Hail in South Dakota, May 21, 2007

Name: Hail in South Dakota, May 21, 2007
Start: 2007-05-21T17:30
End: 2007-05-21T18:50
Location: South Dakota

May 21, 2007 · NWS ABR · 4 events in 2 counties and zones

Severe thunderstorms developed in unstable air along a pre frontal trough across Dewey and Corson counties.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 4

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.

What happened

The episode as NWS ABR wrote it up.

Severe thunderstorms developed in unstable air along a pre frontal trough across Dewey and Corson counties.

What forecasters said that day

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 Aberdeen, SD wrote its last area forecast discussion before the first event at May 21, 1:38 PM MST, 3 hours 52 minutes earlier.

Area forecast discussion, May 21, 1:38 PM MST, 3 hours 52 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
338 PM CDT MON MAY 21 2007

.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
UPPER LEVEL TROUGH MOVING EAST OVER IDAHO THIS AFTERNOON WHILE
SURFACE LOW IS DEEPENING OVER WESTERN SD. SURFACE BOUNDARY ALSO
LOCATED OVER THE FAR WESTERN DAKOTAS. JUST BEGINNING TO SEE
CONVECTION BEGINNING ALONG THE BOUNDARY. SVR WATCH BOXES ARE OUT
FOR THE CENTRAL AND WESTERN DAKOTAS. EXPECTING CONVECTION TO
INCREASE IN INTENSITY AND AREAL COVERAGE THROUGH THE LATE
AFTERNOON AND EVENING HOURS AS ACTIVITY MOVES INTO CENTRAL SD.
FARTHER EAST...MAY SEE SOME SHOWERS AND STORMS LATER TONIGHT AS
LOW LEVEL JET KICKS IN. FEEL THAT ANY HEAVIER RAIN IN THE JAMES
VALLEY WILL HOLD OFF UNTIL LATE TONIGHT OR INTO TUESDAY MORNING AS
THE SHORTWAVE TROUGH NOW OVER KS/OK/CO MOVES MOVES NORTH INTO OUR
AREA. WENT AHEAD AND ISSUED A FLASH FLOOD WATCH FOR THE JAMES
RIVER VALLEY AREA WITH THE POTENTIAL FOR AROUND 2 INCHES OF RAIN
WITH LOCALLY HIGHER AMOUNTS IN SOME PLACES. SURFACE BOUNDARY TAKES
ITS TIME CROSSING THE STATE AND MOST OF THE EASTERN CWA IS STILL
IN SOUTHERLY SURFACE FLOW BY TUESDAY AFTERNOON. SVR PARAMETERS
SHOW BETTER INSTABILITY SOUTH OF THIS AREA ON TUESDAY BUT THE
HEAVY RAIN THREAT REMAINS IN PLACE. AN ABUNDANCE OF CLOUDS WILL
LIKELY LIMIT INSTABILITY TUESDAY AFTERNOON. TAPERED OFF POPS TO
SMALL CHANCES ACROSS CENTRAL SD TUESDAY NIGHT AS IT APPEARS A DRY
PUNCH WILL TRY TO WORK ITS WAY INTO WESTERN/CENTRAL SD DURING THE
EVENING HOURS. TEMPS WERE CHANGED LITTLE AND MILD TEMPS WILL
REMAIN IN PLACE OVERNIGHT ACROSS THE EASTERN CWA WITHIN WARM
SECTOR AND BREEZY SOUTH WINDS. HIGH TEMPS ON TUESDAY A CHALLENGE
ACROSS CENTRAL SD SINCE IT WILL MOSTLY DEPEND ON MOVEMENT OF
SURFACE FRONT.

.LONG TERM...12Z WEDNESDAY THROUGH MONDAY
BIGGEST CHALLENGE IN THE EXTENDED DEALS WITH PCPN CHANCES THROUGH
THE LATER PART OF THE WEEK.

UPPER SYSTEM MOVING INTO THE REGION EARLY THIS WEEK WILL STILL BE
IN THE AREA THROUGH THURSDAY. MODELS ARE NOW BEGINNING TO SHOW SFC
AND UPPER LOWS LIFTING NORTH INTO ND DURING THE DAY WEDNESDAY WITH
LOSS OF ANY APPRECIABLE LIFT THROUGH THE LAYERS. HAVE BEGUN TO
BACK PEDDLE A BIT FOR PCPN ON WEDNESDAY...AND WOULD PREFER TO HAVE
DRY FCST GOING FOR SW CWA AS SPEC HUMIDITIES AND BEST 7H/85H
THETA-E FORCING HAS LIFTED INTO ND WITH STRONG DOWNGLIDE NOTED
ACROSS MUCH OF THE CWA. AS UPPER LOW SHIFTS OFF TO THE EAST
THROUGH THE FIRST PART OF THE WEEKEND...UPPER FLOW FLATTENS...THEN
BEGINS TO TAKE ON UPPER RIDGE LOOK. HAVE KEPT WITH DRY FCST
THROUGH THE REMAINDER OF THE EXTENDED DUE TO THIS.

85H TEMPS ARE NOW A BIT WARMER THAN 24 HOURS AGO...AND ARE NOW
MORE IN LINE WITH OLD ECMWF. HOWEVER...HAVE TWEAKED DOWN MAX T
GRIDS FOR WED/THUR AS ABUNDANT CLOUDS/LINGERING PCPN WILL HELP TO
KEEP ANY HEATING AT BAY. A SLOW WARMUP IS FCST THEN FOR THE
REMAINDER OF THE EXTENDED...WITH TEMPS STILL REMAINING BELOW
NORMAL FOR THIS TIME.

&&
.AVIATION...
BKN VFR CIGS FROM AROUND 4000-10000 FT WILL BE COMMON ACROSS
CENTRAL AND EASTERN SD...AS WELL AS EXTREME WEST CENTRAL MN
THROUGH THE EVENING HOURS. ALSO...TSRA/+TSRA ARE EXPECTED NEAR
KMBG AND KPIR TERMINALS LATER THIS EVENING. CIGS/VSBYS MAY DROP
INTO MVFR IN TSRAS/+TSRAS. PRECIP WILL MOVE INTO PORTIONS OF
EASTERN SD LATER TONIGHT.

&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...FLASH FLOOD WATCH FROM 1 AM CDT TUESDAY THROUGH WEDNESDAY
     MORNING FOR BROWN-CLARK-DAY-EDMUNDS-FAULK-HAND-MARSHALL-
     MCPHERSON-SPINK.

MN...NONE.
&&

SHORT TERM...TT
LONG TERM...DH
AVIATION...TT

Hazardous weather outlook, May 21, 3:46 AM MST, 13 hours 44 minutes before

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE ABERDEEN SD
546 AM CDT MON MAY 21 2007

SDZ003>005-007-009>011-015>017-019-033>037-045-048-051-221100-
CORSON-CAMPBELL-MCPHERSON-MARSHALL-WALWORTH-EDMUNDS-DAY-DEWEY-
POTTER-FAULK-CLARK-STANLEY-SULLY-HUGHES-HYDE-HAND-JONES-LYMAN-
BUFFALO-
546 AM CDT MON MAY 21 2007 /446 AM MDT MON MAY 21 2007/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL SOUTH
DAKOTA...NORTH CENTRAL SOUTH DAKOTA AND NORTHEAST SOUTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS CENTRAL AND
NORTHEAST SOUTH DAKOTA TODAY INTO TONIGHT...AS A LOW PRESSURE
SYSTEM SLIDES EAST OUT OF EASTERN WYOMING. THERE IS A SLIGHT RISK
FOR SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT. BESIDES THE
THREAT OF DANGEROUS LIGHTNING...THE MAIN SEVERE THUNDERSTORM
THREATS ARE LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE ACTIVE PATTERN WILL CONTINUE ACROSS THE AREA INTO TUESDAY AND
WEDNESDAY...BRINGING ADDITIONAL CHANCES FOR SHOWERS AND
THUNDERSTORMS. AT THIS TIME SMALL HAIL...STRONG WINDS...HEAVY
RAINFALL AND FREQUENT LIGHTNING ARE THE MAIN THREATS WITH ANY
THUNDERSTORM DEVELOPMENT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON INTO TONIGHT.

SDZ006-018-221100-
BROWN-SPINK-
546 AM CDT MON MAY 21 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST SOUTH
DAKOTA.

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS CENTRAL AND
NORTHEAST SOUTH DAKOTA TODAY INTO TONIGHT...AS A LOW PRESSURE
SYSTEM SLIDES EAST OUT OF EASTERN WYOMING. THERE IS A SLIGHT RISK
FOR SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT. BESIDES THE
THREAT OF DANGEROUS LIGHTNING...THE MAIN SEVERE THUNDERSTORM
THREATS ARE LARGE HAIL AND DAMAGING WINDS.

FLOODING IS EXPECTED TO CONTINUE ON THE JAMES RIVER FOR AN EXTENDED
PORTION OF TIME. SEE THE LATEST FLOOD STATEMENT FOR SPECIFIC RIVER
STAGE INFORMATION.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE ACTIVE PATTERN WILL CONTINUE ACROSS THE AREA INTO TUESDAY AND
WEDNESDAY...BRINGING ADDITIONAL CHANCES FOR SHOWERS AND
THUNDERSTORMS. AT THIS TIME SMALL HAIL...STRONG WINDS...HEAVY
RAINFALL AND FREQUENT LIGHTNING ARE THE MAIN THREATS WITH ANY
THUNDERSTORM DEVELOPMENT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING INTO TONIGHT.

MNZ039-046-SDZ008-020>023-221100-
TRAVERSE-BIG STONE-ROBERTS-CODINGTON-GRANT-HAMLIN-DEUEL-
546 AM CDT MON MAY 21 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL
MINNESOTA AND NORTHEAST SOUTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

THE CHANCE FOR SHOWERS AND THUNDERSTORMS EXISTS ACROSS NORTHEAST
SOUTH DAKOTA AND WEST CENTRAL MINNESOTA TODAY INTO TONIGHT...AS A
LOW PRESSURE SYSTEM SLIDES EAST OUT OF EASTERN WYOMING. THERE IS A
POSSIBILITY FOR SEVERE WEATHER TONIGHT. BESIDES THE THREAT OF
DANGEROUS LIGHTNING...THE MAIN SEVERE THUNDERSTORM THREATS ARE
LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE ACTIVE PATTERN WILL CONTINUE ACROSS THE AREA INTO TUESDAY AND
WEDNESDAY...BRINGING ADDITIONAL CHANCES FOR SHOWERS AND
THUNDERSTORMS. AT THIS TIME SMALL HAIL...STRONG WINDS...HEAVY
RAINFALL AND FREQUENT LIGHTNING ARE THE MAIN THREATS WITH ANY
THUNDERSTORM DEVELOPMENT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TONIGHT.

ALBRECHT

The radar

The Bismarck radar (KBIS), 163 km away, was scanning. The volume nearest the first event began at 00:29 UTC.

Open the radar archive at this moment

Event by event

4 hail. Local standard time, as filed.

Hail, Dewey

When: May 21, 5:30 PM MST
Where: Dewey County, 2.53 mi ESE of Isabel
Measured: 0.75 in hail
Reported by: Public
Coordinates: 45.370, -101.380

Hail, Dewey

When: May 21, 6:18 PM MST
Where: Dewey County, 2.53 mi ESE of Isabel
Measured: 0.75 in hail
Reported by: Public
Coordinates: 45.370, -101.380

Hail, Corson

When: May 21, 6:30 PM MST
Where: Corson County, 5.41 mi SSE of Athboy
Measured: 1.75 in hail
Reported by: Public
Coordinates: 45.500, -101.880

Hail, Corson

When: May 21, 6:50 PM MST
Where: Corson County, Bullhead
Measured: 0.88 in hail
Reported by: Public
Coordinates: 45.770, -101.080

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in South Dakota in 2007 Every state in 2007 This day in weather history Warnings in South Dakota, May 2007

Sources

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: 36721, 36722, 36723, 36724.