Alert archive / Louisiana / Flash Flood Warnings in 2020

Flash Flood Warning 11, NWS New Orleans, LA

June 10, 2020Jefferson Parish, Orleans Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Jun 10, 2020, 7:50 AM CDT for Jefferson Parish, Orleans Parish, Louisiana. It was in force for 100 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: Jun 10, 2020, 7:50 AM CDT (12:50 UTC)
Expired: Jun 10, 2020, 9:30 AM CDT
In force: 100 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Flood severity: None

Counties Jefferson Parish, LA, Orleans Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 0.8 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: 2155 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 565 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.5

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood 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 flash flood warning went out at Jun 10, 3:45 AM CDT, 4 hours 5 minutes earlier.

Area forecast discussion, Jun 10, 3:45 AM CDT, 4 hours 5 minutes before

Area Forecast Discussion
National Weather Service New Orleans LA
345 AM CDT Wed Jun 10 2020

.SHORT TERM...
A front is on its way to the area today. Its hard to call it a
cold front as temps behind it will be hotter than they have been
for several days now. But it will be drier which is going to feel
a lot better if you are in the shade. Nights will be nice though
as temps should also cool off more than they have the last several
days. The line accompanying the front will move through this
morning and should be through by mid afternoon. Some of the
thunderstorms along the line could be strong to low end severe.
This may be more of a concern after daylight when heating can be
taken advantage of causing even better lift.

.LONG TERM...
Overall the extended forecast looks quiet however the models are
struggling with the evolution of the ridge over the Plains and the a
s/w dropping down out of Canada this weekend. The weekend will be
quiet nice for June. The ridge axis will still be to the west with
dry air over the region initally. The airmass will begin to slowly
moisten but dewpoints should remain in the 60s for the most part
(may be in the upper 50s Saturday morning in a few places still)
while LL temps warm up with H925 temps of around 22-24C on Saturday
and 23-25C on Sunday. This will yeild highs in the upper 80s to near
90 Saturday and then mostly lower 90s on Sunday.

Heading into next week is a little more uncertain. Most of the
ensembles suggest an unusal pattern setting up with a deep closed
low developing around the Great Lakes and dropping south over the
eastern CONUS. This along with the ridge remaining just off to the
west may keep the region under mostly northerly flow. This would
also keep the bulk of the hot airmass off to the west as well. /CAB/

&&

.AVIATION...Most if not all terminals will get a few sh/ts today.
These conditions should cause MVFR to possibly IFR cigs and
especially vis restrictions during the time of TSRA but outside
this activity VFR should be the rule. VFR at all terminals overnight.

&&

.MARINE...
A frontal boundary will move through the northern gulf tonight. This
will bring northerly winds to all coastal waters through the end of
the week. The initial surge of northerly winds should be around 20kt
tonight and slowly ease during the day Thursday. These winds will
have a diurnal flux. Basically, they will rise overnight to around
20kt and ease during the day to around 10kt as stability decreases
and increases respectfully over the coastal waters. Winds will
slowly ease with each passing night as the gradient settles through
the weekend into the new week.
&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  89  66  86  65 /  30   0   0   0
BTR  90  66  86  65 /  30   0   0   0
ASD  91  67  88  66 /  60   0   0   0
MSY  90  72  86  71 /  60   0   0   0
GPT  87  68  86  67 /  70  10   0   0
PQL  89  66  88  65 /  70  10   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

In the hours before

Special weather statement, Jun 10, 4:43 AM CDT, 3 hours 7 minutes before

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Special weather statement, Jun 10, 5:58 AM CDT, 1 hour 52 minutes before

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<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
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Special weather statement, Jun 10, 6:00 AM CDT, 1 hour 50 minutes before

Special Weather Statement
National Weather Service New Orleans LA
600 AM CDT Wed Jun 10 2020

LAZ034-101145-
Pointe Coupee-
600 AM CDT Wed Jun 10 2020

...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN POINTE COUPEE
PARISH...

At 600 AM CDT, a strong thunderstorm was located near Melville,
moving southeast at 20 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
New Roads, Livonia, Fordoche and Lottie.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 3062 9174 3066 9175 3067 9173 3071 9173
      3074 9175 3071 9144 3049 9158 3050 9175
      3051 9173 3056 9176 3061 9176
TIME...MOT...LOC 1100Z 293DEG 17KT 3064 9182

Special weather statement, Jun 10, 6:30 AM CDT, 1 hour 20 minutes before

Special Weather Statement
National Weather Service New Orleans LA
630 AM CDT Wed Jun 10 2020

LAZ040-101215-
St. Tammany-
630 AM CDT Wed Jun 10 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT ST. TAMMANY PARISH...

At 630 AM CDT, radar indicated strong thunderstorms were located
along a line extending from near Madisonville to near New Orleans.
Movement was northeast at 20 mph.

Winds in excess of 30 mph are possible with these storms.

Locations impacted include...
Slidell, Covington, Pearl River, Abita Springs, Madisonville, Sun,
Bush, Lacombe, Pearlington and Slidell Airport.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3064 8982 3062 8983 3055 8979 3046 8969
      3040 8968 3034 8963 3025 8963 3020 8959
      3019 8976 3022 8985 3025 8987 3026 8998
      3032 9001 3037 9010 3038 9018 3041 9019
      3067 8999 3067 8985
TIME...MOT...LOC 1130Z 215DEG 16KT 3041 9012 3010 8999

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 10, 4:43 AM CDT	Special Weather Statement	LIX	Pointe Coupee, West Feliciana	62 min
Jun 10, 5:58 AM CDT	Special Weather Statement	LIX	East Feliciana	32 min
Jun 10, 6:00 AM CDT	Special Weather Statement	LIX	Pointe Coupee	45 min
Jun 10, 6:30 AM CDT	Special Weather Statement	LIX	Saint Tammany	45 min
Jun 10, 7:08 AM CDT	Special Marine Warning	LIX		37 min
Jun 10, 7:23 AM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	112 min
Jun 10, 8:03 AM CDT	Special Marine Warning	LIX		57 min
Jun 10, 8:06 AM CDT	Special Weather Statement	LIX	Jefferson	54 min
Jun 10, 9:22 AM CDT	Flash Flood Warning Considerable damage threat	LIX	Jefferson, Orleans	83 min
Jun 10, 9:57 AM CDT	Special Marine Warning	LIX		48 min
Jun 10, 10:06 AM CDT	Special Weather Statement	LIX	Jefferson	24 min
Jun 10, 10:44 AM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard	61 min
Jun 10, 10:54 AM CDT	Special Weather Statement	LIX	Plaquemines	66 min
Jun 10, 11:45 AM CDT	Areal Flood Advisory	LIX	Orleans	2 hr
Jun 10, 12:15 PM CDT	Special Marine Warning	LIX		60 min
Jun 10, 8:05 AM CDT	Special Weather Statement	LIX	Hancock, Harrison	55 min
Jun 10, 8:47 AM CDT	Special Weather Statement	LIX	Harrison, Jackson	58 min
Jun 10, 8:50 AM CDT	Areal Flood Advisory	LIX	Harrison	115 min

Nearby

Flash Flood Warnings in Louisiana, 2020 Every flash flood 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.