LIX issues Area Forecast Discussion (AFD) at Mar 3, 11:43 PM CST ...New AVIATION...428
FXUS64 KLIX 040543
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
1143 PM CST Mon Mar 3 2025
...New AVIATION...
.UPDATE...
Issued at 913 PM CST Mon Mar 3 2025
Current forecast is well within expectations, with all elements
tracking well. Will refresh the warning and advisory statements,
as well as the usual evening CWF update, but there will be no
changes made.
&&
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 616 PM CST Mon Mar 3 2025
It was a very pleasant day across the region today with generally
mostly sunny skies across SELA south of I-10 and partly to mostly
cloudy across the rest of the area. Highs climbed into the 60s
everywhere and even a few low 70s. That said it still looks like
tomorrow we will see significant impacts as the area begins to
recover tonight. This is not going to play nice with Mardi Gras
day and severely hamper the areas parades and celebrations.
Very deep and intense mid lvl disturbance is already beginning to
move over the southern rockies with Lee side cyclogenesis already
underway. The warm front is already set up to our west and was
stretching from near Grand Isle northwest to Toledo Bend and north-
northwest to north of Dallas and into southeastern CO.
Main Points for Tomorrow in order of impacts:
Severe weather expected across the entire area
- Enhanced Risk (level 3 of 5) along and north of I-12 in SELA and
across coastal MS. Slight Risk (2 of 5) for the rest of the area
- All modes of severe weather possible
-- Damaging winds (greatest risk)
-- Tornadoes; a few could be strong (EF2 or greater) and long track
- Main time frame is noon to 10pm
-- noon to 6pm west of a line from Liberty, MS to Thibodaux, LA...
this includes the Baton Rouge metro
-- 2pm to 8pm from previous line east to a from Bogalusa, LA to
Grand Isle, LA...this includes most of the north and south
shores, McComb, and Houma
-- 4pm to 10pm east of that line to the MS/AL border...this
includes the rest of the New Orleans metro and all of coastal MS
Very High Winds
- High Wind Warning issued for the entire area
- Winds quickly ramp up after sunrise. Strongest sustained winds and
gusts expected from noon till 6/7pm
- Frequent wind gusts of 40 to 45 mph with peak wind gusts greater
than 50 mph. This is not associated with storms
Coastal Flood Advisory - entire coast expect the Southshore
- 1 to 1.5 feet of inundation in the typical problem areas
- Peak during high tide tomorrow afternoon
So what is culprit; that intense mid lvl low dropping across the
southern Rockies. This deep system and trough will continue to work
east overnight and into the southern and central Plains before
sunrise tomorrow. With the bulk of the H5 jet still in the base of
the trough and moving across the Mexico/US border along with the
ridging out ahead of it over the eastern CONUS it will not lift to
the northeast. This system will continue to work east towards the
Ozarks with the base of the trough swinging east through the
southern Plains, TX and into the Lower MS Valley by 00z Wednesday.
The trough axis finally moves through the area overnight tomorrow
night. H5 hghts fall about 12-13 dm or even more by late tomorrow
evening from midday. Due to the intense dynamics of this system the
sfc low which is only just now starting to quickly take shape over
southeast CO will quickly deepen overnight and through tomorrow
moving into the Mid MS Valley by tomorrow evening.
The sfc low could already be in the low 980s as it moves out of
eastern KS and into MO late tomorrow afternoon and early evening.
Combine that with a large area of high pressure over the western
Atlantic and through the eastern Gulf and the pressure gradient will
already be rather tight but what could be making things even more
impressive from a wind standpoint is that the mid lvl jet mentioned
earlier moving into the Lower Ms Valley and what appears to be a
subtle lead impulse. This looks like it is aiding in a prefrontal
trough developing with a few mesoscale waves along it locally
enhancing the pressure gradient With both CAMs and Global models
indicating a pressure gradient of 8-9mb across the CWA tomorrow.
This is a very impressive gradient for our area and that alone would
lead to a very day. However, that is not all we will see as LL winds
respond with a very intense LL jet developing across the Lower MS
valley and even well back into southern LA. H85 winds could approach
70kts across southwest MS and the adjacent FL parishes.
How about instability which right now is probably one of the main
things that could hold this back from being an even more severe
system. With the rapidly increasing LL wind field out of the south
it could allow the area to recover quickly. Dewpoints are still in
the upper 40s to lower 50s across the area and the warm front is
just now starting to slide north but it will be slow tonight. Winds
will increase overnight but the bulk of the increase will occur
after sunrise tomorrow and the question will be if those mid and
upper 60s dewpoints in the northwestern Gulf can penetrate far
enough north across the area by tomorrow afternoon. In addition how
much cloud cover we have will help determine how unstable we become.
scattered to few clouds and a lot of sun will not bode well for
multiple reasons. First it will just make things more unstable for
severe storms tomorrow afternoon and evening and second it will make
it even easier for those very strong LL winds to mix down to the
ground.
A strengthening subtropical jet streak will move out of northern
Mexico and across southern TX but as it tries to move into the Lower
MS Valley it will try to split with part of it trying to take a hard
turn to the left while the rest tries to continue to push due east
across the northern Gulf and the coast. This will lead to a
diffluent pattern over the area tomorrow afternoon and early
evening. Everything continue to quickly push off to the east and
northeast and one good thing is that this will be a quick hitting
system.
As you can see this is a very dynamic system and the potential is
there for a rather rough day across the region. It is already
causing havoc on Mardi Gras as many areas have either made
significant adjustments to parades and events or outright cancelled
them. At this time it appears we should be rain free during the
first half of the day as we continue to recover but winds will
quickly ramp up. We could see widespread wind gusts or 30-35 mph by
9am and these will only increase through the morning and into the
afternoon hours. By noon widespread wind gusts of 40 mph will likely
be occuring with numerous wind gusts of 40-45 mph through the
afternoon. From about 16z to 00/01z winds will not be completely
unidirectional from the sfc to h85 but will be very close. This aids
in downward momentum transport and with h85 winds easily in the 50-
60kt range these could easily translate to wind gusts of 50-60 mph.
Some of the values from the Extreme Forecast Index is indicating
that this is a very rare event. The last time we had values like
this was the last time we had a High Wind Warning and thus increases
the confidence that we will at the least be right on the edge of
High Wind Warning criteria but given the amount of societal impacts
due to tomorrow being Mardi Gras felt it was a better decision to
not play around with near criteria numbers and get the seriousness
of the situation out. As for the severe aspect we could see severe
storms impact most of the area but feel the highest risk is exactly
in the Enhanced Risk area being shown by SPC. This area will have a
lot coming together that many times is just missing one or two
things. First the LL jet even though we are close to the tail end of
the core it doesn't lift out and actually slides east through the
area tomorrow afternoon and early evening. This places us on the
east side which will at least provide some LL convergence. As
mentioned in the paragraph directly preceding this, the upper jet
by splitting right over the Lower MS Valley, we actually move under
an area of enhanced upper lvl diffluence. This is directly over the
same areas with the strong LL convergence. Also mentioned earlier is
the mid lvl hght falls through the afternoon and this will be
accompanied by mid lvl winds mid lvl winds increasing from near 50kt
in the morning to possibly 100kt by 00z. That is very strong forcing
again occurring around the same times. What is not going to be
missing either. 0-6km bulk shear is expected to be around 60-75kts
out of the W or WSW. Helicity is ridiculous but honestly is being
highly driven off of the speed shear. That said winds do veer with
hght some from. 0-3km SRH could range from 300-600 m2/s2 while 0-1km
SRH could range from 250-400 m2/s2. The main problem is going to be
the LL with respect to instability. There is a chance that storms
could struggle initially to become sfc based but there appears to be
a window that everything could come together between 18z and 03z
that could allow for a few Supercells to develop. These would
absolutely be capable of producing tornadoes and with this amount of
forcing and shear that is why a few strong tornadoes is not out of
the question. Even though the entire area has a risk of severe
weather the main reason the northern half could have a greater risk
of tornadoes is because the marine layer could keep things across
the southern half of the area just stable enough in the boundary
layer thus keeping things just off the deck. The northern half of
the area could be far enough away from the influence of the marine
layer and if there is enough breaks in the clouds the could have a
better boundary layer environment.
At this time we expect to see scattered thunderstorms develop around
midday/early afternoon just west of the Baton Rouge metro and as
these storms move east could become quite strong as everything comes
together. Scattered to numerous wind damage reports are likely and
it a few tornadoes are expected. Yes the greatest risk for tornadoes
is along and north of I-12 and across coastal MS but the threat for
tornadoes will be real across the entire CWA. Even away from storms
the gradient wind will likely lead to some tree damage and scattered
power outages.
Everything should push east of the area quickly and could be through
coastal MS by 3z. If storms develop quickly and consolidate into a
a solid line then the line will speed up and move through the area
even faster likely out of the area a few hours earlier but nothing
is indicating the line doing that and it remains broken with
individual cells. /CAB/
&&
.LONG TERM...
(Thursday night through Monday night)
Issued at 616 PM CST Mon Mar 3 2025
Moving into Wednesday, in the wake of the cold front high
pressure will start to build to our west and temperatures will be
slightly lower than normal Wednesday night with lows in the mid
30s north of I-12, low to mid 40s for the south shore and coastal
areas. Conditions will be benign other than that through the
weekend.
Another cold front will sweep through the area Saturday with showers
and embedded thunderstorms forecast Saturday morning into the
afternoon hours. Confidence is not very high right now but there
could be some marginally severe. CAPE values look to be generally
less than 1000 J/kg and SRH around 50-250 m2/s2. PW values are
roughly 1 to 1.5 in near/offshore and around 0.8 in away from the
coast. The higher numbers (>1in) would be in the 75th percentile for
the day. Overall, it would be enough to support some storms which
could be strong but low level lapse rates currently fairly poor. But
it's still a few days out so will need to monitor as we get a little
closer. -BL
&&
.AVIATION...
(06Z TAFS)
Issued at 1127 PM CST Mon Mar 3 2025
Quite a bit of cirrus moving across the area at forecast issuance
time. There have been several observations of SCT-BKN025 over the
last hour or so. Brief periods of BKN025 are expected overnight,
but any widespread MVFR ceilings probably won't occur until after
sunrise, and even then, it may just be for a few hours prior to
convection getting going. At least during the morning hours, the
main concern will be the increase in wind speeds on southeast to
south winds. Sustained winds in excess of 20 knots could get going
as early as 15z, with many, if not all, terminals reporting
sustained 25KT gusting 40KT by 18z. Tried to limit the TEMPO TSRA
groups to 2-3 hours Tuesday afternoon, with timing of those
groups somewhat along the lines of the most recent GFS and HRRR
solutions. Based on low level wind fields, carrying VRB35G50KT
with most of the TEMPO groups. Considering there are forecast to
be 50KT winds near or below FL030 for the afternoon and early
evening hours, it's not going to take much downward transport with
thunderstorms to realize that at the surface.
LLWS will also be mentioned during the late afternoon and evening
at most terminals. Ceiling and visibility conditions will improve
on Wednesday, but winds will continue to pose some crosswind
issues depending on runway configurations.
&&
.MARINE...
Issued at 616 PM CST Mon Mar 3 2025
The frontal boundary is now slowly moving north as a warm front and
winds will become SE and rise to 20-25kt ahead of the next stronger
cold front expected to move through late Tue with strong southerly
gales ahead of it and W to NW winds of 20-30kt behind it. Winds will
rapidly ease Thu as a sfc high moves over the northern gulf. But
this will be quick and the sfc high will be east of the area late
Thu bringing return flow back to the coastal waters. Wind speeds
will quickly move back up to around 20kt by Thu night into Fri.
CAB/TE
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 53 75 48 64 / 0 100 20 0
BTR 58 80 51 67 / 0 90 10 0
ASD 57 77 54 68 / 0 80 60 0
MSY 60 78 55 68 / 0 90 40 0
GPT 57 73 54 67 / 0 60 90 0
PQL 54 77 56 70 / 0 40 100 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...High Wind Warning from 9 AM to 9 PM CST Tuesday for LAZ034>037-
039-046>048-056>060-064>071-076>090.
Coastal Flood Advisory from 6 AM to 9 PM CST Tuesday for
LAZ066>070-076-078-080-082.
GM...Small Craft Advisory until 6 AM CST Tuesday for GMZ530-532-534-
536-538-550-552-555-557-570-572-575-577.
Gale Warning from 6 AM to 9 PM CST Tuesday for GMZ530-532-534-
536-538-550-552-555-557-570-572-575-577.
MS...High Wind Warning from 9 AM to 9 PM CST Tuesday for MSZ068>071-
077-083>088.
Coastal Flood Advisory from 6 AM to 9 PM CST Tuesday for
MSZ086>088.
GM...Small Craft Advisory until 6 AM CST Tuesday for GMZ532-534-536-
538-550-552-555-557-570-572-575-577.
Gale Warning from 6 AM to 9 PM CST Tuesday for GMZ532-534-536-
538-550-552-555-557-570-572-575-577.
&&
$$
SHORT TERM...CAB
LONG TERM....BL
AVIATION/UPDATE...RW
MARINE...CAB
Source:
LIX issues Area Forecast Discussion (AFD) at Mar 3, 11:43 PM CST ...New AVIATION...---------------
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