263 
FXUS64 KLIX 071916
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
116 PM CST Fri Feb 7 2025

...New AVIATION...

.SHORT TERM...
(Today through Saturday)
Issued at 346 AM CST Fri Feb 7 2025

Fog this morning will likely be more dense than it has been so far 
this week. A low level strat deck has moved in just under the bottom 
of the sub inversion at 1004mb. This layer under the inversion is 
about 400ft thick. The 1004mb sub inversion has a strong wet bulb 
drying as well. ThetaE numbers are very good. Winds are veering off 
the sfc and winds just off the sfc are transporting air from the SW 
which is high dew pt high RH air from the gulf. Since the winds at 
the sfc are basically calm, the transport is occurring above the sfc 
and has to cool via radiative processes. SST are about the same temp 
as the dew pt temp of the incoming air within this 400ft layer, 
therefore the sfc can support but not produce. But, when we look 
upward in the sounding profile we can see very well where this 
cooling is coming from. Basically, this pattern is part advective 
and part radiation. The advective part has been explained. The 
radiative part is from two levels. The first is the sub inversion at 
1004mb where the heat from the 300ft deck can escape efficiently. 
This causes the low level cloud deck to cool and lower as time moves 
forward. Earlier there was a 7kft deck that can still be seen with 
sat imagery moving over the SE portion of the area. This deck is 
responsible for the lower 300ft deck not being able to make it to 
the sfc and so vis is higher under this 7kft deck. The reason for 
this is the 7kft deck slows the radiative heat exchange from below 
to a crawl. Even though the sub inversion above the 7kft deck has
a huge wet bulb drop of 9C through a deep layer, the radiative 
heat has to pass through this upper deck first which slows this 
process to a crawl. But when this 7kft deck moves away, the 
cooling through this layer is so efficient and quick that vis 
rapidly falls to 1/4 mile or less as the lower 300ft deck hits the
sfc. This sounding profile is also a strong super fog sounding 
indicated by these two strong sub inversions with strong wet bulb 
falls. This is very typical of a build down fog regime. It acts 
like a conveyor, whereas the moisture and heat is brought in on SW
winds above the sfc beneath the lowest sub inversion. The heat is
then lost upward through the inversions, the strat deck cools and
sinks and as the droplets are accumulating on everything taking 
moisture out of the air, it is replenished by this conveyor 
process. The reason we call this a super fog process is that any 
additional particulate matter, such as smoke from fires, will add 
to the condensation process much faster producing an extreme 
amount of droplets causing vis to go rapidly to zero where these 
additional aerosols are located. This is compounded by a stalling 
front, which is also a good fog producer, over southern Arkansas 
to central Miss this morning. This front will move back north 
tonight while another front starts to move toward the area Sat. 
This front will begin to slow late Sat into Sat night. This does 
not help with the fog problem and successive nights of dense fog 
is likely through the weekend. 

&&

.LONG TERM...
(Saturday night through Thursday)
Issued at 346 AM CST Fri Feb 7 2025

There is very little upper level support for the cold front moving 
in for Sun as the H3 jet begins to parallel the sfc boundary. This 
means the front will creep into the northern most portion of the 
area and meander around at best. Basically we should just see a few 
light showers and fog around. The front will stall over the northern 
most part of the area Sun night into Monday. A digging trough will 
give some forcing to this boundary as it draws it slowly northward 
Mon night into early Tue. Another front will move in as the upper 
support begins to lift out causing this thermal boundary to move 
back over the same area and maybe even deeper into our area by Wed.
This time there could be some storms with it as the support begins 
to lift out. As the pattern becomes more progressive, this front 
will stall then get brought north and again another frontal system 
moves in to possibly clear all this mess out toward the end of next 
week. 

&&

.AVIATION...
(18Z TAFS)
Issued at 1244 PM CST Fri Feb 7 2025

Greatest concern with TAFs will be fog and low clouds again
tonight. Both are expected to quickly develop and move back inland
this evening and by midnight or shortly after most terminals will
be back in IFR or even LIFR status from either cigs or vsbys and 
likely both. Marine fog and low clouds will develop fastest among
terminals that are on the immediate coast like NEW and GPT with
impacts possibly as early as 2/3Z. Fog will quickly move into
those sites and then 1/4sm vis or lower may plague those two
locations for 10-12 hours. OVC and BKN cigs will also be around 
800-1k ft early this evening and then continue falling through the
night. MSY will quickly follow behind these two and then the rest
of the area will see conditions deteriorate. Conditions much like
this morning will be slow to improve with the most inland
terminals improving the fastest and NEW and GPT seeing impacts 
last the longest. /CAB/

&&

.MARINE...
Issued at 346 AM CST Fri Feb 7 2025

Light southerly winds will remain into the first half of next week 
and should also remain 15kt or less. Fog is expected to be an issue 
for some coastal waters mainly in the nearshore waters and 
especially the Miss River nightly. Most if not all of the Miss River 
will have dense fog through mid morning today. The dense fog 
advisory will remain for all protected and nearshore waters through 
10 am today. There is the possibility that some marine areas hold 
this fog for a large portion of the day. Marine roadways will be 
impacted as well. 

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  61  81  62  79 /   0   0   0  10 
BTR  65  84  65  83 /   0   0   0  10 
ASD  63  81  62  80 /   0  10   0  10 
MSY  64  80  63  79 /   0  10   0  10 
GPT  60  72  60  75 /  10  20  10  10 
PQL  62  78  60  79 /   0  10  10  10 

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Dense Fog Advisory until 2 PM CST this afternoon for GMZ532-534-
     536-538-555-557.

MS...None.
GM...Dense Fog Advisory until 2 PM CST this afternoon for GMZ534-536-
     538-555-557.

&&

$$

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