Alert archive / Louisiana / Special Weather Statements in 2017

Special Weather Statement, NWS New Orleans, LA

May 4, 2017Plaquemines Parish, Louisiana

NWS New Orleans, LA issued this special weather statement at May 4, 2017, 12:13 AM CDT for Plaquemines Parish, Louisiana. It was in force for 47 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
May 4, 2017, 12:13 AM CDT (05:13 UTC)
Expired
May 4, 2017, 1:00 AM CDT
In force
47 min
Issued by
NWS New Orleans, LA

County Plaquemines Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 5.2 hours before the alert went out and 113 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 00:00Z on 2017-05-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 00:00Z on 2017-05-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 71 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1194 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
71 m²/s²
0-3 km storm-relative helicity
6 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<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.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at May 3, 8:28 PM CDT, 3 hours 45 minutes earlier.

Area forecast discussion, May 3, 8:28 PM CDT, 3 hours 45 minutes before
Area Forecast Discussion
National Weather Service New Orleans LA
828 PM CDT Wed May 3 2017

.SOUNDING DISCUSSION...
There were no problems with the upper air release this evening.
The 00Z sounding indicated a stable layer in the lower levels of
the atmosphere...below 850 mb...beneath an inversion. Above this
inversion, the sounding was unstable up through the mid levels. A
layer of drier air was noted below 700 mb. The precipitable water
value was 1.35 inches. Moderate to strong southeast flow was
present below the aforementioned inversion, with southwest winds
above the inversion veering to the west with height in the mid
levels. 11

&&

.PREV DISCUSSION... /issued 354 PM CDT Wed May 3 2017/

SYNOPSIS...

Low pressure currently centered near Texarkana with one warm front
along the southern border of Tennessee and a second warm front
just south of the Louisiana coast, where it has been anchored all
day. Convection has been riding just north of this front this
afternoon across areas south of Interstate 10. While many areas
warmed to near forecast highs this morning, as rain moved in,
temperatures have fallen significantly into the 60s for much of
the area. Likely to see a brief spurt of gusty winds over the next
hour or two as pressures near Lake Pontchartrain have jumped about
4 mb in the last hour. Will drop Tornado Watch 190 with issuance
of forecast package as convection has moved out of those areas.

SHORT TERM...

Mesoscale models have struggled with convection today, as warm
front still has not moved inland. This is bringing heavy rain axis
closer to the coast, and heavy rain emphasis more likely to be
south of Lake Pontchartrain tonight. Reluctant to drop Flash Flood
Watch over northern portions of the area, as convection with
squall line could still drop a quick couple of inches of rain. As
we have not gotten into the warm sector for significant
destabilization, threat of severe weather is somewhat less, but
not zero.

Will need to monitor areas downwind of Lake Pontchartrain behind
the front for the potential of a Wind Advisory. For now, it
appears winds will be short of advisory criteria...which is 25
mph sustained.

Current scenario would have heaviest precipitation east of the
CWA prior to 12z, but still could see lingering showers/rain
through the morning hours. Should see some clearing by late
afternoon as system shifts east across Mississippi and Alabama.

Friday and Saturday will be dry and cool. Lows both mornings
likely to be 10-15 degrees below normal. With dry air in place,
highs 75 to 80 both days. 35

LONG TERM...

Upper ridging will move into the area and take up residence Sunday
through the middle of next week. Dry weather with temperatures
warming into the mid, and possibly upper 80s. Lows gradually
moderating from the 50s to the 60s. No large variations in medium
range guidance.

AVIATION...

A generally messy forecast for the next 24 hours with widespread
showers and thunderstorms. While there is lower than normal
confidence, have tried to capture short term trends and the timing
of the worst conditions as the squall line moves through this
evening and tonight. Conditions should gradually improve from west
to east Thursday morning, but winds will remain elevated and gusty
depending on location due to a tight pressure gradient as high
pressure builds into the area. 95/DM

MARINE...

Headlines remain in place with exercise caution headlines now and
Small Craft Advisories going into effect at 06z. Could see a few
gusts to gale force, but confidence not high enough for a warning.
Advisories currently through 00z Friday, but likely to need
extended beyond that. Probably will be carrying headlines through
at least Friday night for most of the coastal waters before
conditions begin to subside. 35

DECISION SUPPORT...

DSS CODE...Orange.
DEPLOYED...None.
ACTIVATION...None.
ACTIVITIES...Flash Flood Watch and Severe threat through tonight.

Decision Support Service (DSS) Code Legend:
GREEN  = No weather impacts that require action
BLUE   = Long fused Watch/Warning/Advisory in effect or high
         visibility event
YELLOW = Heightened impacts with short fused
         Watch/Warning/Advisory issuances; Radar support
ORANGE = High Impacts - Slight to Moderate risk of severe weather;
         Nearby tropical events, HAZMAT or other large episodes
RED    = Full engagement for moderate risk of severe weather; Direct
         tropical threats; events of national significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  55  65  46  73 / 100  10   0   0
BTR  56  69  50  74 / 100  10   0   0
ASD  61  69  49  76 / 100  40  10   0
MSY  63  70  53  75 / 100  30   0   0
GPT  65  72  51  75 / 100  60  10   0
PQL  64  73  47  76 / 100  60  10   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flash Flood Watch until 7 AM CDT Thursday for LAZ034>037-039-040-
     046>050-056>072.

GM...Small Craft Advisory from midnight tonight to 7 PM CDT Thursday
     for GMZ530-532-534-536-538-550-552-555-557-570-572-575-577.

MS...Flash Flood Watch until 7 AM CDT Thursday for MSZ068>071-077-
     080>082.

GM...Small Craft Advisory from midnight tonight to 7 PM CDT Thursday
     for GMZ532-534-536-538-550-552-555-557-570-572-575-577.

&&
Hazardous weather outlook, May 3, 6:03 PM CDT, 6 hours 10 minutes before
Hazardous Weather Outlook
National Weather Service New Orleans LA
603 PM CDT Wed May 3 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>082-041115-
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-
603 PM CDT Wed May 3 2017

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

.DAY ONE...Tonight

There is a slight risk of severe thunderstorms for all of southern
Mississippi and southeast Louisiana tonight. The main hazards
with severe weather will be tornadoes, damaging winds and large
hail.

A Flash Flood Watch is in effect for all of southern Mississippi
and southeast Louisiana through 7 am Thursday. Total rainfall
amounts are expected to be 3 to 5 inches with locally higher
amounts possible.

Small craft advisories are posted starting at midnight tonight
through at least Thursday afternoon.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Small craft advisories may be extended into Friday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is likely later tonight.

In the hours before

Special weather statement, May 3, 7:55 PM CDT, 4 hours 18 minutes before
Special Weather Statement
National Weather Service New Orleans LA
755 PM CDT WED MAY 3 2017

LAZ049-050-058-071-072-040130-
Livingston-Ascension-Northern Tangipahoa-Southern Tangipahoa-St. John
The Baptist-
755 PM CDT WED MAY 3 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN ST. JOHN THE BAPTIST...
CENTRAL ASCENSION...LIVINGSTON AND TANGIPAHOA PARISHES...

At 755 PM CDT, a strong thunderstorm was located near Whitehall, or
16 miles northeast of Gonzales, moving east at 55 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Hammond, Gonzales, Ponchatoula, Walker, Livingston, Independence,
Sorrento, French Settlement, Albany, Port Vincent, Springfield,
Natalbany, Robert, Whitehall, Killian and Tickfaw.

LAT...LON 3074 9026 3035 9025 3025 9034 3022 9041
      3015 9043 3016 9064 3017 9064 3015 9070
      3016 9092 3034 9091 3034 9090 3052 9090
      3078 9028
TIME...MOT...LOC 0055Z 263DEG 47KT 3036 9070
Special weather statement, May 3, 9:24 PM CDT, 2 hours 49 minutes before
Special Weather Statement
National Weather Service New Orleans LA
924 PM CDT WED MAY 3 2017

LAZ040-062-MSZ080-081-040300-
Orleans-St. Tammany-Harrison-Hancock-
924 PM CDT WED MAY 3 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN ORLEANS AND
SOUTHEASTERN ST. TAMMANY PARISHES...WESTERN HARRISON AND HANCOCK
COUNTIES...

At 924 PM CDT, a strong thunderstorm was located near Pearlington, or
11 miles east of Slidell, moving east at 40 mph.

Wind gusts up to 50 mph are possible with this storm.

Locations impacted include...
Slidell, Long Beach, Bay St. Louis, Waveland, Diamondhead, Pearl
River, Kiln, Pearlington, Shoreline Park and Stennis Space Center.

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 3030 8929 3036 8928 3037 8935 3033 8938
      3034 8934 3031 8933 3025 8942 3018 8946
      3019 8946 3016 8962 3018 8958 3018 8960
      3011 8970 3016 8971 3016 8966 3017 8972
      3038 8977 3060 8920 3034 8916
TIME...MOT...LOC 0224Z 261DEG 34KT 3030 8958

CAB
Local storm report, May 3, 9:31 PM CDT, 2 hours 42 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
931 PM CDT WED MAY 03 2017

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

0908 PM     MARINE TSTM WIND LAKEFRONT AIRPORT       30.04N 90.03W
05/03/2017  M41 MPH          ORLEANS            LA   ASOS

&&

PGRIGSBY
Local storm report, May 3, 9:55 PM CDT, 2 hours 18 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
955 PM CDT WED MAY 03 2017

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

0850 PM     TSTM WND DMG     LACOMBE                 30.31N 89.93W
05/03/2017                   ST. TAMMANY        LA   AMATEUR RADIO

            TREES REPORTED DOWN IN LACOMBE ON HIGHWAY 434 AND
            PONTCHARTRAIN ROAD.

&&

PGRIGSBY
Local storm report, May 3, 11:12 PM CDT, 1 hour 1 minute before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1112 PM CDT WED MAY 03 2017

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

0745 AM     LIGHTNING        BATON ROUGE             30.45N 91.13W
05/03/2017                   EAST BATON ROUGE   LA   BROADCAST MEDIA

            LIGHTNING STRUCK A HOUSE ON MELROSE BOULEVARD AROUND
            745PM WHICH LED TO A FIRE. THE HOUSE SUSTAINED HEAVY
            SMOKE DAMAGE ACCORDING TO BATON ROUGE FIRE DEPT.

&&

CBANNAN
Special weather statement, May 4, 12:13 AM CDT, 0 minutes before
Special Weather Statement
National Weather Service New Orleans LA
1213 AM CDT THU MAY 4 2017

LAZ067>069-040600-
Lower Plaquemines-Lower Jefferson-Lower Lafourche-
1213 AM CDT THU MAY 4 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN LAFOURCHE
AND CENTRAL PLAQUEMINES PARISHES...

At 1212 AM CDT, radar indicated strong thunderstorms were located
along a line extending from Golden Meadow to 12 miles southwest of
Leeville. Movement was east at 50 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Galliano, Golden Meadow, Leeville and Grand Isle.

Torrential rainfall is also occurring with these storms, 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 2915 9027 2915 9028 2947 9026 2937 8999
      2935 9000 2938 8985 2930 8946 2921 8947
      2935 8996 2928 8994 2936 9007 2934 9004
      2926 8995 2920 9004 2925 8998 2933 9010
      2932 9010 2918 9007 2909 9024
TIME...MOT...LOC 0512Z 289DEG 43KT 2940 9027 2909 9031

TD

The office that day

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

IssuedProductOfficeCountiesLasted
May 3, 7:22 PM CDTSpecial Weather StatementLIXAscension, East Baton Rouge, Iberville, Livingston, Saint James23 min
May 3, 7:55 PM CDTSpecial Weather StatementLIXAscension, Livingston, Tangipahoa35 min
May 3, 8:58 PM CDTSevere Thunderstorm WarningLIXSaint Tammany32 min
May 3, 9:07 PM CDTSpecial Marine WarningLIX53 min
May 3, 9:32 PM CDTRiver Flood WarningLIXSaint Tammany45 hr
May 3, 9:43 PM CDTSpecial Marine WarningLIX92 min
May 3, 11:18 PM CDTAreal Flood AdvisoryLIXJefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles3 hr
May 3, 11:19 PM CDTAreal Flood AdvisoryLIXSaint Tammany3 hr
May 4, 12:12 AM CDTSpecial Marine WarningLIX63 min
May 4, 12:16 AM CDTSpecial Marine WarningLIX59 min
May 4, 12:39 AM CDTSevere Thunderstorm WarningLIXJefferson, Plaquemines51 min
May 4, 1:11 AM CDTSpecial Marine WarningLIX64 min
May 4, 1:13 AM CDTSpecial Marine WarningLIX62 min
May 4, 2:15 AM CDTSpecial Marine WarningLIX60 min
May 4, 2:18 AM CDTSpecial Marine WarningLIX57 min
May 4, 3:11 AM CDTSpecial Marine WarningLIX49 min
May 4, 3:13 AM CDTSpecial Marine WarningLIX47 min
May 4, 5:26 AM CDTSpecial Marine WarningLIX79 min
May 4, 6:42 AM CDTSpecial Marine WarningLIX63 min
May 3, 9:24 PM CDTSpecial Weather StatementLIXHancock36 min

Nearby

Special Weather Statements in Louisiana, 2017Every special weather statement 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.