May 2019: Exceptionally Wet and Stormy Across Illinois

May 2019 will be a month remembered for exceptional, record-breaking wet conditions locally, as well as an active, stormy, and at times severe weather pattern across the state.

Preliminary data suggest that May 2019 finished significantly wetter than average, with temperatures marginally below the long-term average. The preliminary average statewide May temperature was 62.5°F, which is 0.2°F below the long-term average. The preliminary average statewide precipitation was 8.43 inches, which is 3.83 inches above the long-term average.

Precipitation

Preliminary statewide average precipitation for May was 8.43 inches, which is 3.83 inches above the long-term average, marking six consecutive months with above average statewide precipitation. As it stands now, spring 2019 will rank within the top four wettest spring seasons in state history (March–May), with May 2019 ranking as the third wettest May in state history.

The multi-sensor precipitation departure map for Illinois shows that practically the entire state received above average precipitation for the month. The only exception was a small region in east-central Illinois near Edgar County, where near to slightly below average precipitation occurred (see maps below).

Portions of west-central and northern Illinois reported the heaviest rainfall for the month, where monthly precipitation departures of 5 to 8 inches above average were common, bringing 200 to 300 percent of average monthly rainfall.  An area roughly defined between Quincy and the Quad Cities extending eastward to near Peoria received the most precipitation in the state, with 7 rain gages in this region recording 13 or more inches of rainfall during May.

A gage near Dallas City (Hancock County) reported the highest precipitation total for May, with an impressive 14.75 inches.

Data from the National Weather Service showed that with a report of 8.25 inches, Chicago experienced its wettest May on record, beating the 8.21-inch reading that was set just last year in May 2018.

The abnormally wet May weather has led to a continuation of elevated flooding risks and significant planting delays for the Illinois agricultural community.  Moderate and major flooding along many local streams and rivers is still ongoing, with flood warnings along both the Illinois and Mississippi Rivers in effect until further notice.

Wet, active, and stormy weather has not only been an issue for Illinois, but also the weather has been a growing risk across much of the central and southern Midwest including the Corn Belt where notable above average precipitation departures for May were also present (see map below).

Severe Weather

In addition to the relentless rainfall, multiple rounds of severe weather impacted the state throughout the month. Statewide, 218 severe weather reports were noted from the Storm Prediction Center, 20 for tornadoes (red), 52 for hail (green), and 146 for wind (blue). Note that multiple reports may be generated for a single event.

Map of May 2019 Severe Weather Reports in Illinois, updated 6/4/2019

Temperature

Preliminary results show that May 2019 finished with a statewide average temperature of 62.5°F, which is 0.2°F below the long-term average.

Monthly temperature departures showed that the northern third of the state generally saw average temperatures of 1 to 3 degrees below normal, while the southern third of the state generally saw average temperatures of 1 to 3 degrees above normal, with near normal temperatures occurring throughout central Illinois.

The highest maximum temperature in the state was recorded at the Kaskaskia River Navigation Lock (Randolph County) with a reading of 93°F on May 26. In contrast, the lowest minimum temperature of 31°F was recorded at the Chicago Botanical Garden (Cook County) on May 4.

June 2019

Although an active weather pattern looks to continue at least for a portion of the first full week of June, the monthly outlook from the Climate Prediction Center favors equal probabilities for below, near, or above average precipitation and temperatures across Illinois for June 2019.

April 2019: An Active Weather Pattern and Late Season Snow!

April 2019 will be a month remembered for a continuation of an active and stormy weather pattern across Illinois, with two short lived, yet notable and uncommon late season snow events which impacted many in northern portions of the state.

The month finished noticeably wetter than average, with temperatures marginally below the long-term average. The preliminary average statewide April temperature was 52.0°F, which is 0.6°F below the long term average. The preliminary average statewide precipitation was 4.58 inches, which is 0.80 inches above the long term average.

Note: Data are provisional and may change slightly over time.

Precipitation

Preliminary statewide average precipitation for April was 4.58 inches, which is 0.80 inches above the long term average.

Precipitation in Illinois has been above average since December 2018. Preliminary data would rank this as the 7th wettest December – April period in state history. The end of April 2019 marked six months since any portion of the state has been classified as in drought, or abnormally dry by the U.S Drought Monitor..

An active spring weather pattern resulted in a majority of regions in northern, eastern, and southern portions of the state receiving over 100% of average monthly precipitation, with localized amounts approaching 200%.  Smaller regions of the state in west-central Illinois – roughly between the Mississippi and Illinois rivers are the only locations to receive near or below average precipitation for the month (see map below).

The heaviest precipitation fell in extreme southern Illinois, especially in counties bordering the Wabash and Mississippi Rivers, where 6 to 8+ inches were common (see map below).  The highest total in the state was reported at a station near Cobden (Union County) with 8.31 inches.

Heading into May, flooding remains an ongoing concern for the state, as soil moisture percentiles remain in the 90th to 95th percent range.

As of April 30th, 134 river gauges affecting Illinois were reported with crests in minor, moderate, or major flood stages. The greatest threat continues to remain along the Mississippi River. River flooding concerns were intensified by several days or heavy rains during the last week of April.

Snowfall

A majority of April snowfall came from two short lived, yet notable late season events that impacted many in northern portions of the state.

The first event on the weekend of April 13th and 14th brought widespread reports of 1 to 5 inches along a corridor extending from near Quincy, and running northeast toward Chicago and the Illinois/Wisconsin border. Several localities west and north of Chicago reported 6 to 8+ inches. Notable accumulations were measured as far south as Peoria. An accumulation of 5.4 inches at Chicago O’Hare Airport tied the record for the snowiest calendar day this late in the season.  April 16, 1961 also recorded 5.4 inches of snow.

The second snow event on April 27th brought a variety of wintry precipitation types to locations in northern Illinois, including another round of accumulating snow for many from Chicago and points north and west.  With 3.7 inches, this was the latest 2+ inch snow event on record for Rockford (Winnebago County).

The maximum monthly snowfall in Illinois was reported at a station near St. Charles (Kane County) with an impressive 13.5 inches.

Temperature

Preliminary results show that April 2019 finished with a statewide average temperature of 52.0°F which is 0.6°F below the long term average.

Despite several significant temperature swings throughout the month, which are common during springtime, statewide April temperatures finished right around the long term average. A few pockets in extreme southern Illinois reported slightly above average, and sporadic regions in northern Illinois reported slightly below the long term average.  This is a welcome change from last year,  April 2018, which ranked as the second coldest April on record.

The highest temperature in the state was recorded at a station near Jerseyville (Jersey County) with a reading of 85°F on April 23.  In contrast, the lowest temperature of 18°F was recorded at a station in Altona (Knox County) on April 1.

May 2019

Looking ahead at the rest of May 2019, the Climate Prediction Center (CPC) is favoring probabilities of above average temperatures for the southeast half of the state, with equal chances of above, near, or below average temperatures for the northwest half of the state. Unfortunately, an active weather pattern looks to persist, as the May outlook favors probabilities of above average precipitation statewide.

Late April 2019 Snow Event

4/29/2019 – A strong and considerably cold low pressure system took aim at Illinois on Saturday April 27th, bringing a large area of widespread precipitation and unseasonably cool weather to a majority of the state.  The greatest impacts were felt in Northern Illinois, where temperatures were cold enough to support a variety of wintry precipitation types. This included a late season and uncommon accumulating snow for many from Chicago and points north and west.

According to the National Weather Service, the final snowfall total at Chicago O’Hare of 2.5 inches was the latest accumulating snowfall for the city since 1989, and the latest 2+ inch single calendar day snowfall in station history. The two day period of May 1-2, 1940 saw 2.2 inches.

Typically, Chicago O’Hare can expect 1.2 inches of snow in April, with the record for the month being 11.1 inches which was set in April 1975.  To date, April 2019 has seen 7.9 inches.

The official snowfall total in Rockford of 3.7 inches was the latest accumulating snow since 1994, and ranks as the latest 2+ inch snow event on record.  Beating out April 23, 1986 with 3.8 inches, and April 23-24, 1910 with 2.5 inches.

A station in Stockton (Jo Daviess County) reported 6.0 inches of snow with this event.  See the interpolated map below of preliminary snowfall accumulation across the state. (Note: Locally higher snowfall reports were common)

Behind this system, and with the aid of fresh spring snow cover, temperatures dropped across Northern Illinois, with Rockford tying the record daily low temperature on the morning of April 28th with a reading of 28°F.

In total 26 weather stations reported temperatures below freezing on the morning of April 28th, with Stockton (Jo Daviess County) reporting the lowest weekend reading in the state with just 21°F.

March 2019: A cold start to the month, with a stormy and wet finish

March 2019 will be a month remembered for an unseasonably cold start, followed by an active and wet weather pattern which resulted in a continuation of excess soil moisture, and major flooding events on many local streams and rivers.

Statewide, March ended colder and substantially wetter than the long term average.  The preliminary average statewide March temperature was 36.6°F, which is 4.7°F below the long term average.  The preliminary average statewide precipitation was 4.16 inches, which is 1.20 inches above the long term average.

Data are provisional and may change slightly over time.

Temperature

Preliminary results show that March 2019 finished with a statewide average temperature of 36.6°F which is 4.7°F below the long term average.

The first full week or March begun with a brutal Arctic outbreak in which temperature departures of 15° to 25°  below normal were common across Illinois (see map below).

During this time three stations recorded minimum temperatures of -10° or colder.  The lowest reading in the state, -12°F, occurred at the Little Red School House station (Cook County) on March 5th.

In contrast, the warmest reading in the state was 76°F, reported at a station near Dixon Spring (Pope County) on March 13th.

The map below depicts average monthly statewide temperature departures for Illinois.  March temperature departures finished below average statewide, with the coldest departures occurring across large areas of central Illinois, and in the northwest corner of the state.

Precipitation

Preliminary statewide average precipitation for March was 4.16 inches, which is 1.20 inches above the long term average.

A persistent active weather pattern along with above average precipitation were the biggest weather stories in March.  Major and historic flooding on the lower Ohio River Basin in Southern Illinois continued into the first week of March, resulting from substantial February rain events.  By the middle of the month, a strong and historic low pressure system brought heavy rain, storms, and strong wind to Illinois and the rest of the Midwest.  The heavy rains and combined regional snow melt resulted in additional widespread flooding concerns across the region.  This included a major flooding event for northern and northwest Illinois, with the Rock, Fox, and Mississippi Rivers experiencing significant crests.

The heaviest March precipitation fell across central and southern portions of the state where 4 to 6 inches were common.  Five stations in these regions reported over 6 inches of precipitation for the month.  Totals were lower in Northern Illinois with generally 1.5 to 3 inches. The lowest totals for the month occurred along the Illinois/Wisconsin border.

The highest March precipitation total of 6.41 inches was reported at a station near Jerseyville (Jersey County).

Above average March wetness led to precipitation anomalies over 100% of average for the southern two-thirds of the state, with the most impressive anomalies of 200-300% percent of average in a large area of central Illinois (see map below).

Snowfall in March did occur statewide, although it was rarely long lasting.  Storm tracks are apparent on the accumulated snowfall map, with two distinct snow maximums. One in the vicinity of the corridor from Rushville to Springfield, and a second centered near Kankakee.  In both cases 3 to 5 inches of accumulation were measured.

Spring Outlook

Soil moisture profiles across Illinois remain in the 90th percentile or higher as we head into April.  This leaves soil conditions favorable for spring runoff, and is an ever-growing concern for the agricultural community.

The National Weather Service (NWS) spring flood outlook places the entire state in its flood risk zone. Eastern and central Illinois are subject to a minor flood risk, while western, extreme northern and southern portions of the state are in a moderate flood risk zone.  Locations immediately along the banks of the Mississippi river are in a major flood risk zone.

April 2019

Looking ahead at the rest of April 2019, the Climate Prediction Center (CPC) is favoring probabilities of above average temperatures statewide.  This is a welcome change compared to April 2018, which ranked as the second coldest April in state history.  An active weather pattern looks to persist, as the April outlook favors slight probabilities of above average precipitation for the western half of the state.

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

Meteorological Winter Recap: 2018-2019

Winter Review:  December – February (2018-2019)

Although the first week of March 2019 does not give us the satisfaction that spring will be arriving in the near future, it does mark the end of the meteorological winter season, which runs from December – February.

Despite what felt like an eternity of below average temperatures, the season as a whole finished with temperatures relatively close to the long term average. Referring to the map below, which represents average temperature departures, a few localities in the west-central and northwest portions of the state saw temperature departures of 1°F or more below average.  On the opposite end, locations in southern Illinois experienced temperature departures of 1-2°F above average during the 2018-19 winter season.

Statewide temperatures averaged 29.9°F, 0.8° above the long term average.

Average temperature for the season ranged from the low 20s north, to around 40° toward extreme southern Illinois.  Large variations occurred with seasonal highs in the 70s and lows in the -30s. The maximum temperature of 71°F occurred on Dec. 1 at Kaskaskia Navigation Lock in Randolph County.  The lowest temperature of -38°F occurred on Jan. 31 at Mt. Carroll in Carroll County, setting a new state record minimum temperature.

The last two days of January brought widespread cold weather to Illinois.  Many locations experienced some of the coldest weather that has been seen in decades allowing numerous daily and station record lows to be broken.  This event produced statewide temperature departures of 20 to 30° below average.

To gain additional perspective on this event, the updated map below displays the minimum temperature recording at stations throughout Illinois with at least 20 years of data.  The color of the station plot represents the month of occurrence, and temperatures in bold represent new records that were set in 2019 (click the map for a larger PDF version).

Precipitation was abundant throughout the state this winter season (see map below), this allowed the entire state to remain free of any abnormally dry, or drought designations during this period. Above average precipitation occurred every month during the season. Generally precipitation totals across Illinois ranged from 5 to nearly 15 inches, with counties south of I-70 experiencing the most precipitation.

Most remarkable was the 21.18 inches of precipitation reported at Smithland Lock and Dam on the lower Ohio River.  Overall, both southern and northwest Illinois received over 150% of their average winter precipitation, with several localities approaching 200% (see map below).

Statewide seasonal precipitation averaged 9.67 inches, which is 2.85 inches above the long-term average, ranking as the 6th wettest winter season on record for the state (with records going back to 1895-96).

The total accumulated snowfall map shows that snowfall occurred statewide this winter, with the heaviest accumulations centered in northwestern Illinois, and counties along the Illinois/Wisconsin border. Totals ranged from 1 to 10 inches in southern Illinois, 10 to 20 inches in central Illinois, and 20 to over 40 inches in northern Illinois.

 

Stormy, wet, and chilly February for Illinois

February 2019 will be a month remembered for an unseasonably active storm pattern, a majority of the month was characterized by a seemingly constant succession of storms resulting in moderate snow accumulations for the northern counties, and persistent rain events and widespread flooding for the far southern counties.  Between storm systems we experienced noticeable temperature swings, and periods of seasonable weather.

Statewide, February ended colder and substantially wetter than the long term average.  The preliminary average statewide February temperature was 28.6°F, which is 2.3°F below the long term average.  The preliminary average statewide precipitation was 3.33 inches, which is 1.27 inches above the long term average.

Data are provisional and may change slightly over time.

Temperature

Preliminary results show that February 2019 finished with a statewide average temperature of 28.6°F which is 2.3°F below the long term average.

The maximum February temperature of 70°F was reported at two stations, Dixon Springs (Pope County) on February 3rd, and Kaskaskia River Lock (Randolph County) on February 4th.  These temperatures came less than a week after the historic Arctic outbreak in late January, which shattered numerous all time station and daily record lows across Illinois.  Over the course of five days many stations across the state saw temperature differences of around 70 degrees or more from Jan. 31 to Feb. 4.

The minimum state temperature was -36°F reported at the Mt. Carroll observation station (Carroll County) on February 1st, a day after the station recorded a potential record state minimum temperature of -38°F on last day of January 2019.

The map below depicts average monthly statewide temperature departures for Illinois.  In February, the departure gradients tended to align in a southwest to northeast fashion, following the larger scale storm tracks.   Overall, Southeastern Illinois saw temperature departures averaging one to three degrees above normal, while much of Central Illinois was near the long term average, and a larger region in the vicinity of Northwest Illinois saw temperature departures averaging two to five degrees below normal.

Precipitation

Preliminary statewide average precipitation for February was 3.33 inches, which is 1.27 inches above the long term average.

Total precipitation was one of the biggest weather concerns for February.  While locations in the center of the state, roughly between I-80 and I-70, received anywhere from 1.5-4.0 inches of precipitation for February, the most impressive totals fell in far Northwestern and Southern Illinois (see map below). In Southern Illinois February totals in excess of 6.0 inches were common, with five stations reporting over 8.0 inches of precipitation for the month.

The highest monthly total was reported at Smithland Lock and Dam (Pope County) with an impressive 10.68 inches.  This ranks as the wettest February on record for the station, with records going back to 1981.

The persistent February precipitation corresponded to monthly totals of 300-400% percent of normal for Northwestern Illinois, and 200-300+% of normal for Southern Illinois (see map below).

Once final numbers are calculated, Feb. 2019 is on track to rank within the top 15 wettest statewide February’s on record.  Abundant regional February rainfall also contributed to a major flooding event in the lower Ohio River.  Both the Smithland Lock and Dam and Cairo river gauges crested at over 10 feet above flood stage during the last week in February. Maximum river stages are expected to be within the top 5 highest on record, according to data compiled by the National Weather Service.

Soil moisture percentiles for the month of February remained in the  90th percentile or higher across Illinois.

Snowfall

Snowfall occurred statewide during February, but was most plentiful in counties along the Illinois/Wisconsin border, where 10+ inches of accumulation were common (see map below)

The highest point snowfall total of 25.7 inches was reported at a station in Galena (Jo Daviess County).

Outlook for March 2019

Looking ahead at the rest of March 2019, the Climate Prediction Center is favoring moderate probabilities of colder than average temperatures statewide.  The highest probabilities are located in the northwestern portion of the state.  Slightly increased probabilities of a wetter than normal March are forecast for extreme southern Illinois, the same regions that have already experienced unseasonably wet conditions for a majority of the winter.

Check back soon for a recap of the 2018-2019 meteorological winter season.

Previous records slashed with monumental cold conditions in Illinois

CHAMPAIGN, Ill., 1/31/19: Illinois has been experiencing some of the coldest weather that has been seen in decades and, in some locations, ever.

The National Oceanic and Atmospheric Administration cooperative weather observer at Mt. Carroll in northeastern Illinois reported a temperature of -38 degrees on the morning of Jan. 31.

“The temperature in Mt. Carroll may be a new state record, if officially confirmed,” said Brian Kerschner, spokesperson for the Illinois State Climatologist’s Office at the Illinois State Water Survey.

When it appears that a state record temperature may have been broken, a state climate extremes committee reviews the observations to assess its validity. This team typically includes the State Climatologist’s Office, the Midwestern Regional Climate Center, and federal climate experts, such as from the National Weather Service and the National Center for Environmental Information.

Most of Illinois has been in the deep freeze for the past two days. With a recording of -31 degrees, Rockford broke their all-time low temperature, which was previously -27 degrees on Jan. 10, 1982, the National Weather Service Forecast Office in Chicago reports.

During the mornings of Jan. 30 and 31, numerous locations in northern Illinois reported temperatures in the -20s and some locations going below -30 degrees. Minimum temperatures were below 0 degrees throughout most of the state, except for the southern regions. Daily mean temperatures were generally 15 to 20 degrees lower than the 30-year average temperature.

Some other notable temperatures included -35 degrees at Elizabeth, -32 at Galena, -30 at Rochelle, -33 at Aledo, -26 at DeKalb, -22 at Joliet, -21 at Galesburg, -17 in Champaign, and -16 in Decatur.

In the southern counties, Cairo reached 12 degrees and Carbondale and Rosiclare saw 4 degrees.

Numerous schools, businesses, and government offices were closed throughout the state because of the dangerously cold wind chills.

——-

Note: Data for this press release were obtained from the Office of the Illinois State Climatologist, Midwestern Regional Climate Center, and National Weather Service Offices responsible for the state.

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

David Kristovich, head of the Climate and Atmospheric Science Section, Illinois State Water Survey, (217) 333-7399, dkristo@illinois.edu

A warm start to January, followed by an abundance of snow and record breaking cold!

January 2019 will be a month remembered by an unseasonably warm start, followed by several cold air outbreaks and a torrent of winter storms that finally made it feel like January in the Midwest. The last two days of the month brought a monumental Arctic air outbreak that shattered many record cold temperatures across the state.

January ended cooler, and substantially wetter than the long term average.  The preliminary average statewide January temperature was 24.7°F, which is -1.7°F below the long term average.  The preliminary average statewide precipitation was 3.51 inches, which is 1.44 inches above the long term average.

Data are provisional and may change slightly over time

Temperature

State Record Cold Temperature in Jeopardy:

A National Oceanic and Atmospheric Administration (NOAA) cooperative (COOP) weather observer at Mt. Carroll (Carroll County) reported a temperature of -38°F  on the morning of January 31st.  This unofficial temperature is currently under review by the State Extremes Committee, and if confirmed with be a new state record.  The current record is -36°F recorded in Congerville (Woodford County) on January 5, 1999.

In addition, multiple all time station record lows were set in Illinois on the morning of January 31st.  Some notable records include, Moline (Rock Island County) with a reading of -33°F , and Rockford (Winnebago County) with a reading of -31°F, as reported by the National Weather Service.

Preliminary results show that January 2019 finished with a statewide average temperature of 24.7°F which is -1.7°F degrees below the long term average.

January temperatures were a roller coaster over the course of the month, as depicted in the plot below, showing high and low temperatures and averages for Champaign-Urbana throughout the month.  Champaign-Urbana was chosen since the State Climate Office is located here, but this trend can be representative of the state as a whole.

Trends in temperatures across the entire state are depicted in the maps below.. The first 10 days of January saw statewide average temperature departures of around +9 to +14 degrees.  On the reverse end, looking at the last 10 days of the month, we experienced average temperature departures of around -5 to -21 degrees in a south to north pattern across the state.  The most extreme departures were in Northwest Illinois.

Temperatures for the month as a whole were closer to the long term average (see map below).  Regions near, and south of I-70 generally reported departures of one to three degrees above the long term average.  However, many locations in Northern Illinois reported departures of one to three degrees below the long term average, while the central portion of the state was near to slightly below average.

  • The highest temperature recorded for the month, was 66°F which occurred at two separate stations, Grand Chain Dam (Pulaski County) on January 2nd, 2019, and Jerseyville (Jersey County) on January 8th, 2019.
  • The lowest temperature recorded for the month was -38°F* at Mount Carroll (Carroll County) on January 31st, 2019 – *this recording is currently under review by the State Extremes Committee.

Precipitation

Preliminary statewide average precipitation for January was 3.51 inches, which is 1.44 inches above the long term average.

An active weather pattern beginning in the middle of the month allowed several large weather systems, and numerous smaller clipper type systems to traverse the state.  These storms were accompanied by heavy rains, accumulating snowfall, and sometimes icy precipitation.  The heaviest precipitation fell in the south/southwestern portion of the state where 5 to 6+ inches were measured (see first map below).  Many regions in Central and Northern Illinois received well over 100% of their average January precipitation, with Northwest Illinois receiving 200 to 300% (see second map below).

  • The highest monthly rainfall total of 6.50 inches occurred at a station near Cobden (Union County), 1.50 inches of which fell in a single day on January 5th, 2019.

Snowfall

Snow was abundant across the state in January, with all of Illinois recording at least some accumulating snowfall.  The highest snowfall totals of 15 to over 20+ inches were common in West-central and Northwest Illinois (see map below).

These same regions generally recorded accumulations on the order of 10 to 15+ inches above the long term average.

  • The highest monthly snowfall total was from Moline (Rock Island County) where 30.2 inches were reported, which is 20.8 inches above the long term average, ranking this as the snowiest January on record for the station.
  • Rockford (Winnebago County) received 24.9 inches, which is 14.7 inches above the long term average for January.
  • Chicago O’Hare reported a trace or more of snowfall for 15 consecutive days, from January 17th through January 31st.

Ice cover on Lake Michigan increased to nearly 35% by the end of the month, according to data from the Great Lakes Environmental Research Laboratory (chart below).

MODIS Imagery of Lake Michigan Ice Cover (Feb 1 2019)

Outlook for February 2019

Looking ahead at the rest of February 2019, the Climate Prediction Center is forecasting an above normal chance for a wetter than average February statewide. The highest probabilities are located toward the eastern side of Illinois.  Below average temperatures are favored for much of Central and Northern Illinois, with no strong signal further south.

 

2018 Illinois Climate Recap

 A Climatologic Review: 2018

Now that 2019 is well underway, lets take a moment to reflect back on the climate averages and departures from 2018.

Note:  Data are provisional and may change slightly over time

Temperatures

2018 was a year marked with several climatologically dramatic temperature swings.  The chart below shows monthly temperature departures from the 1980 – 2010 long term average for Illinois.  The most noteworthy feature is the -7.8°F departure that occurred in April, ranking April 2018 as the second coldest April on record for the state (records extend back to 1895).  And with the turn of a calendar page, May saw a +8.0°F departure from the long term mean, ranking May 2018 as the warmest May in state history.

The plot below shows the average statewide temperature (F) by month for 2018, the colors represent meteorological seasons.

The map below shows spatially average temperature departures for the year 2018.   Despite several dramatic temperature swings throughout the seasons, the year as whole finished right around the long term mean statewide.  A few regions in the northwest were a degree below, and a few regions in the south/southeast were a degree above the long term mean.

The statewide average temperature for 2018 was 52.5°F which is 0.2°F  above the long term average.

  • The highest temperature recorded in the state: MORRIS 1 NW in Grundy County with 100°F on May 28th, 2018
  • The lowest temperature recorded in the state:  MORRISON in Whiteside County with -24°F on January 1st, 2018
  • The warmest mean temperature: LAWRENCEVILLE 2WSW in Lawrence County with 59.3°F
  • The coldest mean temperature: PALESTINE in Crawford County with 43.1°F

Precipitation

The chart below shows monthly precipitation departures from the 1980 – 2010 long term average for Illinois in inches.  February saw the wettest departure from average at 2.82 inches.  April saw the driest departure from average at -1.36 inches,

The plot below shows the average statewide precipitation (in) by month for 2018, the colors represent meteorological seasons.

The map below shows precipitation as a percent of normal for the year 2018 in inches.  It was a rather wet year statewide, the highest percentages above average were reported in numerous regions across the extreme northern and southern portions of Illinois, where 125 to 150 percent of normal precipitation was measured.

The statewide estimated average precipitation for 2018 stands at 45.75 inches which is an impressive 5.79  inches above the long term average.

  • The highest yearly precipitation in the state: NASHVILLE 1E in Washington County, with 66.79 inches
  • Largest one day maximum event: CISNE 2.5 in Wayne County with 8.54 inches on September 8th, 2018
  • Snowiest location in the state: BULL VALLEY 2.5 WNW with 55.4 inches, the one day maximum snowfall for the site was 13.1 inches on November 26, 2018

Severe Weather

Severe weather reports for Illinois in 2018 from the NOAA Storm Prediction Center. Note: It is possible to generate multiple report for the same storm/event

Month Total Reports Tornado Hail Wind
January 2 0 2 0
February 1 0 0 1
March 0 0 0 0
April 20 9 4 7
May 170 6 48 116
June 184 11 15 158
July 54 0 6 48
August 40 2 7 31
September 40 2 1 37
October 3 0 0 3
November 0 0 0 0
December 52 34 11 7
Total 566 64 94 408

Illinois Climate Minute: 2018 Recap


Thanks for reading!