Alert archive / Iowa / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 270, NWS Des Moines, IA
NWS Des Moines, IA issued this severe thunderstorm warning at Jul 18, 1998, 11:07 PM CDT for Kossuth County, Pocahontas County, Iowa. It was in force for 33 min. 1 report 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
- Jul 18, 1998, 11:07 PM CDT (04:07 UTC)
- Expired
- Jul 18, 1998, 11:40 PM CDT
- In force
- 33 min
- Issued by
- NWS Des Moines, IA
- Area
- Whole counties
Counties Kossuth County, IA, Pocahontas County, IA
The radar
The Des Moines radar (KDMX), 150 km from the middle of the area, began a volume at 04:10 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 | Remark |
|---|---|---|---|
| Jul 18, 11:50 PM CDT | Thunderstorm Wind 52 | Algona, 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 |
|---|---|---|---|
| Jul 18, 10:30 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 4.1 hours before the alert went out and 220 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.
- Mixed-layer CAPE
- 16 J/kg
- Mixed-layer CIN
- -548 J/kg
- Mixed-layer LCL
- 2130 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- -72 m²/s²
- 0-3 km storm-relative helicity
- 450 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KDSM 190408 SVRDSM IAC109-151-190440- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE DES MOINES IA 1107 PM CDT SAT JUL 18 1998 THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... KOSSUTH COUNTY IN NORTH CENTRAL IOWA POCAHONTAS COUNTY IN NORTHWESTERN IOWA * UNTIL 1140 PM CDT * AT 1106 PM CDT... DOPPLER RADAR INDICATED A LINE OF SEVERE THUNDERSTORMS 21 MILES EAST OF SPENCER OR 14 MILES WEST OF WHITTEMORE MOVING EAST AT 50 MPH. * THIS STORM CAN BE EXPECTED NEAR... FENTON BY 1118 PM CDT WHITTEMORE BY 1121 PM CDT LONE ROCK BY 1124 PM CDT POCAHONTAS BY 1130 PM CDT BURT BY 1131 PM CDT ALGONA BY 1132 PM CDT DAMAGING WINDS AND HEAVY RAIN ARE LIKELY. GO INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS! 67 MPH WINDS OCCURRING WITH THESE STORMS IN SPENCER. BSS/EP 4
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.
In the hours before
Special weather statement, Jul 18, 9:21 PM CDT, 1 hour 46 minutes before
IAZ004>007-015>017-023>028-033>039-046>050-059>062-073>075-084>086- 096-097-190900- CENTRAL IOWA THUNDERSTORM OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 921 PM CDT SAT JUL 18 1998 HAZARD--SCATTERED THUNDERSTORMS WITH A FEW POSSIBLY SEVERE AND CAPABLE OF PRODUCING WIND GUSTS TO 75 MPH. HEAVY RAINS OF 1 TO 2 INCHES ARE ALSO POSSIBLE ESPECIALLY IN AREAS THAT RECEIVE MORE THAN ONE ROUND OF THUNDERSTORMS. AREA OF CONCERN--THE THREAT OF THUNDERSTORMS IS ALONG AND NORTHEAST OF A SAC CITY...TO ADEL...TO CENTERVILLE LINE WITH THE STRONGEST STORMS AND BEST CHANCES FOR SEVERE WEATHER ALONG AND NORTH OF HIGHWAY 20. TIMING--SCATTERED THUNDERSTORMS OVER SOUTH DAKOTA WILL CONTINUE MOVING SOUTHEAST AT 30 TO 40 MPH REACHING ESTHERVILLE AND SAC CITY BY 1030 OR 1100 PM AND AREAS EAST OF INTERSTATE 35 DURING THE EARLY MORNING HOURS. METEOROLOGICAL COMMENTS--A WARM FRONT FROM NORTHWEST IOWA TO JUST SOUTH OF DES MOINES TO THE SOUTHEAST TIP OF IOWA WILL CONTINUE TO BE THE FORCING MECHANISM FOR THUNDERSTORM DEVELOPMENT TONIGHT. CONVERGENCE OF WARM...MOIST AIR ALONG AND NORTH OF THE FRONT HAS PRODUCED THUNDERSTORMS JUST NORTHWEST OF SIOUX FALLS THIS EVENING AND MAY ALSO SUSTAIN THOSE STORMS AS THEY MOVE INTO THE NORTHEAST TWO- THIRDS OF IOWA OVERNIGHT. WIND SHEAR PROFILES ARE FAVORABLE FOR DAMAGING WINDS WITH SOME OF THE STORMS...BUT VERY WARM TEMPERATURES ALOFT SHOULD PRECLUDE LARGE HAIL FROM BEING A PROBLEM. ALTHOUGH THERE IS PLENTY OF MOISTURE AVAILABLE NEAR THE SURFACE WITH DEWPOINTS IN THE 70S...THE STORMS SHOULD BE BASED ABOVE THE SURFACE AND A LACK OF DEEPER MOISTURE MAY KEEP WIDESPREAD SEVERE WEATHER FROM DEVELOPING AND COULD EVEN LIMIT THE EXTENT OF THUNDERSTORMS ALTOGETHER. THIS ELEVATED NATURE OF THE STORMS WOULD DIMINISH THE CHANCES FOR TORNADO DEVELOPMENT AS WELL. PRECAUTIONS--SPOTTER ACTIVATION MAY BE REQUIRED OVER NORTHERN IOWA TONIGHT. THERE IS STILL SOME UNCERTAINTY AS TO THE AREAL COVERAGE AND SEVERITY OF THE STORMS HOWEVER SO EMERGENCY MANAGERS AND PEOPLE WITH OUTDOOR CONCERNS SHOULD CONTINUE TO MONITOR THE LATEST FORECASTS AND THUNDERSTORM OUTLOOKS. . SMALL
The office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 18, 10:52 PM CDT | Severe Thunderstorm Warning | DMX | Emmet, Palo Alto | 33 min |
| Jul 18, 11:23 PM CDT | Severe Thunderstorm Warning | DMX | Emmet, Palo Alto | 17 min |
| Jul 18, 11:34 PM CDT | Severe Thunderstorm Warning | DMX | Humboldt, Kossuth, Pocahontas | 31 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 1998Every severe thunderstorm warning in 1998
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.