Flash Flood Warning 56, NWS New Orleans, LA

Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
946 AM CDT Wed Aug 10 2022

...UPDATE...

Heavy rainfall over the MS Gulf Coast, especially over Jackson Co.
continues this morning. Instantaneous rates have decreased a bit
over the last half hour or so, but 7 to 8 inches of rain have
fallen over generally around the Pascagoula/Moss Point areas.
Generally east of the Pearl River, deep layer flow is a bit higher
than locations further west. This is allowing for convection to
move, however, back-building is taking place with abundant low
level convergence and the constant tropical moisture feed from the
southwest. The 12z RAOB this morning tells the story with a
tropical airmass over the region. PWATS in excess of 2.2" will
lead to very efficient rainfall producers (again, as we saw this
morning for Jackson Co., MS).

Further to the west over SE Louisiana and interior South MS, the
flow is more stagnant. This will likely lead to diurnally driven
convection to move slower and likely propagate with outflow.
Additional hydro concerns will remain possible this afternoon.
CAMs show the convection should initiate west of the MS river
sometime around the noon hour (give or take). With a mostly
moisture inundated column, think that severe potential will be
mitigated, but a strong wind gust or two may be possible in the
more robust updrafts that develop. Additionally, with the very
weak mean flow, waterspouts may be possible, especially where
updrafts ingest older boundaries. And finally temperatures will be
held down a bit today with the uptick in clouds and precip.
Overall, no changes in temps, but did up POPs respectively this
morning along the MS Coast and over SE LA/interior S MS this
afternoon. (Frye-28)

&&

.PREV DISCUSSION... /issued 411 AM CDT Wed Aug 10 2022/

SHORT TERM (Today through Friday)...

At the risk of sounding repetitive, another day of high rain
chances is on tap for the area. Once again, these storms can
easily produce hourly rainfall rates that will be capable of
causing flooding issues. Short term models are consistent on
showing this activity likely beginning earlier than yesterday with
some heavy rainfall moving into the Mississippi coastal counties
around daybreak before filling in more across the area by the
afternoon hours. While it is very likely that some areas see heavy
rainfall, the somewhat chaotic setup to the rainfall has been
helping keep the problem areas to a minimum. That said, deep
tropical moisture associated with a tropical wave and persistent
onshore flow will surely keep the level of concern elevated. The
entire forecast area is outlooked for a slight risk of excessive
rainfall through today as storms that develop today could once
again easily produce rainfall rates of 2 to 3 inches per hour.

Much of the same is expected tomorrow as a boundary currently
situated over the southern Plains moves toward the area,
potentially helping to act as a focus for the rainfall should it
make enough progress. Once again the potential will certainly be
there for heavy rainfall with the locations being much harder to
pinpoint. The area is outlooked for a marginal risk of excessive
rainfall for tomorrow but could certainly be upgraded given
rainfall that occurs today. On that same note, held off on a flood
watch of any kind but that could be needed as well given rainfall
that occurs today.

In addition to the rainfall concerns, a coastal flood advisory
remains in effect through midday Thursday due to the persistent
onshore flow. This is mainly for issues that may develop during
the normal high tide periods.

LONG TERM (Saturday and beyond)...

Persistent ridging over the central Rockies will slide slightly
east and south by the end of the week. This will place our area on
the eastern periphery bringing a period of northerly flow into
the area. Due to this, the focus for the shower and thunderstorm
activity over the weekend will shift somewhat from a heavy
rainfall threat to more strong storms with wind gust potential.
Rain chances should moderate back to more normal summertime
expectations as we move into next week as the ridge moves closer
to the area.

AVIATION...

Mostly VFR conditions across the area terminals this morning with
some occasional MVFR periods mainly due to low ceilings. Cannot
rule out the possibility of some lowering visibilities before
sunrise but so far it has not materialized. The most likely
locations would be at KMCB and KBTR. After daybreak, focus will
shift to showers and thunderstorm activity with all terminals
likely to see some impacts during the day.

MARINE...

Onshore flow will continue over the coastal waters through much of
the weekend with only a small reprieve on Saturday. This, in
combination with the spring tide is likely to cause some minor
coastal flooding issues and a coastal flood advisory remains in
effect through midday tomorrow. In addition, shower and
thunderstorm activity over the coastal waters will bring increased
winds and seas along with the possibility of waterspouts.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  85  70  85  69 /  70  60  90  30
BTR  90  73  87  72 /  70  60 100  30
ASD  88  73  87  72 /  80  60  90  40
MSY  87  76  86  75 /  80  60  90  50
GPT  87  74  86  73 /  80  60  90  50
PQL  87  73  86  73 /  80  60  90  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Coastal Flood Advisory until 1 PM CDT Thursday for LAZ066>070-
     076-078.

GM...None.
MS...Coastal Flood Advisory until 1 PM CDT Thursday for MSZ080>082.

GM...None.
&&

Update...Frye-28

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
905 AM CDT WED AUG 10 2022

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

0847 AM     FLASH FLOOD      MOSS POINT              30.43N 88.53W
08/10/2022                   JACKSON            MS   EMERGENCY MNGR

            MULTIPLE FLOODED ROADWAYS REPORTED.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
952 AM CDT WED AUG 10 2022

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

0903 AM     FLASH FLOOD      2 SSE MOSS POINT        30.40N 88.52W
08/10/2022                   JACKSON            MS   FIRE DEPT/RESCUE

            REPORTS OF ROAD FLOODING AT FREDERIK ST AND
            ROSE DR.

&&

CAB