Alert archive / Iowa / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 9, NWS Des Moines, IA

April 8, 1999Boone County, Story County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 8, 1999, 1:16 PM CDT for Boone County, Story County, Iowa. It was in force for 34 min. 5 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Apr 8, 1999, 1:16 PM CDT (18:16 UTC)
Expired: Apr 8, 1999, 1:50 PM CDT
In force: 34 min
Issued by: NWS Des Moines, IA
Area: Whole counties

Counties Boone County, IA, Story County, IA

The radar

The Des Moines radar (KDMX), 34 km from the middle of the area, began a volume at 18:16 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
Apr 8, 1:26 PM CDT	Hail 0.75	Ames, IA
Apr 8, 1:32 PM CDT	Thunderstorm Wind 52	Sheldahl, IA
Apr 8, 1:33 PM CDT	Tornado F1	Slater, IA
Apr 8, 1:35 PM CDT	Thunderstorm Wind 61	Slater, IA
Apr 8, 1:44 PM CDT	Hail 1	Ames, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 8, 1:00 PM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 6.3 hours before the alert went out and 269 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2467 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 6 m²/s²
0-3 km storm-relative helicity: 115 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 
TTAA00 KDSM 081816 RRA
SVRDSM
IAC015-169-081850-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
116 PM CDT THU APR 8 1999

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EASTERN BOONE COUNTY IN CENTRAL IOWA
  WESTERN STORY COUNTY IN CENTRAL IOWA

* UNTIL 150 PM CDT

* AT 115 PM CDT... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 22
  MILES NORTH NORTHWEST OF DES MOINES OR 4 MILES WEST SOUTHWEST OF
  KELLEY... MOVING NORTH NORTHEAST AT 40 MPH.

* THIS STORM CAN BE EXPECTED NEAR...
   AMES               BY 129 PM CDT
   GILBERT            BY 135 PM CDT
   STORY CITY         BY 144 PM CDT
   ROLAND             BY 145 PM CDT

GO INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS. A TORNADO
WATCH IS IN EFFECT. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO
PRODUCE TORNADOES WITH LITTLE OR NO ADVANCE WARNING.

JJ/KJ

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 Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 8, 10:00 AM CDT, 3 hours 16 minutes earlier.

Area forecast discussion, Apr 8, 10:00 AM CDT, 3 hours 16 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1000 AM CDT THU APR 8 1999

LOTS OF THINGS GOING ON.  SENT A QUICK UPDATE TO BETTER REFLECT
CONDITIONS.  MARGINAL EVENT FROM ONE CELL MOVING EAST ACROSS COUNTIES
JUST TO THE SOUTH OF DSM.  STORM WILL BECOME DVNS CONCERN SHORTLY.
SAT PIX AND OVERLAYED OBS ALREADY SHOWING LOCATION OF THE DRY LINE
AND CONVECTION BEGINNING TO FIRE OVR KS.  THIS WILL BE OUR AFTERNOON
CONCERN.  FURTHER DETAILED ANALYSIS WILL TAKE PLACE TO BEST DEFINE
AREA FOR SVR WX.

.DSM...NONE
FAB

In the hours before

Local storm report, Apr 8, 10:01 AM CDT, 3 hours 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1001 AM CDT THU APR 08 1999

TIME(CDT)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0834 AM    INDIANOLA                 IA    .88 INCH HAIL
04/08/99   WARREN

0844 AM    NEW VIRGINIA              IA    .88 INCH HAIL
04/08/99   WARREN

0910 AM    KNOXVILLE                 IA    .88 INCH HAIL
04/08/99   MARION

0925 AM    PELLA                     IA    .75 INCH HAIL
04/08/99   MARION

Local storm report, Apr 8, 10:01 AM CDT, 3 hours 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1001 AM CDT THU APR 08 1999

TIME(CDT)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0834 AM    INDIANOLA                 IA    .88 INCH HAIL
04/08/99   WARREN

0844 AM    NEW VIRGINIA              IA    .88 INCH HAIL
04/08/99   WARREN

0910 AM    KNOXVILLE                 IA    .88 INCH HAIL
04/08/99   MARION

0925 AM    PELLA                     IA    .75 INCH HAIL
04/08/99   MARION

Local storm report, Apr 8, 10:13 AM CDT, 3 hours 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1013 AM CDT THU APR 08 1999

TIME(CDT)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1000 AM    6 S BARNES CITY           IA    1 INCH HAIL
04/08/99   MAHASKA

Local storm report, Apr 8, 10:13 AM CDT, 3 hours 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1013 AM CDT THU APR 08 1999

TIME(CDT)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1000 AM    6 S BARNES CITY           IA    1 INCH HAIL
04/08/99   MAHASKA

Special weather statement, Apr 8, 11:45 AM CDT, 1 hour 31 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-090000-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CDT THU APR 8 1999

HAZARD--NUMEROUS THUNDERSTORMS CAPABLE OF SEVERE WEATHER
INCLUDING TORNADOES...HAIL GREATER THAN 1 INCH...AND DAMAGING
WINDS HIGHER THAN 65 MPH.  UP TO 2 INCHES OF RAIN MAY FALL BY 600
AM FRIDAY MORNING...ESPECIALLY OVER THE NORTH HALF OF IOWA.  THIS MAY
CAUSE LOCALIZED FLOODING.

AREA OF CONCERN--A HIGH RISK OF SEVERE WEATHER EXISTS
SOUTHEAST OF A BURLINGTON TO CENTERVILLE LINE.  A MODERATE
RISE OF SEVERE WEATHER EXISTS FOR THAT AREA SOUTH OF IDA
GROVE...FORT DODGE...TO WATERLOO.  A SLIGHT RISK OF SEVERE WEATHER
EXISTS OVER THE REST OF NORTHERN IOWA.

TIMING DETAILS--THE GREATEST THREAT PERIOD WILL BE FROM 200 PM UNTIL
600 PM.

METEOROLOGICAL COMMENTS--AN OUTBREAK OF SEVERE THUNDERSTORMS IS
FORECAST FOR MUCH OF IOWA...EASTERN KANSAS...MISSOURI AND ILLINOIS
TODAY.  NEARLY ALL INGREDIENTS FOR WIDESPREAD THUNDERSTORMS WITH
SEVERE WEATHER ARE COMING TOGETHER TODAY...ESPECIALLY OVER SOUTHERN
IOWA INTO MISSOURI.  A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS
NEBRASKA AND IOWA THIS AFTERNOON AND THIS EVENING WITH STRONG
SOUTHERLY WINDS EAST OF THE LOW PUSHING WARM MOIST UNSTABLE AIR INTO
THE CENTRAL UNITED STATES. A COLD FRONT WILL MEANWHILE ADVANCE
EASTWARD ACROSS THE MISSOURI AND MISSISSIPPI VALLEY REGIONS WITH THE
COOLER DRIER AIR BEHIND THE FRONT COLLIDING WITH THE WARM HUMID AIR
TO THE EAST. IN ADDITION...STRONG WINDS IN EXCESS OF 120 MILES AN
HOUR WILL FLOW ACROSS THE AREA IN THE UPPER PORTIONS OF THE
ATMOSPHERE.

A DRY LINE AT THE SURFACE WAS SWEEPING ACROSS KANSAS AT MID DAY.
SURFACE DEW POINT TEMPERATURES ARE IN THE MID 60S AHEAD OF THE LINE
AND FALL RAPIDLY TO THE UPPER TEENS AND 20S TO THE WEST OF IT.  THIS
LINE WILL BE THE FOCUS FOR INTENSE STORM DEVELOPMENT BY EARLY
AFTERNOON.  THE STORMS WILL MOVE INTO WESTERN IOWA SHORTLY AFTER 100
PM...AND RACE EAST ACROSS THE STATE AT 40 TO 50 MPH...REACHING THE
INTERSTATE 35 CORRIDOR BY 300 PM TO 400 PM...AND MOVE INTO EASTERN
IOWA BY 500 PM.

PRECAUTIONS--SKYWARN AND SPOTTER GROUPS WILL LIKELY BE ACTIVATED
THIS AFTERNOON.  REVIEW SEVERE WEATHER SAFETY RULES AT SCHOOL...HOME
OR AT WORK TO BE READY IF SEVERE WEATHER WERE TO AFFECT YOUR AREA.
BE SURE TO HAVE A BATTERY POWERED NOAA WEATHER RADIO OR COMMERCIAL
RADIO WITH YOU TODAY TO GET THE LATEST INFORMATION.  THIS IS A
DANGEROUS SITUATION.

MS APR 99

Special weather statement, Apr 8, 11:45 AM CDT, 1 hour 31 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-090000-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CDT THU APR 8 1999

HAZARD--NUMEROUS THUNDERSTORMS CAPABLE OF SEVERE WEATHER
INCLUDING TORNADOES...HAIL GREATER THAN 1 INCH...AND DAMAGING
WINDS HIGHER THAN 65 MPH.  UP TO 2 INCHES OF RAIN MAY FALL BY 600
AM FRIDAY MORNING...ESPECIALLY OVER THE NORTH HALF OF IOWA.  THIS MAY
CAUSE LOCALIZED FLOODING.

AREA OF CONCERN--A HIGH RISK OF SEVERE WEATHER EXISTS
SOUTHEAST OF A BURLINGTON TO CENTERVILLE LINE.  A MODERATE
RISE OF SEVERE WEATHER EXISTS FOR THAT AREA SOUTH OF IDA
GROVE...FORT DODGE...TO WATERLOO.  A SLIGHT RISK OF SEVERE WEATHER
EXISTS OVER THE REST OF NORTHERN IOWA.

TIMING DETAILS--THE GREATEST THREAT PERIOD WILL BE FROM 200 PM UNTIL
600 PM.

METEOROLOGICAL COMMENTS--AN OUTBREAK OF SEVERE THUNDERSTORMS IS
FORECAST FOR MUCH OF IOWA...EASTERN KANSAS...MISSOURI AND ILLINOIS
TODAY.  NEARLY ALL INGREDIENTS FOR WIDESPREAD THUNDERSTORMS WITH
SEVERE WEATHER ARE COMING TOGETHER TODAY...ESPECIALLY OVER SOUTHERN
IOWA INTO MISSOURI.  A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS
NEBRASKA AND IOWA THIS AFTERNOON AND THIS EVENING WITH STRONG
SOUTHERLY WINDS EAST OF THE LOW PUSHING WARM MOIST UNSTABLE AIR INTO
THE CENTRAL UNITED STATES. A COLD FRONT WILL MEANWHILE ADVANCE
EASTWARD ACROSS THE MISSOURI AND MISSISSIPPI VALLEY REGIONS WITH THE
COOLER DRIER AIR BEHIND THE FRONT COLLIDING WITH THE WARM HUMID AIR
TO THE EAST. IN ADDITION...STRONG WINDS IN EXCESS OF 120 MILES AN
HOUR WILL FLOW ACROSS THE AREA IN THE UPPER PORTIONS OF THE
ATMOSPHERE.

A DRY LINE AT THE SURFACE WAS SWEEPING ACROSS KANSAS AT MID DAY.
SURFACE DEW POINT TEMPERATURES ARE IN THE MID 60S AHEAD OF THE LINE
AND FALL RAPIDLY TO THE UPPER TEENS AND 20S TO THE WEST OF IT.  THIS
LINE WILL BE THE FOCUS FOR INTENSE STORM DEVELOPMENT BY EARLY
AFTERNOON.  THE STORMS WILL MOVE INTO WESTERN IOWA SHORTLY AFTER 100
PM...AND RACE EAST ACROSS THE STATE AT 40 TO 50 MPH...REACHING THE
INTERSTATE 35 CORRIDOR BY 300 PM TO 400 PM...AND MOVE INTO EASTERN
IOWA BY 500 PM.

PRECAUTIONS--SKYWARN AND SPOTTER GROUPS WILL LIKELY BE ACTIVATED
THIS AFTERNOON.  REVIEW SEVERE WEATHER SAFETY RULES AT SCHOOL...HOME
OR AT WORK TO BE READY IF SEVERE WEATHER WERE TO AFFECT YOUR AREA.
BE SURE TO HAVE A BATTERY POWERED NOAA WEATHER RADIO OR COMMERCIAL
RADIO WITH YOU TODAY TO GET THE LATEST INFORMATION.  THIS IS A
DANGEROUS SITUATION.

MS APR 99

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 8, 7:36 AM CDT	Severe Thunderstorm Warning	DMX	Adair	34 min
Apr 8, 7:47 AM CDT	Severe Thunderstorm Warning	DMX	Madison	33 min
Apr 8, 8:37 AM CDT	Severe Thunderstorm Warning	DMX	Warren	33 min
Apr 8, 11:43 AM CDT	Severe Thunderstorm Warning	DMX	Adair	32 min
Apr 8, 12:02 PM CDT	Severe Thunderstorm Warning	DMX	Boone	33 min
Apr 8, 12:05 PM CDT	Severe Thunderstorm Warning	DMX	Greene	35 min
Apr 8, 12:39 PM CDT	Severe Thunderstorm Warning	DMX	Dallas	36 min
Apr 8, 12:48 PM CDT	Severe Thunderstorm Warning	DMX	Marshall	47 min
Apr 8, 1:48 PM CDT	Severe Thunderstorm Warning	DMX	Story	32 min
Apr 8, 2:45 PM CDT	Tornado Warning	DMX	Adams, Taylor	50 min
Apr 8, 2:57 PM CDT	Severe Thunderstorm Warning	DMX	Grundy, Hardin	33 min
Apr 8, 2:59 PM CDT	Tornado Warning	DMX	Cass	31 min
Apr 8, 3:18 PM CDT	Tornado Warning	DMX	Adair	42 min
Apr 8, 3:32 PM CDT	Severe Thunderstorm Warning	DMX	Audubon, Cass	48 min
Apr 8, 3:46 PM CDT	Tornado Warning	DMX	Guthrie	49 min
Apr 8, 3:52 PM CDT	Tornado Warning	DMX	Union	33 min
Apr 8, 3:55 PM CDT	Tornado Warning	DMX	Madison	35 min
Apr 8, 4:20 PM CDT	Tornado Warning	DMX	Dallas	50 min
Apr 8, 4:44 PM CDT	Tornado Warning	DMX	Wayne	36 min
Apr 8, 4:47 PM CDT	Tornado Warning	DMX	Polk	48 min
Apr 8, 4:56 PM CDT	Tornado Warning	DMX	Lucas, Warren	49 min
Apr 8, 5:07 PM CDT	Tornado Warning	DMX	Marion	48 min
Apr 8, 5:15 PM CDT	Tornado Warning	DMX	Dallas	35 min
Apr 8, 5:37 PM CDT	Tornado Warning	DMX	Marion, Monroe	33 min
Apr 8, 5:37 PM CDT	Tornado Warning	DMX	Jasper	33 min
Apr 8, 5:49 PM CDT	Tornado Warning	DMX	Appanoose	31 min
Apr 8, 5:51 PM CDT	Tornado Warning	DMX	Polk	49 min
Apr 8, 6:05 PM CDT	Tornado Warning	DMX	Davis	35 min
Apr 8, 6:06 PM CDT	Tornado Warning	DMX	Mahaska	34 min
Apr 8, 6:16 PM CDT	Tornado Warning	DMX	Wapello	34 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1999 Every severe thunderstorm warning in 1999

Sources

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