A cold front moved through eastern Iowa during the early morning hours producing scattered showers and thunderstorms. A couple of these thunderstorms became severe over Iowa County producing damaging wind gusts exceeding 60 mph near Williamsburg.
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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 cold front moved through eastern Iowa during the early morning hours producing scattered showers and thunderstorms. A couple of these thunderstorms became severe over Iowa County producing damaging wind gusts exceeding 60 mph near Williamsburg.
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 Aug 16, 2:05 AM CST, 2 hours 51 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 305 AM CDT THU AUG 16 2012 .SYNOPSIS... ANALYSIS AT 2 AM SHOWS RAPID DEVELOPMENT OF SHOWERS AND STORMS BLOOMING A ALONG AND BEHIND VIGOROUS AND SEASONALLY VERY STRONG COLD FRONT NOW NEAR I-35. THIS IS SIMILAR TO WHAT WAS DISCUSSED PAST FEW NIGHTS AND NOWCAST TOOLS SUPPORT THIS LOOSE CONVECTIVE COMPLEX TO PASS ACROSS AT LEAST THE NORTHERN 1/2 TO 2/3 AREA BETWEEN NOW AND NOON THIS MORNING. LOCAL TECHNIQUES SUGGEST LIGHT TO MAINLY MODERATE RAIN AMOUNTS NORTH OF HIGHWAY 34 WITH SOME LOCALIZED 1 PLUS INCH AMOUNTS. UPPER AIR ANALYSIS SUPPORTS FRONT AS STRONG AS PROGGED WITH GUSTY NW WINDS THIS AFTERNOON AND THEN BELOW NORMAL TEMPERATURES NEXT SEVERAL DAYS. && .SHORT TERM...TODAY AND TONIGHT... TODAY...NOWCAST TOOLS SUPPORT HIGHEST RISK OF HEAVIER PRECIPITATION NEXT 6 PLUS HOURS TO PASS ALONG AND POSSIBLY JUST SOUTH OF I-80 CORRIDOR. TRENDS SUPPORT 1 PLUS INCHES VERY POSSIBLE IN THE HEAVIEST SWATH WITH MOST SECTIONS PICKING UP .2 TO .5+ TENTHS OF AN INCH OF RAIN WITH SYSTEM. MOST PRECIPITATION SHOULD END BY LATE MORNING ACROSS ALL BUT FAR SOUTHEAST SECTIONS. SEVERE RISK APPEARS NIL AS SATURATION AND CAA BEHIND FRONT SHOULD LIMIT STRONGEST CELLS TO PEA HAIL AND GUSTY WINDS AOB 40 MPH. HIGH TEMPERATURES SHOULD BE MOSTLY OR TOTALLY ALL IN THE 70S WITH LOWER 70S NW SECTIONS AND UPPER 70S SOUTHEAST SECTIONS. CLOUD COVER TODAY MAY IMPACT HIGHS TODAY MANY LOCATIONS BY 3 TO 5 DEGREES AS TIMING CLEARING A MAIN CHALLENGE FOR DAY SHIFT. MOST AREAS SHOULD BE MOSTLY SUNNY ALL BUT SOUTHEAST SECTIONS BY 4 PM. NW WINDS OF 15 TO 25 MPH EXPECTED THIS AFTERNOON. TONIGHT...CLEAR AND CRISP WITH NW WINDS DECREASING TO 5 TO 10 MPH BY LATE EVENING. MINS SHOULD SETTLE IN THE UPPER 40S FAR NORTHWEST SECTIONS TO LOWER 50S ELSEWHERE. AREA MINS SHOULD BE WITHIN 1 TO 3 DEGREES OF RECORD LOWS. QUITE REMARKABLE BECAUSE WIND WILL LIMIT DECOUPLING OF BL. NICHOLS .LONG TERM...THURSDAY THROUGH NEXT TUESDAY... MODEL DATA SUGGESTS THAT THE BETTER FORCING WITH THE FRONT WILL BE POST FRONTAL ON THURSDAY. THUS THE BETTER POPS WOULD BE OVER THE NORTHWEST HALF OF THE CWFA DURING THE MORNING AND THE SOUTHEAST HALF DURING THE AFTERNOON. AREAS BEHIND THE FRONT SHOULD SEE MINIMAL TEMPERATURE RECOVERY DURING THE DAY THURSDAY WHILE THE SOUTHEAST HALF WARMS. THERE ARE STILL SUGGESTIONS THAT RESPECTABLE STRONG CONVECTION WILL DEVELOP MID TO LATE THURSDAY AFTERNOON IMMEDIATELY SOUTH/EAST OF THE CWFA. LINGERING CONVECTION WILL LIKELY OCCUR THROUGH SUNSET ACROSS THE FAR EAST AND SOUTHEAST/SOUTH PARTS OF THE CWFA. AFTER SUNSET...QUIET CONDITIONS ARE EXPECTED AS SKIES SLOWLY CLEAR FROM NORTHWEST TO SOUTHEAST. QUIET AND DRY CONDITIONS WILL BE SEEN ACROSS THE AREA FRI/FRI NIGHT WITH BELOW NORMAL TEMPERATURES. SATURDAY ON... MODEL CONSENSUS IS GENERATING DIURNAL SHRA WITH SCHC POPS FOR SAT AND SUNDAY. MOISTURE AVAILABILITY IS QUESTIONABLE IN SPITE OF THE VORT MAXES DROPPING DOWN IN THE DEEPENING TROF OVER THE GREAT LAKES. IF SOMETHING WOULD DEVELOP EITHER SAT OR SUN IT WOULD BE ISOLD IN NATURE AND AREAL COVERAGE WOULD PROBABLY BE NOT MORE THAN 10 PERCENT. AS SUCH A LARGE MAJORITY OF THE AREA WILL REMAIN DRY. SUNDAY NIGHT THROUGH TUESDAY THE MODEL CONSENSUS GIVES DRY CONDITIONS WITH TEMPERATURES STARTING OUT BELOW NORMAL BUT TRENDING CLOSER TO NORMAL BY TUESDAY. ..08.. && .AVIATION... PASSING COLD FRONT IS PRODUCING SHOWERS AND THUNDERSTORMS THAT WILL PASS ACROSS ALL TERMINALS BETWEEN 09-16Z. CLOUDS WITH VFR CONDITIONS TO DETERIORATE TO MVFR CONDITIONS FOR A FEW HOURS OR SO WITH PASSAGE OF COLD FRONT AND ACCOMPANYING PRECIPITATION WITH CIGS 1-3K AGL AND 1-4 MILES IN RAIN. CONDITIONS TO THEN RAPIDLY BECOME VFR AND CLEAR BETWEEN 16-20Z ALL TERMINALS WITH NW WINDS OF 15 TO 25KTS UNTIL 00Z. CLEAR SKIES WITH NW WINDS OF 5 TO 10 KTS AFTER 17/00Z. NICHOLS && .CLIMATE... RECORD LOWS FOR AUGUST 17TH AND 18TH AUGUST 17TH BURLINGTON.......53 IN 1899 CEDAR RAPIDS.....46 IN 1924 DUBUQUE..........47 IN 1879 MOLINE...........48 IN 1992 AUGUST 18TH BURLINGTON.......49 IN 1977 CEDAR RAPIDS.....46 IN 2002 DUBUQUE..........46 IN 2002 AND PREVIOUS YEARS MOLINE...........44 IN 1963 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && NICHOLS/08
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 355 AM CDT THU AUG 16 2012 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-170900- 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- 355 AM CDT THU AUG 16 2012 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 TODAY...A SEASONALLY STRONG COLD FRONT WILL PRODUCE SCATTERED THUNDERSTORMS...MAINLY THIS MORNING. LIMITED INSTABILITY WILL LOWER THE RISK OF SEVERE STORMS. THE STRONGEST STORMS MAY STILL PRODUCE GUSTY WINDS TO OVER 45 MPH WITH POSSIBLY PEA SIZED HAIL. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION SHOULD NOT BE NEEDED TODAY OR TONIGHT. REPORTS OF WINDS OVER 40 MPH...PEA SIZED HAIL OR RAIN AMOUNTS OF AN INCH OR MORE WOULD BE APPRECIATED. NICHOLS/08
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE QUAD CITIES IA IL 344 AM CDT THU AUG 16 2012 IAZ040>042-051>054-063>068-076>078-087-088-ILZ001-015-024-161200- BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON- CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON- HENRY IA-JO DAVIESS-ROCK ISLAND-MERCER- INCLUDING THE CITIES OF...INDEPENDENCE...MANCHESTER...DUBUQUE... VINTON...CEDAR RAPIDS...ANAMOSA...MAQUOKETA...MARENGO... IOWA CITY...TIPTON...CLINTON...MUSCATINE...BETTENDORF... DAVENPORT...SIGOURNEY...WASHINGTON...WAPELLO...FAIRFIELD... MOUNT PLEASANT...GALENA...MOLINE...ROCK ISLAND...ALEDO 344 AM CDT THU AUG 16 2012 ...SHOWERS AND THUNDERSTORMS EXPECTED BY 7 AM... A DEVELOPING AREA OF SHOWERS AND THUNDERSTORMS WILL OVERSPREAD THE REGION THROUGH 7 AM. MOST AREAS WILL PICK UP AT LEAST A QUARTER INCH OF RAIN WITH MORE LOCALIZED AMOUNTS OF A HALF INCH UP TO AROUND 1 INCH OR MORE. THE STRONGEST STORMS MAY PRODUCE PEA SIZED HAIL AND GUSTY WINDS UP TO AROUND 40 MPH WITH BRIEF TORRENTIAL RAIN. MINOR WATER ISSUES ARE POSSIBLE...MOSTLY IN URBAN LOCATIONS WITH HEAVIER RAIN TOTALS. NICHOLS
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
514 AM CDT THU AUG 16 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0513 AM HEAVY RAIN 1 SSE CEDAR RAPIDS 41.95N 91.66W
08/16/2012 M1.10 INCH LINN IA TRAINED SPOTTER
OCCURRED BETWEEN 4 AND 5 AM.
&&SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE QUAD CITIES IA IL 544 AM CDT THU AUG 16 2012 IAZ063>068-076>078-087>089-098-099-ILZ015-016-024>026-161400- IOWA-JOHNSON-CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON- LOUISA-JEFFERSON-HENRY IA-DES MOINES-VAN BUREN-LEE-ROCK ISLAND- HENRY IL-MERCER-HENDERSON-WARREN- INCLUDING THE CITIES OF...MARENGO...IOWA CITY...TIPTON... CLINTON...MUSCATINE...BETTENDORF...DAVENPORT...SIGOURNEY... WASHINGTON...WAPELLO...FAIRFIELD...MOUNT PLEASANT...BURLINGTON... KEOSAUQUA....FORT MADISON...MOLINE...ROCK ISLAND...KEWANEE... ALEDO...OQUAWKA...MONMOUTH 544 AM CDT THU AUG 16 2012 ...SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG THROUGH 9 AM... A DEVELOPING AREA OF SHOWERS AND THUNDERSTORMS WILL OVERSPREAD THE REGION THROUGH 9 AM. MOST AREAS WILL PICK UP AT LEAST A QUARTER INCH OF RAIN WITH LOCALIZED AMOUNTS OF A HALF INCH UP TO AROUND 1 INCH OR MORE. THE STRONGEST STORMS MAY PRODUCE PEA SIZED HAIL AND GUSTY WINDS UP TO AROUND 45 MPH WITH BRIEF TORRENTIAL RAIN. MINOR WATER ISSUES ARE POSSIBLE...MOSTLY IN URBAN LOCATIONS WITH HEAVIER RAIN TOTALS. NICHOLS
The Quad Cities radar (KDVN), 117 km away, was scanning. The volume nearest the first event began at 10:56 UTC.
3 thunderstorm wind. Local standard time, as filed.
Ten evergreen trees were blown down by thunderstorm winds. Time of the event was estimated using an earlier report, but it may have been from the first of two storms to impact this area around an hour earlier.
Emergency Manager reported several large trees down in Williamsburg with the power out in half of the town. The time of the event was estimated by radar.
The public reported a wood and metal fence knocked over during a thunderstorm. Some of the posts were pulled completely out of the ground while others were broken off. A mobile home on the property was pushed over along with a pair of trailers on an adjacent lot. The garage door attached to the house was dented.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2012Every state in 2012This day in weather historyWarnings in Iowa, August 2012
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: 410271, 410272, 410273.