Alert archive / Louisiana / Flash Flood Watches in 2018

Flash Flood Watch 6, NWS New Orleans, LA

September 3, 201813 parishes in Louisiana; 5 counties in Mississippi

NWS New Orleans, LA issued this flash flood watch at Sep 3, 2018, 4:45 AM CDT for 13 parishes in Louisiana; 5 counties in Mississippi. It took effect at Sep 4, 2018, 12:00 PM CDT. It was in force for 28 hr.

The area

The counties it named.

The facts

Issued: Sep 3, 2018, 4:45 AM CDT (09:45 UTC)
In effect from: Sep 4, 2018, 12:00 PM CDT
Expired: Sep 5, 2018, 3:30 PM CDT
In force: 28 hr
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

Slidell Radar S, LA (KSIL), launched 00:00Z, 9.8 hours before the alert went out and 108 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: 816 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 747 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 93 m²/s²
0-3 km storm-relative helicity: 112 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 Sep 3, 4:39 AM CDT, 6 minutes earlier.

Area forecast discussion, Sep 3, 4:39 AM CDT, 6 minutes before

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Hazardous weather outlook, Sep 2, 5:46 PM CDT, 10 hours 59 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
Sep 2, 11:07 PM CDT	Storm Surge Watch	LIX	Saint Bernard	47 hr
Sep 3, 4:28 AM CDT	Tropical Storm Warning	LIX	Assumption, East Baton Rouge, Iberville, Saint Bernard, Saint James, Saint John the Baptist and 3 more	48 hr
Sep 3, 10:34 AM CDT	Storm Surge Warning	LIX	Saint Bernard	42 hr
Sep 3, 4:11 PM CDT	Special Weather Statement	LIX	West Feliciana	49 min
Sep 3, 4:13 PM CDT	Special Weather Statement	LIX	Saint Charles	47 min
Sep 3, 10:34 AM CDT	Hurricane Watch	LIX		6 hr
Sep 3, 4:32 PM CDT	Hurricane Warning	LIX		33 hr

Nearby

Flash Flood Watches in Louisiana, 2018 Flash Flood Watches in Mississippi, 2018 Every flash flood watch 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.