-- Discussion containing changed information from previous version are highlighted. --
748
FXUS64 KLIX 231739
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1239 PM CDT Mon Sep 23 2024

...New AVIATION...

.SHORT TERM...
(Today through Tuesday Night)
Issued at 203 AM CDT Mon Sep 23 2024

Another rather hot day is forecast for today as a H5 ridge roughly
around 592dam resides over the northern Gulf. The higher
thicknesses/heights will allow the region to remain above average
in terms of temperatures and as for any rain chances...slim to
none with plenty of subsidence helping keep things on the dry
side. The ridge will begin to spread east later this afternoon and
especially overnight tonight and an upper level shortwave begins
to weaken the western periphery of the ridge. At the surface, a
weak frontal boundary will begin to move southward through the
Ozarks and into the Mid MS River Valley. This feature looks to
bring at least an uptick in POPs late on Tuesday and there also
could be some morning fog Tuesday morning...especially in the more
fog favored locations as moisture begins to pool out ahead of the
slowly advancing front. Models have been struggling a bit with
fog potential over the last day or so and at this juncture it may
be worth mentioning once probs increase a bit more in subsequent
packages. Otherwise, patchy fog seems appropriate this morning
again in those favored lower spots. (Frye)

&&

.LONG TERM...
(Wednesday through Sunday)
Issued at 203 AM CDT Mon Sep 23 2024

Things begin to become a bit more interesting going out into
midweek. First, the synoptic pattern is interesting as the
aforementioned shortwave/weakness takes shape across the northwest
and north Gulf. Within the flow a mid/upper level low begins to
pinch off over the Cornbelt region and drops southward over the
mid MS River Valley. This is important because Invest 97L is
forecast to deepen and move generally northward out of the
western Caribbean and into the southern Gulf of Mexico. Where the
feature goes will really depend on two things. First
timing...both of the upper level low as well as what is forecast
to likely become a tropical cyclone. As well as exact placement of
the upper level low. Any slight adjustment could cause the
forecast to change. Models have come into agreement in terms of
timing with respective ensemble spreads also starting to hone in
on a faster solution with a landfall point somewhere along the
Florida Panhandle Thursday or Thursday night. Again, stressing
here that any slight change in strength of the synoptic features
could cause some changes in the actual path.

So, in terms of the local area, keeping in mind a TC isn`t just a
point on the map and impacts may extend well away from the
center...our local impacts seem to be rather limited since we will
be on the dry side of the TC. In fact, QPF values have mostly
been dropping off with a tight gradient of anticipated rainfall
amounts setting up on the western periphery. Frictional divergence
as well as subsidence aloft could also point to a much drier
forecast, but there again remains uncertainty in the rainfall
amounts depending on the exact track. That said, the globals have
shown a fairly "large" system with a larger wind field. This could
lead to at least higher gradient winds offshore (see marine
section).

As the system moves inland over the southeast US, the TC starts
mingling with the upper level feature and eventually rotates north
and west with the flow around the ULL as the tropical
characteristics decay. The low and the much cooler upper levels
could signal for some convection later this weekend and into the
weekend. Albeit lower end POPs/QPF signal for now with mostly dry
air (dry slot?) over our region...a few hailstones would certainly
be possible in this environment, especially across far southwest
MS in the more robust updrafts. As for temperatures, with the
upper level heights crashing for much of the long term, MaxTs will
be a bit cooler and instead of the lower 90s we will likely
experience lower and middle 80s throughout much of the period with
temperatures being just a skosh warmer by next weekend. (Frye)

&&

.AVIATION...
(18Z TAFS)
Issued at 1236 PM CDT Mon Sep 23 2024

The primary forecast concern is the potential for IFR visibility
and ceiling restrictions at MCB between 11z and 13z tomorrow
morning. This period of IFR conditions will be tied into the
strength of an expected surface based temperature inversion that
forms as temperatures cool. Probabilities are high enough to
warrant including these IFR conditions, and have gone with 300
foot ceilings and 1 mile visibility from 11z to 13z. Outside of
this threat at MCB, VFR conditions are forecast at all of the
remaining terminals through the end of the forecast period. PG

&&

.AVIATION...
(12Z TAFS)
Issued at 638 AM CDT Mon Sep 23 2024

Mostly VFR conditions anticipated through the period. Winds will
remain generally out of the ESE and less than 10 kts. Otherwise,
some patchy fog may be possible for HUM and MCB terminals Tuesday
morning. (Frye)

&&

.MARINE...
Issued at 203 AM CDT Mon Sep 23 2024

Mostly benign marine conditions expected early this week as the
low level flow remains quite light across the local waters. This
quiet period will quickly end going into late Tuesday and
especially through mid to late week as AL97 is likely to continue
to move into the southern and eventually central or eastern Gulf
of Mexico as a formidable tropical cyclone. Pressure gradient
over the local waters will tighten as the system move northward
toward the Southeast U.S. The increase in winds and seas will
likely lead to hazardous marine conditions, especially over the
local gulf waters. Conditions will be slow to improve through
Friday, but eventually as the TC moves inland conditions will
begin to settle. (Frye)

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
MCB  68  89  68  85 /   0  10  30  60
BTR  74  94  73  91 /   0  10  20  50
ASD  71  90  72  89 /   0  10  10  60
MSY  74  90  75  88 /   0   0  10  50
GPT  72  88  72  87 /   0   0  10  70
PQL  71  92  73  90 /   0  10  20  70
-- End Changed Discussion --

&&

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

$$

SHORT TERM...RDF
LONG TERM....RDF
AVIATION...PG
MARINE...RDF