Alert archive / Iowa / Tornado Warnings in 2017
Tornado Warning 34, NWS Sioux Falls, SD
NWS Sioux Falls, SD issued this tornado warning at Aug 18, 2017, 8:37 PM CDT for Clay County, O'Brien County, Iowa. It was in force for 23 min. 5 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
- Aug 18, 2017, 8:37 PM CDT (01:37 UTC)
- Expired
- Aug 18, 2017, 9:00 PM CDT
- In force
- 23 min
- Issued by
- NWS Sioux Falls, SD
- Area
- Storm-based polygon
- Tornado
- Radar indicated
- Hail
- 2.0 in
Counties Clay County, IA, O'Brien County, IA
The radar
The Sioux Falls radar (KFSD), 111 km from the middle of the area, began a volume at 01:38 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 |
|---|---|---|---|
| Aug 18, 8:41 PM CDT | HAIL 1 | 2 W Hartley, IA | |
| Aug 18, 8:44 PM CDT | HAIL 1.5 | 3 E Primghar, IA | TIME ESTIMATED FROM RADAR. |
| Aug 18, 8:44 PM CDT | HAIL 1.75 | 4 E Primghar, IA | HAIL FROM 830PM TO 845PM. TIME OF LARGEST HAIL ESTIMATED FROM RADAR. |
| Aug 18, 8:56 PM CDT | HAIL 1 | 4 N Sutherland, IA | TIME ESTIMATED FROM RADAR. |
| Aug 18, 8:56 PM CDT | HAIL 1.25 | 3 Nnw Sutherland, IA | TIME ESTIMATED FROM RADAR. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Aug 18, 4:51 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 1.6 hours before the alert went out and 205 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
- 1353 J/kg
- Mixed-layer CIN
- -118 J/kg
- Mixed-layer LCL
- 1673 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 30 m²/s²
- 0-3 km storm-relative helicity
- 61 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted.
852
WFUS53 KFSD 190137
TORFSD
IAC041-141-190200-
/O.NEW.KFSD.TO.W.0034.170819T0137Z-170819T0200Z/
BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Sioux Falls SD
837 PM CDT FRI AUG 18 2017
The National Weather Service in Sioux Falls has issued a
* Tornado Warning for...
Western Clay County in northwestern Iowa...
Eastern O'Brien County in northwestern Iowa...
* Until 900 PM CDT
* At 837 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Primghar, or 13 miles east of Sheldon, moving
southeast at 25 mph.
HAZARD...Tornado and hail up to two inches in diameter.
SOURCE...Radar indicated rotation.
IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed.
Damage to roofs, windows, and vehicles will occur. Tree
damage is likely.
* This dangerous storm will be near...
Sutherland around 900 PM CDT.
Other locations impacted by this tornadic thunderstorm include
Calumet.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.
Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!
Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!
&&
LAT...LON 4312 9569 4320 9551 4297 9535 4291 9555
TIME...MOT...LOC 0137Z 331DEG 21KT 4312 9560
TORNADO...RADAR INDICATED
HAIL...2.00IN
$$
FergusonThe office that day
Everything else NWS Sioux Falls, SD issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 7:45 PM CDT | Severe Thunderstorm Warning | FSD | Osceola | 30 min |
| Aug 18, 7:49 PM CDT | Tornado Warning | FSD | Osceola | 26 min |
| Aug 18, 8:06 PM CDT | Tornado Warning | FSD | Clay, O'Brien, Osceola | 24 min |
| Aug 18, 8:25 PM CDT | Tornado Warning | FSD | Clay, O'Brien, Osceola | 35 min |
| Aug 18, 8:54 PM CDT | Tornado Warning | FSD | Buena Vista, Cherokee, Clay, O'Brien | 36 min |
| Aug 18, 9:26 PM CDT | Tornado Warning | FSD | Buena Vista, Cherokee, O'Brien | 34 min |
| Aug 18, 9:53 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Cherokee, Ida | 37 min |
Nearby
Tornado Warnings in Iowa, 2017Every tornado warning in 2017Tornadoes in 2017
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.