An approaching warm front triggered a broken line of strong thunderstorms during the late afternoon and evening of August 3rd. A few of the cells produced marginally severe wind gusts of around 60mph and heavy downpours.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS ILX wrote it up.
An approaching warm front triggered a broken line of strong thunderstorms during the late afternoon and evening of August 3rd. A few of the cells produced marginally severe wind gusts of around 60mph and heavy downpours. Isolated wind damage occurred, including a downed tree in DeWitt County.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Lincoln, IL wrote its last area forecast discussion before the first event at Aug 3, 1:59 PM CST, 36 minutes earlier.
Area Forecast Discussion National Weather Service Lincoln IL 259 PM CDT Thu Aug 3 2017 .SHORT TERM...(This evening through Friday) ISSUED AT 259 PM CDT Thu Aug 3 2017 Pre-frontal convection has been tracking across central Illinois this afternoon, aided by surface based CAPE's reaching 3500 J/kg. The storms are still ahead of the better shear though, and have mainly been responsible for heavy rain and some winds to around 40 mph or so. Main cold front is still back across eastern Iowa into west central Missouri, with a sizable gap in convection along it. In terms of any threat of strong storms, what's going on now may actually be the main show, as the higher resolution models suggest more of a disorganized line ahead of the front this evening. The NAM and ARW suggest the rain should be done as early as midnight in our CWA, while the HRRR, GFS and RAP linger it a bit longer in the far southeast. In the forecast, rain will be gone from the Illinois River valley by about 10 pm, and will limit any post- midnight rain to areas along and east of I-57. Strong upper low currently over north central Minnesota will swing eastward toward eastern Lake Superior by Friday afternoon. Associated stratocumulus deck is expected to linger across areas northeast of I-74 into the afternoon hours, which should help keep high temperatures down, close to 70 degrees. Some afternoon sunshine further west and a warming air mass behind the main trough will allow for some warmer conditions, but still only in the mid 70s. && .LONG TERM...(Friday night through Thursday) ISSUED AT 259 PM CDT Thu Aug 3 2017 Main focus in this period will be with timing of rain trends Saturday night into Monday night, as a strong west-east upper trough near the Canadian border swings southeast toward the mid- Mississippi Valley. The ECMWF and NAM models develop an MCS west of the Mississippi Saturday afternoon and roll it into much of the CWA as early as Saturday evening, associated with a leading shortwave, while the GFS is weaker and keeps us dry most of the night. Didn't go quite as fast with the rain, but have brought in healthy chance PoP's in most areas by midnight, with likely PoP's in the far southwest after midnight Saturday night. As this MCS tracks toward southern Illinois, the northwest CWA will see temperatures kept down a fair amount with a northeast flow, mainly lower 70s for Sunday. Areas further south will see periods of rain and a few storms as the system passes, largely out of the area by late Sunday evening as the cold front exits the area. Beyond that, while the ECMWF would suggest dry conditions with high pressure building eastward, the arrival of the earlier mentioned trough axis would support at least chance PoP's on Monday. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1230 PM CDT Thu Aug 3 2017 Scattered convection starting to fire between KSPI-KPIA, and a few showers are within 10NM of KPIA as of 1725Z. Have included VCTS out of the gate at KPIA/KBMI and will have it at the remainder of the TAF sites by 20Z as storms continue to increase. Storms will organize more into a line across eastern Iowa this afternoon and move into central Illinois ahead of a cold front, and have included a TEMPO period for gusty winds and MVFR conditions as the line passes. The storms will be out of the TAF sites by 06Z. Toward morning, some lower clouds will be swinging eastward across the northern third of the state, and have included a short period of MVFR ceilings from KBMI-KDEC east toward 12Z. However, the lower clouds will be moving out by late morning. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Geelhart LONG TERM...Geelhart AVIATION...Geelhart
Hazardous Weather Outlook National Weather Service Lincoln IL 312 PM CDT Thu Aug 3 2017 ILZ027>031-036>038-040>057-061>063-066-042015- Cass-Champaign-Christian-Clark-Coles-Cumberland-De Witt-Douglas- Edgar-Effingham-Fulton-Knox-Logan-Macon-Marshall-Mason-McLean- Menard-Morgan-Moultrie-Peoria-Piatt-Sangamon-Schuyler-Scott- Shelby-Stark-Tazewell-Vermilion-Woodford- 312 PM CDT Thu Aug 3 2017 This Hazardous Weather Outlook is for portions of central Illinois, east central Illinois, southeast Illinois and west central Illinois. .DAY ONE...TONIGHT... Thunderstorms are expected across the area ahead of an advancing cold front. The storms will be most numerous this evening. A few of the storms may become severe, with damaging wind gusts and large hail the primary threats. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY... Thunderstorm chances return to the area by Sunday, and again next week Thursday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed between 4 pm and 9 pm. ILZ067-068-071>073-042015- Clay-Crawford-Jasper-Lawrence-Richland- 312 PM CDT Thu Aug 3 2017 This Hazardous Weather Outlook is for portions of southeast Illinois. .DAY ONE...TONIGHT... Thunderstorms are expected across the area ahead of an advancing cold front. The storms will be most numerous this evening. Organized severe storms are not anticipated, but a few stronger storms may contain gusty winds and hail. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY... Thunderstorm chances return to the area by Sunday, and again next week Thursday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. Shimon
Special Weather Statement National Weather Service Lincoln IL 1219 PM CDT THU AUG 3 2017 ILZ036-037-041-048-031815- Tazewell-Mason-Menard-Fulton- 1219 PM CDT THU AUG 3 2017 ...SPECIAL WEATHER STATEMENT... At 1218 PM CDT, local law enforcement reported a strong thunderstorm over Havana, moving east at 20 mph. Half inch hail is occurring with this storm. Locations impacted include... Havana, Mason City, Manito, Green Valley, San Jose, Easton, Forest City, Topeka, Chatauqua Park, Goofy Ridge and Poplar City. PRECAUTIONARY/PREPAREDNESS ACTIONS... To report severe weather, contact your nearest law enforcement agency. They will relay your report to the National Weather Service office in Lincoln. && LAT...LON 4028 9016 4041 8992 4042 8960 4014 8961 TIME...MOT...LOC 1718Z 272DEG 17KT 4032 9004 Shimon
Special Weather Statement
National Weather Service Lincoln IL
111 PM CDT THU AUG 3 2017
ILZ037-038-041>043-048-031915-
Logan-Tazewell-Mason-Menard-McLean-De Witt-
111 PM CDT THU AUG 3 2017
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN MENARD...LOGAN...
NORTHWESTERN DE WITT...SOUTHEASTERN TAZEWELL...SOUTHWESTERN MCLEAN
AND SOUTHEASTERN MASON COUNTIES UNTIL 215 PM CDT...
At 111 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Tremont to near Emden to Greenview.
Movement was east at 25 mph.
Nickel size hail will be possible with these storms.
Locations impacted include...
Bloomington, Lincoln, Mason City, Normal, Heyworth, Tremont,
Mackinaw, Atlanta, Delavan, Mount Pulaski, Minier, Danvers, Hopedale,
McLean, Greenview, San Jose, Stanford, Emden, Waynesville and
Elkhart.
This includes the following highways...
Interstate 155 between mile markers 0 and 26.
Interstate 39 between mile markers 0 and 1.
Interstate 55 between mile markers 113 and 168.
Interstate 74 between mile markers 124 and 138.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Lincoln.
&&
LAT...LON 4055 8890 4018 8900 3995 8932 4007 8987
4029 8967 4055 8949
TIME...MOT...LOC 1811Z 274DEG 24KT 4049 8946 4027 8955 4010 8973
ShimonSpecial Weather Statement
National Weather Service Lincoln IL
215 PM CDT THU AUG 3 2017
ILZ038-032000-
McLean-
215 PM CDT THU AUG 3 2017
...SPECIAL WEATHER STATEMENT...
At 215 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Colfax to near Cooksville. Movement was
east at 25 mph.
Half inch hail will be possible with these storms.
Locations impacted include...
Lexington, Colfax, Saybrook, Cooksville, Pleasant Hill, Arrowsmith,
Cropsey, Ellsworth, Anchor and Holder.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Lincoln.
&&
LAT...LON 4062 8857 4061 8846 4042 8846 4045 8887
4065 8880 4071 8858
TIME...MOT...LOC 1915Z 250DEG 21KT 4063 8854 4050 8864
ShimonSpecial Weather Statement National Weather Service Lincoln IL 249 PM CDT THU AUG 3 2017 ILZ043>045-053-032045- Macon-Piatt-De Witt-Champaign- 249 PM CDT THU AUG 3 2017 ...SIGNIFICANT WEATHER ADVISORY FOR PIATT...EASTERN DE WITT... SOUTHERN CHAMPAIGN AND NORTHEASTERN MACON COUNTIES UNTIL 345 PM CDT... At 247 PM CDT, emergency management reported strong thunderstorms along a line extending from near Farmer City to Forsyth. Movement was east at 30 mph. Dime size hail will be possible with these storms. A funnel cloud was sighted on Hwy 150 between Farmer City and Mansfield at 245 pm. No tornadic activity is expected, but additional funnels may develop this afternoon. Locations impacted include... Champaign, Decatur, Monticello, Urbana, Savoy, Mahomet, Forsyth, Tolono, Farmer City, Bement, Philo, Cerro Gordo, Warrensburg, Thomasboro, Argenta, Mansfield, Oreana, Pesotum, De Land and Bondville. This includes the following highways... Interstate 57 between mile markers 218 and 246. Interstate 72 between mile markers 139 and 182. Interstate 74 between mile markers 158 and 191. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with these storms, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4025 8795 3988 8826 3990 8910 4027 8865 TIME...MOT...LOC 1947Z 271DEG 28KT 4022 8858 3995 8896 Shimon
The Chicago radar (KLOT), 131 km away, was scanning. The volume nearest the first event began at 20:36 UTC.
3 thunderstorm wind. Local standard time, as filed.
A machine shed was damaged and a few tree branches were blown down.
Several small tree branches were blown down across Minier.
A tree was blown down across Illinois Highway 54 about 2 miles west of DeWitt.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2017Every state in 2017This day in weather historyWarnings in Illinois, August 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 718697, 718699, 718698.