Alert archive / Iowa / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 228, NWS Des Moines, IA

September 18, 2002Franklin County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Sep 18, 2002, 9:41 PM CDT for Franklin County, Iowa. It was in force for 64 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 18, 2002, 9:41 PM CDT (02:41 UTC)
Expired: Sep 18, 2002, 10:45 PM CDT
In force: 64 min
Issued by: NWS Des Moines, IA
Area: Counties, with a storm outline in the text

County Franklin County, IA

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

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 watch it was issued in

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

Issued	Product	Office	Lasted
Sep 18, 6:00 PM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 2.7 hours before the alert went out and 240 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: 946 J/kg
Mixed-layer CIN: -22 J/kg
Mixed-layer LCL: 628 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 188 m²/s²
0-3 km storm-relative helicity: 230 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 5.1

Open this sounding in Storm Lab

The text

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

290 
WUUS53 KDMX 190241
SVRDSM
IAC069-190345-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
941 PM CDT WED SEP 18 2002

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  FRANKLIN COUNTY IN NORTH CENTRAL IOWA

* UNTIL 1045 PM CDT

* AT 939 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 10 MILES EAST OF POPEJOY...OR ABOUT 42 MILES
  SOUTH OF MASON CITY...MOVING NORTH AT 40 MPH.

* THE SEVERE THUNDERSTORM WILL BE...

  4 MILES WEST OF GENEVA AROUND 955 PM...
  NEAR HAMPTON AROUND 1000 PM AND
  NEAR SHEFFIELD AROUND 1015 PM.

HAIL UP TO THE SIZE OF QUARTERS IS LIKELY IN THE WARNED AREA.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 200 AM THURSDAY
MORNING FOR IOWA.

LAT...LON 4257 9349 4257 9307 4289 9304 4289 9348

KINNEY

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 Sep 18, 3:25 PM CDT, 6 hours 16 minutes earlier.

Area forecast discussion, Sep 18, 3:25 PM CDT, 6 hours 16 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
325 PM CDT WED SEP 18 2002

IMMEDIATE FORECAST PROBLEM IS THUNDERSTORM CHANCES TONIGHT.
OUTFLOW/WARM FRONT ALONG I35 IN CENTRAL IOWA ATTM.  AMS OVER FA
APPEARS TO BE CAPPED BASED ON LAPS SOUNDINGS AND CU FIELDS ON
VISIBLE SATELLITE IMAGERY.  IF CAP BREAKS AND SB TSTMS DEVELOP VCNTY
OF THE BOUNDARY...EXPECT STORMS TO QUICKLY BECOME SEVERE GIVEN
AMOUNT OF SHEAR AND CAPE.  TO THE NORTH...CHANCE OF SEVERE WEATHER
BIG TIME SEVERE WEATHER APPEARS TO BE LESS.  WILL FORECAST SCT TSTMS
TONIGHT WITH SVR WORDING IN THE SOUTH.

UPPER PATTERN INTERESTING TO SAY THE LEAST.  NRN STREAM S/WV LIFTING
OUT ACROSS THE NORTHERN PLAINS. SRN S/WV DIVING SE INTO SRN PLAINS
SUPPORTED BY IMPRESSIVE UPPER JET.  NRN S/WV SHUD BE ABLE TO PUSH
CDFNT THRU FA TONIGHT. BOUNDARY SHOULD THEN STALL JUST TO THE EAST
IN RESPONSE TO SRN S/WV.  AVN QUICKER LIFTING THE SRN S/WV OUT THU
NIGHT AND FRIDAY IN RESPONSE TO STRONG UPR TROF DIVING INTO THE NRN
PLAINS WHICH IS PREFERED. AVN DOES SUFFER FROM CONVECTIVE FEEDBACK
TONIGHT AND THURSDAY OVER IA AND WILL DISREGARD IT.

EXPECT CLOUDS AND SHOWERS THRU INTO FRI AM FM S/WV ENERGY. WILL END
PCPN IN PASSAGE OF 700 MB TROF. HIGHER POPS SOUTHEAST AND LESS
NORTHWEST.

FOR THE EXTENDED...MODELS FORECAST ON CDFNT MOVING THROUGH AND A
SECOND STRONGER FRONT SUNDAY NIGHT.  WILL FORECAST CHC OF SHOWERS
WITH PASSAGE OF SECOND FRONT AND A CHANCE OF OVERUNNING TYPE RAIN
TUESDAY.  LOW DIURNAL RANGES DUE TO CLOUDS EARLY NEXT WEEK.

.DSM...NONE
JOHNSON

In the hours before

Local storm report, Sep 18, 8:41 PM CDT, 1 hour before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
841 PM CDT WED SEP 18 2002

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

0836 PM    LIBERTY                   IA   60 MPH TSTM GUST
09/18/02   CLARKE                         EVENT DURATION 2
                                          MINUTES. REPORTED BY
                                          LAW ENFORCEMENT OFFICIAL.

Local storm report, Sep 18, 8:52 PM CDT, 49 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
852 PM CDT WED SEP 18 2002

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

0841 PM    6 SW ALBIA                IA   .88 INCH HAIL
09/18/02   MONROE                         REPORTED BY STORM
                                          SPOTTER.

Local storm report, Sep 18, 8:54 PM CDT, 47 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
854 PM CDT WED SEP 18 2002

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

0851 PM    3 E LIBERTY CENTER        IA   .75 INCH HAIL
09/18/02   WARREN                         REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

Local storm report, Sep 18, 9:09 PM CDT, 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
909 PM CDT WED SEP 18 2002

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

0905 PM    2 N LUCAS                 IA   60 MPH TSTM GUST
09/18/02   LUCAS                          REPORTED BY HAM RADIO
                                          OPERATOR.

Local storm report, Sep 18, 9:20 PM CDT, 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
920 PM CDT WED SEP 18 2002

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

0905 PM    DALLAS                    IA   .88 INCH HAIL
09/18/02   MARION                         REPORTED BY KNIA RADIO.

0907 PM    MELCHER                   IA   60 MPH TSTM GUST
09/18/02   MARION                         REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.

Local storm report, Sep 18, 9:27 PM CDT, 14 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTION
NATIONAL WEATHER SERVICE DES MOINES IA
927 PM CDT WED SEP 18 2002

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

0905 PM    2 N OAKLEY                IA   60 MPH TSTM GUST
09/18/02   LUCAS                          REPORTED BY HAM RADIO
                                          OPERATOR.

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 18, 7:12 PM CDT	Severe Thunderstorm Warning	DMX	Ringgold, Union	63 min
Sep 18, 7:15 PM CDT	Severe Thunderstorm Warning	DMX	Guthrie	60 min
Sep 18, 7:29 PM CDT	Tornado Warning	DMX	Ringgold, Union	46 min
Sep 18, 7:51 PM CDT	Severe Thunderstorm Warning	DMX	Greene	54 min
Sep 18, 7:55 PM CDT	Severe Thunderstorm Warning	DMX	Dallas	50 min
Sep 18, 7:58 PM CDT	Severe Thunderstorm Warning	DMX	Clarke	47 min
Sep 18, 8:02 PM CDT	Severe Thunderstorm Warning	DMX	Adair	58 min
Sep 18, 8:12 PM CDT	Severe Thunderstorm Warning	DMX	Boone	63 min
Sep 18, 8:13 PM CDT	Tornado Warning	DMX	Clarke	47 min
Sep 18, 8:13 PM CDT	Tornado Warning	DMX	Clarke	47 min
Sep 18, 8:22 PM CDT	Severe Thunderstorm Warning	DMX	Webster	53 min
Sep 18, 8:26 PM CDT	Severe Thunderstorm Warning	DMX	Warren	34 min
Sep 18, 8:27 PM CDT	Severe Thunderstorm Warning	DMX	Warren	48 min
Sep 18, 8:29 PM CDT	Severe Thunderstorm Warning	DMX	Warren	46 min
Sep 18, 8:38 PM CDT	Severe Thunderstorm Warning	DMX	Lucas	37 min
Sep 18, 8:45 PM CDT	Severe Thunderstorm Warning	DMX	Madison	60 min
Sep 18, 8:52 PM CDT	Severe Thunderstorm Warning	DMX	Lucas, Monroe	53 min
Sep 18, 9:00 PM CDT	Severe Thunderstorm Warning	DMX	Marion	45 min
Sep 18, 9:47 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Marion	58 min
Sep 18, 10:27 PM CDT	Severe Thunderstorm Warning	DMX	Polk	33 min
Sep 18, 11:51 PM CDT	Severe Thunderstorm Warning	DMX	Poweshiek	39 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2002 Every severe thunderstorm warning in 2002

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.