Alert archive / Iowa / Flash Flood Warnings in 2018
Flash Flood Warning 39, NWS Sioux Falls, SD
NWS Sioux Falls, SD issued this flash flood warning at Sep 20, 2018, 4:35 AM CDT for 5 counties in Iowa; Clay County, Lincoln County, Union County, South Dakota. It was in force for 5 hr. 16 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
- Sep 20, 2018, 4:35 AM CDT (09:35 UTC)
- Expired
- Sep 20, 2018, 9:30 AM CDT
- In force
- 5 hr
- Issued by
- NWS Sioux Falls, SD
- Area
- Storm-based polygon
- Flood severity
- None
Counties Clay County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Sioux County, IA, Clay County, SD, Lincoln County, SD, Union County, SD
The radar
The Sioux Falls radar (KFSD), 60 km from the middle of the area, began a volume at 09:37 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 |
|---|---|---|---|
| Sep 20, 4:45 AM CDT | FLASH FLOOD | 3 Wnw Everly, IA | HIGHWAY 18 NEAR THE CLAY, OBRIEN COUNTY LINE IS UNDERWATER. CURRENTLY BARRICADING. |
| Sep 20, 5:38 AM CDT | HEAVY RAIN 4 | Hull, IA | RAINFALL SINCE 9 PM WEDNESDAY NIGHT. |
| Sep 20, 5:45 AM CDT | FLASH FLOOD | 3 E Lennox, SD | WATER OVER NUMEROUS ROADS IN WESTERN LINCOLN COUNTY SD. MOST ROADS ARE STILL PASSABLE, BUT WATER SEVERAL INCHES DEEP SO CONES ARE NEEDED TO SLOW TRAFFIC DOWN. EM CURRENTLY MARKING A ROAD EAST OF LENNOX SD. |
| Sep 20, 5:45 AM CDT | FLASH FLOOD | Lennox, SD | FLASH FLOODING IN LENNOX WITH PICTURES VIA SOCIAL MEDIA. LENNOX HAS ALREADY RECEIVED APPROXIMATELY 5 INCHES OF RAIN IN TWO EVENTS THE PAST 24 HOURS. |
| Sep 20, 6:18 AM CDT | HEAVY RAIN 7 | 2 Wnw Everly, IA | STORM TOTAL SO FAR IN THE PAST 36 HOURS. |
| Sep 20, 7:00 AM CDT | FLASH FLOOD | Orange City, IA | SIGNIFICANT URBAN FLOODING IN ORANGE CITY. |
| Sep 20, 7:00 AM CDT | HEAVY RAIN 2.75 | Sioux Center, IA | 2.75 INCHES OF RAIN IN SIOUX CENTER SINCE MIDNIGHT. |
| Sep 20, 7:30 AM CDT | FLASH FLOOD | 2 N Alcester, SD | FIELDS FLOODED FROM HEAVY RAIN. REPORT VIA SOCIAL MEDIA. |
| Sep 20, 7:40 AM CDT | HEAVY RAIN 6.35 | 4 E Sanborn, IA | REPORT VIA SOCIAL MEDIA. RAINFALL OVERNIGHT. |
| Sep 20, 7:45 AM CDT | HEAVY RAIN 6 | Doon, IA | 24 HOUR RAINFALL FROM 7 AM WEDNESDAY TO 7 AM THURSDAY. |
| Sep 20, 7:49 AM CDT | HEAVY RAIN 5.3 | Sioux Center, IA | REPORT VIA SOCIAL MEDIA. RAINFALL TOTAL SINCE IT STARTED ON TUESDAY. |
| Sep 20, 7:53 AM CDT | HEAVY RAIN 4.8 | 4 Nnw Moneta, IA | RAINFALL OVERNIGHT ONLY. HAD AN ADDITIONAL 1.55 OF RAIN DURING THE DAY ON WEDNESDAY. |
| Sep 20, 8:11 AM CDT | HEAVY RAIN 5.5 | Hospers, IA | REPORT VIA SOCIAL MEDIA. GREATER THAN 5.50 INCHES OF RAINFALL. |
| Sep 20, 8:13 AM CDT | FLOOD | Hospers, IA | REPORT VIA SOCIAL MEDIA. FLOYD RIVER OUT OF ITS BANKS, AND MOST GRAVEL ROADS ACROSS THE AREA ARE CLOSED. |
| Sep 20, 8:38 AM CDT | HEAVY RAIN 6 | 1 Nw Hull, IA | REPORT VIA SOCIAL MEDIA. RAINFALL GREATER THAN 6 INCHES. |
| Sep 20, 9:29 AM CDT | FLASH FLOOD | Hartley, IA | REPORT VIA SOCIAL MEDIA. STREET FLOODING ON MAIN STREET IN HARTLEY IOWA. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 9.6 hours before the alert went out and 201 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
- 1307 J/kg
- Mixed-layer CIN
- -12 J/kg
- Mixed-layer LCL
- 1889 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km storm-relative helicity
- 71 m²/s²
- 0-3 km storm-relative helicity
- 123 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 6.4
The text
As transmitted.
109
WGUS53 KFSD 200935
FFWFSD
IAC041-119-141-143-167-SDC027-083-127-201430-
/O.NEW.KFSD.FF.W.0039.180920T0935Z-180920T1430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Sioux Falls SD
435 AM CDT THU SEP 20 2018
The National Weather Service in Sioux Falls has issued a
* Flash Flood Warning for...
Southern Lyon County in northwestern Iowa...
Southern Osceola County in northwestern Iowa...
Sioux County in northwestern Iowa...
Southwestern Clay County in northwestern Iowa...
O'Brien County in northwestern Iowa...
Northern Clay County in southeastern South Dakota...
Lincoln County in southeastern South Dakota...
Northern Union County in southeastern South Dakota...
* Until 930 AM CDT.
* At 432 AM CDT, emergency management reported multiple roads with
water flowing over roads with a couple reports of vehicles
hydroplaning into ditches. One and a half to three inches of rain
has already fallen on saturated ground overnight, with additional
rain through the morning hours. Flash flooding is occurring and
will likely continue for the next several hours.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
Please report flooding to your local law enforcement agency when you
can do so safely.
&&
LAT...LON 4291 9536 4291 9716 4304 9716 4299 9706
4300 9693 4331 9681 4334 9693 4344 9692
4326 9586 4326 9540 4312 9527
$$
VandenBoogartThe office that day
Everything else NWS Sioux Falls, SD issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 19, 8:49 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Clay | 12 min |
| Sep 20, 6:32 AM CDT | River Flood Warning | FSD | O'Brien | 41 hr |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Lyon | 51 hr |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Plymouth, Sioux | 10 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Plymouth | 12 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Clay | 8 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Lyon | 4 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Lyon, Sioux | 4 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Sioux | 28 hr |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | O'Brien | 24 hr |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Sioux | 4 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Clay, Dickinson | 12 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Clay | 14 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Buena Vista, Clay | 32 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | O'Brien | 4 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Cherokee | 12 days |
| Sep 20, 7:06 AM CDT | River Flood Warning | FSD | Plymouth | 3 days |
| Sep 20, 9:15 AM CDT | River Flood Warning | FSD | Plymouth, Sioux | 61 hr |
| Sep 20, 9:15 AM CDT | River Flood Warning | FSD | Plymouth | 4 days |
| Sep 20, 9:15 AM CDT | River Flood Warning | FSD | Clay | 42 hr |
| Sep 20, 9:15 AM CDT | River Flood Warning | FSD | Woodbury | 8 days |
| Sep 20, 9:15 AM CDT | River Flood Warning | FSD | Lyon | 47 hr |
| Sep 20, 9:30 AM CDT | Flash Flood Warning | FSD | Clay, Lyon, O'Brien, Osceola, Sioux | 3 hr |
| Sep 20, 11:17 AM CDT | River Flood Warning | FSD | Lyon | 6 days |
| Sep 20, 12:39 PM CDT | Areal Flood Warning | FSD | Clay, Lyon, O'Brien, Sioux | 12 hr |
| Sep 20, 2:44 PM CDT | River Flood Warning | FSD | Lyon, Sioux | 5 days |
| Sep 20, 3:32 PM CDT | Severe Thunderstorm Warning | FSD | Lyon | 43 min |
| Sep 20, 3:59 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth, Woodbury | 46 min |
| Sep 20, 4:17 PM CDT | Tornado Warning | FSD | Plymouth, Woodbury | 28 min |
| Sep 20, 5:02 PM CDT | Severe Thunderstorm Warning | FSD | Clay, Dickinson, O'Brien, Osceola | 28 min |
| Sep 20, 5:50 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Ida | 25 min |
| Sep 20, 3:36 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Turner | 6 hr |
| Sep 20, 4:51 AM CDT | Flash Flood Warning | FSD | Hutchinson, Turner, Yankton | 5 hr |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Brookings, Moody | 5 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Minnehaha, Moody | 4 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Minnehaha | 3 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Hutchinson, Yankton | 6 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Yankton | 7 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Turner | 7 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Clay | 7 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Minnehaha | 4 days |
| Sep 20, 6:49 AM CDT | River Flood Warning | FSD | Minnehaha | 63 hr |
| Sep 20, 7:22 AM CDT | River Flood Warning | FSD | Lincoln, Minnehaha | 63 hr |
| Sep 20, 9:15 AM CDT | River Flood Warning | FSD | Minnehaha | 6 days |
| Sep 20, 9:29 AM CDT | Flash Flood Warning | FSD | Clay, Lincoln, Turner | 3 hr |
| Sep 20, 9:36 AM CDT | River Flood Warning | FSD | Clay | 8 days |
| Sep 20, 9:41 AM CDT | Flash Flood Warning | FSD | Hutchinson, Turner, Yankton | 3 hr |
Nearby
Flash Flood Warnings in Iowa, 2018Flash Flood Warnings in South Dakota, 2018Every flash flood warning in 2018
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.