Thunderstorms formed in an unstable airmass within the monsoonal moisture plume across southwest into central Iowa. CAPE was in the 2000 to 3000 J/kg range with the lifted index around -6 C.
Every event with a place to put it. 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.
Thunderstorms formed in an unstable airmass within the monsoonal moisture plume across southwest into central Iowa. CAPE was in the 2000 to 3000 J/kg range with the lifted index around -6 C. There was little shear, under 20 kts. Considerable moisture was present with precipitable water values over 2 inches. Thunderstorms formed with bases near 10,000 feet and a relatively dry area noted in the sounding below the bases. Several of the cells produced microbursts. Downdraft CAPE was between 1000 and 1600 J/kg around the thunderstorm area. One storm downed a tree onto a house in Adams County. Another produced high winds that blew several semi-trucks off of Interstate 80 in Adair 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 Jul 23, 5:51 AM CST, 9 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 651 AM CDT SAT JUL 23 2011 .UPDATE FOR 12Z AVIATION DISCUSSION... .SHORT TERM /TODAY/... CONVECTIVE TRENDS AND THE HEAT/HUMIDITY ARE THE SIGNIFICANT ITEMS TODAY. DIFFUSE SURFACE BOUNDARY REMAINS ALIGNED ROUGHLY EAST-WEST THROUGH CENTRAL IOWA...WITH HIGH DEWPOINTS AND TEMPERATURES HOVERING NEAR 80 DEGREES OVERNIGHT ALONG AND SOUTH OF IT. OTHER IMPORTANT FEATURE IS DEEP MOISTURE PLUME THAT EXTENDS FROM SOUTHWESTERN STATES INTO IOWA FROM SOUTHWEST TO NORTHEAST. LOW-LEVEL JET AND ADVECTION OF MOISTURE NORTH OF THE SURFACE BOUNDARY HAS ALLOWED REDEVELOPMENT OF THUNDERSTORMS FROM HIGHWAY 30 TO 20...WITH STORMS MATURING NEAR WATERLOO WITH SOME LOCALLY HEAVY RAIN. THIS ACTIVITY IS LIKELY TO CONTINUE MOST OF THE MORNING BEFORE DYNAMICS BEGIN TO LIFT FORCING NORTHWARD AHEAD OF THE DAKOTAS WEATHER SYSTEM. IN ADDITION...MID LEVEL SHOWERS OVER SOUTHWEST IOWA WITHIN THE DEEP MOISTURE PLUME COULD LINGER THROUGH THE MORNING AS WELL...BUT FORCING ASSOCIATED IS WEAK AND DIFFICULT TO PINPOINT. LAST IN THE PRECIPITATION DEPARTMENT IS LINE OF STORMS IN EASTERN SOUTH DAKOTA. THESE ARE NOT EXPECTED TO REACH NORTHERN IOWA DUE TO RIDGING AHEAD OF THE NEXT SHORT WAVE...BUT WILL NEED TO BE MONITORED. THE HEAT AND HUMIDITY WILL PERSIST. PATTERN IS FAVORABLE FOR WARMING AS SURFACE LOW PULLS INTO SOUTHERN MINNESOTA LATER TODAY...AND DEWPOINTS/HUMIDITY WILL REMAIN HIGH WITH BOUNDARY LIFTING NORTH. MID LEVEL CLOUD COVER MAY HOLD BACK HIGH TEMPERATURES SLIGHTLY...BUT HEAT INDICES STILL TOP OUT IN THE 105 TO 110 RANGE. SO EXISTING HEAT HEADLINES LOOK GOOD...WITH WARNING IN THE SOUTH DUE TO PERSISTENT NATURE OF THE HEAT AND WARM OVERNIGHT. .LONG TERM /TONIGHT THROUGH FRIDAY/... A STRONG UPPER LEVEL LOW OVER CANADA AND ASSOCIATED SHORT WAVE OVER THE NORTHERN HIGH PLAINS WILL PIVOT NORTHEAST TONIGHT. THIS WILL FLATTEN THE UPPER RIDGE OVER THE CENTRAL PLAINS AND UPPER MIDWEST. AT THE SURFACE A LOW OVER THE PLAINS WILL GET PUSHES NORTHEAST BY THE SHORT WAVE AND THIS WILL PUSH A COLD FRONT ACROSS THE UPPER MIDWEST TONIGHT INTO MID DAY SUNDAY. THERE WILL BE ISOLATED TO SCATTERED THUNDERSTORMS WITH THE FRONTAL BOUNDARY BUT SHEAR IS WEAK OVER CENTRAL IOWA SO I AM NOT LOOKING AT ANYTHING BIG WITH THE FROPA. HOWEVER...THE BEST DYNAMICS ARE JUST TO THE NORTH...OVER SOUTHERN/CENTRAL MINNESOTA INTO WISCONSIN. EXPECT STRONGER CONVECTION IN THESE AREAS. THE CAVEAT IS WHERE WILL THE WARM FRONT BE. IF IT IS INDEED WHERE THE MODELS PLACE IT THEN THE BETTER ACTIVITY WILL BE NORTH AND EAST. HOWEVER...IF THE FRONT LIES OVER NORTHERN OR NORTHEASTERN IOWA THEN THERE WILL BE A BETTER CHANCE FOR STRONG STORMS ACROSS THE NORTH. I DID RAISE POPS ACROSS THE NORTH FOR THIS REASON AND EVEN IF THE STRONGER STORMS DO STAY NORTH WE SHOULD STILL SEE SOME RAIN NORTH DUE TO PROXIMITY OF THE FRONT. HIGH PRESSURE THEN REBUILDS INTO THE REGION FOR SUNDAY NIGHT THROUGH MONDAY NIGHT/TUESDAY BUT NUMEROUS SHORTWAVES WILL BE TOPPING THE RIDGE MONDAY NIGHT THROUGH WEDNESDAY OR THURSDAY AND EACH ONE WILL CARRY WITH IT A CHANCE FOR THUNDERSTORMS. AS FOR HEAT NPW PRODUCTS...NO CHANGES MADE THERE. FRONT WILL PUSH THROUGH BUT DEWPOINTS WILL STILL MAKE THINGS UNCOMFORTABLE SUNDAY EVENING. && .AVIATION...23/12Z FORCING FOR CONVECTION NOT WELL DEFINED AND OCCURING WELL ABOVE SURFACE BOUNDARY...WHICH NOW LIES FROM WEST CENTRAL IOWA TO SOUTH OF KOTM. BOUNDARY PUSHED SOUTHWEST OVERNIGHT WITH OUTFLOW FROM STORMS TO THE NE. BOUNDARY WILL PUSH BACK NORTH TODAY AND ELEVATED THUNDERSTORMS FROM SW INTO NE IOWA SHOULD DIMINISH AROUND MIDDAY. VFR CONDITIONS OUTSIDE OF STORMS...AND NEXT ROUND SHOULD HOLD OFF UNTIL 03-09Z AS COLD FRONT MOVES IN FROM THE NW. STORMS ARE MORE LIKELY TO BE SCATTERED TO BROKEN WITH THE COLD FRONT...RATHER THAN A SOLID LINE. && .DMX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING FROM NOON TODAY TO 7 AM CDT SUNDAY FOR ADAIR-ADAMS-APPANOOSE-CASS-CLARKE-DAVIS-DECATUR-JASPER-LUCAS- MADISON-MAHASKA-MARION-MONROE-POLK-POWESHIEK-RINGGOLD-TAYLOR- UNION-WAPELLO-WARREN-WAYNE. HEAT ADVISORY IN EFFECT FROM 10 AM TIL 10 PM SATURDAY FOR EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN- WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE- BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS- && SHORT TERM...JUNGBLUTH LONG TERM...FAB AVIATION...JUNGBLUTH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 425 AM CDT SAT JUL 23 2011 IAZ004>007-015>017-023>028-033>039-044>050-057>059-241100- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN- WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE- BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS- 425 AM CDT SAT JUL 23 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR A PORTION OF CENTRAL IOWA MAINLY ALONG AND NORTH OF HIGHWAY 30. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED THIS MORNING AND AGAIN TONIGHT. A FEW OF THE STORMS MAY BE SEVERE PRIMARILY THIS MORNING WITH DAMAGING WINDS THE PRIMARY THREAT. HEAVY RAIN IS ALSO POSSIBLE. AN ISOLATED SEVERE STORM CANNOT BE RULED OUT TONIGHT EITHER BUT THE LARGER THREAT WILL BE NORTHEAST OF THE OUTLOOK AREA. HEAT ADVISORY IS IN EFFECT SATURDAY AND SATURDAY EVENING. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. RIVER FLOOD WARNINGS REMAIN IN EFFECT FOR PORTIONS OF THE UPPER DES MOINES RIVER BASIN. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THERE WILL BE SEVERAL ROUNDS OF SCATTERED THUNDERSTORMS THROUGHOUT THE PERIOD AND SOME STORMS MAY BECOME SEVERE BUT IT IS TOO EARLY TO PINPOINT SEVERE WEATHER THREATS OR TIMING...ESPECIALLY FOR LATER IN THE WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE OFF AND ON THROUGH THE COMING WEEK...ESPECIALLY LATER IN THE WEEK. IAZ060>062-070>075-081>086-092>097-241100- POLK-JASPER-POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS- UNION-CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE- APPANOOSE-DAVIS- 425 AM CDT SAT JUL 23 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR A PORTION OF CENTRAL IOWA MAINLY SOUTH OF HIGHWAY 30. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED THIS MORNING AND AGAIN TONIGHT. A FEW OF THE STORMS MAY BE SEVERE PRIMARILY THIS MORNING WITH DAMAGING WINDS THE PRIMARY THREAT. HEAVY RAIN IS ALSO POSSIBLE. AN ISOLATED SEVERE STORM CANNOT BE RULED OUT TONIGHT EITHER BUT THE LARGER THREAT WILL BE NORTHEAST OF THE OUTLOOK AREA. AN EXCESSIVE HEAT WARNING IS IN EFFECT FOR THE AREA UNTIL SUNDAY MORNING. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. RIVER FLOOD WARNINGS REMAIN IN EFFECT FOR PORTIONS OF THE DES MOINES RIVER BASIN. PLEASE REFER TO THE NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR FURTHER DETAILS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THERE WILL BE SEVERAL ROUNDS OF SCATTERED THUNDERSTORMS THROUGHOUT THE PERIOD AND SOME STORMS MAY BECOME SEVERE BUT IT IS TOO EARLY TO PINPOINT SEVERE WEATHER THREATS OR TIMING...ESPECIALLY FOR LATER IN THE WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED OFF AND ON THROUGH THE COMING WEEK...ESPECIALLY LATER IN THE WEEK. FAB
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 102 AM CDT SAT JUL 23 2011 IAZ027-028-230700- BREMER-BUTLER- 102 AM CDT SAT JUL 23 2011 ...SPECIAL WEATHER STATEMENT... AT 100 AM CDT...SLOW MOVING THUNDERSTORMS CONTINUED TO REDEVELOP OVER CENTRAL AND NORTHEAST BUTLER COUNTY...AND BREMER COUNTY. PERIODS OF HEAVY RAINFALL CAN BE EXPECTED...WITH 1 TO 2 INCHES POSSIBLE IN HOUR...ESPECIALLY FROM WAVERLY INTO CENTRAL BREMER COUNTY. THIS HEAVY RAINFALL COULD LEAD TO PONDING OF WATER...ESPECIALLY IN LOW LYING AND URBANIZED AREAS. CLOUD TO GROUND LIGHTNING ALSO IS OCCURRING WITH THESE STORMS. LOCATIONS IMPACTED INCLUDE... PLAINFIELD... WAVERLY... WAVERLY... DENVER... TRIPOLI... SUMNER... READLYN... DO NOT DRIVE INTO FLOODED AREAS.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 235 AM CDT SAT JUL 23 2011 IAZ037-038-230800- GRUNDY-HARDIN- 235 AM CDT SAT JUL 23 2011 AT 231 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER CENTRAL AND EASTERN HARDIN COUNTY...OVER AND JUST WEST OF ELDORA...MOVING EAST AT 35 MPH. PENNY SIZE HAIL...WINDS UP TO 50 MPH...FREQUENT CLOUD TO GROUND LIGHTNING...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THIS STORM. * THE THUNDERSTORM WILL BE NEAR... STEAMBOAT ROCK AND ELDORA BY 240 AM CDT... WELLSBURG BY 255 AM CDT... HOLLAND BY 300 AM CDT... GUSTY WINDS MAY CAUSE SMALL BRANCHES TO BE BLOWN DOWN...AND LOOSE OBJECTS TO BLOW AROUND. SEEK SHELTER INDOORS UNTIL THIS STORM HAS PASSED. IN ADDITION...TORRENTIAL RAINFALL COULD CAUSE LOCAL STREET FLOODING AS THE STORM PASSES.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 323 AM CDT SAT JUL 23 2011 IAZ028-039-230915- BLACK HAWK-BREMER- 323 AM CDT SAT JUL 23 2011 ...THUNDERSTORMS WITH ADDITIONAL HEAVY RAINFALL WILL MOVE THROUGH WAVERLY AND WATERLOO BY 4 AM... AT 315 AM CDT...THUNDERSTORMS WERE MOVING BACK INTO BLACK HAWK AND THE SOUTHERN HALF OF BREMER COUNTIES. ESPECIALLY BETWEEN WAVERLY AND WATERLOO AND POINTS EAST ALONG THE BLACK HAWK AND BREMER COUNTY LINE...THESE STORMS WILL DROP HEAVY RAIN ACROSS AREAS THAT HAVE ALREADY SEEN AMOUNTS IN EXCESS OF 2 INCHES. PONDING OF WATER CAN BE EXPECTED ON ROADWAYS...AND DITCHES AND SMALL STREAMS MAY APPROACH BANK FULL. STORMS ARE ALSO EXPECTED TO REACH AREAS SOUTHEAST OF WATERLOO THAT HAD SUBSTANTIAL RAIN EARLIER. IF YOU ENCOUNTER WATER ON A ROADWAY...DO NOT DRIVE INTO IT. WINDS GREATER THAN 40 MPH...ARE ALSO POSSIBLE WITH THESE STORMS. GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW AROUND. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. JUNGBLUTH
The Des Moines radar (KDMX), 94 km away, was scanning. The volume nearest the first event began at 11:58 UTC.
2 thunderstorm wind. Local standard time, as filed.
A tree fell on a house with other large limbs down, caused by microburst.
Sheriff reported several semi-trucks blown off of Interstate 80 at the intersection of Highway 25.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2011Every state in 2011This day in weather historyWarnings in Iowa, July 2011
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: 314384, 314385.