311
FXUS64 KLIX 160902
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
402 AM CDT Wed Jul 16 2025

...New UPDATE...

.UPDATE...
Issued at 401 AM CDT Wed Jul 16 2025

Given the latest trends in more widespread cloud coverage from the
marine storms ongoing and the likelihood that this inhibits some
of the warming and higher heat indices we would see later today,
we have moved to cancel the Heat Advisory for coastal Mississippi
(Pearl River, Hancock, Harrison, Jackson), northshore (St.
Tammany), and southshore (Orleans, Jefferson, St. Charles,
Lafourche, Terrebonne, and Plaquemines). A heat advisory still
remains in effect for the remainder of areas to the northwest of
Lake Pontchartrain (including Baton Rouge metro) and southwest
Mississippi. However, we will have to monitor trends over the next
6 hours to determine whether further adjustments to the Heat
Advisory are necessary. TS/TE

&&

.SHORT TERM...
(Today)
Issued at 105 AM CDT Wed Jul 16 2025

Yesterday was quite warm with very little convection. That said
there were still a few storms out there but overall most of the
region remained rain free and about half of the area likely
remains rain free again today. This will lead to another warm one
but the eastern half of the area may see some cooling rain in the
afternoon and maybe as early as midday.

Today will begin very warm and humid. The ridge that is helping to
steer the flow and our Gulf disturbance remains entrenched across
the southeastern CONUS and Lower MS Valley nosing down into
southeastern TX. This is leading to very warm LL temps across the
Lower MS Valley which is sinking down into southern MS and SELA but
h925 temps are only around 26/27C. Under optimal conditions this
would lead to mid to even upper 90s easily but this ridge again
isn`t that August early September type ridge So getting much above
96 is going to be very difficult combine the fact that storms could
be moving in from the east and looking at radar last night and
satellite there was a large area of precip that has been displaced
well west of our Gulf disturbance. This surge of moisture is already
moving into the area and there is a good chance that we could see
convection begin to develop along coastal MS and coastal SELA late
morning/midday. In addition high clouds are already quickly
spreading west and could also impact temps today and that could help
keep the heat index in check some. The other issue that has been
occurring for the last week or so is the mixing. We have really been
able to mix these dewpoints down efficiently north of I-12 and north
of I-10 in coastal MS the for some reason and that has helped keep
the heat index under control in and around places like BTR and MCB.
With all of that there are some question with the heat today however
around the lakes and on the immediate MS coast where the moisture is
higher it has been more oppressive and the only thing that will help
to keep it in check will be convection...which is a concern today.
That said the heat advisory that is currently out...will not make
changes to it yet as see if convection does fire early today. /CAB/

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 105 AM CDT Wed Jul 16 2025

The extended portion of the forecast is highly focused
on the system over the northeastern Gulf. Models have begun to come
more in line with this system really hugging the northern Gulf but
remaining on the weak side from an organization standpoint. Overall
no major changes made to the forecast with the risk of very heavy
rain still possible across the region mainly Thursday through Friday
night but rain could linger around the area into the weekend.

So first...there is still some potential for heavy rain with flash
flooding possible however the confidence is not the highest given
the latest trends. That said it will not take much to get some
rather high rain totals over portions of the CWA given the amount of
moisture over the area and favorable upper lvl environment in place.
The tropical wave we are watching is still sitting at 40% of
developing into the tropical depression in the next 48 hours but it
is not looking very organized at this time. It moved inland
yesterday over the FL peninsula but almost as soon as it moved
inland it became detached with the sfc low quickly surging north
while the mid lvl low continued west. By 5z the LL center was east
of TLH and approaching southern GA while the mid lvl center was
south of Apalachicola. So the question is can a sfc low redevelop
underneath the convection and then will it just continue to barrel
west towards the LA coast or will it struggle to see much if any
consolidation with a very messy and disorganized system approaching
the coast Thursday. At this time it is beginning to feel like we may
want some consolidation as this would likely focus the heavier rain
and along and south of the eventual track which would likely be the
immediate SELa coast and the coastal water. However, if this is
messy disorganized system convection will be more diurnal in nature.
Yes that will keep us from seeing widespread rain and a complete
washout everywhere but will be more favorable to seeing scattered
storms which will be extremely efficient rain producers. PWS are
still expected to be well over 2" and models are now explicitly
showing PWS near 2.5" at times Thursday and Friday. The upper lvl
setup is still very favorable Thursday and into Thursday evening so
the concern may be trending to scatted storms tapping into that
rather extreme moisture with a nice diffluent setup aloft and weak
steering currents. The problem then becomes storms easily capable of
dropping multiple inches of rain in under an hour but that alone
isn`t necessarily a problem, the problem is just where that would
occur. There are many locations that will have no problem handling
even more than 2-3" of rain in an hour but if that falls over the
wrong locations say like any of our more urban areas that will lead
to big problems.

Now the obligatory and we hate to say but "there is still a lot of
uncertainty". Most of the time there really is and in this case
there are but trends in radar and satellite along with guidance are
suggesting that there is a good chance that the bulk of the heavy
rain will remain along and south of the coast. Small
adjustments/changes can have rather significant implications in
impacts and with our system there are a few things that could lead
to most of the area seeing relatively light impacts. The biggest
determining factor in this case is track and there are more than a
few solutions suggesting that it will struggle to really develop and
remain just a little too far south with most of the rain hanging
south especially since there is a good chance that a bulk of the
rain will remain on the southern side of this system.

At this time we will continue to advertise widespread 2 to 4 inches
of rain with isolated amount of 6 to 8 possible. However if trends
continue these values may trend down some more or at the least the
area may be a little more confined to coastal LA. The one caveat is
if this just remains a disorganized mess where convection become
highly diurnal in nature and that would then lead to scattered
storms across the entire CWA leading to isolated pockets of very
heavy rain. /CAB/

&&

.AVIATION...
(00Z TAFS)
Issued at 645 PM CDT Tue Jul 15 2025

VFR conditions will persist through the night and first half of
the day tomorrow however by afternoon we will likely begin to see
convection develop or move in from the east. Locations with the
greatest risk of seeing convection tomorrow afternoon are along
coastal MS and south of Lake Pontchartrain. /CAB/

&&

.MARINE...
Issued at 105 AM CDT Wed Jul 16 2025

Benign conditions will continue today but convection is already
quickly moving in from the east. We will begin to see impacts
increase later today and through the rest of the week as a
disturbance from the northeaster Gulf moves into the area
tomorrow. Winds and seas will increase over local waters,
Thursday through the weekend. /CAB/

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  95  74  90  73 /  30  40  90  30
BTR  95  77  90  75 /  30  40  90  50
ASD  95  74  87  74 /  40  70  90  60
MSY  95  79  88  78 /  40  70 100  60
GPT  95  75  88  77 /  70  60  90  70
PQL  94  74  88  76 /  80  60  90  60

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory from 10 AM this morning to 7 PM CDT this evening
     for LAZ034>037-039-046>048-057-058-071-081>086.

     Flood Watch from 1 PM CDT this afternoon through late Friday
     night for LAZ034>037-039-046>048-056>060-064>071-076>090.

GM...None.
MS...Heat Advisory from 10 AM this morning to 7 PM CDT this evening
     for MSZ068>071.

     Flood Watch from 1 PM CDT this afternoon through late Friday
     night for MSZ077-083>088.

GM...None.
&&

$$

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