033 
FXUS64 KLIX 201839
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
139 PM CDT Sun Sep 20 2026

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

.KEY MESSAGES... 
Updated at 136 PM CDT Sun Sep 20 2026

- Hot conditions will persist through much of the week, with 
  highs near records thru mid week and generally above normal thru
  next weekend. 

- Rain chances will be highest Monday into Tuesday, but rain
  amounts will generally be less than one half inch this week as
  not much rain is expected for the remainder of the forecast
  period. 

&&

.SHORT TERM...
(Now through Wednesday night)
Issued at 136 PM CDT Sun Sep 20 2026

Upper ridging remains the dominant influence across the region this 
afternoon, although that high centered over east Texas continues to 
gradually weaken. A weak upper disturbance that was over the eastern 
Gulf yesterday hasn'te moved any. At the same time, additional 
shortwave energy is progressing eastward across the Northern and 
Central Plains. At the surface, broad high pressure extends across 
much of the Southeast and northern Gulf Coast, keeping the local 
pressure gradient weak. In local terms, strong subsidence beneath 
the ridge aloft will continue to suppress convection across nearly 
the entire area. The main exception will be in southern Mississippi 
and adjacent coastal waters where an old outflow boundary from 
convection to the east may provide just enough low-level convergence 
for an isolated afternoon shower or thunderstorm. Visible satellite 
imagery from the last hour does show some CU enhancement which may 
be the start of isolated convection. Should be noted that it would 
be more inland than CAMs suggest. Otherwise, mostly sunny skies will 
allow temperatures to climb into the lower to middle 90s, with a few 
upper 90s possible across the northwest portion of the CWA. 
Increasing boundary-layer moisture will result in heat indices 
reaching the lower to middle 100s, locally as high as around 106, 
just shy of the 108 degree Heat Advisory threshold.

A somewhat more noticeable change develops Monday as the upper ridge 
weakens further and a shortwave currently moving through the central 
Plains approaches the Mid Mississippi Valley. At the same time, low-
level moisture will continue to increase across the area. The 
combination of less subsidence, increasing column moisture, daytime 
instability, and weak mesoscale boundaries should support scattered 
afternoon showers and thunderstorms. Convective coverage should 
initially favor coastal seabreeze boundaries before spreading inland 
during peak heating. Current guidance continues to suggest the 
highest probabilities from the Mississippi coast westward into the 
Northshore and coastal southeast Louisiana, while locations farther 
northwest toward Baton Rouge and southwest Mississippi may see 
considerably less activity. The weak flow through much of the column 
will result in slow-moving, pulse-type convection. Locally heavy 
rainfall possible beneath stronger cells, but limited overall 
coverage and a lack of a persistent focusing boundary should keep 
the flooding threat low. Monday will otherwise remain hot, with 
highs generally in the lower to middle 90s and perhaps upper 90s 
near Baton Rouge. Increasing dewpoints will again allow peak heat 
indices to reach the mid to upper 100s. Cloud and precipitation 
coverage should limit both the spatial extent and duration of the 
highest heat indices.

The shortwave to the north will shift east of the region Monday 
night into Tuesday while upper ridging begins rebuilding eastward 
from Texas into western Louisiana. This will begin to increase 
subsidence again, but enough residual moisture should remain for 
isolated afternoon convection Tuesday, particularly across eastern 
and coastal portions of the forecast area. Coverage should be lower 
than Monday, with most locations remaining dry. Temperatures will 
remain well above normal with highs generally in the lower to middle 
90s and upper 90s possible. 

MEFFER 
&&

.LONG TERM...
(Thursday through Saturday night)
Issued at 136 PM CDT Sun Sep 20 2026

Confidence continues to increase that upper ridging will rebuild 
across the Lower Mississippi Valley during the middle and latter 
portions of the week. This is a notable change from guidance a few 
days ago, which had suggested a stronger eastern CONUS trough would 
suppress the ridge farther west and allow a wetter pattern to 
develop. By Wednesday, the northern-stream shortwave will be 
progressing toward the Ohio Valley while the ridge expands eastward 
from Texas across Louisiana. Some lingering low-level moisture may 
still support an isolated afternoon shower or thunderstorm, mainly 
near the coastal areas, but increasing subsidence should quickly 
reduce convective coverage. 

The ridge becomes increasingly dominant Thursday into Friday with 
mainly dry conditions expected. However, the developing eastern U.S. 
trough and surface high pressure building southeastward behind it 
should allow a more persistent northeasterly low-level flow to 
develop across the local area. This should gradually advect somewhat 
drier air into southeast Louisiana and southern Mississippi despite 
continued ridging aloft. Temperatures will consequently remain above 
normal through mid, with highs mainly in the lower to middle 90s 
Wednesday. A gradual downward trend in temps is expected Thursday 
through Saturday as the drier northeasterly flow strengthens. Highs 
should trend toward the upper 80s to lower 90s by Friday and 
Saturday across much of the area. Overnight temperatures should also 
begin responding to the drier air late in the week, with lows 
eventually falling into the middle and upper 60s across southwest 
Mississippi and portions of the Florida Parishes, while remaining in 
the lower to middle 70s closer to the Southshore. Confidence is 
reasonably high in a predominantly dry late-week pattern. The 
primary uncertainty remains the exact strength and eastward extent 
of the upper ridge and how aggressively the eastern trough can drive 
lower dewpoints southward into the region.

MEFFER 
&&

.AVIATION...
(18Z TAFS)
Issued at 136 PM CDT Sun Sep 20 2026

VFR conditions are expected to prevail through the period with mid 
level CU field spreading across the area thru the next several 
hours. Isolated convection is possible, but probs too low to have 
any mention in TAFs. If any showers do develop, more likely 
terminals to be impacted would be KGPT, KASD, and maybe KHDC. Winds 
will be light and variable for the majority of the next 24 hours.

MEFFER 
&&

.MARINE...
Issued at 136 PM CDT Sun Sep 20 2026

Broad surface high remains close to the northern Gulf Coast, 
maintaining a weak pressure gradient and generally benign marine 
conditions. Weakening subsidence aloft has allowed for some 
convection over the open Gulf waters this afternoon but coverage is 
quite isolated. Winds will remain light and somewhat variable 
nearshore, becoming more consistently onshore during the afternoon 
with the sea breeze. Convective coverage will increase Monday as 
deeper moisture returns and upper-level subsidence further weakens. 
Any thunderstorm could briefly produce locally higher winds and 
seas, frequent lightning, and reduced visibility, but widespread 
marine hazards are not expected.

High pressure will remain close enough to the region through Tuesday 
to maintain generally light winds. A more persistent northeast to 
east flow should develop Wednesday through the latter part of the 
week as surface high pressure builds southeastward across the 
eastern United States. At this time, winds and seas are still 
expected to remain below headline criteria.

MEFFER
&&

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

$$

SHORT TERM...ME
LONG TERM....ME
AVIATION...ME
MARINE...ME