An occluding low pressure system was located across the eastern Dakotas on May 20, 2013. A cold front was approaching the area from the west during the evening hours, along with the nose of a mid level speed maximum arriving from northeast Kansas.
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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.
An occluding low pressure system was located across the eastern Dakotas on May 20, 2013. A cold front was approaching the area from the west during the evening hours, along with the nose of a mid level speed maximum arriving from northeast Kansas. A couple of storms produced ping pong size hail and winds over 80 mph.
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 May 20, 2:26 PM CST, 2 hours 48 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 326 PM CDT MON MAY 20 2013 .SYNOPSIS... ISSUED AT 248 PM CDT MON MAY 20 2013 LATEST SFC ANALYSIS WAS INDICATING OCCLUDING CYCLONE COMPLEX ACRS THE EASTERN SD/ND REGION...WITH LEAD FRONT PUSHING ACRS WESTERN IA BUT BETTER COLD WRAP AROUND NOTED ACRS SD INTO CENTRAL NEB. THE REGION HAS BEEN PRETTY MUCH BATHED IN PRESSURE RISES TODAY...BUT FALLS INCREASING ACRS WESTERN AND NORTHWESTERN MO. MAIN WARM FRONT ACRS CENTRAL MN...FAR NORTHERN WI INTO THE NORTHERN LOWER MI. SECONDARY FRONT ACRS WESTERN OK...AND REMNANT OUTFLOW BOUNDARY ACRS CENTRAL MO ACTING AS BETTER SFC DPT POOLING MECHANISMS. LOCALLY IN SOUTHWEST SFC FLOW...SFC DPTS HAVING TROUBLE GETTING OUT OF THE LOWER 60S WITH FETCH BACK INTO SIMILAR AIR MASS IN NORTHEASTERN KS/FAR NW MO. CUT-OFF UPPER LOW ALMOST STACKED OVER SFC FEATURE...WITH WATER VAPOR IMAGERY INDICATING NOSE OF MID/UPPER LEVEL SPEED MAX PUSHING ACRS NORTHEASTERN KS. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY MORNING) ISSUED AT 248 PM CDT MON MAY 20 2013 TONIGHT...ASSESSING LOCAL INSTABILITY PARAMETERS...CAPES HAVE GROWN TO ONLY 500 TO MAYBE 1000 J/KG ACRS PORTIONS OF THE DVN CWA...WITH 18Z SOUNDING SHOWING ROBUST H85 CAP/CONVECTIVE TEMP IN THE UPPER 80S. LACK OF AMBIENT CU LOCALLY A CLUE. DEEP UNIFORM SOUTHWESTERLIES MAKING FOR MODERATE SHEAR/SPEED/ AT BEST. WITH MAIN VORT AND MID/UPPER LEVEL VORT MAX STILL ACRS KS...DEEPER FORCING TO NOT ARRIVE UNTIL MAINLY AFTER 00Z. THUS REST OF THIS AFTERNOON MAY SEE A LACK OF CONVECTIVE ACTIVITY. WITH DEEP CONVECTIVE INDICE MAX REALIGNING ACRS EASTERN KS INTO WESTERN/NORTHWEST MO THE REST OF THIS AFTERNOON AND EARLY EVENING...EXPECT STORM DEVELOPMENT IN THESE AREAS TO MOVE NORTHEAST AND BE THE SCTRD STORMS TO AFFECT PORTIONS OF THE CWA THIS EVENING. THIS AND POSSIBLY SOME DEVELOPMENT AHEAD OF THE WESTERN IA FRONT IN CU FIELD ONGOING OUT THERE ATTM. BUT WITH YET UNFAVORABLE AIRMASS IN PLACE TO SUPPORT STRONG CONVECTION...THIS ACTIVITY MAY WEAKEN AS IT ARRIVES UNLESS SOME THERMODYNAMIC SUPPORT IS ADVECTED INTO THE AREA FROM THE SOUTHWEST. MUCH UNCERTAINTY REGARDING THIS ATTM. IF STORMS DO MAINTAIN AND MAKE IT INTO THE AREA...STILL A CHANCE FOR SOME SVR CELLS LOOKING AT CURRENT AND PROGGED SHEAR PROFILES BUT MAIN THREATS WOULD BE LARGE HAIL AND DAMAGING WIND GUSTS WITH ANY LINER/BOWING DEVELOPMENT IN UNIFORM VERTICAL WIND FIELDS. LLVL SHEAR DIRECTION AND HIGHER LCL/S OF AT LEAST 3K FT AGL CURRENTLY NOT THAT CONDUCIVE FOR TORNADIC DEVELOPMENT. WILL KNOCK DOWN 00Z-06Z COVERAGE TO HIGH CHC AND LIKELY POPS ACRS MOST OF THE DVN CWA...THEN WALK OUT ANY LINGERING ACTIVITY AFTER 08Z FROM THE EASTERN CWA. LOCALLY HEAVY RAINFALL BURSTS POSSIBLE...BUT MOVEMENT OF STORMS HOPEFULLY WILL PRECLUDE MUCH OF ANY FLASH FLOOD THREAT UNLESS THE SAME AREA GETS HIT REPEATEDLY AND HAD SIGNIFICANT RAIN LAST NIGHT. LOWS MAY DIP INTO THE UPPER 50S IN THE NORTHWESTERN FCST AREA...BUT HELD IN THE 60S ELSEWHERE. ..12.. .LONG TERM...(TUESDAY THROUGH NEXT MONDAY) ISSUED AT 248 PM CDT MON MAY 20 2013 UPPER LOW OVER THE NORTHERN PLAINS TO GRADUALLY FILL AND SHIFT EASTWARD THROUGH MIDWEEK...REPLACED BY HIGH PRESSURE AT THE SURFACE AND MID LEVEL RIDGING. THIS WILL PROVIDE A CHANGE TO BELOW NORMAL TEMPERATURES AND DRY WEATHER BY LATE WEEK. OVER THE WEEKEND...A COOLER...UNSETTLED PATTERN DEVELOPS AS RETURNING MOISTURE INTERACTS WITH A BOUNDARY OVER THE AREA. TUESDAY...SURFACE LOW GRADUALLY EJECTS EASTWARD INTO THE UPPER MS VALLEY. THIS WILL SEND THE OCCLUDED FRONT EASTWARD THROUGH THE FORECAST AREA IN THE MORNING...THEN A SECONDARY TROUGH IS INDICATED BY THE NAM DURING PEAK HEATING. EACH OF THESE FEATURES WILL POSSIBLY TRIGGER SHOWERS AND THUNDERSTORMS...BUT WITH LOW CONFIDENCE IN THE TIMING...STRENGTH...OR AVAILABLE INSTABILITY WITH THESE FEATURES...HAVE ONLY CHANCE POPS THROUGH THE DAY. SUPPORT FOR SEVERE STORMS IS LACKING DUE TO LESS FAVORABLE SHEAR PROFILES AND LIKELY LESS AVAILABLE INSTABILITY THAN THE PAST COUPLE DAYS. COOLER TEMPERATURES AT 850 MB AND LIKELIHOOD OF MORE CLOUDS SHOULD LIMIT HIGHS TO THE MID 70S WEST TO POSSIBLY MID 80S EAST. TUESDAY NIGHT INTO WED...SURFACE LOW TRANSITIONING EASTWARD INTO THE GREAT LAKES AND FILLING UPPER LOW MIGRATING OVERHEAD TO KEEP CHANCES FOR MAINLY DIURNAL SHOWERS GOING WITH HIGHEST POPS IN THE EAST. ADVECTION OF COOLER... DRIER AIR TO ALLOW MINS TO COOL INTO THE 50S WITH WED HIGHS LIMITED TO THE UPPER 60S TO LOWER 70S. THURSDAY AND FRIDAY...UPPER TROUGH ADVANCES EASTWARD ALLOWING CANADIAN HIGH PRESSURE TO BUILD SOUTHEAST INTO THE GREAT LAKES. HAVE TWEAKED TEMPERATURES DOWNWARD SOME TO LIMIT HIGHS TO THE 60S AND POSSIBLY LOWER 70S FOR FRI...WHILE LOWS THURSDAY NIGHT SHOULD BE WIDESPREAD IN THE 40S AS THE CENTER OF THE INCOMING RIDGE PASSES OVERHEAD. SATURDAY THROUGH MONDAY REMAINS A BELOW AVERAGE CONFIDENCE FORECAST PERIOD AS THERE IS LITTLE AGREEMENT IN THE DETAILS OF RETURN WARM...MOIST ADVECTION FLOW...THE ASSOCIATED BOUNDARY...AND WHERE PRECIPITATION WILL SET UP. FOR NOW...A BLENDED APPROACH TO DIVERSE SOLUTIONS WILL KEEP AN EXTENDED PERIOD OF CHANCE POPS WITH TEMPERATURES GRADUALLY WARMING TO NEAR OR ABOVE NORMAL BY MONDAY WHEN THE ODDS ARE GREATER THAT THE FRONT WILL HAVE LIFTED NORTH OF THE AREA. SHEETS && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1243 PM CDT MON MAY 20 2013 HAVE PUSHED BACK STORM DEVELOPMENT TIME AT CID AND DBQ TIL LATE AFTERNOON...BRL AND MLI TO 20Z TO 21Z. BUT SOME SIGNS MOST OF THE TERMINALS WILL BE VFR THROUGH 00Z IF STORM CLUSTERS DON/T DEVELOP OUT OF NORTHEAST MO OR SOUTHEASTERN IA THIS AFTERNOON AND THEN MOVE TOWARD BRL AND MLI. IF AFTERNOON STORMS DON/T DEVELOP OR STAY SOUTH/EAST OF THE TERMINALS...BEST CHANCE WILL COME LATER THIS EVENING AFTER 01Z AS MAIN FRONT APPROACHES FROM THE WEST. THESE STORMS COULD BE STRONG TO SVR TOO WITH DAMAGING WIND AND HAIL...BUT ADEQUATE INSTABILITY QUESTIONS FOR BOTH THIS AFTERNOON AND EVENING CONTINUE WITH SFC DPTS STRUGGLING TO GET OUT OF THE LOWER 60S. OTHERWISE GOOD VISIBILITY THIS AFTERNOON WITH MAINLY CLR SKIES OR HIGH CLOUD BLOW OFF FROM STORMS IN MO. SOUTHWEST WINDS AT 10 TO 20 KTS WITH SOME HIGHER GUSTS...TO BECOME SOUTH SOUTHWEST OVERNIGHT WITHOUT THE GUSTS. BUT STILL A CHANCE FOR VARIABLE GUSTS OVER 35-40 KTS WITH THE EVENING LINE OF STORMS. SOME MVFR FOG POSSIBLE TOWARD SUNRISE BEFORE SOUTHWEST WINDS INCREASE AGAIN BY MID TUE MORNING. 12 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...12 SHORT TERM...12 LONG TERM...SHEETS AVIATION...12
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 329 PM CDT MON MAY 20 2013 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-212030- BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON- CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON- HENRY IA-DES MOINES-VAN BUREN-LEE-JO DAVIESS-STEPHENSON-CARROLL- WHITESIDE-ROCK ISLAND-HENRY IL-BUREAU-PUTNAM-MERCER-HENDERSON- WARREN-HANCOCK-MCDONOUGH-SCOTLAND-CLARK- 329 PM CDT MON MAY 20 2013 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...THIS AFTERNOON AND TONIGHT THUNDERSTORMS...SOME SEVERE...WILL AGAIN BE SEEN ACROSS THE AREA TONIGHT. THE MOST FAVORED TIME PERIOD FOR SEVERE STORMS WILL BE FROM 6 PM UNTIL POSSIBLY MIDNIGHT. DAMAGING WINDS AND LARGE HAIL ARE EXPECTED. THE STORM PREDICTION CENTER HAS A SLIGHT RISK OF SEVERE STORMS ACROSS THE ENTIRE AREA. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THUNDERSTORMS MAY OCCUR ALONG A COOL FRONT TUESDAY AFTERNOON AND EVENING. A FEW SEVERE STORMS WITH LARGE HAIL AND DAMAGING WINDS WILL BE POSSIBLE EAST OF A FREEPORT...KEWANEE ILLINOIS LINE. WEDNESDAY...ANY ISOLATED THUNDERSTORMS SHOULD REMAIN BELOW SEVERE LEVELS DUE TO LIMITED INSTABILITY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING. DLF
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 PM CDT MON MAY 20 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0935 PM TSTM WND DMG INDEPENDENCE 42.47N 91.89W
05/19/2013 BUCHANAN IA EMERGENCY MNGR
A DOWNBURST WITH WINDS ESTIMATED OVER 70 MPH STRUCK
INDEPENDENCE. THE NORTHWEST SECTIONS OF TOWN SUSTAINED
THE MOST DAMAGE...WITH TREES DOWN...POWER POLES
SNAPPED...AND SIGNS BLOWN DOWN.
1055 PM TSTM WND DMG 3 SE BLAIRSTOWN 41.88N 92.04W
05/19/2013 BENTON IA EMERGENCY MNGR
DELAYED REPORT. STRAIGHT-LINE WIND DAMAGE FROM A
DOWNBURST FROM THE COUNTY LINE 3.5 MILES SOUTHEAST OF
BLAIRSTOWN TO 2.8 MILES SOUTHEAST OF SHELLSBURG.
MILE-WIDE SWATH OF NEAR CONTINUOUS DAMAGE TO FARM
OUTBUILDINGS...TREE BRANCHES...AND SOME POWER POLES. THE
GREATEST DAMAGE WAS FROM 3 MILES SOUTH OF NEWHALL...WHERE
A MACHINE SHED AND GARAGE WERE COMPLETELY DESTROYED...TO
ABOUT 3 MILES WEST-NORTHWEST OF ATKINS...WHERE
SIGNIFICANT DAMAGE OCCURRED TO OUTBUILDINGS.
1112 PM TSTM WND GST 3 NNW PARIS 42.27N 91.60W
05/19/2013 M76.00 MPH LINN IA TRAINED SPOTTER
DELAYED REPORT. ANEMOMETER BROKE AT 76 MPH. LARGE TREES
BLOWN DOWN.
&&
DMDThe Quad Cities radar (KDVN), 194 km away, was scanning. The volume nearest the first event began at 23:15 UTC.
3 hail. Local standard time, as filed.
Hail fell for about two to three minutes ending around 617 pm CDT. The biggest hail was the size of a quarter.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Missouri in 2013Every state in 2013This day in weather historyWarnings in Missouri, May 2013
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: 451587, 451590, 451591.