Special Weather Statement, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
1047 AM CDT Sat Apr 10 2021

.MORNING UPDATE...

MCS has moved offshore. Have noted over the last hour or so the
redevelopment of convection behind the MCS between Houma and
Morgan City. Ostensibly, this convection should be moving into a
more stable modified airmass in the wake of the MCS and weakening,
but that hasn't started occurring yet. At this time, it appears
these storms should remain south of the New Orleans metro area,
but will continue to monitor. Held onto PoPs south of Lake
Pontchartrain for a few more hours, but cannot rule out the need
for additional updates over the next few hours. Updated first
period grids to reflect post storm temperatures dropping further
than expected earlier this morning. 35

&&

.PREV DISCUSSION... /issued 358 AM CDT Sat Apr 10 2021/

SHORT TERM (Today through Monday Night)...
Prefrontal trough and wind shift will move through this morning
after sunrise but the cold front or actual sfc air mass change will
be slow to move through but will begin to do so around noon and
should be through the entire area by midnight tonight. Some
lingering showers can be expected along the frontal boundary as it
slowly moves through so have left some token 20% pop numbers for
this reason. Not expecting any thunderstorms along the front as a
moderate inversion will set up behind the prefrontal trough pushing
all the weather through this morning. This front will stall over the
northern gulf and could become a focus for sh/ts development mainly
over the gulf starting Monday.

LONG TERM...Focus is on the current severe weather event but
overall the long term forecast remains similar to last nights.
Ensembles, operational models, and the NBM are all in fairly good
agreement with an active pattern next week. Not really in the sense
of severe just multiple rounds of showers and thunderstorms which
could lead to heavy rain over the long period. Stuck closely to the
NBM for the most part with the exception of PoPs on Tuesday and
Wednesday. Confidence seems to be highest in those two days and
given the NBM prob guidance showing 60% of getting greater than 0.1"
which will continue to lead to better confidence.

Still looks like the region will be a few degrees of latitude south
of what looks like a blocking pattern over much of the CONUS. The
closed low over the western CONUS and another closed low slowly
moving southeast across the Great lakes and towards the DELMARVA
region. There will be a ridge between the two centered over the
central Plains and extending into Canada. However, with our area
farther south we remain under fast zonal flow. There still looks to
be quite a bit energy streaming out of the Pac which will come
across the region. At the same time we will still have a boundary
draped some where across the central Gulf coast. With zonal flow
basically paralleling a boundary and multiple impulses coming
through rain chances will be quite high during the middle and
possible latter portions of the week. Combine this with the
likelihood of the atmosphere being quite moisture loaded and locally
heavy rain is a possibility. This could lead to some flash flooding
concerns but a possible greater impact could be rivers. Depending on
how much rain we get tonight over our area and to the north we could
have a number of rivers well elevated. Combine with the possibility
that  The severe potential at this time looks to be low but
obviously we can not rule anything out at this time. /CAB/

AVIATION...IFR conditions will be in and out at all terminals
through 15z as TSRA moves over each site. Conditions will begin to
improve afterwards but cigs will remain around BKN-OVC015 through at
least noon. Cigs will also begin to clear out by afternoon and
especially overnight with fropa.

MARINE...
Strong to severe thunderstorms this morning over the near shore
waters may continue through late morning. South winds of 20-25kt
will remain until a cold front passes tonight. The cold front will
shift winds to a northerly direction but only around 10-15kt after
midnight tonight into Sunday morning. These winds will begin to
shift around the compass to easterly and SE by Monday night. Tuesday
will find a very tight sfc low developing to the southeast of the
coastal waters. A linear convergent boundary will also set up from
the low to the mouth of the Miss River causing winds to be somewhat
erratic Wed along with sh/ts. After Wed, winds become stable from a
south direction at around 15-20kt for a few days.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  81  51  79  53 /  40   0   0   0
BTR  82  53  80  57 /  50   0   0   0
ASD  82  56  80  57 / 100  10   0   0
MSY  83  62  81  63 /  90  10   0   0
GPT  79  58  80  58 / 100  10   0   0
PQL  78  58  80  55 / 100  10   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 4 PM CDT this afternoon for GMZ532-
     536-538-550-552-555-557-570-572-575-577.

MS...None.
GM...Small Craft Advisory until 4 PM CDT this afternoon for GMZ536-
     538-550-552-555-557-570-572-575-577.

&&

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
827 AM CDT SAT APR 10 2021

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

0110 AM     HAIL             1 N MONTPELIER          30.69N 90.65W
04/10/2021  E0.88 INCH       ST. HELENA         LA   BROADCAST MEDIA

            BROADCAST MEDIA REPORTS NICKEL SIZED HAIL IN MONTPELIER,
            LA.

&&

MEGANWIL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
944 AM CDT SAT APR 10 2021

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

0242 AM     TSTM WND DMG     8 E PICAYUNE            30.54N 89.54W
04/10/2021                   HANCOCK            MS   EMERGENCY MNGR

            EM REPORTED TREE DOWN AT OLD KILN RD AND
            NORTH BIENVILLE RD. TIME ESTIMATED BY RADAR.

0245 AM     TSTM WND DMG     3 NE KILN               30.45N 89.41W
04/10/2021                   HANCOCK            MS   EMERGENCY MNGR

            EM REPORTED A TREE DOWN ON OLD JOE MORAN RD
            NE OF KILN. TIME ESTIMATED BY RADAR.

0245 AM     TSTM WND DMG     9 NNE KILN              30.53N 89.37W
04/10/2021                   HANCOCK            MS   EMERGENCY MNGR

            EM REPORTED TREE DOWN ON STANDARD DEDEAUX RD
            NE OF KILN. TIME ESTIMATED BY RADAR.

0505 AM     TSTM WND DMG     PEARLINGTON             30.25N 89.59W
04/10/2021                   HANCOCK            MS   EMERGENCY MNGR

            EM REPORTED A COUPLE TREES DOWN FROM
            PEARLINGTON TO BAY ST. LOUIS. TIME ESTIMATED
            FROM RADAR.

&&

Special Weather Statement
National Weather Service New Orleans LA
1115 AM CDT Sat Apr 10 2021

LAZ065-066-101645-
Lower Terrebonne-Upper Terrebonne-
1115 AM CDT Sat Apr 10 2021

...A STRONG THUNDERSTORM WILL AFFECT ESTERN TERREBONNE PARISH...

At 1115 AM CDT, a strong thunderstorm was located 9 miles south of
Bayou Vista, moving east at 35 mph.

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

This storm will remain over mainly rural areas of western Terrebonne
Parish.

If outdoors, consider seeking shelter inside a building.

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 2951 9126 2954 9127 2955 9124 2956 9123
      2958 9123 2961 9118 2959 9116 2962 9109
      2966 9087 2944 9084 2945 9126 2948 9128
TIME...MOT...LOC 1615Z 265DEG 30KT 2955 9125

95/DM

Special Weather Statement
National Weather Service New Orleans LA
1151 AM CDT Sat Apr 10 2021

LAZ059-065>067-101730-
Lower Terrebonne-Upper Terrebonne-Lower Lafourche-Upper Lafourche-
1151 AM CDT Sat Apr 10 2021

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL TERREBONNE AND CENTRAL
LAFOURCHE PARISHES...

At 1151 AM CDT, a strong thunderstorm was located southwest of
Houma, moving east at 50 mph.

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

Locations impacted include...
Houma, Larose, Cut Off, Galliano, Golden Meadow, Chauvin, Montegut,
Bayou Cane and Dulac.

If outdoors, consider seeking shelter inside a building.

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 2942 9101 2959 9100 2965 9025 2938 9024
TIME...MOT...LOC 1651Z 269DEG 45KT 2951 9077

95/DM