Bay St. Louis, Mississippi 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

178
FXUS64 KLIX 050349
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
949 PM CST Thu Dec 4 2025

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

.KEY MESSAGES...
Updated at 939 PM CST Thu Dec 4 2025

1. A widespread area of 2-4" of rainfall has been measured over the
past 24 hours along the I-10/12 corridor. A slightly higher swath of
5-6" of rainfall exists along a line from Morganza, LA east through
Amite, LA and to Saucier, MS. Coastal Louisiana and Southwest MS
received lower totals of 0.5" to 2.5" during this period.

2. The slow-moving frontal boundary associated with the coastal low
is progressing southeastward and will clear land areas through the
morning hours. Drier air filtering in will lower rainfall rates and
reduce the risk for excessive rainfall and flash flooding on Friday.
Additional rainfall of up to 3" could occur mainly along and east of
the I-55 corridor, near the coast. However, most areas are likely
(>60%) to see between 0.5" and 1.5" of additional rainfall with
scattered shower activity Friday through Saturday.

3. Another shot of colder air will come from a stronger cold front
late on Sunday. Colder air from this front won`t arrive until Monday
so the coldest night of the forecast period will see temperatures
near freezing in southwest MS and adjacent parishes on Tuesday
morning.

&&

.SHORT TERM...
(Tonight through Saturday night)
Issued at 939 PM CST Thu Dec 4 2025

Southeasterly surface winds are beginning to flip northerly across
the I-10/12 corridor indicating the passaging of a weak frontal
boundary in association with the coastal trough of low pressure
scooting east along the northern Gulf coast. Shower activity is
finally tapering off as this frontal boundary pushes southeast. Weak
shower and misty, low-stratus conditions will continue through the
overnight hours, but a lull in rainfall is expected through the most
of the morning. Drier air aloft will gradually filter in behind this
front causing PWATs to drop from daily max levels down closer to the
75-90th percentile. This will reduce the efficiency of rainfall
rates and consequently reduce the risk of flash flooding over the
area on Friday and Saturday.

PWATs will remain elevated (~1.5") near the coast as the frontal
boundary stalls out and southwest flow aloft persists into the
weekend. Another weak shortwave within the longwave flow will help
to kick up more convective activity later on Friday morning and into
with the heaviest rainfall likely to occur near the coast. An
additional round is likely to develop beyond this wave as we head
into Saturday which will likely be the final round before the
shortwave finally pushes through. Additional rainfall will be
lighter especially farther inland, but NBM guidance points to some
areas receiving upwards of 1.5 to 2" of additional rainfall along
and east of the I-55 corridor, closer to the coast where PWATs are
higher through Saturday. However, rainfall rates should remain
limited enough to mitigate the flash flood risk.

&&

.LONG TERM...
(Sunday through Thursday night)
Issued at 939 PM CST Thu Dec 4 2025

The longwave trough situated over the central CONUS will gradually
propagate east and lift out allowing for southwest flow aloft to
become northwesterly and pushing a stronger frontal boundary and a
colder air mass through the area on Sunday and into Monday. This
will not only notably dry things out areawide, but also bring near
freezing temperatures to southwest MS and adjacent Louisiana
parishes. Surface high pressure will dominate early next week, but
it may not last long before another shortwave dives out of the
northern Great Plains, following the northwest flow aloft. Global
model guidance remains in some disagreement pertaining to the
timing and depth of this shortwave trough which will determine
whether a substantive frontal boundary increases PoPs and breaks
down surface high pressure by later in the week.

&&

.AVIATION...
(06Z TAFS)
Issued at 939 PM CST Thu Dec 4 2025

SHRA has gradually tapered off from west to east, but IFR CIGs
will linger through the overnight hours. Winds have switched to
northerly at all terminals in response to a frontal boundary
passage which is progressing offshore tonight. Another round of
-SHRA begins midday Friday and will spread from southwest to
 northeast across the area. Some areas closer to the coast could
 see some TSRA conditions, but this should remain south of all
 terminals. Onset appears to be closer to 1800 UTC and will
 persist into the overnight hours on Friday night. Have introduced
 these SHRA lines to the end of the forecast cycle to depict
 latest forecast timing at respective terminals.

&&

.MARINE...
Issued at 939 PM CST Thu Dec 4 2025

Winds will relax and return to offshore late Friday post-frontal
passage and then more variable on Saturday with the passage of
another weak sfc low. A stronger frontal passage on Sunday night
will bring another push of strong offshore winds on Monday which
could prompt small craft headlines for much of the coastal waters.

With the wind direction being primarily out of the east, minor
coastal flooding is expected mainly for St. Bernard, eastern
Orleans, southeastern St. Tammany parishes, as well as coastal
Hancock and Harrison counties on Friday morning. Subsequent
forecasted tide cycles appear elevated but will be lower than
Friday so no additional headlines appear to be warranted for this
weekend at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  50  41  48  42 / 100  70  50  30
BTR  54  42  50  45 / 100  60  40  40
ASD  57  44  55  44 /  90  80  50  60
MSY  61  50  56  50 /  90  70  50  60
GPT  57  46  56  47 /  90  90  50  60
PQL  58  44  57  45 /  90  90  50  60

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Coastal Flood Advisory until 6 AM CST Friday for LAZ070-076-078.

GM...None.
MS...Coastal Flood Advisory until 6 AM CST Friday for MSZ086-087.

GM...None.
&&

$$

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