323
FXUS64 KLIX 102356
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
656 PM CDT Thu Sep 10 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 647 PM CDT Thu Sep 10 2026

- Deep tropical moisture moving into the area is causing localized
  heavy rainfall and flooding across urban parts of the I-10/12
  corridor.

- This elevated risk for localized heavy rainfall leading to
  street flooding and overflowing of poor drainage will continue
  on Friday and into Saturday.

&&

.SHORT TERM...
(Now through Sunday night)
Issued at 109 PM CDT Thu Sep 10 2026

Deep tropical moisture has pushed back into the local area as
indicated by the LIX 1200 UTC sounding which had a 2.42" PWAT value,
near the daily maximum for September 10th. This is in association
with a weak area of low pressure situated south of Port Fourchon
that is slowly encroaching on coastal Louisiana. The enhanced low-
level convergence in association with this feature and deep tropical
moisture is aiding in the development of small bands of showers and
storms that are producing highly efficient rainfall rates (2-3" per
hour) and frequent lightning. In addition, these bands are anchoring
and training over the same areas which is only exacerbating the
locally heavy rainfall threat.

Localized areas of the New Orleans metro, coastal MS, and Hammond
area have received upwards of 3 to 6 inches of rain over the least 6
hours per radar estimates and a few unofficial gauge locations. This
illustrates just how efficient and real the threat for locally heavy
rainfall that can cause street flooding and overflowing of poor
drainage areas.

As this weak area of low pressure rounds the surface high centered
over the Carolinas, it will gradually lift northward into southeast
Louisiana tonight and into Friday. This will keep the risk for
locally heavy rainfall elevated as PWATs remain in excess of 2.3
inches. This will mean the excessive rainfall risk will follow this
low inland. The latest CAM guidance seemed to be less enthused about
coverage of showers and storms on Friday compared to today, but the
environment will still be in place to support locally heavy rainfall
if any storm sits in one place too long. The main caveat and
reasoning for less coverage would be to do with the surface trough
and associated surface convergence weakening though simultaneously
there will be height falls associated with a weak shortwave trough
dipping into the lower Mississippi River valley that would aid
updraft growth so there`s some uncertainty here regarding which
factors will prevail with storm coverage.

As we move into Saturday, this mid-upper shortwave trough will slow
and gradually weaken over the area. This will cause heights to
slowly rise. Even though PWATs will still remain elevated (>2"), the
confidence in afternoon shower and storm coverage has decreased
somewhat compared to what is advertised as "Definite" by NBM
guidance. As such, PoPs have been lowered 5-15% in most places, but
still advertise 60-75% across much of the area which could be
generous still.

&&

.LONG TERM...
(Monday through Wednesday night)
Issued at 109 PM CDT Thu Sep 10 2026

Ridging over the southeast CONUS will gradually expand and intensify
as the weak shortwave trough lifts out on Sunday. Healthy afternoon
rain chances will linger though they will gradually lower into early
next week as rising heights and strengthening ridging put a
stronger cap in place and limit afternoon pop up shower and storm
activity. This will also mean high temperatures will creep back
toward the mid 90s as we kick off the new work week and heat
indices could get closer to 108 degrees in a few places,
especially over southeast Louisiana.

The resurgence in hotter conditions in mid September doesn`t appear
to be long-lived as the ridge retrogrades back toward the west and
east coast troughing erodes the eastern periphery of the ridge. This
would invite the potential for backdoor or decaying fronts by late
next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 647 PM CDT Thu Sep 10 2026

Only one TSRA remaining on radar, about halfway between KMCB and
KHDC, and would expect that one to dissipate in the next hour or
so. Have seen some clouds reported that could cause MVFR ceilings
overnight. Questionable whether we would be able to get any fog to
develop overnight, unless we lose quite a bit of the cirrus
overcast across the area.

With the weak low pressure in the area, would expect that we`ll
get convective development over the Gulf later tonight (08z-ish),
which will move near the coastal terminals around sunrise. Will
carry PROB30 for SHRA for this at several terminals, with a threat
for TSRA by about mid-morning.

&&

.MARINE...
Issued at 109 PM CDT Thu Sep 10 2026

Though no reports of waterspouts have been received, the surface
vorticity associated with a weak surface low near Port Fourchon
and high 0-3km CAPE (>150 j/kg) has been create highly favorable
environment for waterspout development off the southeast
Louisiana coast.

A weak area of low pressure will move through the waters today with
light and variable winds of 10 knots or less are expected. As the
low shifts to the west on Friday, winds will turn more south-
southwesterly at 10 to 15 knots. These conditions will persist into
Saturday. High pressure centered over the eastern Gulf and
southeastern United States will become more dominant as we move into
next week, and this will cause winds to turn more south-
southeasterly at 5 to 10 knots from Sunday onward.  Seas will
generally remain in the 1 to 3 feet range with the highest seas well
offshore.  Additionally, thunderstorm activity will develop each
day, peaking in the early to mid-morning hours, and these storms
will produce higher wind gusts, waterspouts, and lightning
concerns.

&&

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

$$

SHORT TERM...TJS
LONG TERM....TJS
AVIATION...RW
MARINE...TJS