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000
FXUS64 KLIX 051400
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
900 AM CDT Mon Jun 5 2023

...New UPDATE...

.UPDATE...
Issued at 838 AM CDT Mon Jun 5 2023

Starting out early this morning glancing at various GOES-16 bands,
most notable feature is a patch of remnant mid-level clouds
around most central portions of the CWA, with a secondary thin
layer of upper-level clouds lingering from overnight convection.
This may be a bit of an important player going into today, which
we will discuss shortly.

HREF sim reflectivity members pinpoint yet again another afternoon
hit-or-miss convective coverage. Went ahead and introduced pure
1hr NBM pop coverage aiming around 50-70% PoPs areawide timed
relatively well to HREF trends. It`ll be yet another day where by
the time we reach convective T (which is generally around the
lower 90`s), storms will pop. The item to watch however will be if
we are delayed reaching this by the current cloud cover slowing
the diurnal curve into the afternoon - meaning, storms may be a
bit late to develop unless these clouds can break up over time. It
should be noted, where there are no clouds (Atchafalaya basin,
coastal LA and seeing coastal MS breaking up as I type this),
these areas will have no problem reaching Tc and seeing storms pop
up in the 17-19Z hour. But if clouds linger more into the late
afternoon across central areas, this could delay it more into the
20-22Z hour. It will be something to monitor.

Otherwise, for areas that warm up quick enough, we`ll see yet
another day of a strongly, well-mixed PBL and steep dry-adiabatic
thermal layer extending from the super-adiabatic surface layer to
H7. Not alot of winds aloft with mean storm motion slowly to the
west today, meaning propagation/motion will be moreso forced by
local boundary interactions. Still seeing the same -10 to -11C
pool aloft in the H5 layer to support hail in any stronger storms,
with the potential of isolated severe hail as we saw yesterday.
The 12Z KLIX RAOB measured -11.1C (right above the mid-level
clouds) which is more than enough support for hail today. DCAPE
was noticeably high yesterday thanks to a patch of drier mid-
level air creeping in from the east - not seeing as definite of
this intrusion today yielding not as high DCAPE values and given
weak winds aloft, regardless of strong downward mixing potential,
damaging winds/wet microbursts may be tough to come by. Still
can`t rule out sub-severe winds in any stronger storm 30-45mph or
so, but widespread damaging winds might be a bit harder to come
by. Additionally due to slow storm motions, can`t rule out flash
flooding especially where updrafts become rooted to boundary
interactions becoming briefly stationary.

Will not be surprised if convection lingers beyond the 5-6PM time
frame even into early overnight hours - especially due to the
delay of surface warming with any remnant boundaries re-igniting
more isolated convection similar to what we`ve seen the past 2
days. Hard to determine where, and just depends on where
boundaries set up so don`t be shocked to see an isolated strong,
possibly severe storm lasting into the overnight hours within the
area. But eventually, this activity will dissipate with only a
lingering mid/upper-level anvil canopy in areas that saw most
convection, but we`ll become more quiet past midnight with the
typical switchover to marine convection going into daybreak
Tuesday. KLG

&&

.SHORT TERM...
(Today through Wednesday Night)
 Issued at 251 AM CDT Mon Jun 5 2023

A very persistent pattern of convective development is expected to
continue through Wednesday as the region remains entrenched
beneath a very weak and very broad upper level low centered over
Texas and Gulf South. The main impact from this weak upper level
feature has been a lowering of freezing levels and wet bulb zero
heights to around 12k feet and 10.5k feet respectively as a
slightly cooler airmass lingers in the upper levels. This slight
cooling aloft has also allowed for steeper mid-level lapse rates
of around 6.5C/km and an increase in CAPE to around 2000J/KG each
afternoon. Given that no significant change in the overall upper
level pattern is anticipated through the Wednesday, the lower
freezing levels and increased instability will remain in place
through the short term period.

The instability will interact with mesoscale boundaries like the
seabreeze or any pre-existing outflow boundaries to induce
convective activity each day. Convection will peak in the late
afternoon and early evening hours when overall instability is
maximized with peak daytime heating rising into the lower 90s. A
few of the storms will develop deeper and more sustained updrafts,
and these storms could turn to strong to severe given the
favorable conditions aloft. The primary concern from these strong
to severe storms would be hail and strong damaging wind gusts. The
convection should begin to wane in the late evening hours, and
largely dry conditions are expected during the overnight hours
except for areas in the offshore waters where the diurnal cycle
actually maximizes in the early morning hours. Despite the warm
daytime highs, somewhat lower dewpoints in the mid 60s and
clearing skies will allow overnight lows to dip into the upper
60s and lower 70s each night.

Spring tide conditions also continue to impact areas around Bay
St. Louis and Waveland with minor tidal flooding of low lying
roads possible both this afternoon and Tuesday afternoon. Given
this, a coastal flood advisory has been extended for coastal
Hancock County through Tuesday afternoon.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 251 AM CDT Mon Jun 5 2023

There will be an upper level pattern change starting Thursday that
will linger through Friday. This change will be entirely driven
by a deepening of a strong upper level trough across the eastern
third of the CONUS as a series of impressive upper level vorticity
maxima slide through the Great Lakes and Mid-Atlantic states.
Across the forecast area, the development of a stronger northwest
flow regime will lead to a drier airmass taking hold in the mid-
levels and a continued risk of strong downburst wind events as
deeper updrafts entrain this drier air into the storm. This is
supported by DCAPE values of around 800 J/KG each afternoon.
However, the drying and warming of the airmass aloft will also
limit the hail threat as wet bulb zero heights increase to 12.5k
feet. Initially, the focus for convection will continue along
mesoscale boundaries on Thursday, and as is typical with
northwest flow patterns, the convection will develop in the late
afternoon and evening hours once the convective temperature in the
lower to middle 90s is achieved. However, on Friday, a decent
backdoor cold front is expected to move through the area, and this
front will be the primary focusing mechanism for any convection
that develops Friday afternoon.

By the weekend, the northwest flow pattern will weaken and overall
flow will turn more zonal across the region. Additionally, a much
drier airmass will be advecting into the area in the wake of the
now weakening backdoor cold front. This is noted by lower than
average precipitable water values of 1.3 to 1.4 inches Saturday
afternoon. Given the drier airmass and warming of the mid-levels,
overall instability will be reduced on Saturday. Overall
convective potential will be largely inhibited, and only have 20
percent PoP in place to reflect the risk of an isolated storm
forming along the seabreeze in the afternoon hours. Otherwise, a
mostly sunny and hot Saturday is expected as highs climb into the
low to mid 90s. Sunday will see increased convective coverage as
moisture advection into the mid-levels pushes precipitable water
values back to climatology of 1.6 to 1.8 inches. This increase in
moisture will allow CAPE to rise back into the 1500 to 2000 J/KG
range, and overall a more typical Summer pattern is expected on
Sunday with storms firing up in the afternoon and lingering
through the early evening hours before dissipating. Temperatures
will remain warm in the lower to middle 90s. Fortunately, recovery
will occur each night as temperatures cool to near 70.

.AVIATION...
(06Z TAFS)
Issued at 251 AM CDT Mon Jun 5 2023

The primary concern will be the risk of convection developing near
or over a terminal primarily between 20z and 03z. As has been the
case the past few days, the highest probabilities of convection
impacting a terminal will be at HUM, BTR, and MCB during the
aforementioned time period. This is largely due to higher
preponderance of outflow boundary interactions taking hold in
these regions. Closer to the coast, a strong seabreeze boundary
will greatly limit convective activity through the afternoon
hours. If a storm impacts a terminal, a brief period of gusty
winds, reduced visibilities, and lightning can be expected.
Outside of the convective threat, prevailing VFR conditions are
forecast at all of the terminals.

&&

.AVIATION...
(06Z TAFS)
Issued at 251 AM CDT Mon Jun 5 2023

The primary concern will be the risk of convection developing near
or over a terminal primarily between 20z and 03z. As has been the
case the past few days, the highest probabilities of convection
impacting a terminal will be at HUM, BTR, and MCB during the
aforementioned time period. This is largely due to higher
preponderance of outflow boundary interactions taking hold in
these regions. Closer to the coast, a strong seabreeze boundary
will greatly limit convective activity through the afternoon
hours. If a storm impacts a terminal, a brief period of gusty
winds, reduced visibilities, and lightning can be expected.
Outside of the convective threat, prevailing VFR conditions are
forecast at all of the terminals.

&&

.MARINE...
Issued at 251 AM CDT Mon Jun 5 2023

A persistent east-southeast flow of around 10 knots and seas of 1
to 3 feet will be the rule over the waters through Tuesday as high
pressure resides over the Deep South states. However, winds will
turn more westerly at around 10 knots on Wednesday and remain so
through the end of the week as the high to the north weakens and
another area of high pressure strengthens over the central Gulf of
Mexico. Despite the wind shift, largely benign conditions are
expected in terms of marine operations. The biggest concern will
be the typical development of thunderstorms during the early
morning hours and again in the late afternoon early evening hours.
These storms could produce waterspouts, strong wind gusts, heavy
rainfall, and frequent lightning strikes as they pass through.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  91  64  90  66 /  80  30  50  30
BTR  93  69  91  70 /  70  30  50  30
ASD  89  68  88  70 /  60  20  40  30
MSY  90  72  87  73 /  70  20  50  30
GPT  87  69  86  72 /  50  20  40  20
PQL  89  66  88  70 /  40  10  30  20

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...Coastal Flood Advisory until 7 PM CDT Tuesday for MSZ086.

GM...None.
&&

$$

UPDATE...KLG
SHORT TERM...PG
LONG TERM....PG
AVIATION...PG
MARINE...PG