721
FXUS64 KLIX 151810
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
110 PM CDT Tue Jul 15 2025

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

.SHORT TERM...
(This afternoon through Wednesday)
Issued at 1144 AM CDT Tue Jul 15 2025

Tonight through Wednesday afternoon, conditions will be fairly dry
overall. Showers and storms will be fairly isolated until the late
afternoon and evening hours, most likely. Moisture and humidities
will be increased thanks to the approaching Gulf moisture. As a
result, temperatures will be quite warm with highs in the mid 90s
and heat index values across the area around 105-110 degrees. A
heat advisory is in effect from 10AM through 7PM tomorrow to
account for the heat risk. There is some uncertainty on when the
storms will begin, which could influence the heating. If the
storms fire up earlier, it could tamp down on the heat index
values a little earlier. We still think that heat index values
will be high enough early to warrant heat advisory conditions, but
we just may need to cancel the advisory earlier if storm coverage
becomes widespread. MSW

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 1144 AM CDT Tue Jul 15 2025

Wednesday evening through the weekend, rain chances will be
enhanced thanks to the increase in Gulf moisture from the
disturbance moving west across the northern Gulf. NHC has a 40%
chance of development for this system in the next 7 days.
Regardless of development, heavy rainfall and flash flooding will
be the main threat with this system. Generally, the environment is
quite conducive for flash flooding with long skinny CAPE,
abundant moisture throughout the atmospheric column and fuel
source, high PWs around 2.2 inches or greater, low shear, etc.
Additionally, some of the models are hinting at parallel flow in
the vertical column, which could be a big concern for training.
These storms will have the potential for Looking at recent model
guidance, we are forecasting widespread 3 to 6 inches of rainfall
with locally higher amount up to 10 inches possible. This rainfall
will also be highly efficient with rainfall rates in excess of 2
to 4 inches per hour likely.

Numerous rounds of rainfall will begin off and on Wednesday night
through Saturday with the bulk of the rainfall occurring Thursday
and Friday. Right now, there is still a lot of model uncertainty
as it pertains to the location of the highest rainfall threat and
totals. While this has been fluctuating somewhat, WPC has outlined
our westernmost areas on Friday as being in a Moderate Risk
(level 3 out of 4) for flash flooding, including the Baton Rouge
metro and the Atchafalaya Basin. Given some of the lingering
uncertainties, would not be surprised to see this adjusted or
expanded in the next 1-2 days. A Flood Watch has been issued to
account for this risk of flash flooding. It starts at 18z
Wednesday and runs through 00z Saturday for now to highlight the
days with the greatest threat, but it could be extended in time
further as we get closer to the weekend. It is worth noting that
any changes to the track of the disturbance west or east could
have a major influence on the locations with the heaviest
rainfall.

In terms of the impacts, they could be quite significant,
especially Friday, depending on the track of the system. While
widespread minor to moderate street flooding, impassable roads,
etc. will possible, it is not outside the realm of possibility
that we could see more significant localized flooding, especially
in urban/vulnerable areas like Baton Rouge, the MS Coast, or even
New Orleans. It will highly depend on how the system develops and
moves over the next 1-2 days. We especially want to emphasize the
worst case scenario (i.e. the highest potential) that we could
see from this event. While we have low confidence in the location
of the greatest flash flooding impacts, we have medium to high
confidence that someone will see those locally higher totals up to
10 inches and significant flooding in our area. The key, as
always in Southeast Louisiana and Coastal Mississippi, is where it
falls and how quickly. If the higher rainfall totals fall in the
Atchafalaya Basin or west, the impacts will be much less
concerning. If the higher rainfall totals fall in any urban areas
(Baton Rouge, New Orleans, MS Coast) or train multiple times over
rural areas, this could cause significant concerns.

Another point we wanted to mention was that a lot of the models
have been showing a dry overnight bias that seems unrealistic.
There will still be medium to high (60-80%) chances of heavy
rainfall and flooding overnight, similar to the daytime hours. As
a result, extra caution should be used if you will be planning to
drive at night, since depth of water and any flooding will be
impossible to see at night.

This event could be a quite significant rain producer for our area
and with so much uncertainty in the location of the heaviest
rainfall, it is important to prepare now, while there is still
time. Clean out those ditches and catchbasins and make a plan now
ahead of time for the potential for flash flooding. MSW

&&

.AVIATION...
(18Z TAFS)
Issued at 1144 AM CDT Tue Jul 15 2025

VFR conditions prevail at all area airports and will persist
through the forecast period. Afternoon and evening showers and
storms are possible, so TEMPO groups are in effect to reflect
these conditions briefly dropping to MVFR as a result. MSW

&&

.MARINE...
Issued at 1144 AM CDT Tue Jul 15 2025

Benign conditions will continue through the next few days as high
pressure remains overhead or at least nearby. Winds generally onshore
at 10 knots or less with seas under 2 feet. The only exception would
be brief gale force wind gusts from isolated storms. A broad area of
low pressure moving into the northeastern Gulf later this week will
increase winds/seas over local waters, especially Thursday through
the weekend. MSW

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  73  96  73  90 /  10  30  40  90
BTR  76  95  76  90 /  10  40  40  90
ASD  75  95  73  88 /  10  60  70 100
MSY  80  94  78  89 /  10  60  70 100
GPT  77  96  75  88 /  10  70  70 100
PQL  76  95  74  89 /  20  70  70  90

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory until 7 PM CDT this evening for LAZ034>037-039-
     046>048-056>060-064-065-070-071-076>090.

     Heat Advisory from 10 AM to 7 PM CDT Wednesday for LAZ034>037-
     039-046>048-056>060-064-065-070-071-076>090.

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

GM...None.
MS...Heat Advisory until 7 PM CDT this evening for MSZ068>071-077-
     083>088.

     Heat Advisory from 10 AM to 7 PM CDT Wednesday for MSZ068>071-
     077-083>088.

     Flood Watch from Wednesday afternoon through late Friday night
     for MSZ077-083>088.

GM...None.
&&

$$

SHORT TERM...MSW
LONG TERM....MSW
AVIATION...MSW
MARINE...MSW