LIX issues Area Forecast Discussion (AFD) at Dec 16, 2:37 PM CST ...New SHORT TERM, LONG TERM, MARINE...740
FXUS64 KLIX 162037
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
237 PM CST Mon Dec 16 2024
...New SHORT TERM, LONG TERM, MARINE...
.SHORT TERM...
(This evening through Tuesday night)
Issued at 230 PM CST Mon Dec 16 2024
Upper ridging currently along the East Coast and over the
Intermountain West. Troughing extended from the western Great
Lakes to near El Paso. At the surface, it was pretty much a repeat
of the upper pattern with high pressure along the East Coast. Low
pressure over western Ontario had a frontal boundary southward
into Missouri, then southwest to west Texas. Under mostly cloudy
skies at mid afternoon, temperatures were in the 70s with dew
points in the mid and upper 60s.
While some brief very light rain showers can't be entirely ruled
out, most places will likely remain dry. The main concerns over
the next 36 hours will be the potential for advective fog
development. Low clouds appear to be a bit more likely overnight
tonight with GFS and HRRR forecast soundings indicating a moist
layer between 850 and 925 mb potentially producing a low cloud
layer, with somewhat higher fog potential tomorrow night as that
moist layer will be gone. Coordinated with neighboring offices
that a pre-emptive Dense Fog Advisory isn't currently planned for
overnight tonight, but can't rule out an eventual issuance by the
evening or midnight shifts.
Would note that current dew points are running several degrees
above guidance, and if those trends continue, with low clouds
holding in, guidance lows are too cool. Have bumped up NBM
deterministic lows for tonight several degrees. Highs for tomorrow
should be pretty close to today's. With fewer clouds for much of
tomorrow night, did not adjust those lows at this time.
&&
.LONG TERM...
(Wednesday through Sunday night)
Issued at 230 PM CST Mon Dec 16 2024
Strong northern stream shortwave moves across the Lower
Mississippi River Valley Wednesday afternoon and evening. This
system doesn't have much in the way of moisture coming along with
it, and would be surprised if there's much more than a few showers
associated with it, and that would primarily be north of the
Interstate 10-12 corridors. Forecast surface wind fields and
forecast soundings would indicate that any significant cold air
advection will not arrive until around sunset Wednesday, or a
little later. This should allow the area to get back into the 70s
on Wednesday for highs.
Once the front clears the area Wednesday night, that ends any
significant precipitation threat for the remainder of the forecast
period. Highs Thursday and Friday will be a good 10-15 degrees
cooler than the first half of the week. A second shortwave early
Friday will reinforce the colder air, so highs Saturday and Sunday
will struggle to get much past 60 degrees. Overnight lows in the
30s and lower 40s are expected Saturday and Sunday mornings, but
widespread freezing temperatures are not expected. Temperatures
are expected to warm back up to above normal levels early next
week heading toward the Christmas holiday.
&&
.AVIATION...
(18Z TAFS)
Issued at 1129 AM CST Mon Dec 16 2024
All terminals have improved to at least MVFR ceilings, with KGPT
and KNEW at VFR. Expect somewhat variable conditions this
afternoon, bouncing between VFR and MVFR. Cannot rule out a few
SHRA this afternoon, but any impacts wouldn't be more than a few
minutes.
Main forecast issue continues to be the potential for advective
fog development overnight. Definitely comfortable with ceilings
falling to IFR or lower beyond about 10z Tuesday, but similar to
this morning, some forecast soundings indicate the potential for a
cloud deck near FL020 that could choke off heat transfer. Will
include TEMPO conditions near field minima at most terminals, and
prevailing for the rest. Should see improvement to at least MVFR
by 15-16z Tuesday.
&&
.MARINE...
Issued at 230 PM CST Mon Dec 16 2024
In the near term, will need to monitor the fog threat in the
nearshore waters, but not confident there's enough of a
temperature difference between the air temperature and water
temperature to promote widespread advective fog. The frontal
passage late Wednesday will likely increase winds to 15-20 knots
with Small Craft Exercise Caution headlines likely to be
necessary. The better chance of Small Craft Advisory conditions is
likely to be with the reinforcing front Friday/Friday night.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 63 74 55 71 / 20 10 0 30
BTR 66 78 58 75 / 10 10 0 20
ASD 61 75 55 75 / 0 0 0 10
MSY 63 74 58 73 / 0 0 0 10
GPT 59 72 55 73 / 0 0 0 10
PQL 56 78 55 78 / 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
Source:
LIX issues Area Forecast Discussion (AFD) at Dec 16, 2:37 PM CST ...New SHORT TERM, LONG TERM, MARINE...---------------
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