A slow, south moving cold front and an outflow boundary from morning thunderstorms over northern Illinois, combined with a hot and humid environment to produce widespread showers and thunderstorms across eastern Iowa and northwest Illinois overnight. Several thunderstorms became severe, and produced large hail and damaging winds.
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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 DVN wrote it up.
A slow, south moving cold front and an outflow boundary from morning thunderstorms over northern Illinois, combined with a hot and humid environment to produce widespread showers and thunderstorms across eastern Iowa and northwest Illinois overnight. Several thunderstorms became severe, and produced large hail and damaging winds. Quarter sized hail was reported across Clinton and Iowa counties, while destructive winds of 70-90 MPH were reported Iowa and Washington Counties. In addition, torrential rainfall amounts of 1 to 2 inches were reported along the Interstate 80 corridor as storms slowly moved across the area. This lead to flash flooding across many major roadways, including Interstate 80 near Coralville and Highway 965 in Oakdale.
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 Quad Cities, IA wrote its last area forecast discussion before the first event at May 16, 5:28 AM CST, 3 hours 57 minutes earlier.
Area Forecast Discussion National Weather Service Quad Cities IA IL 628 AM CDT Thu May 16 2019 ...AVIATION UPDATE... .SYNOPSIS... Issued at 258 AM CDT Thu May 16 2019 High pressure responsible for yesterday's beautiful day is now found over Ohio, with return flow well underway over the Plains through MN, ahead of a cold front. The nose of the warm advection, aimed into central MN has a cluster of storms that is going to begin shifting southeast towards southern WI, these storms could impact our north half of the area this morning, but may also miss, as this tail end convection will be fighting a growing EML limited storms. && .SHORT TERM...(Today and Tonight) ISSUED AT 258 AM CDT Thu May 16 2019 The capping EML will be hugely in question today and tonight, and it's presence adds a level of uncertainty that will keep us from issuing a flash flood watch, which in the end, may be warranted for tonight. The cold front will approach our northern counties this afternoon and will sink to just south of I-80 tonight. In this process, we will see southwest winds and very warm temperatures today. Even with clouds, highs in the lower to mid 80s should be easily reached, and our south, where cloud cover should be very thin if not full sun, highs around 90 are likely. Dewpoints will increase through the day, but we are not going as high as some model guidance, and staying in the lower to mid 60s. That should keep the heat index very tight to the actual temperatures. This afternoon, models are mainly showing the area holding in a capped environment, but there will be a slight chance spread along the front if any storm could fire in the 3000 J/KG environment, it would go quickly into a near severe storm. What is more likely, is that storms hold off until evening, as the increasing SW LLJ feeds into the boundary overhead. While PWATS will be in the 1 to 1.6 range tonight, well above normal for May, the slow moving boundary, is likely to allow for storms to train/repeat along the boundary, especially into IL where the boundaries alignment will be more normal to the LLJ orientation. In any case, the exact location of storms tonight could vary from near I-80 to near Highway 30 this evening, and may lift to Highway 20 late tonight. For now, will hold off on any headline, but will work with LOT/Chicago to include heavy rain in the grids. Severe storms are most possible in the afternoon and evening, but could still see a hail threat on on the western periphery of the storms overnight. CAPE will remain high through the night in the warm sector, keeping the threat for strong new updrafts going through the night. It does seem the wind threat is mainly tied to this morning's activity which is likely to miss our CWA, and the afternoon lower probability storm threat during peak heating through early evening. .LONG TERM...(Friday through Wednesday) ISSUED AT 258 AM CDT Thu May 16 2019 The main forecast concern trough the middle of next week are chances of showers and storms through the period as well as temperatures on Friday. Models are in good overall agreement but some significant disagreement on the finer details. Friday morning at 12z, the 500 hpa ridge axis basically stretches along the Missouri River with eastern Iowa, northeast Missouri, and northwest Illinois under a zonal or west to east flow aloft. Showers and thunderstorms will be ongoing across the are in the vicinity of a cold front across the area. The GFS has the front near I-80 while the ECMWF, GEM, and NAM have it south of I-80. The frontal position will be very important for highs on Friday which will be discussed later. Warm, unstable air to the south of the of the boundary will continue to feed shower and thunderstorm development through the day. Heavy rain as well as isolated severe thunderstorms are possible. CAPE values of 600 to 1600 j/KG and 0 to 6km shear of 40 to 50 knots are sufficient for large hail and damaging winds with these storms although hail is the primary threat. The Storm Prediction Center has the northern half of the area in a Marginal Risk of severe storms during the period. There is also a a marginal risk of excessive rainfall over the same area. Because of the ongoing convection and frontal boundary across the area on Friday there will be a large temperature gradient across the area with highs in the mid 50s in far northwest Illinois to potentially the mid 80s in northeast Missouri and far southeast Iowa. The forecast for now has the frontal boundary near I-80 through the day on Friday but the position of this front and who has the north to northeasterly winds will dictate how cool or warm we get. There is a 10 to 15 degree temperature difference between the various models across mainly the northern half of the area. I tried to make the high temperature forecast in the middle of all of these solutions. I have higher confidence in high temperatures across the southern CWA where the model spread is smaller. The remainder of the long term will be dominated by active southwesterly flow through at least the middle of next week as a series of closed upper level lows move from the Pacific into the Western US. This will send a series of strong storm systems into the Plains about every 24 to 36 hours. The strongest storm systems currently depicted by the models are Saturday night into Sunday and another very potent system Tuesday into Wednesday. These two storm systems will need to be monitored for both heavy rain potential as well the possibility of severe thunderstorms. The Storm Prediction Center has eastern Iowa under a Slight Risk of severe weather west of a Independence Iowa to Memphis Missouri line with a Marginal Risk to the east. Please stay tuned to the weather foecast over the next several days as the active weather continues across the region. && .AVIATION...(For the 12Z TAFS through 12Z Friday Morning) ISSUED AT 619 AM CDT Thu May 16 2019 A hot and breezy day with mostly clear skies is forecast, with a chance for storms handled by Prob30 for all sites along and north of Interstate 80, in the 00z to 08z window of time. These storms may not be widespread, but are likely to bring IFR conditions and heavy rainfall, as well as gusty winds and hail. By morning, east winds will begin to spread over northeast Iowa and northern Illinois, with much colder air moving in. && .HYDROLOGY... Issued at 1020 AM CDT Wed May 15 2019 Overall Mississippi River levels will continue to slowly recede. Some locations upstream up the Quad Cities may see a slight rise or levels remain steady for a few days as some routed water from Minnesota and Wisconsin works it's way downstream. Downstream of Rock Island, the rate of fall will slow down. Moderate to major flooding will continue in and downstream of Rock Island, with the exception of Keokuk where minor flooding will continue. A large scale weather pattern change will bring more active weather to the Midwest along with several rounds of rain. This pattern will set up late this week and into next week. The timing and placement of each round of rain will be important in future river levels. Additionally, the ground remains saturated so most of the rain would runoff into area rivers. Rises on tributary rivers are likely over the weekend and into next week. A slowing of the rate of fall or minor rises is possible on the Mississippi. If the rainfall is heavy, which is possible, and occurs over the same area, then new flooding would be possible on tributary rivers that would prolong the flooding on the Mississippi River. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...Ervin SHORT TERM...Ervin LONG TERM...Cousins AVIATION...Ervin HYDROLOGY...14
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 327 AM CDT Thu May 16 2019 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-170830- Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson- Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson- Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll- Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson- Warren-Hancock-McDonough-Scotland-Clark- 327 AM CDT Thu May 16 2019 This Hazardous Weather Outlook is for portions of north central Illinois, northwest Illinois, west central Illinois, east central Iowa, northeast Iowa, southeast Iowa, and northeast Missouri. .DAY ONE...Today and Tonight After a hot and somewhat humid day today, a cold front will arrive in northern areas this afternoon and become stationary south of Interstate 80 tonight. An isolated thunderstorm is possible early today in northern Illinois, and again along this front this afternoon. The storms this afternoon and tonight will generally be found north of an Iowa City to Galesburg line. The Storm Prediction Center has much of the area north of Interstate 80 in a Slight Risk for severe storms this afternoon and tonight. The main threat from storms this afternoon and tonight will be hail up to quarter size, and winds to 60 mph. In addition to this, all storms tonight are likely to bring locally heavy rainfall. Since the front is becoming stationary tonight, there is a threat that storms could impact the same areas repeatedly, which could cause flash flooding. The Mississippi River and portions of the Rock River are experiencing flooding. Please see the latest Flood Statements and Flood Warnings for details. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Thunderstorms will be ongoing Friday morning and continuing through the remainder of the day. The Storm Prediction Center has the area in a marginal risk for Friday. There is a risk of isolated large hail, damaging winds, and frequent lightning with any of these thunderstorms. The Weather Prediction Center also has the area in a marginal risk for excessive rainfall on Friday. On Saturday and Saturday night, the Storm Prediction Center has parts of the area in a slight risk of severe thunderstorms west of line from Independence Iowa to Memphis Missouri. East of this line there is a marginal risk of severe thunderstorms. An active weather pattern continues through Sunday through Wednesday with chances of thunderstorms nearly every day. It is still too early to determine the severe potential for any of these periods. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed across portions of the outlook area this afternoon and evening.
Special Weather Statement
National Weather Service Quad Cities IA/IL
933 AM CDT Thu May 16 2019
ILC085-177-161530-
Jo Daviess-Stephenson-
933 AM CDT Thu May 16 2019
...A LINE OF STRONG THUNDERSTORMS WILL AFFECT JO DAVIESS AND
STEPHENSON COUNTIES UNTIL 1030 AM CDT...
At 932 AM CDT, radar indicated strong thunderstorms were located
along a line extending from 7 miles southwest of Lancaster to 7 miles
south of Argyle to Janesville. Movement was southeast at 50 mph.
Wind gusts of 50 to 55 mph and half inch hail are possible with these
storms.
Locations impacted include...
Freeport, Galena, Lena, Stockton, East Dubuque, Warren, Hanover,
Pearl City, Elizabeth, Cedarville, Davis, Woodbine, Dakota, German
Valley, Scales Mound, Apple River, Winslow, Rock City, Menominee and
Ridott.
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4220 8940 4219 9032 4230 9042 4233 9042
4235 9044 4250 9065 4251 9064 4250 8940
TIME...MOT...LOC 1432Z 317DEG 45KT 4276 9078 4260 8991 4268 8903
GibbsThe Quad Cities radar (KDVN), 109 km away, was scanning. The volume nearest the first event began at 15:24 UTC.
3 hail, 3 thunderstorm wind. Local standard time, as filed.
A morning storm produced heavy rain and pea to penny size hail in Stephenson County.
Media reported branches blown down on power lines causing widespread power outages in this area.
Tree limbs and power lines blown down.
Numerous large trees topped off about half way up.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2019Every state in 2019This day in weather historyWarnings in Illinois, May 2019
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: 825597, 825598, 825599, 825600, 825602, 825607.