Alert archive / Louisiana / Flash Flood Watches in 2017

Flash Flood Watch 10, NWS New Orleans, LA

August 27, 201713 parishes in Louisiana; 5 counties in Mississippi

NWS New Orleans, LA issued this flash flood watch at Aug 27, 2017, 3:55 PM CDT for 13 parishes in Louisiana; 5 counties in Mississippi. It was in force for 4 days.

The area

The counties it named.

The facts

Issued: Aug 27, 2017, 3:55 PM CDT (20:55 UTC)
Expired: Aug 31, 2017, 1:14 PM CDT
In force: 4 days
Issued by: NWS New Orleans, LA
Flood severity: None

Counties Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Pointe Coupee Parish, LA, Saint Bernard Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Pearl River County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 8.9 hours before the alert went out and 243 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: 323 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 934 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 181 m²/s²
0-3 km storm-relative helicity: 193 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS New Orleans, LA wrote its last area forecast discussion before this flash flood watch went out at Aug 27, 3:48 PM CDT, 7 minutes earlier.

Area forecast discussion, Aug 27, 3:48 PM CDT, 7 minutes before

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Hazardous weather outlook, Aug 27, 3:54 PM CDT, 1 minute before

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In the hours before

Special weather statement, Aug 27, 11:09 AM CDT, 4 hours 46 minutes before

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Special weather statement, Aug 27, 11:31 AM CDT, 4 hours 24 minutes before

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Special weather statement, Aug 27, 12:02 PM CDT, 3 hours 53 minutes before

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Special weather statement, Aug 27, 12:44 PM CDT, 3 hours 11 minutes before

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Special weather statement, Aug 27, 2:03 PM CDT, 1 hour 52 minutes before

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Special weather statement, Aug 27, 3:35 PM CDT, 20 minutes before

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The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 27, 8:23 AM CDT	Special Marine Warning	LIX		52 min
Aug 27, 10:43 AM CDT	Special Weather Statement	LIX	Orleans	32 min
Aug 27, 11:02 AM CDT	Special Marine Warning	LIX		43 min
Aug 27, 11:09 AM CDT	Special Weather Statement	LIX	Saint Charles	36 min
Aug 27, 11:31 AM CDT	Special Weather Statement	LIX	Saint Charles	29 min
Aug 27, 11:41 AM CDT	Special Marine Warning	LIX		49 min
Aug 27, 12:02 PM CDT	Special Weather Statement	LIX	Saint John the Baptist	43 min
Aug 27, 12:35 PM CDT	Special Marine Warning	LIX		25 min
Aug 27, 12:44 PM CDT	Special Weather Statement	LIX	Saint James	31 min
Aug 27, 1:21 PM CDT	Areal Flood Advisory	LIX	Lafourche	114 min
Aug 27, 2:03 PM CDT	Special Weather Statement	LIX	Saint Charles	27 min
Aug 27, 3:35 PM CDT	Special Weather Statement	LIX	Pointe Coupee	40 min

Nearby

Flash Flood Watches in Louisiana, 2017 Flash Flood Watches in Mississippi, 2017 Every flash flood watch 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; the sounding from the Mesonet's radiosonde archive.