Flash Flood in Louisiana, July 7, 2021

AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
320 AM CDT Wed Jul 7 2021

.SHORT TERM (Today through Thursday)...
The upper level pattern analysis shows the typical summertime ridges
centered to the west over Arizona and to the east in the Atlantic. A
trough swinging through the upper Mississippi Valley will keep an
area of weakness between those ridges. That weakness falls right
over the CWA. At the same time, above climo moisture levels are in
place. The average PW measured yesterday at LIX was 2.2". That
amount of moisture gives the potential for heavy rain to fall and
will lead to high convective coverage. Not all storms will produce
high rainfall totals. The interaction of outflow boundaries and
sea/land breeze boundaries have been the focus of some recent
instances of high rainfall amounts. Other situations of high qpf
events have been backbuilding along the coastal regions where
convergence induced by sea and land frictional differences causes
training. So while the overall threat for flash flooding is too low
to justify a flash flood watch, am fairly confident someone in the
CWA will see over 6" (most locations will be in the 1-3" range).

Really not expecting much change rolling into Thursday. The pattern
looks the same with similar moisture levels still high and little
inhibition. Therefore, should see another 70-90% coverage day with
some locations possibly seeing quite heavy rainfall on a the scale
of the size of a city. We may see a slight reduction in coverage on
Friday as the trough lifts and shifts farther east. The ridge to the
west will try to build farther east as that occurs but its influence
locally will be minimal. The threat for isolated flash flooding will
likely continue. At least the higher rain chances and cloud cover
over the next few days will keep high temps at or below normal.

MEFFER
&&

.LONG TERM (This weekend into early next week)...
Still some uncertainty with respect to the forecast this weekend and
into next week. Main issue is how strong is the ridge that builds
into the area and if the next strong s/w can keep the area in a
favorable area for additional showers and thunderstorms. LAtest
models and ensembles appear to be leaning back towards the ridge
struggling to build in and remain over the area. With that we are
leaning towards the wetter solutions which is in agreement with the
NBM.

The western CONUS ridge will initially nudge into the Lower MS Valley
but a strong s/w working southeast out of southwest Canada will round
the top of the ridge and towards the MS Valley and this will begin
to erode the eastern periphery of the ridge. At the same time the
Ridge over the Atlantic would have tried to build west but this s/w
will stop that as well and this will once again keep the Lower MS
Valley in between the two ridges. With abundant moisture still in
place scattered to numerous showers and thunderstorms will be
possible each day. These will be diurnally driven each day so as
usually with the Summer convection will be more marine based
overnight and then transition inland as the land areas heat up.
Obviously this is exactly what everyone wanted to hear but hopefully
The ridge can build in enough Friday to at least lead to one day of
lower storm coverage.

/CAB/
&&

.AVIATION...
Most terminals should be ok through at least 10Z but after that a
few will likely see low cigs leading to MVFR status at a few sites.
Convection will be likely at all terminals again today. Outside of
convection everyone should be in VFR however it would not be a
surprise to see tempo MVFR cigs around 2500-3k ft.

/CAB/
&&

.MARINE...
The wind field will remain fairly weak with prevailing onshore flow
of 5 to 10 knots remaining in place through Thursday. Nocturnal
increase to 10 to 15 will be possible. A swell train emanating from
Tropical Storm Elsa continues through today. This swell will produce
higher seas of 4 to 6 feet in the open Gulf waters. Otherwise,
mainly 2 feet or less expected in the coastal waters.

MEFFER
&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  85  72  90  73 /  90  30  70  20
BTR  87  73  88  74 /  90  20  70  20
ASD  87  75  89  75 /  80  30  70  20
MSY  88  78  90  78 /  90  20  70  20
GPT  87  75  89  76 /  80  40  60  20
PQL  87  74  88  75 /  80  40  60  20

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1022 PM CDT TUE JUL 6 2021

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

1021 PM     FLASH FLOOD      3 SE LYMAN              30.47N 89.10W
07/06/2021                   HARRISON           MS   LAW ENFORCEMENT

            SHERIFFS OFFICE REPORTED MULTIPLE ROADS
            BEGINNING TO FLOOD AND IN THE PROCESS OF
            BLOCKING/CLOSING A FEW OFF.

&&

CAB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1041 PM CDT TUE JUL 6 2021

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

1040 PM     FLASH FLOOD      4 ESE LYMAN             30.47N 89.07W
07/06/2021                   HARRISON           MS   BROADCAST MEDIA

            APARTMENTS BEGINNING TO TAKE ON WATER OFF OF
            ONEAL RD IN NORTH GULFPORT.

&&

CAB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1109 PM CDT TUE JUL 6 2021

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

1109 PM     FLASH FLOOD      4 NNW GULFPORT          30.44N 89.08W
07/06/2021                   HARRISON           MS   BROADCAST MEDIA

            FLOODING OCCURRING AROUND THE PALMS
            APARTMENTS IN GULFPORT.

&&

CAB