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FXUS64 KLIX 192321 AAA
AFDLIX

Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
621 PM CDT Tue May 19 2026

...NEW AVIATION...

.KEY MESSAGES...
Updated at 617 PM CDT Tue May 19 2026

- Low confidence high impact forecast tonight with the possibility
  of flash flooding across northwestern portions of the CWA. This
  includes the cities of Baton Rouge and McComb.

- Showers and thunderstorms will become more numerous and
  widespread Wednesday through the weekend. 7 day rainfall totals
  will range from 4 to 7 inches in the northwest to less than an
  inch of much of coastal MS and extreme SELA.

- Minor coastal flooding may slightly impact typically known
  problem areas like Waveland, MS today and Wednesday around
  midday.

&&

.SHORT TERM...
(Now through Wednesday)
Issued at 256 PM CDT Tue May 19 2026

The short term forecast is going to focus on the remainder of
this afternoon, evening and then look at tomorrow but probably a
little more focus on the next 6-12 hours than normally with the
regular package. Some of the CAMs for the past 24 to even 30 hours
have consistently focused on the northwestern quadrant of our CWA
developing convection during the late afternoon through the
evening hours. This is remarkable consistency given that they have
been very inconsistent with any MCS or remnants of an MCS moving
into the area overnight tonight.

The convection of concern would begin to develop around 21/22z and
is well ahead of any MCS. The big question is why would this develop
and develop over the areas mainly near and northwest of a line from
Baton Rouge to McComb. A few things look like they could be coming
together. First models are suggesting that even though the LL winds
don`t necessarily increase but there will be a decent increase in
the LL confluence across the northwest starting around 22z and
persisting through the evening or until an MCS or remnant boundary
of an MCS moves through overnight. There is already a mid lvl
impulse pushing into the Lower MS Valley and it is already adding to
the lift giving us isolated to widely scattered showers across the
western half of the CWA. There is also a remnant boundary from an
MCV that was over southeast TX earlier today moving towards the
Atchafalaya and that could help to spark some development across the
northwest in the next few hours. Last we will see an increase in the
diffluence aloft at the same time we are seeing that increase in
the LL confluence. In almost a classic split flow type setup, the
northwestern portions of the CWA will be directly under an enhanced
V which will provide very efficient diffluence aloft.

Looking at the current conditions there is abundant moisture in
place. PWs are ranging from 1.7 to just under 1.9" based off of
GOES19 TPW product. LL moisture has also been increasing for the
past 24 to 36 hours and dewpoints are in the lower to mid 70s.
Instability is also not in short supply with ML CAPE of 2500 and sfc
based CAPE between 3-3500 j/kg however the Mid lvl lapse rates are
likely around 5.5-6 C/km which this makes sense given the moisture
laden airmass we have. This also would tend to take hail off the
board from a standpoint of severe aspects. I won` t say tornadoes
are not possible but they aren`t the top concern given the lack of
shear. 0-1 and 0-3 km helicity is absent basically and 0-6km bulk
shear is generally around 20-30kt. This suggest more multicellular
setup and not really organized severe weather. That said with the
amount of moisture and instability in place there will be a risk
possibly a wet microburst or two with any thunderstorm that can
become a little more potent. So at this time severe can not be ruled
out but it is not the biggest concern, that may actually be flash
flooding but it will be highly dependent on where the storms fire
and of course if we actually get deeper convection to persist for
the 4 to 8 hours that some of the CAMs are advertising.

At this time confidence is still in the medium range mainly do to
convection developing, how long it persists, and especially
location. That said confidence is high that any thunderstorms that
develop late this afternoon and through the evening will be
extremely efficient due to weak steering currents, abundant moisture
and instability, and enhanced diffluence aloft. The REFS PMM shows
widespread totals greater than 4 inches across much of the northwest
with multiple locations possibly seeing greater than 7 inches and
that is before 12z tomorrow. The majority of this risk looks to be
from 22z till 4z today/tonight but storms could persist longer and
there is still a great deal of uncertainty with respect to any MCS
developing and trying to move towards the area overnight. Biggest
concern is if storms get anchored in and around the BTR metro
(includes Denham Springs, Walker, Baker, portions of West Baton
Rouge) or some of the flashier parts of southwest MS where there is
some elevation changes and could lead to some very problematic flash
flooding.

As for overnight and tomorrow this is more of a question mark. It
looks like a disturbance coming out of Mexico may be what helps get
another MCS to develop over southeast TX this evening and that will
try to work east. This lift may also try to help redevelop a
decaying MCS moving south and SSE out of northeast TX and southwest
AR. There is a lot of uncertainty with how all that develops and
move into the region. If it strengthens and develops a strong cold
pool it would surge SSE towards the instability and likely moves
into or skirts the western fringes of the CWA and into the Gulf
early tomorrow...probably before sunrise. However there will be some
remnant boundary stretching back to the north from it across the CWA
which may be the focus of development tomorrow. The biggest question
is how much cloud cover do we have over the area and will it allow
us to destabilize enough to get convection to develop early enough
or does it hold off and we wait for the next subtle impulse to come
across the area in the southwest flow aloft tomorrow
afternoon/evening. /CAB/

&&

.LONG TERM...
(Wednesday night through Monday night)
Issued at 256 PM CDT Tue May 19 2026

Focus is really on the short term especially given the next 4 to
8 hours and uncertainty overnight. That said models have not
changed and the pattern we will be in just screams active weather
for the next week. Obviously rain won`t be occurring the entire
time as there will be breaks and possibly even one or two days
with limited rainfall as timing any of these impulses is difficult
to futile this far out and depending how long one rain event
lasts it could work us over pretty well leading to the area
needing some time to recover. No deviations made from the latest
NBM.

As we have been mentioning for the last few days, we will remain
under persistent southwest flow aloft with abundant moisture in
place. This is going to leave us in a rather favorable regime for
multiple rounds of storms and locally heavy rain. Biggest difference
the previous rain event we have had and is a positive difference is
there is no real well defined front laying up over the area to act
as a sfc/LL focus. That said with the ridge still holding strong
over the eastern Gulf and into the southeastern CONUS and southwest
flow aloft we still look like there could be quite the dichotomy
across the region with the northwest seeing multiple inches of rain,
3-6 inches after tonight and tomorrows possible rain and maybe
struggling to even get an inch of rain over portions of coastal MS
and extreme southeast LA. Temperatures will be slightly above normal
mainly due to above normal lows as we remain very humid throughout
the forecast. /CAB/

&&

.AVIATION...
(00Z TAFS)
Issued at 621 PM CDT Tue May 19 2026

VFR/MVFR conditions through the cycle with a couple of
opportunities for convective development. First will be overnight
for the western half of the area as a decaying line of storms
moves closer to those terminals. Additional convective
development will be possible Wednesday afternoon and evening. If
convection moves over a terminal there will be a bit more erratic
winds as well as IFR or perhaps lower in the heaviest rainfall.
Otherwise, winds will remain light to moderate from the south.
(Frye)

&&

.MARINE...
Issued at 256 PM CDT Tue May 19 2026

A large area of high pressure will remain situated over the
western Atlantic through the week and into the weekend. This will
maintain light to moderate onshore flow through the time. Winds will
bounce around headline criteria with sustained winds right around to
slightly below 15 kts, especially closer to the coast and west of
the MS River. As for showers and thunderstorms, daily isolated to
scattered showers will be possible each day however the bulk of the
coverage will remain inland. With any thunderstorms locally
hazardous winds and waves can be expected.

Any minor coastal flooding that occurred today should quickly
abate and expecting tides to be a little lower each day through
the remainder of the week and into the weekend. /CAB/

&&

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

$$

SHORT TERM...CAB
LONG TERM....CAB
AVIATION...RDF
MARINE...CAB