Scattered thunderstorms developed during the afternoon and evening of July 7th producing isolated wind damage.
Every event with a place to put it. Tap one for its entry below.
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 developed during the afternoon and evening of July 7th producing isolated wind damage.
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 Jul 7, 1:54 PM CST, 2 hours 39 minutes earlier.
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 254 PM CDT Tue Jul 7 2020 .SHORT TERM... 248 PM CDT Through Wednesday night... A generally uncapped environment has been common across much of the CWA early this afternoon, though sources of lift, low-level mixing and mid-level dry air entrainment have limited cumulus growth for most area. A subtle and small kink in the mid-levels evident in WV imagery was the apparent extra trigger for strong convection over northwest Indiana over the past two hours. Since surface moisture was a little higher (dew points around 70F) compared to most of the Illinois portion of the CWA (mid to upper 60s dew points), deeper vertical growth was achieved there. Additional pockets of towering cumulus continue to show up on satellite across the remainder of the CWA, most notably on the lake breeze in Cook County. With a lack of deeper forcing for the next couple hours, development should be somewhat limited away from the lake breeze and any remnant outflow boundaries from storms over the past couple hours. Rapid development of convection ahead of a pronounced MCV across northeast Iowa has occurred in the past hour across southeast MN and southwest WI. This activity is expected to slowly drift east through the remainder of the afternoon amidst weak deep-layer flow. While substantial cold pool development is not expected, outflow from this activity combined with a trailing trough into eastern Iowa will become a renewed focus for convection moving into the CWA early this evening. With mid-level lapse rates becoming more unfavorable with eastward extent, overall coverage and intensity of the activity should diminish with time. Ultimately, residual thunderstorms may reach north-central IL prior to sunset, with possibly some remnant showers surviving into the Chicago metro close to midnight. A mid-level ridge axis drifting over the CWA Wednesday morning will shift far enough east by the afternoon to allow capping from the subsidence inversion to weaken. While slight capping should remain, isolated convection could develop where focused convergence exists. Primarily this would be along the Lake Michigan lake breeze and any potential remnant outflow boundaries from convection this evening. Little change was made to the temperature forecast for Wednesday as the warm stretch continues. With weaker capping in place, daytime mixing should at least lower afternoon dew points a couple degrees from the morning hours as has been the case for several days now. Max temps in the 92-94 range inland combined with afternoon dew points in the upper 60s will produce heat index values in the 95- 100F range. Kluber && .LONG TERM... 254 PM CDT Thursday through Tuesday... Thursday will be similar to Wednesday with hot and humid conditions remaining, with high temps perhaps a smidge lower than before due to increasing cloud cover. Thursday evening into Friday, shower and thunderstorm chances will increase as an upper-level wave and perhaps a convectively-generated MCV approaches from the west. Depending on the timing of the wave, a few "pulsey" strong to severe storms look possible with frequent lightning, torrential downpours, small hail, and wind gusts strong enough to down tree limbs as the main risks. This weekend, the Great Lakes will be positioned beneath weak upper- level troughing leading to a break in the hot and humid conditions. Sunday appears to be the coolest day with highs topping off in the mid to upper 80s as a secondary cold front sneaks in from the north. Hazardous swimming conditions may develop in the wake of the front for Lake Michigan beaches Sunday afternoon and evening. Borchardt && .AVIATION... For the 18Z TAFs... Deep convection is attempting to develop on various surface boundaries across northern Illinois and northwest Indiana at TAF issuance, primarily on a lake breeze in northwest Indiana and a weak surface trough from north-central to west-central Illinois. Isolated to widely scattered activity is expected to continue to develop through the afternoon on these features. Confidence in TS directly affecting a given terminal remains low enough to preclude a TEMPO TS group in the TAF, but coverage should be high enough that airspaces around the terminals minimally see some impacts. While mid-level dry air entrainment will limit intensity of most cells, a few could become deep enough to produce gusty downdrafts of 20-30 knots immediately under and near the cell. A low to mid-level wave moving southeast across southeast MN and north-central IA is expected to force scattered convection through this afternoon. If coverage become high enough to form larger clusters of storms or any existing storms are maintained into the evening, residual showers and outflow winds may affect the Chicago- area terminals mid to late evening. Otherwise, conditions should be relatively quiet through the morning hours on Wednesday, with VRB winds 5 knots or less (favoring the SE quadrant this evening and SW quadrant overnight into Wednesday morning.) Enough capping should exist for ORD/MDW on Wednesday afternoon to limit convective potential on a lake breeze, but a widely isolated thunderstorm cannot be ruled out. Kluber && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && Visit us at weather.gov/chicago 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 315 PM CDT Tue Jul 7 2020 ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002- 010-011-019-082015- Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage- La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford- Northern Cook-Central Cook-Southern Cook-Northern Will- Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton- 315 PM CDT Tue Jul 7 2020 /415 PM EDT Tue Jul 7 2020/ This Hazardous Weather Outlook is for portions of North Central Illinois...Northeast Illinois and Northwest Indiana. .DAY ONE...Tonight. Weather hazards expected... Limited Thunderstorm Risk. Limited Excessive Heat Risk. DISCUSSION... Hot and humid conditions will continue inland from Lake Michigan. Scattered thunderstorms will continue to develop through the evening hours. The strongest storms will be capable of producing torrential downpours, frequent lightning, small hail, and wind gusts strong enough to down small tree limbs. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Wednesday... Limited Thunderstorm Risk. Limited Excessive Heat Risk. Thursday... Elevated Thunderstorm Risk. Limited Excessive Heat Risk. Friday... Elevated Thunderstorm Risk. Limited Excessive Heat Risk. DISCUSSION: Hot and humid conditions are possible Wednesday and Thursday, especially away from the lakeshore. Scattered thunderstorms are possible Thursday into Friday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be necessary through tonight, but any reports of small hail or gusty winds will be appreciated. GENERAL STORM MOTION OF THE DAY: Moving toward the east at 10 mph. LMZ740>745-082015- Winthrop Harbor to Wilmette Harbor IL- Wilmette Harbor to Northerly Island IL- Northerly Island to Calumet Harbor IL- Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN- Burns Harbor to Michigan City IN- 315 PM CDT Tue Jul 7 2020 This Hazardous Weather Outlook is for portions of the Illinois nearshore waters of Lake Michigan and the Indiana nearshore waters of Lake Michigan. .DAY ONE...Tonight. Weather hazards expected... Limited Thunderstorm Risk. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Thursday... Elevated Thunderstorm Risk. Friday through Sunday... Limited Thunderstorm Risk. Borchardt Visit us at http://weather.gov/chicago Follow us on Facebook, Twitter, and Youtube at: www.facebook.com/nwschicago www.twitter.com/nwschicago www.youtube.com/nwschicago
SPECIAL WEATHER STATEMENT National Weather Service Chicago/Romeoville IL 120 PM CDT Tue Jul 7 2020 ILZ033-INZ001-002-010-011-019-072030- Iroquois-Lake IN-Porter-Newton-Jasper-Benton- Including the cities of Watseka, Gilman, Gary, Hammond, Merrillville, Portage, Valparaiso, Chesterton, Roselawn, Kentland, Morocco, Rensselaer, DeMotte, Fowler, and Oxford 120 PM CDT Tue Jul 7 2020 /220 PM EDT Tue Jul 7 2020/ ...GUSTY SHOWERS AND THUNDERSTORMS THIS AFTERNOON... Scattered showers and thunderstorms will continue developing this afternoon across parts of northwestern Indiana and eastern Illinois. The strongest storms will produce frequent lightning, torrential rainfall, wind gusts strong enough to down small tree limbs, and pea size hail. Move indoors if you hear thunder and have multiple ways to receive warnings! Borchardt
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
134 PM CDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0130 PM HAIL 3 NNE VALPARAISO 41.51N 87.04W
07/07/2020 E0.75 INCH PORTER IN TRAINED SPOTTER
0.5 TO 0.75 INCH DIAMETER HAIL FALLING AT
TIME OF CALL.
&&
BBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
201 PM CDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0146 PM TSTM WND GST 4 ESE VALPARAISO 41.45N 87.00W
07/07/2020 M43 MPH PORTER IN ASOS
ASOS STATION KVPZ VALPARAISO AIRPORT.
&&
BBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
412 PM CDT TUE JUL 7 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0100 PM TSTM WND DMG 2 NW WINFIELD 41.43N 87.31W
07/07/2020 LAKE IN PUBLIC
PHOTO OF TWO PINE TREES SNAPPED ABOUT 1-2
FEET UP FROM THEIR BASE FROM SOCIAL MEDIA.
TIME ESTIMATED BY RADAR.
&&
BBThe Chicago radar (KLOT), 51 km away, was scanning. The volume nearest the first event began at 22:33 UTC.
3 thunderstorm wind, 1 hail. Local standard time, as filed.
A large pine tree was uprooted two blocks west of the Mount Prospect Golf Course. A large tree limb was also blown down.
A trained spotter reported several minutes of nickel size hail in Franklin Park which ended as quarter size hail.
A 5 foot diameter tree was blown down, which brought down power lines and a utility pole. The tree was described as rotted.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2020Every state in 2020This day in weather historyWarnings in Illinois, July 2020
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: 904249, 904247, 904248, 904251.