Alert archive / Iowa / Flash Flood Warnings in 2021

Flash Flood Warning 7, NWS La Crosse, WI

August 27, 2021Howard County, Mitchell County, Winneshiek County, Iowa

NWS La Crosse, WI issued this flash flood warning at Aug 27, 2021, 3:33 AM CDT for Howard County, Mitchell County, Winneshiek County, Iowa. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 27, 2021, 3:33 AM CDT (08:33 UTC)
Expired
Aug 27, 2021, 7:30 AM CDT
In force
4 hr
Issued by
NWS La Crosse, WI
Area
Storm-based polygon
Flood severity
None

Counties Howard County, IA, Mitchell County, IA, Winneshiek County, IA

The radar

The La Crosse radar (KARX), 91 km from the middle of the area, began a volume at 08:34 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.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 8.6 hours before the alert went out and 194 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-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2021-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2021-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 393 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
792 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
393 m²/s²
0-3 km storm-relative helicity
392 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

305 
WGUS53 KARX 270833
FFWARX
IAC089-131-191-271230-
/O.NEW.KARX.FF.W.0007.210827T0833Z-210827T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service La Crosse WI
333 AM CDT Fri Aug 27 2021

The National Weather Service in La Crosse has issued a

* Flash Flood Warning for...
  Northeastern Mitchell County in north central Iowa...
  Howard County in northeastern Iowa...
  Northwestern Winneshiek County in northeastern Iowa...

* Until 730 AM CDT.

* At 333 AM CDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  1 and 3 inches of rain have fallen. Additional rainfall amounts of 
  1 to 3 inches are possible in the warned area. Flash flooding is 
  ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Decorah, Cresco, Riceville, Elma, Lime Springs, Stacyville, and 
  Ridgeway.

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.

&&

LAT...LON 4343 9292 4346 9223 4350 9223 4350 9222
      4350 9220 4350 9217 4350 9214 4350 9213
      4350 9212 4350 9208 4350 9206 4350 9199
      4350 9195 4350 9169 4325 9185 4321 9207
      4321 9208 4322 9255

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

KDS
2 follow-up statements
834 
WGUS73 KARX 271051
FFSARX

Flash Flood Statement
National Weather Service La Crosse WI
551 AM CDT Fri Aug 27 2021

IAC089-131-191-271230-
/O.CON.KARX.FF.W.0007.000000T0000Z-210827T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Howard IA-Mitchell IA-Winneshiek IA-
551 AM CDT Fri Aug 27 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 AM CDT THIS 
MORNING FOR NORTHEASTERN MITCHELL, HOWARD AND NORTHWESTERN 
WINNESHIEK COUNTIES...

At 551 AM CDT, Doppler radar and automated rain gauges indicated 
thunderstorms producing heavy rain across the warned area. Between 2 
and 4 inches of rain have fallen. Additional rainfall of up to 1 
inch is possible in the warned area.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar and automated gauges.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Decorah, Cresco, Riceville, Elma, Lime Springs, Stacyville, 
  Ridgeway, Protivin, McIntire, Davis Corners, Schley, Bonair, 
  Vernon Springs, Vernon Springs County Park, Lourdes, Maple Leaf, 
  and Hayden Prairie.

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.

&&

LAT...LON 4343 9292 4346 9223 4350 9223 4350 9222
      4350 9220 4350 9217 4350 9214 4350 9213
      4350 9212 4350 9208 4350 9206 4350 9199
      4350 9195 4350 9169 4325 9185 4321 9207
      4321 9208 4322 9255

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

Kurz
926 
WGUS73 KARX 271224
FFSARX

Flash Flood Statement
National Weather Service La Crosse WI
724 AM CDT Fri Aug 27 2021

IAC089-131-191-271234-
/O.EXP.KARX.FF.W.0007.000000T0000Z-210827T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Howard IA-Mitchell IA-Winneshiek IA-
724 AM CDT Fri Aug 27 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 730 AM CDT THIS MORNING FOR 
NORTHEASTERN MITCHELL, HOWARD AND NORTHWESTERN WINNESHIEK COUNTIES...

While some additional rainfall is expected this morning, the 
heaviest rain has come to an end, and high water has receded. 
Flooding is no longer expected to pose a threat. Please continue to 
heed any remaining road closures.

LAT...LON 4343 9292 4346 9223 4350 9223 4350 9222
      4350 9220 4350 9217 4350 9214 4350 9213
      4350 9212 4350 9208 4350 9206 4350 9199
      4350 9195 4350 9169 4325 9185 4321 9207
      4321 9208 4322 9255

$$

Kurz

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 27, 1:51 AM CDTFlash Flood WarningARXHoward, Mitchell4 hr
Aug 27, 9:42 AM CDTRiver Flood WarningARXWinneshiek60 hr
Aug 27, 3:24 PM CDTSpecial Weather StatementARXHoward, Mitchell51 min
Aug 27, 5:34 PM CDTTornado WarningARXFloyd41 min
Aug 27, 6:09 PM CDTTornado Warning Tornado observedARXChickasaw, Floyd51 min
Aug 27, 6:45 PM CDTTornado Warning Tornado observedARXChickasaw, Fayette45 min
Aug 27, 6:52 PM CDTSevere Thunderstorm WarningARXAllamakee, Fayette, Winneshiek38 min

Nearby

Flash Flood Warnings in Iowa, 2021Every flash flood warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.