331
FXUS64 KLIX 172058
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
358 PM CDT Mon Jun 17 2024

...New SHORT TERM, LONG TERM, AVIATION, MARINE...

.Key Messages...

1. Scattered to numerous showers and thunderstorms are expected
again Tuesday, but the heavy rain threat as a whole will be lower
as the overall coverage and duration of heavier rain decreases.

2. Strong east-southeasterly winds across the northern Gulf will
cause tide levels to rise above normal tonight, with minor coastal
flooding expected Tuesday during the time of high tide and minor
to potentially moderate coastal flooding during high tide
Wednesday. A few low lying roads may become covered with water or
impassable, especially during high tide Wednesday morning.

3. Winds will become quite gusty Tuesday and Wednesday and could
blow around some light weight outdoor items. A wind advisory may
be needed for some portions of the area, mainly south of the tidal
lakes.

&&


.SHORT TERM...
(This evening through Wednesday night)
Issued at 244 PM CDT Mon Jun 17 2024

NHC has started advisories on Potential Tropical Cyclone (PTC) One
in the Bay of Campeche. This system is not expected to have any
direct impacts on the local area, but due to its large size and
interaction with a strong high over the eastern US, some indirect
impacts are likely.

PTC One is forecast to become gradually better organized through
the short term. As this happens, the pressure gradient will
tighten across the local area, resulting in a strengthening wind
field across the local area. Currently the wind and gust forecasts
are still just below wind advisory criteria, but the next shift
or two will need to continue taking a closer look. IF a wind
advisory becomes necessary, it is most likely for areas south of
the tidal lakes in southeast Louisiana.

Strong east-southeasterly flow across the northern Gulf waters
will cause tides to rise above normal by tomorrow morning and
minor coastal flooding is likely during high tide. Water levels
will be highest during high tide on Wednesday, and could result in
a some low lying roads becoming impassable, mainly in the more
vulnerable areas on the west/southwest side of Bay St. Louis.
Based on the forecast, water could also cover some low lying
portions of Hwy 1 between Port Fourchon and Grand Isle. Looking at
the probabilistic water level guidance, there is still some
potential that a coastal flood warning may be needed Wednesday
morning, mainly for areas from Shell Beach to Bay St. Louis.
Regarding water levels in the lake, will again hold off on any
headlines around the lake shores for now as water levels in the
lake are expected to lag those on the open coast by 1-2 days. The
guidance at New Canal on the south shore does indicate an advisory
may be needed by the high tide cycles late Wednesday and Thursday,
though.

The plume of deep tropical moisture that has been with us since
yesterday will shift a bit to the west tomorrow. While there will
still be plenty of moisture to support scattered to numerous
showers and storms across the area, but rainfall rates should come
down just a bit and the duration of heavier rain in any location
should also limit the flood threat. Thus WPC continues to carry
only a marginal risk of excessive rainfall leading to flash
flooding on Tuesday.

By Wednesday the bulk of the moisture shifts even further
southwest with drier air moving into the local area. Generally
scattered showers and storms are still in the forecast, with
possibly higher coverage across coastal southeast Louisiana. With
the precipitable water dropping back down closer to 1.75, which
is above normal but not remarkably so, rainfall rates are not
expected to be as dramatic as what we`ve seen today, and the
flooding rain threat is fairly low.

Afternoon temperatures will generally be near to below normal
through the short term due to cloud cover and the higher rain
chances. Morning lows will be above normal owing to the higher
than normal dewpoints preventing the temps from dropping much
below the mid 70s most places.

&&

.LONG TERM...
(Thursday through Sunday night)
Issued at 244 PM CDT Mon Jun 17 2024

Going into Thursday and the weekend the forecast is a little murky
and kind of depends on where various moisture plumes end up.
Currently, the NBM/consensus approach keeps the deeper tropical
moisture out of our local forecast area, though there is quite a
bit of uncertainty regarding the evolution of various vorticity
features rotating through the central american gyre.

With no confidence in any specific ensemble member solutions, see
no reason to stray from the NBM at this point in the longer term
forecast. This results in scattered to numerous POPs each day mainly
across southern areas with lower POPs farther inland.

Temperatures should be near to above normal based on the current
forecast.

&&

.AVIATION...
(18Z TAFS)
Issued at 244 PM CDT Mon Jun 17 2024

Outside of showers and storms, expect prevailing VFR to MVFR
conditions. Scattered to numerous showers and storms will bring
occasional restrictions to the terminals today as deep tropical
moisture moves through the area. High rainfall rates will
temporarily reduce visibility to ifr conditions as showers and/or
thunderstorms move over the terminals. Convection should wane
somewhat after sunset, but will increase in coverage again by mid
to late morning Tuesday. Winds will also strengthen Tuesday in
response to a tightening pressure gradient.

&&

.AVIATION...
(12Z TAFS)
Issued at 634 AM CDT Mon Jun 17 2024

Most terminals VFR at issuance time this morning, with the
exception of KMCB, where IFR ceilings were in place. Convection
was rather isolated at 11z, but expect areal coverage to blossom
in the next few hours as surface heating kicks in. MVFR ceilings
may become predominant by 15z. SHRA will be main weather for the
next few hours with the threat of TSRA at pretty much all
terminals by midday. Areal coverage should be sufficient for TEMPO
during the afternoon at all terminals with IFR or lower
visibilities and MVFR ceilings. While wind gusts in excess of 30
knots are possible with the strongest cells, not high enough
confidence to carry in most terminals. Areal coverage will
diminish toward 00z Tuesday, with little or no precipitation
between about 02z and 10z. MVFR to IFR ceilings may return toward
sunrise Tuesday.

Sustained winds near 15 knots possible during much of the daytime
hours today before diminishing this evening. With low pressure
expected to develop over or near the Bay of Campeche later today
or tomorrow, stronger sustained winds are anticipated during the
daytime hours tomorrow, with gusts of 25 to 30 knots not out of
the question by mid-morning.

&&

.MARINE...
Issued at 244 PM CDT Mon Jun 17 2024

No significant change to the marine forecast with this package.
Generally still expecting advisory conditions across most of the
coastal waters through midweek as winds respond to a tightening
pressure gradient between low pressure in the Bay of Campeche and
high pressure centered over the east coast. Latest forecast does
have a period of potentially gale conditions, mainly in the form
of gusts from Tuesday night through Wednesday, but confidence is
low enough that we will hold off on any gale watch for the time
being. Regardless of whether winds reach gale conditions, a long
fetch combined with a swell train emanating from the low in the SW
Gulf will likely push seas to at least 9 to 12 feet over the open
waters by Tuesday night into Wednesday. Hazardous to dangerous
conditions will persist through much of the work week, especially
over the open waters, and are not likely to see any significant
improvement until Thursday night or Friday.

As noted above, with the prolonged southeasterly winds, east and
south facing shorelines will see increased water levels beginning
overnight tonight, and a Coastal Flood Advisory will remain in
effect and will likely eventually need extended into Thursday.
Coastal Flood Warnings may be necessary for more sensitive spots
by Tuesday night or Wednesday. Will again hold off on tidal lakes
for now, as it appears their main water concerns may hold off
until Wednesday night or Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  72  85  71  90 /  30  40   0  30
BTR  76  88  76  92 /  40  60  10  50
ASD  75  87  76  90 /  60  60  10  50
MSY  79  88  81  90 /  50  70  10  60
GPT  77  87  76  90 /  30  50  20  40
PQL  75  91  75  92 /  30  40  20  30

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Small Craft Advisory until 7 AM CDT Thursday for LAZ068.

     Coastal Flood Advisory from 1 AM Tuesday to 4 PM CDT Wednesday
     for LAZ066>070-076-078.

GM...Small Craft Advisory from 7 AM Tuesday to 7 AM CDT Thursday for
     GMZ530-532-534.

     Small Craft Advisory until 7 AM CDT Thursday for GMZ536-538-550-
     552-555-557-570-572-575-577.

MS...Coastal Flood Advisory from 1 AM Tuesday to 4 PM CDT Wednesday
     for MSZ086>088.

GM...Small Craft Advisory from 7 AM Tuesday to 7 AM CDT Thursday for
     GMZ532-534.

     Small Craft Advisory until 7 AM CDT Thursday for GMZ538-550-552-
     555-557-570-572-575-577.

&&

$$

SHORT TERM...DM
LONG TERM....DM
AVIATION...DM
MARINE...DM