Alert archive / Iowa / Flash Flood Warnings in 2017

Flash Flood Warning 4, NWS Des Moines, IA

July 21, 2017Bremer County, Iowa

NWS Des Moines, IA issued this flash flood warning at Jul 21, 2017, 10:01 AM CDT for Bremer County, Iowa. It was in force for 6 hr. 3 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: Jul 21, 2017, 10:01 AM CDT (15:01 UTC)
Expired: Jul 21, 2017, 4:00 PM CDT
In force: 6 hr
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Flood severity: None

County Bremer County, IA

The radar

The La Crosse radar (KARX), 138 km from the middle of the area, began a volume at 15:01 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 21, 10:12 AM CDT	HEAVY RAIN 3.5	Sumner, IA	HEAVY RAINFALL 3.5 INCHES FROM MORNING RAINFALL. ROAD CLOSURES IN TOWN REPORTED.
Jul 21, 10:40 AM CDT	FLASH FLOOD	4 Ene Tripoli, IA	WATER OVER THE ROAD IN THE 2900 BLOCK OF 150TH ST. DELAYED REPORT.
Jul 21, 12:00 PM CDT	FLASH FLOOD	4 S Sumner, IA	ROAD WASHED OUT AT 180TH ST AND Y AVE.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 3.0 hours before the alert went out and 198 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: 81 J/kg
Mixed-layer CIN: -302 J/kg
Mixed-layer LCL: 1173 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 125 m²/s²
0-3 km storm-relative helicity: 192 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

825 
WGUS53 KDMX 211501
FFWDMX
IAC017-212100-
/O.NEW.KDMX.FF.W.0004.170721T1501Z-170721T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Des Moines IA
1001 AM CDT FRI JUL 21 2017

The National Weather Service in Des Moines  has issued a

* Flash Flood Warning for...
  Northeastern Bremer County in northeastern Iowa...

* Until 400 PM CDT.

* At 1000 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain entering the warned area. These storms will be capable 
  of producing another 1 to 2 inches of rainfall. This heavy 
  rainfall--combined with earlier heavy rainfall--is expected to 
  lead to flash flooding.

* Some locations that will experience flooding include...
  Sumner, Tripoli and Frederika. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4282 9236 4291 9236 4291 9208 4278 9208

$$

Zogg

1 follow-up statement

624 
WGUS73 KDMX 211857
FFSDMX

Flash Flood Statement
National Weather Service Des Moines IA
157 PM CDT FRI JUL 21 2017

IAC017-212100-
/O.CON.KDMX.FF.W.0004.000000T0000Z-170721T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bremer IA-
157 PM CDT FRI JUL 21 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 400 PM CDT FOR
NORTHEASTERN BREMER COUNTY...

The Bremer County Sheriff's Department reported that flash flooding 
has been occurring within the warned area. At 12 PM, the road was 
reported to be washed out at 180th Street and Y Avenue near Sumner. 
At 1040 AM, water was reported over the road in the 2900 block of 
150th Street also near Sumner.

Some locations that will experience flooding include...
Sumner, Tripoli and Frederika. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

&&

LAT...LON 4282 9236 4291 9236 4291 9208 4278 9208

$$

Zogg

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 7:05 PM CDT	Special Weather Statement	DMX	Sac	55 min
Jul 20, 7:12 PM CDT	Severe Thunderstorm Warning	DMX	Carroll, Crawford, Sac	26 min
Jul 20, 7:13 PM CDT	Special Weather Statement	DMX	Guthrie	47 min
Jul 20, 7:19 PM CDT	Severe Thunderstorm Warning	DMX	Greene, Guthrie	41 min
Jul 20, 7:58 PM CDT	Severe Thunderstorm Warning	DMX	Carroll, Greene	21 min
Jul 20, 8:50 PM CDT	Special Weather Statement	DMX	Dallas	55 min
Jul 20, 8:57 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Dallas, Greene, Guthrie	48 min
Jul 20, 9:19 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Polk, Story	56 min
Jul 20, 10:04 PM CDT	Severe Thunderstorm Warning	DMX	Grundy, Hardin, Jasper, Marshall, Story	56 min
Jul 20, 10:37 PM CDT	Special Weather Statement	DMX	Marion	38 min
Jul 20, 11:06 PM CDT	Special Weather Statement	DMX	Poweshiek	39 min
Jul 20, 11:23 PM CDT	Special Weather Statement	DMX	Tama	37 min
Jul 20, 11:29 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Poweshiek	31 min
Jul 21, 9:55 AM CDT	Flash Flood Watch	DMX	Black Hawk, Bremer, Butler, Grundy, Tama	20 hr
Jul 21, 3:26 PM CDT	River Flood Watch	DMX	Black Hawk	5 days

Nearby

Flash Flood Warnings in Iowa, 2017 Every flash flood warning 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.