The same system that caused the severe weather the night before continued to move northeast. A cold front from the low in northwest Minnesota moved into the state.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 DMX wrote it up.
The same system that caused the severe weather the night before continued to move northeast. A cold front from the low in northwest Minnesota moved into the state. Thunderstorms formed ahead of the cold front. Most of the stronger convection was to the north, however the southern extent of the storms reached into Worth County and produced a 63 MPH wind in Grafton. Strong and gusty winds were also reported across much of the area with a tightened pressure gradient in the area and strong winds mixing down from aloft. One of the stronger gusts blew a tree down in Carroll County.
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 Des Moines, IA wrote its last area forecast discussion before the first event at May 17, 5:46 AM CST, 8 hours 19 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 646 AM CDT SUN MAY 17 2015 .SYNOPSIS... ISSUED AT 453 AM CDT SUN MAY 17 2015 LOW PRESSURE OVER SOUTH DAKOTA WILL MOVE INTO THE MINNESOTA ARROWHEAD TONIGHT AS A COLD FRONT SWEEPS EAST ACROSS IOWA. COOL HIGH PRESSURE WILL BUILD INTO THE CENTRAL U.S. MON AND TUE. A WEAK SYSTEM WILL PASS SOUTH OF IOWA FOR MID WEEK...WITH THE NEXT SIGNIFICANT STORM SYSTEM MOVING IN FOR THE WEEKEND. && .SHORT TERM /TODAY/... ISSUED AT 453 AM CDT SUN MAY 17 2015 AN UPPER LOW IS LIFTING OUT OF NEBRASKA AND INTO SOUTH DAKOTA THIS MORNING WHILE AT THE SURFACE...LOW PRESSURE WILL SHIFT ACROSS SOUTH DAKOTA INTO NORTHWEST MINNESOTA BEFORE SHIFTING EAST. AT PRESENT A WARM FRONT ACROSS WESTERN IOWA WILL SHIFT NORTHEAST AS THE SURFACE LOW LIFTS AND BY 00Z THE COLD FRONT ASSOCIATED WITH THE LOW WILL PUSH INTO WESTERN IOWA. PRESENTLY STORMS THAT HAVE FIRED ALONG THE WARM FRONTAL BOUNDARY WILL CONTINUE TO LIFT NORTHEAST THROUGH THE MORNING. LOW TOPPED SUPERCELLS HAD DEVELOPED ALONG THE FRONT. IN ADDITION...A MESO VORTICY ACROSS SOUTHERN/SOUTHWEST IOWA INTERACTED WITH THE BOUNDARY ACROSS SOUTHERN IOWA AND ENHANCED STORMS ALONG THE BOUNDARY. THIS FEATURE IS CURRENTLY MOVING NORTH ACROSS NORTHERN BUT IS IN LESS FAVORABLE AIR AND MUCH LESS SHEAR SO IT IS NOT EXPECTED TO AID IN PRODUCING ANY MORE SEVERE STORMS THOUGH IT WILL BE WATCHED UNTIL IT EXITS THE CWA. FOR THE REMAINDER OF THE MORNING...ONGOING STORMS WILL LIFT NORTHEAST OUT OF THE FORECAST AREA. IT IS POSSIBLE THAT AN ISOLATED SEVERE STORM WILL DEVELOP ACROSS NORTHEASTERN PORTIONS OF THE FORECAST AREA AS BULK SHEAR REMAINS FAVORABLE IN THAT AREA AND THE FRONT HAS YET TO LIFT INTO THAT AREA. AS THE GRADIENT TIGHTENS...WINDS WILL INCREASE...ESPECIALLY ACROSS NORTHERN IOWA BY LATE MORNING INTO THE AFTERNOON. I DID NOT OPT FOR A WIND ADVISORY AT THIS POINT BECAUSE CLOUD COVER MAY HAMPER MIXING AND THE EVENT WOULD BE BORDERLINE AT BEST AS WINDS ATOP THE MIXED LAYER WERE 30-35 KTS. LATER THIS AFTERNOON...MUCH OF THE FORECAST AREA WILL BE UNDER A DRY SLOT AS THE LOW SHIFTS EAST/NORTHEAST BUT STORMS MAY RE-FIRE ACROSS NORTHERN AND EASTERN IOWA. LARGE HAIL AND DAMAGING WIND LOOK TO BE THE MAIN THREATS BUT AN ISOLATED TORNADO CANNOT BE RULED OUT. LOCATIONS MOST UNDER THE GUN WILL BE EAST OF INTERSTATE 35 AND NORTH OF HIGHWAY 30. OUR FORECAST AREA WILL HAVE A BRIEF PERIOD THIS AFTERNOON FOR SEVERE STORMS BUT THE THREAT SHOULD SHIFT QUICKLY TO THE EAST AND NORTHEAST. COLDER AIR WILL BEGIN TO MOVE INTO THE WEST LATE IN THE AFTERNOON AS A COLD FRONT ENTERS THE AREA. THESE STORMS SHOULD NOT POSE A THREAT. .LONG TERM /TONIGHT THROUGH SATURDAY/... ISSUED AT 453 AM CDT SUN MAY 17 2015 HIGH PRESSURE WILL BRING UNSEASONABLY COOL WEATHER TO THE CENTRAL U.S. FOR THE FIRST AND MIDDLE OF THE WEEK. TEMPS WILL FALL TO THE 30S NORTHWEST AND LOW 40S SOUTH ON TUE AND WILL MENTION SOME PATCHY FROST OVER THE NORTH...NORTH OF HIGHWAY 20...FOR TUE MORNING. DO NOT EXPECT ANY HEADLINES...BUT MENTIONED FOR AWARENESS. THE SYSTEM PASSING SOUTH OF IOWA FOR WED WILL BRING SOME LIGHT RAIN TO THE STATE...ESPECIALLY THE SOUTH...AND HIGHS IN THE 50S. ANOTHER STRONG SYSTEM WILL PUSH NORTHEAST OUT OF THE SOUTHWEST U.S. FOR THE WEEKEND AND BRING THUNDERSTORMS BACK INTO THE WEATHER PICTURE. && .AVIATION...17/06Z ISSUED AT 647 PM CDT SAT MAY 16 2015 AREAS OF MVFR CIGS SHOULD BECOME VFR BY MID MORNING AS THE DRY SLOT FROM A LOW PRESSURE SYSTEM SHIFTS INTO IOWA. A SURFACE LOW WILL SHIFT INTO MN THIS AFTERNOON WITH A FRONTAL BOUNDARY EXTENDING FROM IT INTO NE IA AND WISCONSIN. ADDITIONAL STORMS COULD RE-FIRE NEAR THE LOW AND FRONTAL BOUNDARY AND MAY IMPACT KMCW AND KALO. AT THIS POINT TOO MUCH UNCERTAINTY EXISTS AS TO THE EXTENT OF DESTABILIZATION AND WHERE THE FRONT WILL BE THUS STORM COVERAGE AND LOCATION IS TOO UNCERTAIN TO PUT IN TAFS AT THIS POINT. WINDS WILL BE INCREASING BY MID MORNING OUT OF THE SOUTH THEN TURNING MORE WESTERLY AT SPEEDS OF 20G30KTS. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SYNOPSIS...MS MAY 15 SHORT TERM...FAB LONG TERM...MS MAN 15 AVIATION...FAB
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 513 AM CDT SUN MAY 17 2015 IAZ004>007-015>017-023>028-036>039-050-181100- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-HAMILTON-HARDIN- GRUNDY-BLACK HAWK-TAMA- 513 AM CDT SUN MAY 17 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL MOVE OUT OF THE AREA EARLY THIS MORNING. THUNDERSTORMS WILL AGAIN BY EARLY AFTERNOON. A SEVERE STORM IS POSSIBLE WITH WIND AND HAIL THE MAIN THREATS UNTIL EARLY EVENING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THUNDERSTORMS ARE LIKELY BY FRIDAY NIGHT INTO SATURDAY. SEVERE WEATHER IS POSSIBLE...BUT MORE SPECIFIC DETAILS ARE NOT CLEAR. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS POSSIBLE BETWEEN 2 PM AND 6 PM THIS AFTERNOON. IAZ033>035-044>049-057>062-070>075-081>086-092>097-181100- SAC-CALHOUN-WEBSTER-CRAWFORD-CARROLL-GREENE-BOONE-STORY-MARSHALL- AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-POWESHIEK-CASS-ADAIR-MADISON- WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS-MONROE-WAPELLO- TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS- 513 AM CDT SUN MAY 17 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THUNDERSTORMS ARE LIKELY BY FRIDAY NIGHT INTO SATURDAY. SEVERE WEATHER IS POSSIBLE...BUT MORE SPECIFIC DETAILS ARE NOT CLEAR. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1022 AM CDT SUN MAY 17 2015
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0215 AM TSTM WND DMG 4 E MURRAY 41.05N 93.86W
05/17/2015 CLARKE IA TRAINED SPOTTER
WOODED BARN COMPLETELY DESTROYED ALONG 180TH
AVE. TIME ESTIMATED.
&&
BSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1037 AM CDT SUN MAY 17 2015
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 AM TSTM WND DMG 3 NNW PATTERSON 41.39N 93.90W
05/17/2015 MADISON IA LAW ENFORCEMENT
HOUSE WITH WINDOW AND ROOF DAMAGE, CARS
MOVED INTO A FIELD AND DAMAGE TO A BARN.
TIME ESTIMATED FROM RADAR.
&&
AWBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1040 AM CDT SUN MAY 17 2015
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0250 AM TSTM WND DMG 6 NW PATTERSON 41.42N 93.95W
05/17/2015 MADISON IA PUBLIC
TREE DAMAGE WITH TREE TOPS SNAPPED, FLAG
POLE BENT, HEAVY OUTDOOR OBJECTS MOVED. TIME
ESTIMATED FROM RADAR.
&&
AWBSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 1258 PM CDT SUN MAY 17 2015 IAZ004>007-015>017-023>025-033>035-044>046-057-171930- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-SAC-CALHOUN-WEBSTER-CRAWFORD-CARROLL- GREENE-AUDUBON- INCLUDING THE CITIES OF...ESTHERVILLE...ALGONA...FOREST CITY... LAKE MILLS...NORTHWOOD...MANLY...EMMETSBURG...GARNER...BRITT... KANAWHA...MASON CITY...CLEAR LAKE...POCAHONTAS...LAURENS... ROLFE...FONDA...GILMORE CITY...HUMBOLDT...EAGLE GROVE...CLARION... BELMOND...SAC CITY...LAKE VIEW...ODEBOLT...WALL LAKE...SCHALLER... EARLY...ROCKWELL CITY...MANSON...LAKE CITY...POMEROY... FORT DODGE...DENISON...CARROLL...JEFFERSON...AUDUBON...EXIRA 1258 PM CDT SUN MAY 17 2015 ...STRONG STORMS WITH WIND AND HAIL POSSIBLE THIS AFTERNOON... SCATTERED THUNDERSTORMS FROM DENISON TO ALGONA WILL CONTINUE MOVING NORTHEAST AT 30 MPH EARLY THIS AFTERNOON...WITH ADDITIONAL DEVELOPMENT POSSIBLE OVER THE NORTHWEST HALF OF IOWA. THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING NICKEL SIZED HAIL AND WIND GUSTS TO 40 MPH THROUGH 230 PM. SMALL
The national radar mosaic for the moment the first event began.
1 high wind, 1 thunderstorm wind. Local standard time, as filed.
A tree was blown down.
Minor tree branch damage was reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2015Every state in 2015This day in weather historyWarnings in Iowa, May 2015
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: 566562, 566449.