492
FXUS64 KLIX 222004
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
304 PM CDT Thu May 22 2025

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

.SHORT TERM...
(This evening through Friday night)
Issued at 300 PM CDT Thu May 22 2025

Troughing from the Great Lakes to Florida this afternoon with
ridging over the Rockies. At the surface, the axis of high
pressure extended from the Dakotas to Alabama. An old frontal
boundary was off the Louisiana coastline, with a reinforcing front
near Interstate 20. Isolated thunderstorms were noted on radar
southeast of Houma and Thibodaux at early afternoon. Temperatures
in the area were in the middle and upper 80s, but dew points
ranged from the middle 50s across northeastern sections of the
area to the lower and middle 70s south of Lake Pontchartrain.

Expect the isolated convection over the coastal parishes to
dissipate this evening. With the axis of the surface high off to
the east of the area, winds should generally have a southerly
component over the next 36 hours. Dew points should gradually
rebound to around 70 or higher, even over northern sections of the
area. This will bring warmer overnight lows across northern
sections of the area as compared to this morning.

With the onshore wind flow, precipitable water values will
gradually increase to near 1.5 inches by tomorrow afternoon. This
may allow isolated convection to develop during the heat of the
afternoon, but most of the area is likely to remain dry. High
temperatures tomorrow are likely to be a couple degrees warmer
than today...upper 80s to lower 90s. Similarly, overnight lows
tomorrow night will be a couple degrees warmer than tonight in
most areas.

&&

.LONG TERM...
(Saturday through Wednesday night)
Issued at 300 PM CDT Thu May 22 2025

As the frontal boundary to the north creeps southward over the
weekend, and mid level flow becomes southwesterly, conditions
will gradually become more favorable for increased areal coverage
of showers and storms. The operational GFS solution is slower to
do this than the ECMWF. The ECMWF indicates this could happen as
early as Saturday afternoon, but more definitively Sunday,
continuing through midweek and beyond. The greatest potential for
showers and storms looks to be during the afternoon hours Tuesday
and Wednesday. The GFS operational solution is much less
aggressive, holding rain chances in the 20-30 percent range during
much of that period. The NBM solution is much more representative
of the ECMWF operational numbers. Did not deviate from the NBM
PoPs from Sunday onward, but if it appears that the GFS becomes
more representative of expectations, those numbers would need
lowered in later forecasts. With precipitable water values
expected to be in the 1.6 to 1.8 range during the first half of
next week, there will be potential for heavy rainfall. However, by
that point, it will have been two weeks or more since most areas
will have seen significant rainfall, lowering any flash flooding
threat, at least initially.

High temperatures will be impacted by how much convection develops
during the afternoon hours. Where convection develops, high
temperatures will top out in the mid 80s. Where convection is more
limited, highs will be around 90, give or take a couple degrees.
With the PoP forecast being somewhat more driven by the ECMWF
scenario, the NBM high temperature numbers also resemble the ECMWF
high temperature guidance.

&&

.AVIATION...
(18Z TAFS)
Issued at 1226 PM CDT Thu May 22 2025

VFR at all terminals with the exception of KHUM, where MVFR
ceilings are in place. Frontal boundary that moved through the
area yesterday, may have already dissipated, as dew points have
already increased to around 70 to the south of Interstate 10, and
winds become east to southeast. Convection to the south of
Terrebonne Parish (south of KHUM) has shown no inclination to work
northward. Any warming at all this afternoon should lift cloud
bases at KHUM above FL030. Primarily VFR overnight, but some
threat of light fog at KMCB. Will mention MVFR visibilities there,
but guidance has been too aggressive on very low conditions there
recently. With higher dew points in place tomorrow, likely to be a
brief period of MVFR ceilings as cumulus field develops, but not
confident for any length of time prior to 18z.

&&

.MARINE...
Issued at 300 PM CDT Thu May 22 2025

Main concern for marine operations through the 5 day forecast
period will be the threat of thunderstorms producing localized
higher winds and season. Aside from thunderstorm development,
winds should generally remain less than 15 knots and seas in the 1
to 3 foot range.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  68  90  70  90 /   0  10   0  20
BTR  70  91  73  92 /  10  20   0  20
ASD  69  90  72  90 /   0  10   0  20
MSY  74  89  75  90 /  10  10   0  20
GPT  70  88  73  87 /   0   0   0  10
PQL  66  91  71  89 /   0   0   0  10

&&

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

$$

SHORT TERM...RW
LONG TERM....RW
AVIATION...RW
MARINE...RW