Alert archive / Louisiana / Flash Flood Watches in 2017

Flash Flood Watch 6, NWS New Orleans, LA

June 19, 201713 parishes in Louisiana; 5 counties in Mississippi

NWS New Orleans, LA issued this flash flood watch at Jun 19, 2017, 3:52 PM CDT for 13 parishes in Louisiana; 5 counties in Mississippi. It took effect at Jun 20, 2017, 7:00 AM CDT. It was in force for 60 hr.

The area

The counties it named.

The facts

Issued
Jun 19, 2017, 3:52 PM CDT (20:52 UTC)
In effect from
Jun 20, 2017, 7:00 AM CDT
Expired
Jun 22, 2017, 7:00 PM CDT
In force
60 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 12:00Z, 8.9 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-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2017-06-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1415 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2017-06-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -8 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1415 J/kg
Mixed-layer CIN
-32 J/kg
Mixed-layer LCL
801 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
-8 m²/s²
0-3 km storm-relative helicity
1 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 Jun 19, 12:34 PM CDT, 3 hours 18 minutes earlier.

Area forecast discussion, Jun 19, 12:34 PM CDT, 3 hours 18 minutes before
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Hazardous weather outlook, Jun 19, 11:18 AM CDT, 4 hours 34 minutes before
Hazardous Weather Outlook
National Weather Service New Orleans LA
1118 AM CDT Mon Jun 19 2017

GMZ530-532-534-536-538-550-552-555-557-570-572-575-577-LAZ034>037-
039-040-046>050-056>072-MSZ068>071-077-080>082-200430-
Lake Pontchartrain and Lake Maurepas-Mississippi Sound-
Lake Borgne-Chandeleur Sound-Breton Sound-
Coastal Waters from Port Fourchon LA to Lower Atchafalaya River
LA out 20 nm-
Coastal waters from the Southwest Pass of the Mississippi River
to Port Fourchon Louisiana out 20 NM-
Coastal Waters from Boothville LA to Southwest Pass of the
Mississippi River out 20 nm-
Coastal waters from Pascagoula Mississippi to Stake Island out
20 NM-
Coastal waters from Port Fourchon Louisiana to Lower Atchafalaya
River LA from 20 to 60 NM-
Coastal waters from Southwest Pass of the Mississippi River to
Port Fourchon Louisiana from 20 to 60 NM-
Coastal Waters from Stake Island LA to Southwest Pass of the
Mississippi River from 20 to 60 nm-
Coastal waters from Pascagoula Mississippi to Stake Island
Louisiana out 20 to 60 NM-Pointe Coupee-West Feliciana-
East Feliciana-St. Helena-Washington-St. Tammany-Iberville-
West Baton Rouge-East Baton Rouge-Ascension-Livingston-Assumption-
St. James-St. John The Baptist-Upper Lafourche-St. Charles-
Upper Jefferson-Orleans-Upper Plaquemines-Upper St. Bernard-
Upper Terrebonne-Lower Terrebonne-Lower Lafourche-Lower Jefferson-
Lower Plaquemines-Lower St. Bernard-Northern Tangipahoa-
Southern Tangipahoa-Wilkinson-Amite-Pike-Walthall-Pearl River-
Hancock-Harrison-Jackson-
1118 AM CDT Mon Jun 19 2017

This Hazardous Weather Outlook is for portions of Southeast
Louisiana...South Mississippi and the adjacent coastal waters.

.DAY ONE...This Afternoon and Tonight

A marginal risk of severe thunderstorms exists for areas north of
the I-12 corridor in Southeast Louisiana and for all of Southwest
Mississippi today. The primary threat from any severe
thunderstorms will be strong damaging wind gusts. Any severe
thunderstorm activity should be isolated. All of the
thunderstorms
that form today, severe or non-severe, could produce frequent
lightning strikes and locally heavy downpours.

Small craft advisory conditions may develop tonight over the open
Gulf waters. An east wind of 20 to 25 knots and increasing seas
of
up to 10 feet are currently forecast for the Gulf waters tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The National Hurricane Center has a high chance of tropical
cyclone development during the next 2 days near the Yucatan
Peninsula and into the southern and central Gulf of Mexico. There
is still quite a bit of uncertainty in the evolution of this
system so please continue to follow the latest updates.

Depending on if a tropical system develops, east winds of 20 to
30 knots with higher gusts and waves of up to 14 feet may develop
over the open Gulf coastal waters Tuesday and Tuesday night.
Winds
may turn to the south at 20 to 25 knots by Wednesday and remain
at these levels through Friday. These conditions could result in
the continuation of Small Craft Advisories for portions of the
coastal waters Tuesday through Friday.

If the tropical system forms, persistent east and southeast winds
of 20 to 25 knots combined with high offshore seas could increase
tide levels 2 to 4 feet above normal levels on east facing shores
beginning Tuesday and lasting through Thursday.

A period of heavy rainfall could occur across Southeast Louisiana
and Southern Mississippi. A marginal to slight risk of excessive
rainfall is currently forecast for the area on Tuesday and
Wednesday. Rainfall totals of 4 to 8 inches could occur between
Tuesday and Friday along the Louisiana and Mississippi coasts
including metro New Orleans with localized rainfall potential
for 10 to 15 inches plus.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be requested at some point over the week.

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 19, 4:26 PM CDTTropical Storm WarningLIXAssumption, Saint Bernard, Saint John the Baptist60 hr

Nearby

Flash Flood Watches in Louisiana, 2017Flash Flood Watches in Mississippi, 2017Every 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.