LIX issues Area Forecast Discussion (AFD) at Dec 17, 11:58 AM CST ...New AVIATION...240
FXUS64 KLIX 171758
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
1158 AM CST Tue Dec 17 2024
...New AVIATION...
.SHORT TERM...
(Today through Thursday Night)
Issued at 430 AM CST Tue Dec 17 2024
Deep layer onshore flow on the southwest periphery of a vertically
stacked high pressure system will continue to usher in an
unseasonably warm and humid airmass across the Gulf South through
tomorrow morning. Temperatures will be a good 15 to 20 degrees
above normal today and tonight, and dewpoints in the mid to upper
60s will once again support the development of advection fog. The
advection fog this morning has been more limited due to stronger
boundary layer winds of around 15 knots, but a weakening of the
overall gradient flow to between 5 and 10 knots is expected to
occur late tonight into early tomorrow morning in advance of an
approaching upper level trough and frontal boundary. This lighter
flow will be more favorable for advection fog to remain surface
based instead of lifting into a low stratus deck, and expect to
see fog penetrate much further inland and be more consistent than
observed this morning.
The fog will linger through the mid-morning hours tomorrow, but
rapid clearing will take place from the northwest to the southeast
as a strong frontal boundary slides through the region. A few
showers will also be possible mainly across the northern half of
the CWA as the front moves through, but the most favorable
dynamic support will be displaced well to the northeast of the
forecast area. Temperatures will remain mild in advance of the
front and readings will once again warm into the 70s. However, a
cool down is expected to begin as early as the mid-afternoon hours
as winds shift to the northwest and a thermal trough axis begins
to advect into the area. Wednesday night will see the cold pool
continue to move into the area and readings will fall into the
upper 40s and lower 50s. The temperatures could be even cooler if
winds drop off faster than expected and thermal mixing is reduced.
As cold air advection persists on Thursday highs will be near
average in the low to mid 60s and lows will be near to slightly
below average in the upper 30s and lower 40s as winds decrease
and clear skies allow for strong radiational cooling.
&&
.LONG TERM...
(Friday through Monday)
Issued at 430 AM CST Tue Dec 17 2024
Cool and dry is the theme for the upcoming weekend as a longwave
trough axis deepens across the eastern third of the CONUS. This
will keep the forecast area beneath a deep layer northwest flow
regime, and a reinforcing frontal boundary will slide through on
the back of this flow on Friday. This front will be moisture
starved, but a surge of even cooler air will follow the frontal
passage. Temperatures will once again climb to near average
readings in the lower 60s Friday afternoon, but the surge of
cooler air into the area Friday night as another 925mb thermal
trough axis slides through will help push temperatures into the
low to mid 30s over inland areas and the upper 30s south of the
lakes. As a surface high and a thermal trough pass through over
the weekend, below normal temperatures and clear skies can be
expected. Saturday into Saturday night will be the coldest period
of weather as the heart of the 925mb thermal trough axis moves
through the region, and this will push temperatures down about 10
degrees below average. Some slight modification in temperatures is
expected on Sunday and Monday with readings rising back to normal
levels by Monday. Overall, have opted to lean cooler, NBM 50th
and 75th percentiles, than the deterministic NBM output this
weekend as the NBM has shown a recent warm bias for these colder
temperature events.
&&
.AVIATION...
(18Z TAFS)
Issued at 1149 AM CST Tue Dec 17 2024
All terminals were VFR at forecast issuance time. There could
briefly be a few MVFR ceilings this afternoon, but generally
should remain VFR. Larger issue will be the potential for fog
overnight tonight. This appears to be a more clear cut radiation
fog scenario, and expect that most or all terminals will fall to
IFR or lower beyond 06z Wednesday, with conditions below field
minima possible, if not likely. Improvement will occur around
mid-morning Wednesday as frontal boundary begins to move into the
area.
&&
.MARINE...
Issued at 430 AM CST Tue Dec 17 2024
The primary concern early this morning and once again from late
this evening through tomorrow morning is development of widespread
dense fog across the sounds, lakes, and nearshore Gulf waters.
Light onshore winds and very warm air will pass over the cooler
waters to produce this fog. A cold front will then move through
the waters Wednesday afternoon and evening, and stronger northerly
winds of up to 20 knots will develop behind the front Wednesday
night. These winds will briefly decrease Thursday as high pressure
builds in, but a reinforcing front on Friday will push winds back
to near 20 knots for Friday night. Winds and seas will once again
decrease for the upcoming weekend as a surface high pressure
system becomes centered over the region.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 75 55 72 45 / 10 10 40 30
BTR 80 59 77 49 / 0 0 20 20
ASD 77 56 75 51 / 0 0 10 10
MSY 75 58 74 54 / 0 0 10 10
GPT 72 57 74 52 / 0 0 10 10
PQL 79 57 78 51 / 0 0 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
SHORT TERM...PG
LONG TERM....PG
AVIATION...RW
MARINE...PG
Source:
LIX issues Area Forecast Discussion (AFD) at Dec 17, 11:58 AM CST ...New AVIATION...---------------
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