is coming when cattle lie down in the pasture and birds fly low.
“Many animals have a better sense of hearing and smell than we do, so when humidity, air pressure and wind direction change right before a storm, as well as the distant rumble of thunder, some animals may become restless,” Angel said.  “They can pick up on weather changes hours before we can.”
Predictions based on the appearance of the sky are thought to be particularly valuable, since certain clouds are associated with certain weather conditions, according to Angel.  Clouds described as mare’s tails and mackerel scales are very high-level cirrus and cirrocumulus clouds that can precede an approaching warm front, with rain not far behind.
Likewise, a halo around the moon is actually the refraction of moonlight through the ice crystals that make up high-level cirrus clouds, indicating an approaching low-pressure system bringing rain or snow.
Long-term forecasts, such as winter weather predictions, are much more uncertain.
“Centuries ago, it was important to determine how severe the winter would be so that adequate wood and supplies would be stored for the duration,” Angel said.  “The early settlers’ lives may have depended on their predictions, so they were grasping at anything to forecast the coming weather.  However, the size of the brown band on woolly worms, the groundhog seeing its shadow, or spoon-shaped persimmon seeds are just happenstance.”
Even with today’s modern technology, the theoretical limit of daily weather forecasts is about two weeks. Within the 6- to 14-day range, forecast errors can be large enough to limit their usefulness.
That is why forecasters typically only discuss general patterns of weather behavior beyond five days, usually in terms of probability or odds. For example, the 8- to 14-day forecast may show the eastern U.S. with an increased chance of below-normal temperatures.
The same is true for seasonal forecasts that are driven by both long-term trends and specific weather patterns such as El Niño.
For the upcoming winter, forecasters look at historical records to decipher a pattern.  The Midwest is under the La Niña effect, which is characterized by unusually cold waters in the eastern tropical Pacific Ocean.
The National Weather Service’s winter forecast for Illinois is an increased chance for above normal temperatures in the southern two-thirds of Illinois, and equal chances of above, below, and normal temperatures in the northern third of Illinois. All of Illinois has an increased chance of above normal precipitation.
What does the woolly worm predict?
-30-
Source: Jim Angel, Ph.D. (217) 333-0729, Fax: (217) 244-0220, jimangel@illinois.edu
Editor: Lisa Sheppard (217) 244-7270, sheppard@illinois.edu
The Illinois State Water Survey at the University of Illinois at Urbana-Champaign, a division of the Institute of Natural Resource Sustainability, is the primary agency in Illinois concerned with water and atmospheric resources.

Historical Record High Temperatures

With the recent warm weather, have you wondered what the record high temperatures are for Chicago and elsewhere? In the last few years, a group composed of NWS, Regional Climate Centers, and State Climatologists stitched together the weather records for 270 major metropolitan areas. The results of this project can be found at http://threadex.rcc-acis.org/
The sites in Illinois include Chicago, Moline, Peoria, Rockford, and Springfield. Amongst other things, the program reports the daily record high and low temperature and precipitation.
Here I selected the record highs for Chicago and pulled out the results for September. The program gives you the top three candidates and their dates.

Threaded Climate Extremes for Chicago Area, IL
Period of record: 1872 - 2009
Date	Highest Maximum Temperatures (degrees F)
Top 	Record		2nd Record	3rd Record
9/1	101 in 1953	96 in 1984	95 in 1960+
9/2	101 in 1953	98 in 1922	97 in 1913
9/3	97 in 1953	95 in 1960	95 in 1947
9/4	95 in 1983	95 in 1960	95 in 1954
9/5	98 in 1899	97 in 1954	95 in 1983+
9/6	97 in 1960	97 in 1954	96 in 1990+
9/7	100 in 1960	100 in 1939	99 in 1985
9/8	96 in 1960	96 in 1959	96 in 1933+
9/9	95 in 1983	95 in 1959	95 in 1955
9/10	95 in 1983	94 in 1964	94 in 1931+
9/11	95 in 1952	92 in 1908	92 in 1895
9/12	96 in 1952	94 in 1939	93 in 1962
9/13	98 in 1939	95 in 1927	94 in 2005+
9/14	99 in 1939	95 in 1927	95 in 1893
9/15	99 in 1939	94 in 1927	92 in 1955
9/16	92 in 1955	92 in 1931	89 in 1948+
9/17	93 in 1955	90 in 1988	90 in 1891
9/18	94 in 1955	92 in 1953	90 in 1963+
9/19	93 in 1955	92 in 1963	92 in 1948
9/20	91 in 1931	91 in 1895	90 in 1980+
9/21	92 in 1970	90 in 1931	90 in 1924+
9/22	92 in 1956	90 in 1986	90 in 1959+
9/23	91 in 1937	88 in 1892	87 in 1945+
9/24	91 in 1891	90 in 2007	90 in 1920
9/25	90 in 1933	89 in 1920	89 in 1900
9/26	90 in 1998	87 in 1973	86 in 1999+
9/27	91 in 1971	89 in 1987	89 in 1954
9/28	92 in 1953	90 in 1952	89 in 1971
9/29	99 in 1953	87 in 1921	87 in 1898
9/30	92 in 1971	88 in 1943	87 in 1952
+ indicates same value also occurred in a previous year.

Monitoring US and Global Climate Conditions

NOAA has an excellent website for monitoring global and U.S. conditions at http://www.ncdc.noaa.gov/climate-monitoring/index.php This site gives an overview of temperatures, precipitation, global hazards, tornadoes, wildfires, droughts, and other conditions for each month. The monthly reports are typically posted about a week or so after the end of the month. You can choose from the archive of past months/years as well.
Here is a screen shot of one of the many products available. This one is called the “U.S. Climate at a Glance” product. With this particular product you can generate national, regional, statewide maps as well as plots for key cities. Give it a try.

U.S. Climate at a Glance
Screenshot of U.S. Climate at a Glance product from NCDC showing April temperature departures.

First Documented Radar Hook Echo

The Illinois State Water Survey is home to the first ever documented radar hook associated with an actual tornado. Water Survey staff captured the historic event on film on April 9, 1953. This was a major turning point in monitoring severe weather, demonstrating that tornadoes could be identified by radar. This discovery helped lead to the first national weather radar network in the United States.
The radar was located at Willard Airport, south of Champaign IL, and was being used along with a rain gauge network to relate radar signals with rain rates. Don Staggs, the radar technician, had stayed late to complete repairs on the radar. While testing the repairs, he noticed an interesting radar return and began recording the radar scope using the mounted 35 mm camera. As a result, he captured a well-defined hook echo (see photo) on film. Afterwords, researchers related this information to damage and photos along the tornado’s path. More images and information of this event are in the links provided under the photograph.

Radar hook echo
First recorded radar hook echo of a tornado, April 9, 1953, near Champaign, IL (photo courtesy of the Illinois State Water Survey, INRS, University of Illinois).

Additional information on this event:

I talked about this event when Tom Skilling, WGN-TV, hosted his annual Tornado and Severe Storm Seminar at Fermilab in Batavia, IL on April 10, 2010. The video of the presentation is on the WGN-TV web site.