Warm and humid conditions and a weak upper level disturbance produced thunderstorms with one report of large hail.
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The episode as NWS DVN wrote it up.
Warm and humid conditions and a weak upper level disturbance produced thunderstorms with one report of large hail.
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 25, 12:19 PM CST, 1 hour 16 minutes earlier.
Area Forecast Discussion National Weather Service Quad Cities IA IL 119 PM CDT Fri May 25 2018 ...AVIATION UPDATE... .SYNOPSIS... Issued at 249 AM CDT Fri May 25 2018 Warm moist air covers the region in what is very much a July or August weather pattern over the Midwest. Clear skies east to cloudy skies west reflect the over all picture of better moisture transport over the plains states than the Great Lakes. However, there is little in the way of significant boundaries within 400 miles of our area, once again, very mid summer like. && .SHORT TERM...(Today and Tonight) ISSUED AT 249 AM CDT Fri May 25 2018 Convection of mid summer, one of the hardest things to pin down outside of the very short term forecast. The weak flow is generally southwesterly aloft, thus the assortment of convection in KS and MO may in fact develop northeast with time today. This should not occurs a propagating multicell line, but rather a loosely organized cluster of convection. Storms today will have plenty of CAPE, but model soundings show this to be "skinny" CAPE as the mid level lapse rates are not overly steep. That profile should combine with weak shear to bring only a very marginal pulse storm threat of heavy rain and possibly a 30 to 40 mph wind gusts. Tonight, the storms to the north over MN and WI supported by stronger winds aloft, they are expected to have the possibility of organizing on the southern flank outflow, and diving into the northern 1/2 of the CWA. That is not certain, and will rely on storm evolution, but that's at least a decent possibility, and SPC has this covered with the Slight Risk area. I have my doubts on it maintaining any severe wind threats as it moves into the weaker mid level winds forecast over our area, but with 1 to 2K of CAPE in place, we can't rule that out by any means. After mid evening, the convection should be waning, with a mild night and isolated shower/storm threats continuing, but like early today. Temperatures today have been lowered a few degrees based on more extensive clouds, and possible rainfall, especially south. The impact should be limiting the thunderstorm intensity in general today, and making it more warm and humid, vs hot and humid, as highs reach the mid 80s, except for upper 80s east. .LONG TERM...(Saturday through Thursday) ISSUED AT 249 AM CDT Fri May 25 2018 Main story of the long term, hot and somewhat humid weather for the foreseeable future. If you wanted summer without the evapotranspiration from the crops, here it is. Overall blended forecast guidance for temperatures appear to be finally catching up to raw model data with 90 degree temperatures into the holiday weekend. Dewpoints are forecast to be in the 60s for the period. Think this is reasonable because overall H85 advection of moisture is weak. This means that mid summer humidity will not be seen through the long term. Heat indices reaching the mid 90s appear likely this weekend. However, with the lower RH, it will feel slightly more comfortable. The other forecast story of the long term are chances for precipitation. With lower BL moisture, do not see much of a chance for diurnal convection unless there is some forcing. This could come in the way of a MCV from previous convection. Regardless, forecast skill is low with any MCV scenario this far out. Midweek, model consensus for a wave to affect the area looks like the best chance for thunderstorms across the area. The GFS suggests that there will be better shear with these storms on Wednesday of next week. This looks to be the best day for organized updrafts in the long term period. Otherwise, no good signal for precip is seen in the models. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) ISSUED AT 118 PM CDT Fri May 25 2018 VFR conds through most of this taf cycle. However, a surface trough will push across the area this evening accompanied by scattered thunderstorms. Brief MVFR conds can be expected in/near thunderstorms. Confidence is low on the coverage of storms so for now will mention VCTS this evening. South to southwest winds around 10 knots or less. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...Ervin SHORT TERM...Ervin LONG TERM...Gibbs AVIATION...Haase
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 1140 AM CDT Fri May 25 2018 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-261645- 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- 1140 AM CDT Fri May 25 2018 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...THIS AFTERNOON AND TONIGHT The Storm Prediction Center has a marginal risk for severe thunderstorms this afternoon and evening. Some of the storms may produce gusty winds, small hail and locally heavy rainfall. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY During the Memorial Day holiday hot and humid conditions can be expected. Heat indices will reach the mid 90s across the area during the afternoon into the evening. Thunderstorms are possible Tuesday into Wednesday next week. At this time it is too soon to tell if any storms will be severe. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated this afternoon or tonight. 21
The Quad Cities radar (KDVN), 19 km away, was scanning. The volume nearest the first event began at 19:34 UTC.
1 hail. Local standard time, as filed.
Local broadcast media relayed a report of hail falling around 2:35 PM. The hail was reported to be the size of peas, up to the size of nickels.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2018Every state in 2018This day in weather historyWarnings in Illinois, May 2018
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: 749735.