The cold front that entered the state on the 15th made slow progress east during the day on the 16th. The atmosphere became unstable by early to mid afternoon with CAPE values rising to 2000 to 4000 J/kg and the lifted index falling to the -4 to -9 C range.
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.
The cold front that entered the state on the 15th made slow progress east during the day on the 16th. The atmosphere became unstable by early to mid afternoon with CAPE values rising to 2000 to 4000 J/kg and the lifted index falling to the -4 to -9 C range. Downdraft CAPE was not as high as the previous day, in the 500 to 800 J/kg range. Precipitable water was relatively high, in the 1.5 to 1.7 inch range. The freezing level remained around 14,000 feet, helping to limit hail production somewhat. Available CAPE in the -10 to -30 C layer of the atmosphere was between 400 and 600 J/kg. The LCL remained a relatively high 1250 meters. Moderate shear was available with 35 to 45 kts present. Thunderstorms formed along and ahead of the cold front. The strongest storms formed across southern Iowa, where the greatest instability and deeper moisture were present. The cluster of stronger storms then pushed east across the southern two to three tiers of Iowa counties. Heavy rainfall of one to three inches occurred in Ringgold County, along with nickel to quarter size hail. One inch diameter hail occurred in Davis County, with quarter size hail also reported in Taylor County. The storms moved and developed eastward. As they did, wind became more of an issue. Wind damage occurred southwest of Lamoni in Decatur County. As the storms moved through the southeast part of the CWA, 62 MPH winds were recorded at the Ottumwa Airport. As the cluster of storms moved east they became more cold pool dominated. Winds of 65 to 75 MPH were recorded before the storms left the Des Moines CWA.
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 Jun 16, 12:10 PM CST, 16 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 110 PM CDT SAT JUN 16 2012 ...UPDATED FOR 18Z AVIATION DISCUSSION... .SHORT TERM.../TODAY/ THE MESSY PATTERN CONTINUES OVER IOWA TODAY. AS OF 4 AM THE MCV THAT DRIFTED ACROSS THE CWA YESTERDAY AND LAST EVENING WAS OVER NORTHEAST IOWA. RADAR ANIMATION SHOWED SHOWERS ROTATING AROUND A LOW THAT WILL CONTINUE TO SHIFT NORTHEAST THROUGH THE MORNING. THE NEXT SHORTWAVE TO AFFECT THE AREA IS OVER THE PLAINS AND WILL SHIFT ACROSS THE AREA TODAY INTO THIS EVENING. IN ADDITION...ANOTHER COLD FRONT WILL SWEEP ACROSS CENTRAL IOWA THIS AFTERNOON. WE HAVE MOISTURE RETURNING TO THE AREA AND INSTABILITY WILL INCREASE TO AROUND 3000 CAPES THIS AFTERNOON. GIVEN THAT STORMS ARE ONGOING ACROSS NEBRASKA AT THIS TIME THERE IS LITTLE DOUBT THAT WE WILL SEE STORMS AGAIN THIS AFTERNOON. THE AFOREMENTIONED SHORT WAVE SHOULD PROVIDE SUFFICIENT FORCING SO THUNDERSTORMS WILL MOVE INTO THE AREA LATE MORNING/AFTERNOON AND INTENSIFY SOME. NOT SURE ON HOW WIDESPREAD THE SEVERE POTENTIAL MIGHT BE HOWEVER. LOW LEVEL SHEAR IS MODEST BUT DEEP LAYER SHEER IS LACKING. STEEP LAPSE RATES ARE ALSO GOING TO DEVELOP ACROSS THE AREA THIS AFTERNOON AND IT DOES APPEAR THAT THERE IS SOME POTENTIAL FOR SEVERE STORMS ALONG THE FRONT BASED ON SOUNDINGS. STRONG WIND POTENTIAL SHOULD EXIST WITH THESE STORMS SUPPORTED BY DCAPES AROUND 1500 ALONG THE BOUNDARY LATE THIS AFTERNOON. LOCATIONS THAT DO SEE STORMS SHOULD ONCE AGAIN SEE SOME MODERATE TO LOCALLY HEAVY RAINFALL AS WELL WITH PWATS ONCE AGAIN APPROACHING 1.75 INCHES. .LONG TERM.../TONIGHT THROUGH FRIDAY/ THREE MAIN AREAS OF CONCERN EARLY THIS MORNING...PRECIP TRENDS TONIGHT...WARMTH MON THROUGH WED...AND PRECIP ASSOCIATED WITH FRONTAL PASSAGE AROUND WED AND THU. QUESTION FOR TONIGHT WILL BE WHETHER EVENING CONVECTION IS LINGERING FROM CURRENT HIGH PLAINS PRECIP OR ADDITIONAL DEVELOPMENT SHORTLY AFTER PEAK HEATING WITH FRONTAL PASSAGE. 00Z HRW WRF NMM/ARW SOLUTIONS ARE TOO SLOW WITH CURRENT CONVECTION...WHICH IS OFTEN THE CASE AS ITS EXPLICIT CONVECTIVE SCHEMES TRY TO CATCH UP. IF YOU SPEED THOSE SOLUTIONS UP THREE-FOUR HOURS THEY SUGGEST ANY LINGERING PRECIP FROM TODAY WILL BE EAST OF OUR AREA BY 00Z WITH ATTENTION TO ADDITIONAL DEVELOPMENT ALONG THE FRONT. THIS SEEMS REALISTIC CONSIDERING ADEQUATE FORCING SHOULD BE AVAILABLE ON TRAILING EDGE OF CURRENT WY/MT PV ANOMALY/SHORT WAVE AS IT TRACKS INTO MN BY 00Z. WRF RUNS DO NOT DEPICT MUCH IN THE WAY OF AREAL COVERAGE HOWEVER SO HAVE KEPT POPS IN THE CHANCE CATEGORY...TRANSITIONING FROM NW-SE. 0-6KM SHEAR IS NOT TOO IMPRESSIVE SO DO NOT EXPECT MUCH OF A SEVERE THREAT WHICH IS SOMEWHAT CONDITIONAL ANYWAYS DEPENDING ON HOW MUCH WE CAN RECOVER FROM PLAINS DEBRIS. AFTER A BREAK THROUGH MUCH OF THE WEEKEND...A MINOR CONCERN WILL BE ELEVATED CONVECTIVE POTENTIAL SUN NIGHT. GFS/ECMWF THETA-E ADVECTION IS IMPRESSIVE...HOWEVER ADEQUATE MOISTURE ALONG 310K ISENT SURFACE AND BAROCLINIC ZONE IS SUSPECT WITH PRESSURE DEFICITS QUITE LOW. STRONG WARM ADVECTION OFTEN SEEMS TO OVERCOME MOISTURE DEFICIENCIES HOWEVER SO HAVE BEEN A BIT MORE AGGRESSIVE ON POPS WITH THEIR SRN EXTENT. BY MON MORNING WARM ADVECTION PUSHES NORTHWARD WITH IA WELL INTO WARM SECTOR. SOUNDINGS DEPICT BRISK SWLY WINDS SO CONTRARY TO THE GFS...MIXING SHOULD BE QUITE AGGRESSIVE AND COULD VERY WELL PUSH TEMPS CLOSE TO THE NAM. WITH THIS IN MIND HAVE BUMPED UP TEMPS ALL THREE DAYS...ESPECIALLY MON WHICH IS NOW WELL INTO THE 90S IN MOST LOCATIONS. GFS HAS BEEN DIFFICULT TO USE RECENTLY FOR TEMPS...DEWPOINTS AND POTENTIAL INSTABILITY. SOUNDINGS HAVE NOT BEEN AGGRESSIVE ENOUGH MIXING /TOO COOL/ WITH TOO MUCH MOISTURE 1KM AND BELOW. WED INTO THU STILL LOOKS ON TARGET FOR ANOTHER APPRECIABLE PRECIP EVENT. CONFIDENCE IN THIS IS ABOVE AVERAGE AS GFS/GEFS/ECMWF AND GEM ALL OFFER SIMILAR PATTERNS WITH NWRN CONUS LONG WAVE TROUGH DRAGGING FRONT INTO IA BY LATE IN THE DAY WED. FORCING AHEAD OF WAVE AND RIGHT ENTRANCE REGION DIVERGENCE OF MN/ONTARIO JET SEGMENT SHOULD BE SUFFICIENT TO OVERCOME ANY CAP AND PRODUCE PRECIP...ESPECIALLY OF THE MORE ELEVATED VARIETY INTO THE NIGHT. SHEAR SHOULD BE ADEQUATE FOR SEVERE WEATHER FARTHER NORTH IMMEDIATELY ALONG THE FRONT CONSIDERING THE DEGREE OF INSTABILITY. WITH MEAN WIND PARALLEL TO SAGGING FRONT...DEEP WARM CLOUD DEPTHS AND PWS IN EXCESS OF 1.75 INCHES COULD SEE DECENT RAINS. DO NOT EXPECT MUCH OF A FLOOD THREAT HOWEVER WITH HEAT AND BRISK SWLY WINDS PRECEDING EVENT EARLY IN THE WORK WEEK. RELATIVELY HIGHER CONFIDENCE CONTINUES TO END THE WEEK AS WELL WITH MODELS IN AGREEMENT INCREASING AMPLITUDE WITH ROCKIES RIDGE AND NERN CONUS THROUGH. SHOULD DRY OUT FOR A BIT BEHIND MIDWEEK SYSTEM...BUT WARM ADVECTION PRECIP MAY RETURN TO MO VALLEY BY SAT BEYOND THE PERIOD AND EVEN INTO THE NEXT WEEK. && .AVIATION 16/12Z... MCV MOVING ACRS NORTHERN MISSOURI WILL PRODUCE SCATTERED TO NUMEROUS THUNDERSTORMS IN SOUTHERN IOWA WITH ISOLATED TO SCATTERED CONVECTION IN THE NORTH ALONG A WEAK BOUNDARY SLIDING THROUGH THE STATE THIS AFTERNOON. MVFR TO ISOLD IFR CONDITIONS WILL OCCUR IN AND AROUND THE STORMS ALONG WITH GUSTY WINDS. THIS PRECIPITATION WILL SLIDE SOUTHEAST THIS EVENING WITH WIDESPREAD VFR CONDITIONS OVERNIGHT ALTHOUGH THERE WILL BE SOME THREAT OF FOG DEVELOPMENT TOWARD MORNING WITH THE RAINFALL FROM THIS AFTERNOONS STORMS ALONG WITH LIGHT WINDS. THE VFR CONDITIONS WILL PERSIST INTO SUNDAY AS A WARM AIRMASS EXPANDS INTO THE STATE. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...FAB LONG TERM...BSS AVIATION...COGIL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 548 AM CDT SAT JUN 16 2012 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-171100- 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-POLK-JASPER- POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION- CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE- DAVIS- 548 AM CDT SAT JUN 16 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR MUCH OF CENTRAL IOWA. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS WILL BE POSSIBLE AREA WIDE TODAY BEFORE BEING RELEGATED TO THE SOUTHEAST THIRD OF IOWA OVERNIGHT. A FEW OF THE STORMS MAY BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS THE PRIMARY THREATS. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY THUNDERSTORM CHANCES REMAIN IN THE FORECAST OVER FAR SOUTHERN IOWA SUNDAY...AND ACROSS NORTHERN IOWA SUNDAY NIGHT INTO MONDAY MORNING. SEVERE WEATHER IS NOT EXPECTED. HEAT AND HUMIDITY WILL RETURN BY MONDAY WITH HEAT INDICES APPROACHING OR JUST EXCEEDING 100 DEGREES DURING THE AFTERNOON. THUNDERSTORM CHANCES THEN INCREASE TUESDAY NIGHT NORTHWEST AND OVER THE ENTIRE AREA BY WEDNESDAY NIGHT AND THURSDAY. A FEW OF THESE STORMS MAY BE SEVERE WITH LOCALLY HEAVY RAINS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AT TIMES LATER TODAY...AND AGAIN AROUND MIDWEEK. SMALL
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1030 AM CDT SAT JUN 16 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0403 PM TSTM WND DMG 3 S FONDA 42.54N 94.85W
06/15/2012 CALHOUN IA PUBLIC
SEVERAL SIX TO EIGHT INCH LIMBS DOWN. TOP OF A LARGE TREE
WAS SHEARED OFF. PEA SIZE HAIL ALSO OBSERVED.
&&
DEITSCHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1136 AM CDT SAT JUN 16 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0431 PM TSTM WND DMG SSW JOLLEY 42.48N 94.72W
06/15/2012 CALHOUN IA PUBLIC
SEVERAL LARGE TREES DOWN ACROSS TOWN. ONE TREE FELL ON
TOP OF POWER LINES KNOCKING THEM TO THE GROUND. TIME
ESTIMATED FROM RADAR.
&&
DEITSCHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1157 AM CDT SAT JUN 16 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0444 PM TSTM WND DMG 4 E VARINA 42.66N 94.82W
06/15/2012 POCAHONTAS IA PUBLIC
SEVERAL 6 INCH LIMBS DOWN ACROSS THE YARD. PEA SIZE HAIL
ALSO OBSERVED. TIME ESTIMATED FROM RADAR.
&&
DEITSCHThe Des Moines radar (KDMX), 128 km away, was scanning. The volume nearest the first event began at 18:27 UTC.
8 thunderstorm wind, 4 hail, 3 heavy rain. Local standard time, as filed.
Trained spotter reported 2.3 inches of rain in the past two hours. No flooding observed.
Trained spotter on the west side of Mount Ayr reported nickel size hail and wind gusts of 35 MPH.
A trained spotter reported mostly pea to nickel size hail with a few quarter size mixed in.
Several three to four inch branches were down across the yard.
Trained spotter reported 2.8 inches of rain so far today.
Trained spotter reported 3.3 inches of rain so far today.
Numerous branches six inches or larger were blown down.
Three inch and larger branches down.
Medium size tree down along with numerous branches. Minor street flooding.
Measured by an IDOT RWIS site near Ottumwa on Highway 63.
Larger than one foot diameter trees down. A light pole was also blown down. One large tree was snapped off on the trunk near the school.
Numerous four to six inch diameter tree branches were downed by winds estimated in the 65 MPH range.
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, June 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: 376767, 377046, 376760, 376762, 377047, 376769, 376768, 376763, 376765, 376757, 376758, 376770, 376766, 376771, 376780.