Thunderstorms produced heavy rain in part of northwest Iowa during the mornng of August 4th. The heavy rain caused flash flooding of roads and low areas in the Le Mars and Storm Lake areas.
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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 FSD wrote it up.
Thunderstorms produced heavy rain in part of northwest Iowa during the mornng of August 4th. The heavy rain caused flash flooding of roads and low areas in the Le Mars and Storm Lake areas.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Aug 4, 2:18 AM CST, 2 hours 42 minutes earlier.
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 318 AM CDT SAT AUG 4 2007 .DISCUSSION... LARGE RAIN SHIELD WILL MOVE EAST THROUGH THE REST OF THIS MORNING WITH POCKETS OF HEAVIER RAIN. MAINLY JUST SHOWERS WITH EMBEDDED THUNDERSTORMS. NO SEVERE STORMS ARE EXPECTED THIS MORNING. RAINFALL IS ASSOCIATED WITH STRONG ISENTROPIC FORCING AND MOISTURE ADVECTION...ESPECIALLY NEAR THE H85 BNDRY. AS THIS BNDRY LIFTS NE THIS MORNING...SO WILL THE BEST CHANCES FOR PRECIPITATION. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BACK BUILD...SUCH THAT SCATTERED CONVECTION SHOULD HOLD ON IN SW MN AND NW IA THROUGH MUSH OF THE MORNING. SHOULD STILL SEE A FEW SHOWERS CONTINUE INTO THE AFTERNOON AS WEAKER ISENTROPIC FORCING HOLDS ON ACROSS SW MN AND NW IA...HOWEVER MAIN BNDRY WILL BE ACROSS CNTRL AND ERN MN. SOME UNCERTAINTY WITH THE EVOLUTION OF LOW LEVEL FEATURES THIS AFTERNOON...WHICH CAUSE SOME DIFFICULTLY WITH TEMPERATURES AND THE POSSIBILITY OF SEVERE STORMS THIS EVENING. NAM IS MUCH MORE AGGRESSIVE PUSHING 925 FRONT NWRD...THUS ALLOWING FOR CLEARING OF LOW CLOUDS AND SUBSTANTIAL HEATING. THE NAM SOLUTION PRODUCES 2000-3000 ML CAPES AND VERY UNSTABLE LOW LEVELS AND A VEERING PROFILE WITH HEIGHT...SUPPORTIVE OF SUPERCELL THUNDERSTORMS. GIVEN THE POOR RECENT PERFORMANCE OF THE NAM...FOLLOWING THE GFS SOLUTION. ALSO...ATTM GFS MUCH CLOSER WITH SFC PRESSURE FIELD. THE GFS KEEPS 925 BNDRY FARTHER SOUTH...WITH ERLY SFC FLOW OVER THROUGH MUCH OF THE DAY. THEREFORE...KEPT TEMPERATURES RATHER COOL N AND E OF THE BNDRY...ESPECIALLY INTO SW MN WHERE SHOWERS AND UPSLOPE FLOW DO NOT FAVOR WARMING. ALSO THINKING STRATUS...WHICH CURRENTLY EXTENDS ALL THE WAY BACK INTO NW SD WILL TAKE SOME TIME TO ERODE AND BREAK UP. PROVIDED LOW CLOUDS HOLD AND SFC TEMPS DO NOT WARM APPRECIABLY... SEVERE WEATHER THREAT LATE THIS AFTERNOON WILL BE VERY LOW...BUT IS SOMETHING TO WATCH. WILL NOT MENTION ANY CHANCE OF SEVERE IN THE HWO AT THIS TIME. FOR THE REST OF THE FORECAST PERIOD...CONTINUED CHANCES FOR PRECIPITATION AS WEATHER PATTERN CERTAINLY MORE ACTIVE THAN SEEN IN THE LAST MONTH OR SO. AMPLE AMOUNT OF LOW LEVEL MOISTURE WILL BE IN PLACE THOUGH THE PERIOD...SO DEPENDING ON TIMING AND PLACEMENT OF SMALLER SCALE FEATURES...MOST LOCATIONS SHOULD BE ABLE TO SQUEEZE OUT AT LEAST SOME MOISTURE. AT THIS TIME...THE NEXT DECENT CHANCE FOR RAINFALL LOOKS TO BE MON NIGHT AS UPPER LEVEL ENERGY MOVES ACROSS SD. && .AVIATION... SCATTERED MVFR CEILINGS ARE LIKELY DURING AND IN THE WAKE OF ONGOING MCS THIS MORNING WITH ISOLATED IFR VISIBILITIES. BY EARLY AFTERNOON...THE MAJORITY OF MVFR CEILING AND VISIBILITY ACTIVITY SHOULD BE OUT OF THE AREA. GUSTY EAST WINDS TO 35 MPH WILL ALSO BE POSSIBLE IN THE WAKE OF THE THUNDERSTORM ACTIVITY WHICH COULD CREATE PERIODS OF LOW LEVEL TURBULENCE. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && LIEBL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SIOUX FALLS SD 526 AM CDT SAT AUG 04 2007 SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098- IAZ001>003-012>014-020>022-031-032-NEZ013-014-051200- AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA- CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE- DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON- IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN- LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN- OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN- SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON- 526 AM CDT SAT AUG 04 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA... SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS... SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER MUCH OF THE AREA THIS MORNING...WITH SOME STRONGER STORMS PRODUCING HEAVY RAINFALL. THUNDERSTORM ACTIVITY ACROSS EASTERN SOUTH DAKOTA WILL MAINLY DIE OFF BY LATE THIS MORNING...WHILE SCATTERED SHOWERS AND THUNDERSTORMS WILL PERSIST INTO THE AFTERNOON OVER PORTIONS OF SOUTHWEST MINNESOTA AND NORTHWEST IOWA. BY THIS EVENING THE CHANCES FOR THUNDERSTORMS WILL MAINLY BE CONFINED TO NORTHWEST IOWA. THE THREAT FOR SEVERE THUNDERSTORMS TODAY IS VERY LOW. FLOODING... STRONGER THUNDERSTORMS IN SOUTHWEST MINNESOTA AND NORTHWEST IOWA MAY PRODUCE LOCALIZE FLASH FLOODING EARLY THIS MORNING. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THERE IS A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA FROM LATE MONDAY AFTERNOON INTO MONDAY NIGHT. SOME OF THESE STORMS COULD BECOME SEVERE PRODUCING LARGE HAIL AND DAMAGING WINDS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT LIKELY TODAY && FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WWW.CRH.NOAA.GOV/FSD. THIS INCLUDES THE GRAPHICAL HAZARDOUS WEATHER OUTLOOK. LIEBL
The Sioux Falls radar (KFSD), 101 km away, was scanning. The volume nearest the first event began at 11:00 UTC.
2 flash flood. Local standard time, as filed.
Rainfall of more than 4 inches in the town of Le Mars caused flooding of several streets and yards in town.
Rainfall of 3 to 4 inches caused flooding of several streets in Storm Lake.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2007Every state in 2007This day in weather historyWarnings in Iowa, August 2007
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: 54019, 54020.