119
FXUS64 KLIX 010452
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
1152 PM CDT Tue Apr 30 2024

...New AVIATION...

.UPDATE...
Issued at 856 PM CDT Tue Apr 30 2024

Main question during the overnight period will be whether we see
any significant fog development. Dew points had risen into the
mid and upper 60s around sunset, but have already fallen back a
few degrees in the last 2 hours. The 00z upper air soundings here
and at Jackson indicate that dew points just above the surface
are in the mid and upper 50s. Forecast soundings aren`t quite that
dry, bringing up the question whether fog development is
overdone, especially considering forecast overnight lows.

If there`s a threat area where probabilities are somewhat higher,
it`d be along the Mississippi coast where the sea breeze did
enhance low level moisture. Not enough confidence at this point to
go with a pre-emptive Dense Fog Advisory, but will continue to
monitor.

&&

.SHORT TERM...
(This evening through Wednesday night)
Issued at 259 PM CDT Tue Apr 30 2024

A fairly strong mid to upper level ridge axis will remain in firm
control of the area through Wednesday night. Ample subsidence in
the mid-level will lead to warmer and drier conditions aloft, and
this will help keep a mid-level capping inversion and weak mid-
level lapse rates in place.  The end result will be a
proliferation of fair weather cumulus development tomorrow, but
PoP values will be at 5 percent or less through the entire short
term period. Temperatures will be warmer than average due to the
deep layer subsidence in place, and have highs climbing into the
upper 80s over inland areas and the low to mid 80s along the
coast. These values are around 5 degrees above normal. Onshore
flow in the low levels will also keep dewpoints elevated, and this
will result in overnight lows only dipping into the 60s tonight
and tomorrow night. NBM deterministic values were used for
temperatures.

&&

.LONG TERM...
(Thursday through Monday night)
Issued at 259 PM CDT Tue Apr 30 2024

A series of weak and fast moving shortwave troughs will ride up
and over the mid to upper level ridge axis from Thursday through
Monday. Most of the strongest forcing associated with these
troughs will remain displaced to the north of the CWA, but enough
cooling and forcing aloft should support the development of some
isolated to scattered convection each day. Initially, the ridge
will still be the most dominant feature over the area on Thursday,
and this will greatly limit convective potential as mid-level
lapse rates remain weak at around 5.5 C/km. The main impact
from this system will be an increase in high level cloud cover
and slightly cooler daytime highs in the mid 80s. The only area
that may see an isolated shower or storm pop up will be in areas
to northwest of Baton Rouge where just enough cooling aloft could
help weaken the cap and allow for deeper updraft development.

Friday will have the highest convective potential over the area as
another shortwave trough slides through the region. This trough
will be stronger than the one on Thursday, and will break down the
ridge axis more efficiently. The result will be a weaker mid-level
capping inversion, steeper mid-level lapse rates of around 6.0
C/km, and higher convective potential over the forecast area.
There will be a north to south gradient with the highest PoP
values for areas along and north of the I-10/12 corridor where
scattered to numerous showers and thunderstorms could develop. To
the south, more isolated convective activity is expected as the
ridge axis will be more pronounced. PWATS also increase to around
1.5 to 1.75 inches, and this will support some locally heavy
rainfall rates of 1 to 2 inches per hour with the deepest
convection. The convection will be fairly progressive in forward
motion, so any flood threat will be limited. Fortunately, wind
shear will also be very limited on Friday, so strong to severe
thunderstorm activity is not expected. The increased convective
activity and cloud cover will keep temperatures near average in
the lower 80s. The convective threat will quickly end Friday
evening as the shortwave moves to the east and the deep layer
ridge axis rebuilds back over the area.

Rain chances decrease over the weekend and into early next week as
the mid to upper level ridge axis becomes more dominant and the
ridge riding shortwave troughs shift more toward the mid-
Mississippi Valley. At most, an isolated shower or storm could
develop over the northern third of the CWA on Saturday as the
ridge continues to reassert itself, but dry conditions are
expected for Sunday and Monday. As the ridge builds in,
temperatures will rise in response to the increased subsidence
aloft, and expect to see daytime highs climb a good 10 degrees
above average into the upper 80s and possible the lower 90s by
Sunday and Monday. Persistent onshore flow in the low levels will
keep dewpoints in the 60s and lows will be warmer than average in
the upper 60s and lower 70s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1140 PM CDT Tue Apr 30 2024

Main concern for the 06z TAF package will be the threat of low
conditions around sunrise Wednesday with the potential for
radiation type fog. Potential for fog certainly exists, but the
air a few hundred feet off the surface is considerably drier than
most of the forecast soundings from the morning/afternoon model
runs would indicate, with dew points below 15C. Will carry MVFR to
IFR visibilities at most terminals, but will acknowledge that
there is at least some potential for even lower conditions around
sunrise. Expect any low conditions that do develop will improve by
15z, if not sooner. The remainder of the day will see VFR
conditions. Overnight Wednesday night will see concerns for low
conditions requiring flight restrictions again beyond 06z
Thursday.

&&

.MARINE...
Issued at 259 PM CDT Tue Apr 30 2024

No significant weather concerns are expected for the maritime
zones through the end of the week. A persistent southeast flow of
around 10 knots and seas of 1 to 3 feet can be expected through
the weekend on the southwest periphery of a surface high
dominating the Southeastern CONUS.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  60  89  64  85 /   0   0   0  10
BTR  65  89  67  86 /   0  10   0  20
ASD  65  87  66  85 /   0   0   0  10
MSY  68  85  70  84 /   0  10   0  10
GPT  66  83  68  82 /   0   0   0   0
PQL  64  84  65  83 /   0   0   0   0

&&

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

$$

SHORT TERM...PG
LONG TERM....PG
AVIATION/UPDATE...RW
MARINE...PG