A squall line developed in a semi-moist atmosphere north of a warm front that was in far northern Missouri. Peak wind gust speeds associated with the squall line were generally in the 30 to 40 knot range (35 to 46 mph).
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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 squall line developed in a semi-moist atmosphere north of a warm front that was in far northern Missouri. Peak wind gust speeds associated with the squall line were generally in the 30 to 40 knot range (35 to 46 mph). Two severe downbursts occurred in Cedar Rapids and Wayland.
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 12, 3:05 PM CST, 6 hours 49 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 405 PM CDT THU MAY 12 2005 .SYNOPSIS... SOME SHOWERS AND EVEN A FEW WEAK LITTLE THUNDERSTORMS SLOWLY EXITING THE AREA THIS EVENING...WITH A PRETTY SIGNIFICANT WAKE LOW BEHIND. THIS WAKE LOW PRODUCED SOME VERY STRONG WINDS OVER CENTRAL IOWA...AND EVEN WESTERN PORTIONS OF THE CWA THIS AFTERNOON. WE HAD AN ADVISORY OUT FOR THESE WINDS...BUT SINCE WAKE LOW IS WEAKENING... NO FURTHER REPORTS COMING IN...AND ASOS WINDS ARE ALL DEFINETLY WEAKER THAN EARLIER...HAVE CANCELLED ADVISORY WITH THE 4 PM PACKAGE. DEVELOPING OUT WEST...OVER EASTERN KANSAS AND NEBRASKA...IS THE MAIN SURFACE LOW OVER THE CURRENT WEATHER SYSTEM...WITH A WARM FRONT DRAPED TO THE SOUTHEAST TO NEAR ST LOUIS. FOR OUR AREA...DEEP IN THE COLD AIR AND UNDER LOTS OF CLOUDS...TEMPERATURES HAVE BEEN MAINLY IN THE 50S...WITH SOME TEMPERATURES SNEAKING INTO THE LOWER 60S OVER THE SOUTHEAST. && .SHORT TERM (TONIGHT)...WEATHER TO BECOME VERY ACTIVE OVERNIGHT...WITH THE SURFACE LOW SLOWLY MOVING EAST TOWARDS THE CWA...AND THE WARM FRONT ALSO SLOWLY MOVING NORTH. THE 850MB FRONT...WHICH WAS THE FOCUS FOR THE PRECIP OVERNIGHT...HAS SHIFTED NORTH AND WILL DRENCH MINNESOTA AND WISCONSIN TONIGHT. MAIN CONCERN FOR THE CWA IS THE MOVEMENT OF THE WARM FRONT...AND THE CONVECTION THAT FIRES UPON IT. ESSENTIALLY...PRECIPITATION SHOULD FIRE OVER KANSAS...NEBRASKA...WESTERN IOWA...AND MISSOURI...CLOSER TO THE SURFACE LOW AND THE WARM FRONT...AND THEN MOVE INTO THE AREA. BULK OF PRECIPITATION FOR THE CWA SHOULD BE AFTER MIDNIGHT...MOVING GENERALLY FROM WEST TO EAST. TEMPERATURES TO BE COOL TONIGHT...BUT WITH A LARGE DIURNAL RANGE FROM NORTH TO SOUTH ACROSS THE CWA...MID 40S NORTH TO LOW 60S SOUTH. ...LE... && .LONG TERM (FRIDAY THROUGH NEXT THURSDAY)... WX VERY ACTIVE INITIALLY WITH MANY THINGS TO CONSIDER. HAVE GONE CAT POPS FOR FRIDAY AND FOCUSING THE HEAVY RAIN THREAT OVER ABOUT THE WESTERN THIRD TO HALF OF THE CWFA. ONLY MODEL THAT SEEMS TO MAKE ANY SENSE IS THE UKMET. ETA/NGM/AVN ARE NOT HANDLING THE CURRENT SHORT TERM WX AND I HAVE DOUBTS ON THEIR RESPECTIVE FORECASTS FOR FRIDAY AND FRIDAY NIGHT. UKMET INDICATES THE HEAVIEST RAIN JUST WEST OF THE MISSISSIPPI ON FRIDAY WITH RAIN CONTINUING INTO FRIDAY NIGHT BEFORE ENDING. QUESTION REMAINS ON WHETHER THERE WILL BE A BREAK OR NOT. DON/T KNOW WHETHER TO BELIEVE THE AVN AND ITS PRODUCTION OF HEAVY RAIN FRIDAY NIGHT. NO OTHER MODEL SHOWS THIS. SATURDAY...MODELS ARE FINALLY STARTING TO REALIZE THE POTENTIAL FOR DIURNAL SHRA AS STRONG H5 TROF/SHORT WAVE AND COLD POOL MOVE ACROSS THE AREA. MOST LIKELY TIME FOR THESE TO BE SATURDAY AFTERNOON/EVENING. LATE SATURDAY NIGHT THROUGH MONDAY NIGHT TO BE QUIET AS SURFACE RIDGE MOVES ACROSS THE AREA. IF THE 12/12Z ECMWF IS CORRECT...LOWS IN THE 30S NORTH OF I80 WOULD BE SEEN SATURDAY NIGHT. EITHER WAY...SATURDAY NIGHT OR SUNDAY NIGHT TO BE QUITE CHILLY. DON/T EXPECT ANY RECORDS BUT SOME AREAS COULD BE CLOSE. ATTENTION THEN TURNS TO NEXT SYSTEM TO AFFECT THE AREA LATE TUESDAY AFTERNOON INTO WEDNESDAY. BETTER CHANCES ON POPS APPEAR TO BE TUESDAY NIGHT AND WEDNESDAY. ...08... && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 542 AM CDT THU MAY 12 2005 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-131000- BENTON IA-BUCHANAN IA-BUREAU IL-CARROLL IL-CEDAR IA-CLARK MO- CLINTON IA-DELAWARE IA-DES MOINES IA-DUBUQUE IA-HANCOCK IL- HENDERSON IL-HENRY IA-HENRY IL-IOWA IA-JACKSON IA-JEFFERSON IA- JO DAVIESS IL-JOHNSON IA-JONES IA-KEOKUK IA-LEE IA-LINN IA-LOUISA IA- MCDONOUGH IL-MERCER IL-MUSCATINE IA-PUTNAM IL-ROCK ISLAND IL- SCOTLAND MO-SCOTT IA-STEPHENSON IL-VAN BUREN IA-WARREN IL- WASHINGTON IA-WHITESIDE IL- 542 AM CDT THU MAY 12 2005 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST...EAST CENTRAL...AND SOUTHEAST IOWA...NORTHWEST...NORTH CENTRAL...AND WEST CENTRAL ILLINOIS...AND NORTHEAST MISSOURI. .DAY ONE...TODAY AND TONIGHT THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ALONG AND SOUTH OF HIGHWAY 30 FROM LATE THIS AFTERNOON THROUGH TONIGHT. THE PRIMARY THREAT WILL BE LARGE HAIL. DURING THE LATE AFTERNOON AND EARLY EVENING HOURS THE THREAT OF SEVERE STORMS WILL BE MAINLY ALONG AND SOUTH OF HIGHWAY 34. BY LATE EVENING...THE THREAT WILL SHIFT NORTH INTO THE I80 AND HIGHWAY 30 CORRIDORS. LOCALLY HEAVY RAINS WILL ALSO BE POSSIBLE...LATE TONIGHT. NORTHWEST OF A LINE FROM SIGOURNEY THROUGH DUBUQUE. RAINFALL OF 1 TO 1.5 INCHES WILL BE POSSIBLE IN THIS AREA AFTER MIDNIGHT. THE HEAVY RAIN MAY CAUSE SOME FLOODING OF SMALLER STREAMS AND POORLY DRAINED AREAS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS SOUTHEAST OF A LINE FROM STERLING ILLINOIS TO FAIRFIELD IOWA ON FRIDAY. A WAVE OF LOW PRESSURE WILL LIFT A WARM FRONT NORTH INTO THIS AREA IN THE AFTERNOON. SEVERE STORMS WITH LARGE HAIL AND DAMAGING WINDS WILL BE POSSIBLE ALONG THIS BOUNDARY AND ALSO ALONG A TRAILING COLD FRONT THAT WILL SWEEP THROUGH BY LATE AFTERNOON. THERE IS ALSO A CONTINUED RISK FOR HEAVY RAINFALL...WITH WIDESPREAD AMOUNTS OVER 1 INCH AND LOCALLY AS HIGH AS 2 INCHES EXPECTED BEFORE RAIN ENDS FRIDAY EVENING. THIS COULD LEAD TO FLASH FLOODING WHERE HEAVY RAIN IMPACTS AREAS WHERE THE GROUND MAY BE SATURATED FROM RAINFALL EARLIER IN THE WEEK. THE NEXT CHANCE FOR THUNDERSTORMS IS NEXT WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEED FROM LATE THIS AFTERNOON THROUGH TONIGHT OVER PARTS OF NORTHEAST MISSOURI...SOUTHEAST IOWA AND WEST CENTRAL ILLINOIS. DLF/DLS
The Quad Cities radar (KDVN), 104 km away, was scanning. The volume nearest the first event began at 03:52 UTC.
2 thunderstorm wind. Local standard time, as filed.
Downburst occurred over and immediately east of Wayland, Iowa. Several trees were downed including some that were 14 inches in diameter. One tree in town spared a direct hit on a house but took out the porch.
Downburst occurred a few miles northeast of KCID but was caught by an IDOT RWIS on U.S. 30 just west of Interstate 380.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2005Every state in 2005This day in weather historyWarnings in Iowa, May 2005
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: 5452058, 5452059.