Alert archive / Iowa / Severe Thunderstorm Watches in 2000

Severe Thunderstorm Watch 621

July 25, 200024 counties in Iowa; 5 counties in Nebraska; Union County, South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Jul 25, 2000, 11:00 PM CDT for 24 counties in Iowa; 5 counties in Nebraska; Union County, South Dakota. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Jul 25, 2000, 11:00 PM CDT (04:00 UTC)
Expired: Jul 26, 2000, 3:00 AM CDT
In force: 4 hr
Issued by: the Storm Prediction Center

All 30 counties

Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Crawford County, IA, Dallas County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Monona County, IA, Plymouth County, IA, Pocahontas County, IA, Polk County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Webster County, IA, Woodbury County, IA, Wright County, IA, Burt County, NE, Dakota County, NE, Dodge County, NE, Thurston County, NE, Washington County, NE, Union County, SD

Warnings issued inside it

10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jul 25, 11:19 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay	26 min
Jul 25, 11:32 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	28 min
Jul 25, 11:38 PM CDT	Severe Thunderstorm Warning	DMX	Pocahontas	52 min
Jul 25, 11:47 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	43 min
Jul 25, 11:59 PM CDT	Severe Thunderstorm Warning	FSD	Cherokee	31 min
Jul 26, 12:08 AM CDT	Severe Thunderstorm Warning	DMX	Humboldt	37 min
Jul 26, 12:13 AM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Webster	47 min
Jul 26, 12:23 AM CDT	Severe Thunderstorm Warning	DMX	Sac	52 min
Jul 26, 12:28 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista	32 min
Jul 26, 12:46 AM CDT	Severe Thunderstorm Warning	DMX	Hamilton	44 min

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 4.0 hours before the alert went out and 143 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: 2265 J/kg
Mixed-layer CIN: -76 J/kg
Mixed-layer LCL: 1234 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 29 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

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

526 
WWUS9 KMKC 260328
SEL1  

SEL1  
MKC WW 260324
IAZ000-NEZ000-SDZ000-260800-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 621
STORM PREDICTION CENTER NORMAN OK
1024 PM CDT TUE JUL 25 2000

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   WESTERN IOWA                               
   NORTHEAST NEBRASKA                           
   SOUTHEASTERN SOUTH DAKOTA                       

EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 1100 PM
UNTIL 300 AM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 50 STATUTE MILES
NORTH AND SOUTH OF A LINE FROM 20 MILES SOUTHWEST OF SIOUX CITY
IOWA TO 50 MILES NORTH NORTHEAST OF DES MOINES IOWA.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

OTHER WATCH INFORMATION...  CONTINUE...WW 620...

DISCUSSION...SEVERE THUNDERSTORMS CONTINUE TO PROPAGATE S/SEWD INTO
AXIS OF STRONG INSTABILITY.  AS UPPER TROUGH PASSES BY TO THE N
VEERING SHEAR PROFILES WILL CONTINUE TO SUPPORT SEVERE
THUNDERSTORMS DEVELOPING SWD INTO WRN IA AND EXTREME NERN NEB.


AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550.  MEAN STORM
MOTION VECTOR 33025.


...HALES

425,0963 425,0931 412,0931 412,0963

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 25, 8:30 PM CDT	Severe Thunderstorm Watch	SPC	Clay, Dickinson, Emmet, Kossuth, O'Brien, Osceola and 3 more	6 hr
Jul 26, 2:30 PM CDT	Tornado Watch	SPC	Adair, Adams, Appanoose, Audubon, Boone, Carroll and 34 more	6 hr
Jul 26, 5:45 PM CDT	Severe Thunderstorm Watch	SPC	Arthur, Blaine, Chase, Frontier, Grant, Hayes and 7 more	5 hr

Nearby

Severe Thunderstorm Watches in Iowa, 2000 Severe Thunderstorm Watches in Nebraska, 2000 Severe Thunderstorm Watches in South Dakota, 2000 Every severe thunderstorm watch in 2000

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.