110
FXUS64 KLIX 172343
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
643 PM CDT Tue Sep 17 2024

...New UPDATE, AVIATION...

.UPDATE...
Issued at 623 PM CDT Tue Sep 17 2024

Performed a near-term forecast update this evening to reflect
recent radar trends/short-range guidance. Few lingering showers
around, mainly left over from earlier convection that has surged
an outflow boundary west to the Atchafalaya Basin. These are
expected to dissipate going into sunset as any lingering
instability diminishes. Did take a closer look at the potential
for more widespread patchy fog early Wednesday morning. NBM
Probabilities for VIS <1sm are slightly higher this morning, but
given recent days observation trends, appears to be under doing
the amount of surface/near-surface moisture following showers
earlier in the day, revealing more saturated soils furthering fog
develop/maintenance potential. Given this, did jump a bit heavier
with widespread patchy fog, with emphasis used to 12hr MRMS total
precip for areas that saw rain earlier today. Not very confident
on density potential at this time, but could be dense in some
spots, with timing focused on the 09-13Z time frame, likely
improving after daybreak. Otherwise, CAMs are still coming in
drier for tomorrow but want to emphasize it will not be completely
dry, as some lingering moisture/subtle forcing (moreso confined
to any boundaries counteracting slightly greater large-scale
subsidence) could support a few isolated showers, but coverage
will be noticeably less than the past few days. KLG

&&

.SHORT TERM...
(This evening through Thursday night)
Issued at 256 PM CDT Tue Sep 17 2024

Ongoing convective activity will begin to decrease in coverage
through the evening hours with the loss of daytime heating. This
convective activity is directly related to both a moderate degree
of surface based instability and weak omega on the southwest
periphery of a broad upper level low pressure system over the
Southeastern CONUS. Some mid-level moisture is also still
lingering over the area and this has allowed PWATS to rise to near
2 inches today. Fortunately, the forcing and instability remain
weak enough that only low-topped thunderstorms and showers have
developed this afternoon as temperatures warmed into the mid to
upper 80s.

Later tonight, conditions once again look favorable for boundary
layer decoupling to occur as temperatures cool into the upper 60s
and lower 70s, and fully expect to see widespread low stratus and
areas of light to moderate fog form shortly before daybreak
across inland portions of the CWA. This stratus and fog will
linger into the mid-morning hours tomorrow before lifting as
temperatures warm and boundary layer mixing increases. By tomorrow
afternoon, highs will once again climb back into the mid to upper
80s. Although the upper level low will be pulling out of the
region, enough residual moisture and forcing should be in place to
support the development of isolated convection in the afternoon
hours. Have included a 20 percent POP for much of the area
tomorrow afternoon. By tomorrow evening, the loss of daytime
heating will allow any convection to quickly dissipate.

Increasing subsidence and dry air advection will take hold of the
area on Thursday as a strong deep layer ridge axis moves in from
the west. This will lead to mostly clear skies, much lower PWATS
of around 1.5 inches, and a strong mid-level capping inversion.
The result will be limited cloud development and zero chance of
convective development. Temperatures will also warm a bit more
beneath the subsident airmass with highs in the upper 80s and
lower 90s expected. Fortunately, some recovery is expected at
night given the clear skies, light winds, and lower dewpoints in
place. Lows are projected to fall into the mid to upper 60s over
inland areas and the lower 70s along the coast.

&&

.LONG TERM...
(Friday through Monday night)
Issued at 256 PM CDT Tue Sep 17 2024

The deep layer ridge axis will continue to build over the area
this weekend into early next week, and the result will be a very
dry forecast with near zero percent rain chances and clear skies
in place each day. This is reinforced by anomalously low PWATS of
1.25 inches or less across the area from Friday through Sunday.
Some recovery to around 1.5 inches is expected on Monday, but this
is still below average and will greatly limit any convective
potential with a strong mid-level capping inversion in place.
With strong subsidence in place, temperatures will continue to run
slightly above average each day with highs climbing into the
upper 80s and lower 90s. Fortunately, overnight lows will dip into
the 60s and lower 70s each night due to the dry airmass, light
winds, and clear skies expected. The dry air will also help to
keep apparent temperatures manageable in the upper 90s.

&&

.AVIATION...
(00Z TAFS)
Issued at 623 PM CDT Tue Sep 17 2024

For this evening, a few SCT SHRA continues mainly for western
areas, near KHUM to KBTR but are expected to dissipate after
sunset, revealing mostly dry conditions overnight. Will closely
monitor some patchy surface fog around daybreak for just about
all terminals, with timing generally between 09-13Z. Main impacts
will be periodic lower flight categories by lower VIS/some lower
CIGs but am not currently anticipating widespread dense fog at
this time, with conditions returning to VFR after 13Z. Can`t rule
out some isolated showers during the afternoon on Wednesday, but
coverage is expected to be more isolated. KLG

&&

.MARINE...
Issued at 256 PM CDT Tue Sep 17 2024

Through Friday, very benign conditions are expected across all
of the waters as a broad area of high pressure dominates the
northern Gulf of Mexico. Winds will be 5 knots or less and seas
will be nearly calm over this period. By Saturday, a slight
increase in the pressure gradient over the Gulf as the broad high
pressure system moves inland and becomes more centered over
Mississippi and Alabama. The result will be more sustained
easterly wind of 10 to 15 knots developing in the open Gulf waters
and seas increasing to 2 to 4 feet over the weekend. The sounds
and tidal lakes will see winds in the 5 to 10 knot range and seas
of 1 to 2 feet are expected. Overall, despite the slightly uptick
in winds and seas, no significant maritime impacts are expected
through the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  68  87  68  89 /  10  10  10  10
BTR  73  91  73  91 /  30  20  10  10
ASD  72  88  71  89 /  10  20   0  10
MSY  73  88  75  88 /  20  10   0  10
GPT  72  87  72  87 /  20  20   0  10
PQL  71  91  71  89 /  20  10   0   0

&&

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

$$

UPDATE...KLG
SHORT TERM...PG
LONG TERM....PG
AVIATION...KLG
MARINE...PG