Alert archive / Iowa / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 26, NWS Sioux Falls, SD

May 6, 2009Plymouth County, Woodbury County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at May 6, 2009, 2:34 PM CDT for Plymouth County, Woodbury County, Iowa. It was in force for 41 min. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 6, 2009, 2:34 PM CDT (19:34 UTC)
Expired: May 6, 2009, 3:15 PM CDT
In force: 41 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon

Counties Plymouth County, IA, Woodbury County, IA

The radar

The Omaha radar (KOAX), 125 km from the middle of the area, began a volume at 19:34 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where
May 6, 3:06 PM CDT	HAIL 1	5 E Bronson, IA
May 6, 3:08 PM CDT	HAIL 1.25	4 S Moville, IA
May 6, 3:11 PM CDT	HAIL 1.25	7 E Bronson, IA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 3 storm reports to this severe thunderstorm warning; the first came 32 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 7.6 hours before the alert went out and 125 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 174 J/kg
Mixed-layer CIN: -271 J/kg
Mixed-layer LCL: 633 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 126 m²/s²
0-3 km storm-relative helicity: 130 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS53 KFSD 061934
SVRFSD
IAC149-193-062015-
/O.NEW.KFSD.SV.W.0026.090506T1934Z-090506T2015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
234 PM CDT WED MAY 6 2009

THE NATIONAL WEATHER SERVICE IN SIOUX FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHERN PLYMOUTH COUNTY IN NORTHWEST IOWA
  CENTRAL WOODBURY COUNTY IN NORTHWEST IOWA

* UNTIL 315 PM CDT

* AT 229 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL. THIS
  STORM WAS LOCATED 7 MILES NORTH OF LAWTON...OR 12 MILES NORTHEAST
  OF SIOUX CITY...AND WAS MOVING SOUTHEAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  LAWTON AROUND 245 PM CDT...
  MOVILLE AROUND 250 PM CDT...
  HORNICK AROUND 315 PM CDT...

AT 228 PM...TRAINED SPOTTERS REPORTED GOLFBALL SIZED HAIL WITH THIS 
STORM JUST SOUTH OF HINTON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM HAS A HISTORY OF LARGE DAMAGING HAIL. SEEK SHELTER NOW
INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS

&&

LAT...LON 4261 9634 4268 9612 4228 9582 4220 9614
      4221 9615
TIME...MOT...LOC 1933Z 336DEG 20KT 4256 9618

$$
BT

2 follow-up statements

000 
WWUS53 KFSD 061944
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
244 PM CDT WED MAY 6 2009

IAC149-193-062015-
/O.CON.KFSD.SV.W.0026.000000T0000Z-090506T2015Z/
PLYMOUTH IA-WOODBURY IA-
244 PM CDT WED MAY 6 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM CDT
FOR CENTRAL WOODBURY AND SOUTHERN PLYMOUTH COUNTIES...

AT 240 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING HALF DOLLAR SIZE 
HAIL. THIS STORM WAS LOCATED NEAR LAWTON...OR 12 MILES EAST OF SIOUX 
CITY...MOVING SOUTHEAST AT 25 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
MOVILLE AROUND 250 PM CDT...
BRONSON AROUND 255 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. THIS IS AN
DANGEROUS SITUATION. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND
STAY AWAY FROM WINDOWS.

&&

LAT...LON 4261 9634 4268 9612 4228 9582 4220 9614
      4221 9615
TIME...MOT...LOC 1943Z 336DEG 20KT 4251 9615

$$
BT

000 
WWUS53 KFSD 062005
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
305 PM CDT WED MAY 6 2009

IAC193-062015-
/O.CON.KFSD.SV.W.0026.000000T0000Z-090506T2015Z/
WOODBURY IA-
305 PM CDT WED MAY 6 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM CDT
FOR CENTRAL WOODBURY COUNTY...

AT 300 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL. THIS STORM WAS LOCATED NEAR BRONSON...OR 15 MILES EAST OF SIOUX
CITY...MOVING SOUTH AT 20 MPH.

THIS STORM WILL REMAIN OVER CENTRAL WOODBURY COUNTY. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. THIS IS AN
DANGEROUS SITUATION. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND
STAY AWAY FROM WINDOWS.

&&

LAT...LON 4251 9629 4257 9604 4228 9582 4220 9614
      4221 9615
TIME...MOT...LOC 2004Z 339DEG 19KT 4240 9610

$$

BT

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at May 6, 9:50 AM CDT, 4 hours 44 minutes earlier.

Area forecast discussion, May 6, 9:50 AM CDT, 4 hours 44 minutes before

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
950 AM AM CDT WED MAY 6 2009

.DISCUSSION...
AS OF 1400 UTC...LEADING EDGE OF WK CDFNT IS NOW JUST E OF THE JAMES
RIVER VALLEY. PRETTY DECENT S/W SHOWING UP AT H7 CURRENTLY NEAR THE
I 29 CORRIDOR...WL MOV JUST E OF THE FSD FA BY 21Z. PRETTY STRONG
ASCENT AND WAA HAS DEVELOPED THRU THE ERN PTN OF THE FA ATTM AIDING
THE CONVECTION FM KOTG/KMJF...SWD TO KSPW AND KSLB IN REDEVELOPING.
IN ADDITION...STRONG H85 THTE RIDGING AND POSTIVE LLV THTE ADVECTION
IS NOTED IN THAT AREA THRU 18Z. WITH THE MOVEMENT OF THE H7 WAVE...
WOULD EXPECT THIS ACTIVITY TO EITHER WANE OR MOVE EWD BY THE MIDDAY
HRS. BUT NOT BEFORE THESE STORMS LAY DOWN SOME SMALLER TYPE HAIL AND
QUITE A BIT OF RAINFALL...LOCALLY UP TO 1 TO 2 INCHES JUST SOUTH OF
I 90 AROUND THE IA GRTLKS AREA. TO THE WEST...ALL INDICATIONS IN THE
DYNAMICS FIELDS ARE THAT THE MID LVL SHRA IN OUR WRN FA WL WEAKEN AS
IT MOVES EWD...AND MAY NOT EVEN MAKE IT TO THE I 29 CORRIDOR. BUT DO
NOT WANT TO DROP POPS IN MANY OF OUR SD COUNTIES DUE TO LINGERING
INSTABILITY AND DECENT MOISTURE. HAVE UPDATED THE GRIDS AND ZFP
BASED ON CURRENT TRENDS...BUT OUR GOING HIGHS STILL LOOK GOOD AND
OUR WIND SHIFT TIMING ALSO LOOKS ON TRACK.       /MJF

&&

.AVIATION...
MVFR STRATUS WL STILL BE A THREAT FM ALONG THE I 29 CORRIDOR AND
POINTS EWD. IN FACT...LATEST NAM40 SNDSFC
FRONT SHOULD BE ON OR ERN EDGE BY 21Z ENDING ALL MVFR THREAT. FOR
DETAILS ON THE PCPN THREAT...SEE THE PARAGRAPH ABOVE. HOWEVER
REMEMBER THAT IN THE THUNDERSTORMS AND RAIN ON THE ERN EDGE OF OUR
FA...IFR VIS WL BE A THREAT UNTIL THE END LATE THIS MORNING.    /MJF

ANOTHER QUICK MOVING DISTURBANCE WILL BRING A BETTER CHANCE FOR
THUNDERSTORMS SOUTH OF INTERSTATE 90 FROM 06Z-12Z...WITH THREAT FOR
MVFR CIGS/VSBYS MAINLY FOR KSUX IN LATTER HALF OF PERIOD. /CHAPMAN

&&

.PREV DISCUSSION...
BUSY WX PATTERN UFN WITH VARIOUS SHORT WAVES IN QUASI ZONAL FLOW...
SOME BARELY INTERACTING WITH DECENT LWR LEVEL MOISTURE IN CNTRL
PLAINS. DECENT LLM INFLOW AND MID LVL INSTABILITY EARLIER TOUCHED
OFF ISOLD STG STORMS SE AND SW OF FSD...AND COULD REFIRE SOME THIS
MRNG AHEAD OF TROF MOVG EWD OVER CWA BY AFTN. MORE INSTABILITY IN
AFTN COULD BRING WDLY SCT -TSRA N AND E IN CWA. DUE TO COLD MID
LVLS...MARGINAL HAIL QUITE PSBL IN THE FAR SERN CWA AHEAD OF FNT
TDA. OTRW WITH MAX MIXING EXPCD...A FAIRLY NICE WARM DAY. RESPITE
FROM ANY PRECIP THIS EVE...BUT ANOTHER GOOD SHORT WAVE SHOULD SET
OFF A GARDEN VARIETY MCS MOVG ESEWD ALONG MISSOURI VALLEY AFT MIDN
THRU NWRN IA THU MRNG. CANADIAN MODEL WOULD IMPLY A CHC NWD TO I90
WITH THIS SYSTEM. THEN ANOTHER NICE BREAK THU AFTN AND EVE BEFORE
MUCH STRONGER UPR LVL WAVE MOVES EWD INTO CWA LATE THU NGT THRU
FRI...AND UPPD THE POPS QUITE A BIT WITH THIS SYSTEM DUE TO GOOD
DYNAMICS. INSTABILITY RATHER MARGINAL...SO KEPT JUST THE ISOLD TSTMS
WITH THE GOOD CHC OF SHWRS MOVG EWD OVER CWA. LWRD TEMPS IN THE NRN
CWA FOR FRI...AND OVERALL FOR FRI NGT THRU SAT NGT WITH COOL NWLY
FLOW. NO CHANGES FOR NEXT WEEK...BUT IT LOOKS TO BE QUITE BUSY WITH
GULF MOISTURE INFLOW AND EVEN STRONGER SHORT WAVES. /RSR

&&

.FSD WATCHES/WARNINGS/ADVISORIES...

SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

&&

Hazardous weather outlook, May 6, 12:08 PM CDT, 2 hours 26 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1208 PM CDT WED MAY 06 2009

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-071200-
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-
1208 PM CDT WED MAY 06 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
AN EXITING MID LEVEL DISTURBANCE AND SURFACE COLD FRONT MAY RE
DEVELOP SPOTTY THUNDERSTORMS LATE THIS AFTERNOON EAST OF A SIOUX
CITY TO MARSHALL MINNESOTA LINE. THEN LATE TONIGHT...ANOTHER MID
LEVEL DISTURBANCE WILL AFFECT THE MISSOURI RIVER VALLEY ALONG THE
NEBRASKA AND SOUTH DAKOTA BORDER...AND ADJACENT POINTS JUST
NORTHWARD. SCATTERED THUNDERSTORMS WILL OCCUR WITH THIS LATE
NIGHT DISTURBANCE. WITH ANY OF THIS STORM ACTIVITY...EITHER LATE
THIS AFTERNOON OR TONIGHT...THE AIR IS COOL ENOUGH ALOFT THAT A
ROGUE STORM COULD PRODUCE HAIL TO THE SIZE OF QUARTERS. BUT THE
VAST MAJORITY OF THE ACTIVITY SHOULD PRODUCE ONLY SMALL HAIL.

FLOODING...
FLOODING WILL CONTINUE ALONG THE JAMES RIVER THROUGH MOST OF MAY.
THE RIVER WAS NEAR CREST AT ALL LOCATIONS FROM HURON
SOUTHWARD...AND IN FACT WAS SLIGHTLY FALLING FROM HURON TO
FORESTBURG. PLEASE SEE THE LATEST ISSUED FLOOD STATEMENTS FOR
MORE DETAILED INFORMATION.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE WILL BE CHANCES OF SHOWERS AND A FEW THUNDERSTORMS SOUTH OF
INTERSTATE 90 THURSDAY MORNING...AND OVER THE AREA ON FRIDAY.
SEVERE WEATHER IS NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.

In the hours before

Local storm report, May 6, 10:47 AM CDT, 3 hours 47 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1047 AM CDT WED MAY 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0235 AM     HAIL             3 SW HURLEY             43.25N 97.13W
05/06/2009  E1.00 INCH       TURNER             SD   PUBLIC

&&

PSCHUMAC

Local storm report, May 6, 10:58 AM CDT, 3 hours 36 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1058 AM CDT WED MAY 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0938 AM     HAIL             3 E SPIRIT LAKE         43.42N 95.05W
05/06/2009  E0.88 INCH       DICKINSON          IA   PUBLIC

            LOTS OF HAIL THAT COVERED THE PATIO. MOST HAIL WAS PEA
            SIZE BUT THERE WERE A FEW STONES UP TO NICKEL SIZE.

&&

WILLIAMS

Local storm report, May 6, 11:34 AM CDT, 3 hours before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1134 AM CDT WED MAY 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1130 AM     HAIL             3 E SPIRIT LAKE         43.42N 95.05W
05/06/2009  M0.50 INCH       DICKINSON          IA   TRAINED SPOTTER

            SMALL HAIL STILL UP TO 2 INCHES DEEP IN MANY LOCATIONS 2
            HOURS AFTER EVENT. SIZE CURRENTLY RANGING FROM 1/4 TO 1/2
            INCH.

&&

MFUHS

Local storm report, May 6, 11:43 AM CDT, 2 hours 51 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1143 AM CDT WED MAY 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0940 AM     HAIL             3 ESE SPIRIT LAKE       43.41N 95.06W
05/06/2009  E1.00 INCH       DICKINSON          IA   TRAINED SPOTTER

            MOSTLY PEA TO HALF INCH HAIL WITH A FEW LARGER QUARTER
            SIZE STONES

&&

KWEISSER

Local storm report, May 6, 11:47 AM CDT, 2 hours 47 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1147 AM CDT WED MAY 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1130 AM     HEAVY RAIN       3 E SPIRIT LAKE         43.42N 95.05W
05/06/2009  M2.40 INCH       DICKINSON          IA   TRAINED SPOTTER

&&

MFUHS

Local storm report, May 6, 11:57 AM CDT, 2 hours 37 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1157 AM CDT WED MAY 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0743 AM     HAIL             2 SW WORTHINGTON        43.61N 95.62W
05/06/2009  E1.00 INCH       NOBLES             MN   TRAINED SPOTTER

            HAIL PILED UP ENOUGH TO COVER THE GROUND. MOST OF THE
            STONES ARE ONLY DIME SIZED, BUT SOME ARE THE SIZE OF
            QUARTERS.

&&

TRM

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 6, 9:34 AM CDT	Severe Thunderstorm Warning	FSD	Dickinson	26 min
May 6, 3:07 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	23 min
May 6, 3:30 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	15 min
May 6, 5:15 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, Osceola	45 min
May 6, 5:23 PM CDT	Tornado Warning	FSD	Clay, Dickinson, O'Brien, Osceola	52 min
May 6, 5:54 PM CDT	Tornado Warning	FSD	Clay, O'Brien	35 min
May 6, 6:23 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay	19 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2009 Every severe thunderstorm warning in 2009

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.