Special Weather Statement, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
652 PM CDT Tue Apr 13 2021

.AVIATION (00z Taf cycle)...
Showers and thunderstorms continue this evening for most terminals
that has caused lower ceilings and visibility restrictions and
frequent strong wind gusts. Conditions should begin to improve
going into the overnight hours with ceilings returning to
MVFR/VFR. IFR conditions however will return sometime during mid
morning hours as showers and thunderstorms begin to move into the
area once again Wednesday morning. These conditions should persist
through tomorrow evening.

&&

.PREV DISCUSSION... /issued 422 PM CDT Tue Apr 13 2021/

SHORT TERM...
Tonight through Thursday...
Tonight and Wednesday, upper level ridging and zonal flow will
dominate the upper level pattern for the next few days. Southerly
surface winds will help to enhance the warm air advection and
moisture advection into the area. Upper level divergence will help
to enhance the lifting and buoyancy in the environment. As a
result, showers and storms will be possible tomorrow from mid-
morning through the afternoon hours when daytime peak heating is
most likely to occur. These storms will have the potential to be
severe with the main threats being damaging winds, large hail, and
the potential for locally heavy rainfall inside thunderstorm
development.

Thursday, an upper level low pressure system will be moving
through the eastern coast of the U.S. As it moves off the
coastline, it will create a boundary set up over our area
Thursday. Southerly surface winds will help to enhance the
moisture and warm air advection into the area. And upper level
divergence will help to enhance lifting in the environment.
Consequently, storms will form along the boundary over our area
Thursday, mainly during the afternoon hours with peak daytime
heating. The main threats from these storms will be gusty winds,
frequent lightning, and hail. MSW

LONG TERM...
Friday through Monday...
Friday and Saturday morning, the boundary from the upper level
east coast low pressure system will linger over our area and
weaken. Southerly surface winds will persist and continue to
enhance the warm air advection and moisture advection, along with
the instability. Some storms will be able to fire up along this
boundary, but there will not be as much lifting available for the
storms to develop as much as previous days. As a result, the main
threats will be gusty winds and frequent lightning, but severe
weather is not expected currently. Locally heavy rainfall will be
a concern for Friday into Saturday since these storms will have
the ability to be efficient, particularly Saturday morning when
the boundary seems like it will be training based on the models
(favorable CAPE, upper level divergence, slower wind speeds at the
low and mid levels, and deep moisture availability). The models
have some disagreement on the timing and potential strength for
this system, which will be highly dependent on how the system
develops over the next few days.

Saturday afternoon through Monday, the lingering boundary from
the upper level low pressure system will slowly move off the coast
and into the Gulf of Mexico. Some showers and storms could linger
along the Louisiana coastal areas as it moves off shore Saturday
into Sunday morning. Northerly surface winds will help to
enhance the dry air and stable air in the area. Upper level
divergence over the area these days will allow for some lifting in
the environment. This will allow for some light showers to be able
to develop Saturday afternoon. Otherwise, the second half of the
weekend looks mostly dry. MSW

AVIATION...
18Z TAF Package...
Showers and thunderstorms will be likely for the rest of the
afternoon today and into the early evening hours at most area
airports. These storms will cause lower ceiling and visibilities
where they occur along with IFR conditions. Conditions will return
to mostly MVFR conditions during the overnight hours at most area
airports with the lower ceilings persisting through this time
with the chance for vicinity showers. IFR conditions will return
from mid- morning through the evening hours Wednesday due to lower
ceiling and visibility's from shower and thunderstorm development
again. MSW

MARINE...
Winds will be strong (15-25 knots) and southerly tonight and
Wednesday. Winds will be strong (15-20 knots) and southerly
Thursday. Thursday evening through Friday morning, winds will be
shifting from northerly to easterly and will be moderate (<15
knots). Friday, winds will be easterly shifting to southerly and
moderate (<15 knots). Saturday winds will be southerly shifting to
northerly and will be strong (15-20 knots). Monday, winds will be
northeasterly and strong (15-20 knots). Wave heights will
correspond to the wind speeds. MSW

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  61  73  58  71 /  50  90  70  60
BTR  65  77  61  73 /  90  90  70  70
ASD  63  78  63  75 / 100  80  70  80
MSY  67  80  67  75 / 100  70  60  80
GPT  64  76  63  74 /  80  80  70  80
PQL  62  77  62  73 /  50  70  70  70

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flash Flood Watch through Thursday morning for LAZ034>037-039-
046>050-056>061-063>072-075>078.

     Wind Advisory until 3 AM CDT Wednesday for LAZ056>061-063>070-
     072-075>078.

GM...Small Craft Advisory until 10 AM CDT Wednesday for GMZ550-552-
     555-570-572-575.

     Flash Flood Watch through Thursday morning for GMZ530.

     Small Craft Advisory until 4 AM CDT Wednesday for GMZ530-532-534-
     536-538-557-577.

MS...Flash Flood Watch through Thursday morning for MSZ068>071-077-
     080.

     Wind Advisory until 3 AM CDT Wednesday for MSZ080>082.

     Flash Flood Watch from 4 AM CDT Wednesday through Thursday
     morning for MSZ081-082.

GM...Small Craft Advisory until 10 AM CDT Wednesday for GMZ552-555-
     570-572-575.

     Small Craft Advisory until 4 AM CDT Wednesday for GMZ532-534-536-
     538-557-577.

&&

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NEW ORLEANS LA
621 PM CDT TUE APR 13 2021

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

0538 PM     NON-TSTM WND GST 1 SSW MANDEVILLE        30.36N 90.09W
04/13/2021  M56 MPH          GMZ530             LA   MESONET

            MESONET STATION XMVL MANDEVILLE.

0522 PM     NON-TSTM WND GST 12 SSW MANDEVILLE       30.20N 90.12W
04/13/2021  M55 MPH          GMZ530             LA   MESONET

            MESONET STATION XPTN PONTCHARTRAIN CAUSEWAY.

0400 PM     MARINE TSTM WIND 26 S VENICE             28.91N 89.43W
04/13/2021  M53 MPH          GMZ552             LA   MESONET

            MESONET STATION BURL1 SOUTHWEST PASS.

0330 PM     MARINE TSTM WIND 3 NE GRAND ISLE         29.27N 89.95W
04/13/2021  M75 MPH          GMZ552             LA   PUBLIC

            GISL1 - GRAND ISLE STATION.

0215 PM     FLASH FLOOD      2 S DESTREHAN           29.93N 90.37W
04/13/2021                   ST. CHARLES        LA   EMERGENCY MNGR

            CORRECTS PREVIOUS FLASH FLOOD REPORT FROM 2
            S DESTREHAN. MILLING AVENUE IN LULING
            BETWEEN POST DRIVE AND HALL DRIVE CLOSED DUE
            TO HIGH WATER.

0210 PM     FLASH FLOOD      1 SSE NEW SARPY         29.97N 90.38W
04/13/2021                   ST. CHARLES        LA   EMERGENCY MNGR

            ORMOND VILLAGE DRIVE IN DESTREHAN CLOSED DUE
            TO HIGH WATER.

0210 PM     FLASH FLOOD      1 NE BOUTTE             29.90N 90.39W
04/13/2021                   ST. CHARLES        LA   EMERGENCY MNGR

            ALEXANDER STREET CLOSED DUE TO HIGH WATER.

0202 PM     TSTM WND DMG     1 W METAIRIE            30.00N 90.20W
04/13/2021                   JEFFERSON          LA   PUBLIC

            PORTION OF ROOF TORN OFF PHOEBE HEARST
            ELEMENTARY IN METAIRIE. LIKELY FROM A WAKE
            LOW.

0202 PM     TSTM WND DMG     2 ENE KENNER            30.00N 90.22W
04/13/2021                   JEFFERSON          LA   PUBLIC

            ROOF AWNING BLOWN OFF OF A HOME ON DAVID
            DRIVE NEAR WEST NAPOLEON.

0200 PM     TSTM WND DMG     3 N KENNER              30.02N 90.24W
04/13/2021                   JEFFERSON          LA   PUBLIC

            TREES AND POWERLINES DOWN NEAR ARKANSAS AVE
            AND 37TH ST.

0200 PM     MARINE TSTM WIND 4 ENE METAIRIE          30.03N 90.11W
04/13/2021  M54 MPH          GMZ530             LA   MESONET

            WXFLOW @ NEW CANAL.

0153 PM     TSTM WND GST     6 W EAST NEW ORLEANS    30.05N 90.03W
04/13/2021  M52 MPH          GMZ530             LA   ASOS

            ASOS STATION KNEW NEW ORLEANS LAKEFRONT
            AIRPORT.

0115 PM     HAIL             CUT OFF                 29.53N 90.33W
04/13/2021  E1.00 INCH       LAFOURCHE          LA   BROADCAST MEDIA

            ESTIMATED FROM SOCIAL MEDIA VIDEO. TIME
            BASED ON RADAR.

0112 PM     MARINE TSTM WIND 12 SSW MANDEVILLE       30.20N 90.12W
04/13/2021  M43 MPH          GMZ530             LA   MESONET

            MESONET STATION XPTN PONTCHARTRAIN CAUSEWAY.

1116 AM     TSTM WND DMG     5 E PRAIRIEVILLE        30.29N 90.89W
04/13/2021                   ASCENSION          LA   TRAINED SPOTTER

            LARGE TREE BRANCHES AND FENCE DOWN ON
            NORWOOD RD NEAR STONE RIDGE AVE. TIME
            ESTIMATED FROM RADAR.

1041 AM     TSTM WND DMG     CONVENT                 30.02N 90.83W
04/13/2021                   ST. JAMES          LA   LAW ENFORCEMENT

            A FEW TREES DOWN IN CONVENT.

&&

Special Weather Statement
National Weather Service New Orleans LA
626 PM CDT Tue Apr 13 2021

LAZ050-072-140000-
Livingston-Southern Tangipahoa-
626 PM CDT Tue Apr 13 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN LIVINGSTON AND
SOUTHWESTERN TANGIPAHOA PARISHES...

At 625 PM CDT, a strong thunderstorm was located near Livingston, or
11 miles east of Denham Springs, moving east at 35 mph.

Wind gusts up to 50 mph and pea size hail are possible with this
storm.

Locations impacted include...
Hammond, Ponchatoula, Walker, Livingston, Albany, Springfield,
Natalbany and Tickfaw.

If outdoors, consider seeking shelter inside a building.

LAT...LON 3048 9087 3057 9084 3059 9037 3038 9045
TIME...MOT...LOC 2325Z 276DEG 31KT 3053 9078

JRK

Special Weather Statement
National Weather Service New Orleans LA
627 PM CDT Tue Apr 13 2021

LAZ049-056>058-140000-
Ascension-Assumption-St. John The Baptist-St. James-
627 PM CDT Tue Apr 13 2021

...A STRONG THUNDERSTORM WILL AFFECT WEST CENTRAL ST. JOHN THE
BAPTIST...SOUTHERN ASCENSION...ST. JAMES AND NORTH CENTRAL ASSUMPTION
PARISHES...

At 627 PM CDT, a strong thunderstorm was located over Donaldsonville,
moving east at 40 mph.

Wind gusts up to 50 mph and pea size hail are possible with this
storm.

Locations impacted include...
Donaldsonville, Gramercy, Lutcher, Sorrento, Wallace, Convent, North
Vacherie, Garyville, Belle Rose and Edgard.

If outdoors, consider seeking shelter inside a building.

LAT...LON 3016 9106 3020 9072 3018 9071 3017 9069
      3020 9067 3021 9059 3019 9060 3018 9058
      2996 9062 3002 9107
TIME...MOT...LOC 2327Z 272DEG 34KT 3009 9099

JRK

Special Weather Statement
National Weather Service New Orleans LA
644 PM CDT Tue Apr 13 2021

LAZ056-057-059-065-140030-
Upper Terrebonne-Assumption-St. James-Upper Lafourche-
644 PM CDT Tue Apr 13 2021

...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN ST. JAMES...NORTH
CENTRAL TERREBONNE...NORTHWESTERN LAFOURCHE AND ASSUMPTION
PARISHES...

At 643 PM CDT, a strong thunderstorm was located over Pierre Part, or
near Belle River, moving east at 35 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Thibodaux, Napoleonville, Schriever, Supreme, Gray, Chackbay,
Paincourtville, Labadieville and South Vacherie.

If outdoors, consider seeking shelter inside a building.

LAT...LON 3000 9124 3003 9122 3003 9120 2991 9066
      2965 9079 2980 9110 2984 9113 2985 9118
      2990 9121 2992 9123 2993 9123 2997 9126
      3000 9126
TIME...MOT...LOC 2343Z 290DEG 40KT 2995 9125

JRK

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