Alert archive / Missouri / Flash Flood Warnings in 2018

Flash Flood Warning 8, NWS St. Louis, MO

May 21, 2018Washington County, Missouri

NWS St. Louis, MO issued this flash flood warning at May 21, 2018, 4:00 PM CDT for Washington County, Missouri. It was in force for 6 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: May 21, 2018, 4:00 PM CDT (21:00 UTC)
Expired: May 21, 2018, 9:30 PM CDT
In force: 6 hr
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Flood severity: None

County Washington County, MO

The radar

The St Louis radar (KLSX), 101 km from the middle of the area, began a volume at 21:00 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

Springfield, MO (KSGF), launched 12:00Z, 9.0 hours before the alert went out and 280 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: 219 J/kg
Mixed-layer CIN: -42 J/kg
Mixed-layer LCL: 562 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 45 m²/s²
0-3 km storm-relative helicity: 36 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

020 
WGUS53 KLSX 212100
FFWLSX
MOC221-220230-
/O.NEW.KLSX.FF.W.0008.180521T2100Z-180522T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service St Louis MO
400 PM CDT MON MAY 21 2018

The National Weather Service in St Louis has issued a

* Flash Flood Warning for...
  Southeastern Washington County in east central Missouri...

* Until 930 PM CDT.

* At 359 PM CDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Up to two inches of rain have
  already fallen. Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Irondale, Caledonia and Belgrade. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding is occurring or is imminent. It is important to know where
you are relative to streams, rivers, or creeks which can become
killers in heavy rains. Campers and hikers should avoid streams or
creeks.

&&

LAT...LON 3781 9097 3789 9064 3774 9064 3774 9098

$$

Tilly

1 follow-up statement

612 
WGUS73 KLSX 220224
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
924 PM CDT MON MAY 21 2018

MOC221-220234-
/O.EXP.KLSX.FF.W.0008.000000T0000Z-180522T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington MO-
924 PM CDT MON MAY 21 2018

...THE FLASH FLOOD WARNING FOR SOUTHEASTERN WASHINGTON COUNTY WILL
EXPIRE AT 930 PM CDT...

Flood waters have receded. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining road closures.

LAT...LON 3781 9097 3789 9064 3774 9064 3774 9098

$$

Maples

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 7:13 PM CDT	Severe Thunderstorm Warning	LSX	Moniteau	47 min
May 20, 7:57 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Moniteau	48 min
May 20, 8:24 PM CDT	Severe Thunderstorm Warning	LSX	Crawford, Gasconade, Osage	51 min
May 20, 8:35 PM CDT	Special Weather Statement	LSX	Audrain	40 min
May 20, 8:56 PM CDT	Severe Thunderstorm Warning	LSX	Gasconade, Osage	49 min
May 20, 9:36 PM CDT	Severe Thunderstorm Warning	LSX	Crawford, Franklin, Gasconade, Washington	39 min
May 20, 9:42 PM CDT	Special Weather Statement	LSX	Gasconade	48 min
May 20, 10:10 PM CDT	Special Weather Statement	LSX	Franklin, Saint Charles, Washington	65 min
May 20, 10:55 PM CDT	Special Weather Statement	LSX	Iron, Jefferson, Saint Francois	50 min
May 21, 12:02 AM CDT	Special Weather Statement	LSX	Lincoln	28 min
May 21, 8:55 AM CDT	River Flood Warning	LSX	Crawford, Washington	44 hr
May 21, 3:23 PM CDT	Severe Thunderstorm Warning	LSX	Sainte Genevieve, Saint Francois	20 min
May 21, 3:29 PM CDT	Flash Flood Warning	LSX	Sainte Genevieve, Saint Francois	6 hr

Nearby

Flash Flood Warnings in Missouri, 2018 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.