Alert archive / Iowa / Flash Flood Warnings in 2017

Flash Flood Warning 17, NWS La Crosse, WI

July 21, 2017Chickasaw County, Iowa

NWS La Crosse, WI issued this flash flood warning at Jul 21, 2017, 10:45 AM CDT for Chickasaw County, Iowa. It was in force for 3 hr. 2 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, 10:45 AM CDT (15:45 UTC)
Expired: Jul 21, 2017, 1:45 PM CDT
In force: 3 hr
Issued by: NWS La Crosse, WI
Area: Storm-based polygon
Flood severity: None

County Chickasaw County, IA

The radar

The La Crosse radar (KARX), 118 km from the middle of the area, began a volume at 15:47 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, 11:50 AM CDT	FLASH FLOOD	3 S Boyd, IA	SOME WATER OVER ROADS WEST OF FREDERICKSBURG.
Jul 21, 12:45 PM CDT	HEAVY RAIN 4.2	New Hampton, IA

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, 3.8 hours before the alert went out and 218 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.

509 
WGUS53 KARX 211545
FFWARX
IAC037-211845-
/O.NEW.KARX.FF.W.0017.170721T1545Z-170721T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service La Crosse WI
1045 AM CDT FRI JUL 21 2017

The National Weather Service in La Crosse has issued a

* Flash Flood Warning for...
  Chickasaw County in northeastern Iowa...

* Until 145 PM CDT

* At 1044 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is expected. 
  Over three inches of rain has fallen in the New Hampton area.

* Some locations that will experience flooding include...
  New Hampton, Fredericksburg, Lawler, Ionia, Protivin, Jerico, Alta 
  Vista, and North Washington.

LAT...LON 4321 9208 4291 9208 4291 9246 4321 9255

$$

Shea

2 follow-up statements

879 
WGUS73 KARX 211649
FFSARX

Flash Flood Statement
National Weather Service La Crosse WI
1149 AM CDT FRI JUL 21 2017

IAC037-211845-
/O.CON.KARX.FF.W.0017.000000T0000Z-170721T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chickasaw IA-
1149 AM CDT FRI JUL 21 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 145 PM CDT FOR
CHICKASAW COUNTY...

At 1144 AM CDT, Doppler radar indicated that as much as 3 to 5 
inches of rain has fallen across the southern portions of Chickasaw 
county, mainly in the Republic to Williamstown to Fredericksburg 
areas. Water has been reported over some rural roads in theses 
areas. 

Some locations that will experience flooding include areas around...
New Hampton, Fredericksburg, williamstown, Lawler, Repubic and Boyd. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4321 9208 4291 9208 4291 9246 4321 9255

$$

RRS

143 
WGUS73 KARX 211837
FFSARX

Flash Flood Statement
National Weather Service La Crosse WI
137 PM CDT FRI JUL 21 2017

IAC037-211847-
/O.EXP.KARX.FF.W.0017.000000T0000Z-170721T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chickasaw IA-
137 PM CDT FRI JUL 21 2017

...THE FLASH FLOOD WARNING FOR CHICKASAW COUNTY WILL EXPIRE AT 145 PM
CDT...

The heavy rain has ended. Flood waters were receding. Flash flooding 
is no longer expected to pose a threat. Please continue to heed any 
remaining road closures.

LAT...LON 4321 9208 4291 9208 4291 9246 4321 9255

$$

RRS

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 9:22 AM CDT	Flash Flood Warning	ARX	Howard	3 hr
Jul 21, 10:18 AM CDT	Flash Flood Warning	ARX	Fayette	3 hr
Jul 21, 5:08 PM CDT	Severe Thunderstorm Warning	ARX	Clayton	35 min
Jul 21, 5:57 PM CDT	Severe Thunderstorm Warning	ARX	Clayton, Fayette	48 min
Jul 21, 6:20 PM CDT	Severe Thunderstorm Warning	ARX	Fayette	25 min
Jul 21, 6:45 PM CDT	Special Weather Statement	ARX	Clayton	60 min
Jul 21, 6:54 PM CDT	Flash Flood Warning	ARX	Clayton	15 hr

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.