Scattered thunderstorms once again developed across northern Illinois on Monday, August 29th, bringing isolated very heavy rainfall amounts due to a moist atmosphere and slow storm motion. The locations hardest hit include along the I-90 corridor from Cherry Valley into the northwest Chicago metro, as well as some locations in Lee County near Amboy, and LaSalle County in and near Mendota and…
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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 LOT wrote it up.
Scattered thunderstorms once again developed across northern Illinois on Monday, August 29th, bringing isolated very heavy rainfall amounts due to a moist atmosphere and slow storm motion. The locations hardest hit include along the I-90 corridor from Cherry Valley into the northwest Chicago metro, as well as some locations in Lee County near Amboy, and LaSalle County in and near Mendota and Triumph.
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 Chicago, IL wrote its last area forecast discussion before the first event at Aug 29, 1:56 PM CST, 34 minutes earlier.
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 256 PM CDT MON AUG 29 2016 .SHORT TERM... 234 PM CDT Through Tonight... Very slow moving thunderstorms continue to develop over portions of the area this afternoon. As a this writing, the most pronounced heavy rain producer is the cluster of storms over Lee county. These storms have been dropping up to 2" per hour over a small portion of the county south of the Dixon area. While the individual storm cells are moving slowly eastward, the cluster of storms is propagating slowly north-northwestward into the Dixon area as new development occurs along the outflow. If this heavy rain continues into the Dixon area a flash flood warning may be needed in the near future. Otherwise, expect SCT thunderstorms to continue to develop and impact portions of the area for the next few hours before dissipating by early this evening. The slow eastward movement of these storms could result in some isolated areas of flash flooding due to very heavy rainfall. Some isolated storms are possible over the area tonight, but most areas will likely remain dry. The high dew point air mass and the expectation of light winds tonight could allow for some areas of dense fog to develop. As a result, I have added patchy fog to the forecast for tonight. KJB && .LONG TERM... 250 PM CDT Tuesday through Monday... Tuesday will again be like the past few with a humid, deep moisture air mass in place. The stout upper high with 593dm heights over central Illinois today will begin to be shunted slowly southward as a northern stream trough begins to dig into Ontario. Minor mid-level ripples on water vapor satellite imagery over Iowa today will likely be moving over northern Illinois Tuesday morning and could support isolated/scattered storms in the a.m. hours. In addition, at the low-levels there will be a tad more southwesterly to westerly flow ensuring dew points remain high and once again pooled in the mid 70s by midday. So would expect at least scattered storms, potentially with more coverage than today. Guidance is indicating a decent amount of morning cloud cover which may slow destabilization, though it still should be still achieved given the moisture pooling. Deep layer shear is likely to be 15-20 kt keeping the concerns mainly tied to flooding with efficient rates and slow storm motions. The occasional wet microburst, especially any congealed deep cells, will be possible. As a cold front associated with the aforementioned trough moves southward over Lake Michigan on Tuesday night, the chance for scattered storms should continue into the night. In addition, upper forcing within a right entrance region of an upper jet will also support at least broad lift. Besides the rain chances, Tuesday night looks to remain humid and mild. On Wednesday morning the cold front should be shifting southward into the area and by Wednesday afternoon clearing the south. The front will continue to serve as a focus for storms, though it is looking more likely Wednesday afternoon much of that may be in central Illinois and central Indiana. Reinforcement of drier air will occur later in the day into the night. Winds along the lake front will be the strongest, with gusts of 25 to possibly 30 mph by Wednesday evening. Waves will build to levels conducive for rip currents by mid-late afternoon Wednesday based on the current forecast, with the threat continuing through Thursday. Thursday will see highs in the lower to mid 70s as high pressure advances in. There actually could be some lake effect clouds into northeast Illinois Thursday morning. Pleasant conditions look to persist through the weekend with a rex block in the middle of the continent likely to keep the next precipitation chances not until Monday. MTF && .AVIATION... For the 18Z TAFs... The main weather concerns/challenges will be the extent of thunderstorms over or near the terminals this afternoon and again on Tuesday afternoon. A warm and humid air mass will remain in place over the area through Tuesday. Recent AMDAR soundings out of MDW indicate that thunderstorm development could begin initiation at any time. The main question remains where will thunderstorms focus this afternoon. At this time, it appears that low-level convergence along a developing lake breeze boundary may help act as a focus for SCT storms over or near some of the Chicago area terminals after 19 Z. As a result, I have opted to add a VCTS mention from 19 to 22 Z this afternoon. However, overall confidence on coverage remains a bit on the low side. The next main threat for storms looks to arrive by Tuesday afternoon as a cold front approaches the area. Given the range, it is a bit difficult to pinpoint the best timing at ORD for thunder. So, at this time I have just gone with a long (6hr) PROB30 mention for such until a shorter time range can be established. In addition to the threat for storms, some fog will be possible later tonight, especially outside the Chicago area. The extent of the fog will likely depend on the amount of cloud cover around tonight, but given the high dew point air, some MVFR to IFR visibilities are certainly possible late tonight. KJB && .MARINE... 256 PM CDT Quiet winds and waves will occur over the lake tonight into Tuesday, outside of possibly patchy fog late tonight and Tuesday morning. A cold front will shift southward onto the northern part of the lake by Tuesday evening and then down the lake through the remainder of the night. This will abruptly turn winds northerly with an increase in speed. Gusts to 30 kt are possible by Wednesday afternoon through Thursday night, especially across the central and south. Small craft advisory conditions are presently forecast Wednesday evening through Thursday night across the Illinois and Indiana nearshore zones. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1123 AM CDT MON AUG 29 2016 ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 301630- WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE- DUPAGE-COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON- IROQUOIS-FORD-LAKE INDIANA-PORTER-NEWTON-JASPER-BENTON- 1123 AM CDT MON AUG 29 2016 /1223 PM EDT MON AUG 29 2016/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS... NORTHEAST ILLINOIS AND NORTHWEST INDIANA. .DAY ONE...THIS AFTERNOON AND TONIGHT. WEATHER HAZARDS EXPECTED: LIMITED THUNDERSTORM RISK. LIMITED FLOODING RISK. PORTIONS OF THE ILLINOIS AND KANKAKEE RIVERS WILL REMAIN IN FLOOD. PORTIONS OF OTHER AREA RIVERS AND STREAMS MAY BE NEAR BANKFULL. DISCUSSION: SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN THIS AFTERNOON ACROSS PORTIONS OF NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE SEVERE WEATHER THREAT IS LOW...HOWEVER STORMS WILL LIKELY BE SLOW MOVING AND COULD PRODUCE LOCALIZED FLOODING. IN ADDITION...LOCATIONS THAT RECEIVED HEAVY RAINFALL ON SUNDAY...PARTICULARLY IN GRUNDY AND LIVINGSTON COUNTIES...MAY STILL EXPERIENCE FLOODED ROADWAYS TODAY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. TUESDAY... LIMITED SEVERE THUNDERSTORM RISK. LIMITED FLOODING RISK. WEDNESDAY... LIMITED THUNDERSTORM RISK. HIGH SWIM RISK. SUNDAY... LIMITED THUNDERSTORM RISK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT BUT REPORTS OF RAINFALL AMOUNTS AND FLOODING ARE APPRECIATED. GENERAL STORM MOTION OF THE DAY: VARIABLE MOTION AT 5 MPH OR LESS. && LMZ740>745-301630- WINTHROP HARBOR TO WILMETTE HARBOR- WILMETTE HARBOR TO NORTHERLY ISLAND- NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY- GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY- 1123 AM CDT MON AUG 29 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS NEARSHORE WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE WATERS OF LAKE MICHIGAN. .DAY ONE...THIS AFTERNOON AND TONIGHT. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS THIS AFTERNOON. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. THERE IS A CHANCE OF THUNDERSTORMS TUESDAY INTO EARLY WEDNESDAY. WINDS AND WAVES HAZARDOUS TO SMALL CRAFT ARE EXPECTED WEDNESDAY INTO EARLY THURSDAY. && LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868- 870-872-874-876-878-301630- LAKE MICHIGAN FROM MICHIGAN CITY IN TO ST. JOSEPH MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM SEUL CHOIX POINT TO ROCK ISLAND PASSAGE 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN SOUTH OF A LINE FROM SEUL CHOIX POINT TO THE MACKINAC BRIDGE AND NORTH OF A LINE FROM CHARLEVOIX MI TO SOUTH FOX ISLAND 5 NM OFFSHORE- LAKE MICHIGAN FROM CHARLEVOIX TO POINT BETSIE MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM POINT BETSIE TO MANISTEE MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM ROCK ISLAND PASSAGE TO STURGEON BAY WI- LAKE MICHIGAN FROM STURGEON BAY TO TWO RIVERS WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM TWO RIVERS TO SHEBOYGAN WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM SHEBOYGAN TO PORT WASHINGTON WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM PORT WASHINGTON TO NORTH POINT LIGHT WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM NORTH POINT LIGHT TO WIND POINT WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WIND POINT WI TO WINTHROP HARBOR IL 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WINTHROP HARBOR TO WILMETTE HARBOR IL 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WILMETTE HARBOR IL TO MICHIGAN CITY IN 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM PENTWATER TO MANISTEE MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WHITEHALL TO PENTWATER MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM GRAND HAVEN TO WHITEHALL MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM HOLLAND TO GRAND HAVEN MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM SOUTH HAVEN TO HOLLAND MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM ST. JOSEPH TO SOUTH HAVEN MI 5 NM OFFSHORE TO MID LAKE- 1123 AM CDT MON AUG 29 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE MICHIGAN. .DAY ONE...THIS AFTERNOON AND TONIGHT. THERE IS A CHANCE OF THUNDERSTORMS TONIGHT OVER NORTHERN LAKE MICHIGAN. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. THUNDERSTORMS ARE POSSIBLE ACROSS LAKE MICHIGAN TUESDAY INTO EARLY WEDNESDAY...AND AGAIN SUNDAY. && KJB VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
The Quad Cities radar (KDVN), 91 km away, was scanning. The volume nearest the first event began at 20:28 UTC.
3 flash flood. Local standard time, as filed.
A foot of water moving across Pump Factory Rd between Amboy Rd and McCoy Rd approximately 10 miles south of Dixon.
Irving Park Rd, which is Rt. 19, closed due to flooding. Part of the Rt. 390 frontage road near Irving Park Rd and Wright Boulevard with up to 1 foot of water covering it.
Car stalled in deep water and other flooded roads around town.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2016Every state in 2016This day in weather historyWarnings in Illinois, August 2016
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: 659559, 659560, 659561.