Alert archive / Louisiana / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 50, NWS New Orleans, LA

April 23, 2020Jefferson Parish, Lafourche Parish, Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Apr 23, 2020, 10:38 AM CDT for Jefferson Parish, Lafourche Parish, Louisiana. It was in force for 14 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Apr 23, 2020, 10:38 AM CDT (15:38 UTC)
Expired: Apr 23, 2020, 10:52 AM CDT
In force: 14 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Hail: 2.0 in
Wind: 60.0 mph

Counties Jefferson Parish, LA, Lafourche Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 3.6 hours before the alert went out and 91 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: 2572 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 498 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: 424 m²/s²
0-3 km storm-relative helicity: 449 m²/s²
Significant tornado parameter: 7.7
Supercell composite: 25.5

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning 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 severe thunderstorm warning went out at Apr 23, 4:26 AM CDT, 6 hours 12 minutes earlier.

Area forecast discussion, Apr 23, 4:26 AM CDT, 6 hours 12 minutes before

Area Forecast Discussion
National Weather Service New Orleans LA
426 AM CDT Thu Apr 23 2020

.SHORT TERM...
Very dynamic system moving through this morning. All variables
ahead of the current line are very supportive of all modes of
severe wx. The rainfall rates will also be quite efficient and
will likely cause flooding of streets, underpasses and low lying
areas. This line is expected to eventually weaken as another line
begins to evolve over southshore locations around or just after
daylight. This will eventually become more of a marine issue by
through the day, people in all locations should listen for alerts
and warnings being issued.

As the actual front moves into the picture later this morning,
another line of sh/ts looks to develop around noon today while the
strongest activity should be near the coast or just offshore. The
secondary line that develops along the front should decay by
evening and all activity moving east overnight mainly offshore.

Not a lot of activity noticed until next week around Tue and Wed
when another spring system will get started just to the west
bringing the possibility of strong to severe thunderstorms once
again.

&&

.AVIATION...
Ceilings will generally range between 500 and 1500 feet, and
periods of reduced visibility associated with passing TSRA can be
expected this morning. Some of the storms could be strong to
severe, with large hail and wind gusts in excess of 50 knots
could impact the terminals mainly between 12z and 18z. Conditions
will improve for a short time over the NW portion of the area but
another line of sh/ts will develop around noon to keep those
terminals with a threat of TSRA and lower cielings.

&&

.MARINE...
A cold front will push through Thursday. Strong to severe
thunderstorms will move over the coastal waters today into
tonight. Strong gradient winds will remain through much of the day
today with lighter winds expected by late Thursday into Friday as
high pressure develops. Return flow develops again over the
weekend and another weak front will move through by Sunday giving
the area another round of northerly winds but will be short lived
as southerly winds should become re-established by the start of
the work week and lasting through at least mid week.

&&

.DECISION SUPPORT...
DSS Code : Orange
Activities: Forecast support for IDSS critical locations
            River Flood Warnings for several rivers
            Working severe weather today

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  81  59  83  64 /  40   0   0  10
BTR  83  59  85  64 /  40   0   0   0
ASD  82  60  84  65 /  50  10   0   0
MSY  83  66  84  68 /  30   0   0   0
GPT  79  63  80  67 /  70   0   0   0
PQL  81  60  84  65 /  80   0   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 5 PM CDT this afternoon for GMZ532-
     534-536-538-550-552-555-557-570-572-575-577.

     Small Craft Advisory until 9 AM CDT this morning for GMZ530.

MS...None.
GM...Small Craft Advisory until 5 PM CDT this afternoon for GMZ534-
     536-538-550-552-555-557-570-572-575-577.

&&

In the hours before

Special weather statement, Apr 23, 6:24 AM CDT, 4 hours 14 minutes before

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Local storm report, Apr 23, 6:30 AM CDT, 4 hours 8 minutes before

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Local storm report, Apr 23, 7:15 AM CDT, 3 hours 23 minutes before

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Local storm report, Apr 23, 8:59 AM CDT, 1 hour 39 minutes before

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Special weather statement, Apr 23, 9:36 AM CDT, 1 hour 2 minutes before

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Special weather statement, Apr 23, 10:29 AM CDT, 9 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
Apr 23, 2:37 AM CDT	Special Weather Statement	LIX	East Baton Rouge, East Feliciana, West Baton Rouge	68 min
Apr 23, 2:40 AM CDT	Severe Thunderstorm Warning	LIX	Iberville, Pointe Coupee, West Baton Rouge, West Feliciana	65 min
Apr 23, 2:45 AM CDT	Tornado Warning	LIX	Iberville, Pointe Coupee, West Baton Rouge	45 min
Apr 23, 3:03 AM CDT	Severe Thunderstorm Warning	LIX	East Baton Rouge, East Feliciana, Livingston, Saint Helena	57 min
Apr 23, 3:49 AM CDT	Severe Thunderstorm Warning	LIX	Livingston, Saint Tammany, Tangipahoa, Washington	56 min
Apr 23, 4:50 AM CDT	Severe Thunderstorm Warning	LIX	Saint Tammany, Washington	25 min
Apr 23, 9:36 AM CDT	Special Weather Statement	LIX	Lafourche, Terrebonne	54 min
Apr 23, 10:08 AM CDT	Special Marine Warning	LIX		52 min
Apr 23, 10:29 AM CDT	Special Weather Statement	LIX	Lafourche	46 min
Apr 23, 10:42 AM CDT	Small Craft Advisory	LIX		6 hr
Apr 23, 10:59 AM CDT	Special Marine Warning	LIX		61 min
Apr 23, 11:03 AM CDT	Special Marine Warning	LIX		42 min
Apr 23, 11:19 AM CDT	Special Marine Warning	LIX		56 min
Apr 23, 11:23 AM CDT	Special Weather Statement	LIX	Jefferson	37 min
Apr 23, 11:33 AM CDT	Severe Thunderstorm Warning	LIX	Jefferson, Lafourche, Plaquemines, Terrebonne	27 min
Apr 23, 11:38 AM CDT	Special Marine Warning	LIX		67 min
Apr 23, 11:41 AM CDT	Special Marine Warning	LIX		64 min
Apr 23, 11:56 AM CDT	Special Weather Statement	LIX	Jefferson	34 min
Apr 23, 12:15 PM CDT	Special Marine Warning	LIX		60 min
Apr 23, 12:19 PM CDT	Special Marine Warning	LIX		26 min
Apr 23, 12:23 PM CDT	Special Weather Statement	LIX	Plaquemines	37 min
Apr 23, 12:29 PM CDT	Special Marine Warning	LIX		31 min
Apr 23, 12:41 PM CDT	Special Marine Warning	LIX		34 min
Apr 23, 12:48 PM CDT	Special Weather Statement	LIX	East Baton Rouge	27 min
Apr 23, 1:06 PM CDT	Special Marine Warning	LIX		84 min
Apr 23, 1:08 PM CDT	Special Weather Statement	LIX	East Baton Rouge	37 min
Apr 23, 1:50 PM CDT	Special Weather Statement	LIX	Washington	25 min
Apr 23, 1:52 PM CDT	Special Weather Statement	LIX	Saint Helena	23 min
Apr 23, 2:15 PM CDT	Special Weather Statement	LIX	Saint Helena	60 min
Apr 23, 2:27 PM CDT	Special Marine Warning	LIX		81 min
Apr 22, 10:24 PM CDT	Special Weather Statement	LIX	Wilkinson	51 min
Apr 22, 10:51 PM CDT	Special Weather Statement	LIX	Wilkinson	54 min
Apr 23, 1:53 AM CDT	Special Weather Statement	LIX	Wilkinson	67 min
Apr 23, 2:01 AM CDT	Severe Thunderstorm Warning	LIX	Wilkinson	59 min
Apr 23, 2:06 AM CDT	Tornado Warning	LIX	Wilkinson	39 min
Apr 23, 2:44 AM CDT	Severe Thunderstorm Warning	LIX	Amite, Pike	61 min
Apr 23, 3:04 AM CDT	Tornado Warning	LIX	Amite, Pike	25 min
Apr 23, 3:13 AM CDT	Tornado Warning Tornado observed	LIX	Pike, Walthall	47 min
Apr 23, 5:10 AM CDT	Severe Thunderstorm Warning	LIX	Hancock, Pearl River	35 min
Apr 23, 6:24 AM CDT	Special Weather Statement	LIX	Pearl River	36 min
Apr 23, 2:13 PM CDT	Special Weather Statement	LIX	Walthall	47 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2020 Every severe thunderstorm warning in 2020

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.