LIX issues Area Forecast Discussion (AFD) at Jan 30, 11:46 AM CST ...NEW AVIATION...093
FXUS64 KLIX 301746 AAB
AFDLIX
Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
1146 AM CST Thu Jan 30 2025
...NEW AVIATION...
.SHORT TERM...
(Today through Friday)
Issued at 421 AM CST Thu Jan 30 2025
Just about all of the impacts are in the next 36 hours. Fog and
marine fog along with small craft advisories this morning and today
then possible severe weather tonight. There may also be some fog to
contend with just ahead of the convection overnight. After that the
forecast is fairly quiet for much of next week. Right now we are
dealing with low clouds and fog finally starting to develop east of
the Pearl River and especially along the MS coast.
Today main issue is the fog which may be a little slow to completely
clear out but we should see most if not all fog gone by late
morning. the longest holdout could be coastal MS as marine fog may
try to keep moving in for a while. After that it turns into the
waiting game as storms should begin to impact the northwestern zones
of the CWA late this evening. Prior to that increasing
southerly/southeasterly flow will continue to pump in the moisture
leading to a humid and rather warm day, especially west of I-55.
H925 temps of 15/16C translates to mid to upper 70s and with BTR
hitting 78 yesterday it should have no problem reaching that today
and may hit 80. east of I-55 lower to mid 70s and even upper 60s
near the coast. Main reason for that is the New Orleans metro and
coastal MS will have the wind coming directly off the colder waters
and that will keep these areas from warming as much.
As for tonight and into tomorrow. Not much has changed from what we
have been advertising. Still looks like a line of storms along a
prefrontal trough will move in just before midnight tonight and work
east through the area through the morning. The deep cutoff low over
the 4 Corners is already beginning to lift to the east-northeast and
with the mid lvl jet having already rounded the base and beginning
to move downstream expect it to continue to work east-northeast. By
12z Friday the low should be close to opening up just west of the OH
Valley and start merging with the northern stream L/W trough. This keeps
southwest flow over the area through at least Friday afternoon.
At the surface we are already seeing broad low pressure over central
and eastern TX. The sfc low will begin to quickly eject to the north-
northeast over the Ouachita and Ozarks and into the Mid MS Valley by
this evening. The sfc low will also deepen with a prefrontal trough
taking shape over east TX and moving into western LA late this
afternoon. Convection should begin to initiate along the boundary
and both convection and the boundary will work east through the
evening and overnight hours.
So as has been the question, will we see any severe weather. Again
it is not out of the question but the risk is not widespread nor
very high. First negative aspect which has been mentioned multiple
times this week is the lift. With the track of the h5 low the bulk
of the lift and forcing will be well off to our northwest and well
behind the prefrontal trough. The h5 jet core will still be back
over eastern TX through much of AR and into southern MO while the
prefrontal trough is almost to I-55 from western TN through MS and
into SELA. We can also see that the lift lags behind the inverted
trough as hghts don't fall until after it passes. What about the LL
jet? With the impressive dynamics we will see a potent LL jet
develop but the core also move from northeast TX through AR and
across the northern MS and into northern AL. This actually has the
tail end of the LL jet moving across southwest MS this evening.The
best LL convergence is generally east of the LL jet and at the nose
of it. So with that there is a very small window and really only
across southwest MS late this evening. As the prefrontal trough
moves in the jet is quickly lifting to the northeast we really begin
to lose a lot of the LL convergence. A lot we will see a jet take
shape from east TX through the Mid MS Valley and into the Great
Lakes. Initially this evening there will be some diffluence aloft
but after midnight we begin to see that shift east of the area.
The other big issue is timing and associated lack of instability.
The prefrontal trough will be moving through our area during the
overnight and early morning hours which is generally when
instability is at its lowest. The marine areas it is opposite but
with no strong forcing associated with the prefrontal trough across
our marine zones, coastal convection will be very hard to come by.
The other aspect mentioned this week is that prefrontal troughs are
generally a better focus during the day when there is more
instability to work with since these don't typically provide a lot
of forcing on their own like a strong cold front does.
Now if we can get a few potent storms they may have the ability to
tap into the rather strong shear we will have in place. The one
thing that the prefrontal trough provides is rather good directional
shear from the sfc to h85. 0-1 and 0-3 km SRH are 200-300 and 250-
350 m2/s2 respectively. This is more than enough to get storms
spinning if they can get deep enough and that may be a rather
difficult chore. 0-6km bulk shear is around 40 kts typically is good
enough but it is well ahead of the line convection and weakens as
the the line approaches. Also there will probably be a decent stable
marine layer for coastal counties and parishes and this even
includes the coastal area north of the tidal lakes. The air coming
off these cold bodies of water will make the boundary layer stable.
It may not be until southwest MS where the boundary layer is a
little more favorable to allow strong winds or even a tornado to
reach the surface.
With all that said the risk of severe weather is not high but there
is the potential and it is rather limited in area and time. The most
likely area will be across southwest MS and possible just across the
border into Pointe Coupee and the Felicianas. This should be between
3z and 9z as a narrow band of showers and thunderstorms moves in
from the west. SPC is still highlighting a Slight Risk in that area
with a Marginal basically to the Pearl River and then south-
southwest to Galliano.
The line of storms will continue to work east through the morning
but there is a good chance it will be a very thin line and may only
produce a little rain for areas south of I-10/12 in SELA. This
activity should continue to work east and should be out of the area
by early afternoon.
As mentioned in the first paragraph we may be dealing with fog ahead
of the line over coastal Ms and just into coastal SELA as the very
humid warm air will be moving over much colder shelf water and thus
marine fog will be possible again until the line moves through. /CAB/
&&
.LONG TERM...
(Friday night through Wednesday)
Issued at 421 AM CST Thu Jan 30 2025
The extended portion of the forecast continues to look rather
benign. We remain dry through the weekend and depending on how
things play out we could remain dry through most of next week. The
one hiccup is the left over energy from tonight's system. There are
still indications we could see a weak disturbance over the western
Gulf early next week with ridging ahead of it. This could allow
enough of a weakness to get some showers to develop in the afternoon
but we could also remain in general zonal flow and any influence
from that disturbance would likely remain south of the area. /CAB/
&&
.AVIATION...
(18Z TAFS)
Issued at 1134 AM CST Thu Jan 30 2025
VFR conditions for most will decline later this evening as a line
of convection moves west to east through the region. With th
heavier rainfall expect reduced IFR CIGs/VIS. Otherwise, VIS will
become an issues along the MS Gulf Coast where fog and develop
over the waters and drift inland over GPT. Dry air will filter in
quickly behind the front on Friday, which will lead to better
conditions...VFR from west to east especially after 12z Friday.
(Frye)
&&
.MARINE...
Issued at 421 AM CST Thu Jan 30 2025
High pressure continues to slide east while a broad area of low
pressure is beginning to take shape over central TX. This is slowly
increasing the southerly winds over the waters. The surface low will
slowly deepen today and lift to the northeast moving across the
Ouchita and Ozarks this evening and then into the Ohio Valley midday
Friday. This will lead to winds increasing today and tonight with
headlines already issued. The other immediate issue is dense marine
fog this morning and possibly for a short time frame overnight
tonight ahead of a line of storms. The cold front will finally move
into the coastal waters late Friday. /CAB/
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 58 71 44 68 / 90 30 0 0
BTR 62 74 47 71 / 90 20 0 0
ASD 62 73 47 69 / 60 30 0 0
MSY 62 72 49 67 / 60 20 0 0
GPT 60 70 47 67 / 40 50 0 0
PQL 62 74 47 72 / 20 60 0 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Dense Fog Advisory until noon CST today for GMZ530-532-534-536-
538-550-552-555-557.
Small Craft Advisory until 6 PM CST this evening for GMZ570-572-
575-577.
MS...None.
GM...Dense Fog Advisory until noon CST today for GMZ532-534-536-538-
550-552-555-557.
Small Craft Advisory until 6 PM CST this evening for GMZ572-575-
577.
&&
$$
SHORT TERM...CAB
LONG TERM....CAB
AVIATION...RDF
MARINE...CAB
Source:
LIX issues Area Forecast Discussion (AFD) at Jan 30, 11:46 AM CST ...NEW AVIATION...---------------
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