Alert archive / Louisiana / Flash Flood Watches in 2018

Flash Flood Watch 5, NWS New Orleans, LA

August 18, 2018Saint Bernard Parish, Saint John the Baptist Parish, Louisiana

NWS New Orleans, LA issued this flash flood watch at Aug 18, 2018, 3:31 PM CDT for Saint Bernard Parish, Saint John the Baptist Parish, Louisiana. It took effect at Aug 19, 2018, 7:00 AM CDT. It was in force for 36 hr.

The area

The counties it named.

The facts

Issued: Aug 18, 2018, 3:31 PM CDT (20:31 UTC)
In effect from: Aug 19, 2018, 7:00 AM CDT
Expired: Aug 20, 2018, 7:00 PM CDT
In force: 36 hr
Issued by: NWS New Orleans, LA
Flood severity: None

Counties Saint Bernard Parish, LA, Saint John the Baptist Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 8.5 hours before the alert went out and 51 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: 2057 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 720 m above ground
0-6 km bulk shear: 2 kt
0-1 km storm-relative helicity: -25 m²/s²
0-3 km storm-relative helicity: -5 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 Aug 18, 3:24 PM CDT, 7 minutes earlier.

Area forecast discussion, Aug 18, 3:24 PM CDT, 7 minutes before

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Hazardous weather outlook, Aug 18, 1:15 PM CDT, 2 hours 16 minutes before

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In the hours before

Local storm report, Aug 18, 9:57 AM CDT, 5 hours 34 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
957 AM CDT SAT AUG 18 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0835 AM     MARINE TSTM WIND 44 SSE GRAND ISLE       28.64N 89.79W
08/18/2018  M41.00 MPH       GMZ572             XX   AWOS

            KMDJ - MISSISSIPPI CANYON 311A, SSW 17G36KT.

0935 AM     MARINE TSTM WIND 31 E VENICE             29.30N 88.84W
08/18/2018  M39.00 MPH       GMZ555             LA   AWOS

            KMIS - MISSISSIPPI CANYON 140B AWOS, NW 29G34KT

&&

24/RR

Local storm report, Aug 18, 1:03 PM CDT, 2 hours 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
103 PM CDT SAT AUG 18 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1259 PM     FLOOD            NEW ORLEANS             29.97N 90.08W
08/18/2018                   ORLEANS            LA   EMERGENCY MNGR

            SEVERAL STREETS FLOODED THROUGHOUT CENTRAL CITY FROM
            GENTILLY TO INDUSTRIAL CANAL AREA. ELYSIAN FIELDS AND
            MIRO, LOUISA AND HIGGINS, HARRISON AND GENTILLY BLVD,
            FRANCE ROAD AND LOUISA, FRANKLIN AND CLAIBORNE AVE.

&&

24/RR

Local storm report, Aug 18, 1:18 PM CDT, 2 hours 13 minutes before

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Local storm report, Aug 18, 2:26 PM CDT, 1 hour 5 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 18, 5:56 AM CDT	Special Weather Statement	LIX	Jefferson, Lafourche	64 min
Aug 18, 8:43 AM CDT	Special Marine Warning	LIX		47 min
Aug 18, 8:44 AM CDT	Special Marine Warning	LIX		61 min
Aug 18, 8:51 AM CDT	Special Marine Warning	LIX		54 min
Aug 18, 9:28 AM CDT	Special Marine Warning	LIX		62 min
Aug 18, 9:57 AM CDT	Special Marine Warning	LIX		63 min
Aug 18, 10:51 AM CDT	Special Marine Warning	LIX		54 min
Aug 18, 12:38 PM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Saint Charles	112 min
Aug 18, 1:00 PM CDT	Flash Flood Warning	LIX	Jefferson, Orleans	90 min
Aug 18, 1:06 PM CDT	Flash Flood Warning	LIX	Saint Charles	114 min
Aug 18, 5:30 AM CDT	Special Weather Statement	LIX	Harrison, Jackson	60 min
Aug 18, 4:14 PM CDT	Areal Flood Advisory	LIX	Pike, Walthall	2 hr
Aug 18, 6:43 PM CDT	Special Weather Statement	LIX	Jackson	62 min

Nearby

Flash Flood Watches in Louisiana, 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.